c958 5_final bar_010914
TRANSCRIPT
DEA&DP ref: 16/3/1/1/E4/5/2031/14
FINAL COMBINED BASIC ASSESSMENT REPORT
PROPOSED FLOOD DAMAGE REPAIR PROJECTS
IN THE WESTERN OVERBERG
CONTRACT C958.5
Prepared for:
Department of Environmental Affairs and Development Planning
On behalf of:
BERGSTAN South Africa (Pty) Ltd
for
The Western Cape Government:
Department of Transport and Public Works
JUNE 2014
Environmental assessment
Charl de Villiers
Environmental Consulting
Public participation:
Specialist aquatic assessment
Dr Liz Day
Freshwater Consulting
Aspects of this report may reflect material produced by Charl de Villiers Environmental Consulting on behalf of CCA
Environmental (Pty) Ltd in 2012-2013. In such instances, CCA Environmental (Pty) Ltd and, where relevant, Aurecon, are
acknowledged as the co-authors of such content.
OB1: Botrivier (Kanaan) OB2: Botrivier (Doringkloof)
OB3: Elandskloofrivier (Meerlustkloof)
OB4: Elandskloofrivier secondary flood
channel (Meerlustkloof)
OB5: Unnamed watercourse
(Tarentaalkraal)
OB6: Unnamed watercourse
(Nooitgedacht)
Fig 1: Flood repair sites, western Overberg – Contract C958.5
Proposed flood damage repair projects in the western Overberg (C958.5)
Draft Combined BAR i
Fig 2: Project locations
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR ii
DEA&DP ref: 16/3/1/1/E4/5/2031/14
Combined Basic Assessment Report in terms of the NEMA Environmental Impact Assessment Regulations, 2010
JULY 2014
DEPARTMENTAL REFERENCE NUMBER(S)
File reference number (EIA):
File reference number (Waste): N/A
File reference number (Other): N/A
PROJECT TITLE
Repairs and maintenance to flood-damaged bridges in the western Overberg (Contract No C958.5)
DETAILS OF THE ENVIRONMENTAL ASSESSMENT PRACTITIONER (EAP)
Environmental Assessment
Practitioner (EAP): Charl de Villiers Environmental Consulting
Contact person: Charl de Villiers
Postal address: 14 Bradwell Road
VREDEHOEK Postal
code: 8001
Telephone: (021) 461 2477 Cell: 083 785 0776
E-mail: [email protected] Fax: 086 553 9256
EAP Qualifications Charl de Villiers – B.A. Hons (Journ), M.Phil (Environmental Management), with
distinction
EAP
Registrations/Associations Certified EAP (ICB)
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR iii
DETAILS OF THE EAP’S EXPERTISE TO CARRY OUT BASIC ASSESSMENT PROCEDURES:
NAME Charl de Villiers
RESPONSIBILITY ON PROJECT EAP
DEGREE BA Hons (Journ) (Stellenbosch)
MPhil (Environmental Management), with distinction (Cape Town)
PROFESSIONAL REGISTRATION Certified EAP (ICB)
EXPERIENCE in years 12
EXPERIENCE
Charl de Villiers has worked as an environmental assessment
practitioner since 2002. He has managed environmental processes –
including combined applications – relating to flood repairs, river
maintenance and soil conservation works on behalf of private clients as
well as the Western Cape departments of agriculture and transport and
public works. He specialises in agro-ecosystem governance and
biodiversity mainstreaming and was contributing editor to the Fynbos
Forum Ecosystem Guidelines for Environmental Assessment in the
Western Cape (De Villiers et al., 2005), SANBI's Grassland Ecosystem
Guidelines and Fynbos: Ecology and Management (Esler et al. eds, In
Press). Charl was awarded the IAIA President's Bursary in 2008 and serves
as a part-time lecture on biodiversity and IEM at the universities of Cape
Town, Stellenbosch and the Western Cape. He became a Certified
Environmental Assessment Practitioner in December 2010.
Proposed flood damage repair projects in the western Overberg (C958.5)
iv
EXECUTIVE SUMMARY
1. Introduction
This application has been undertaken as a combined application in terms of Regulation 14 of the July 2010 NEMA EIA
regulations.
This Executive Summary incorporates the main findings of the Draft Basic Assessment Report (DBAR) prepared for
proposed repairs to flood-damaged bridges at six sites in the western Overberg (Theewaterkloof Municipality). Two of the
sites are located on District Road (DR) 1288, which follows the course of the Bot River between the Theewaterskloof Dam
and the N2 to the south. The remainder of the sites are on the DR1313 where it crosses northern tributaries of the
Riviersonderend, along the southern base of the Riviersonderend Mountains.
The projects are:
DR1288
OB1 This project entails the complete replacement of a damaged bridge (C10765) over the Bot River at the
farm Kanaan. The site is about 10 km north of the Bot River village. The new bridge would be repositioned
approximately 15 m upstream of the existing crossing, which requires realignment of the DR1288. The
bridge consist of a single span portal concrete structure with an opening of c. 12 m wide x 4.5 m high with
concrete invert slabs. The upstream and downstream banks will receive gabion mattress protection.
OB2 This project is located about 3 km north of OB1, on the DR1288, where the southern approaches to
structure C10768 are vulnerable to wash-aways. The site is at the confluence of the Bot River and a
seasonal tributary that flows in from the east, via the farm Doringkloof. New concrete slabs required on the
road approaches which will also be equipped with side slope protection.
DR1313
NOTE The repairs relating to the four damaged structures over the northern tributaries of the Riviersonderend (OB3 -OB6)
are particularly urgent, because these crossings on the DR1313 provide the only road access to the Helderstroom
Maximum Security Prison when the Riviersondernd is in flood and cuts off the prison from the DR1311 (the main road
linking the R43 (Caledon-Villiersdorp) with Greyton. This has potentially grave security and humanitarian consequences
and interferes with the effective functioning of the justice system.
OB3 This site is located on the DR1313 where it spans the Elandskloof River by means of a severely damaged
pipe culvert crossing adjacent to the farm 'Meerlustkloof'. A new two-lane causeway is required,
comprising six 3.0 m wide x 1.6 m high openings along a new alignment approximately 12 m downstream
of the existing crossing. Road slabs will be provided. The Western Cape Department of Agriculture is due to
construct groynes in the Elandskloof River, which are designed to control the severe destabilisation and
erosion that periodically contributes to damage of the bridge at this site.
OB4 This project entails constructing short concrete aprons upstream and downstream of a small pipe culvert
crossing about 140 m to the east of OB3. The main object of this work is to control the growth of reeds that
trap sediment and cause the pipes underneath the road to become blocked. Flood water is then forced
upwards on to the road surface where it causes damage. This small side channel of the Elandskloof River
also skirts the farm 'Meerlustkloof'.
OB5 This project entails repairing a box culvert at Tarentaalkraal, some 700 m east of OB4 on the DR1313. An
apron slab at the culvert outlet has become undermined and needs to be repaired and under-pinned. An
additional secondary outlet slab, plus a cut-off wall, will also be constructed downstream. Rock will be
dumped in the plunge pool to limit further scour.
OB6 This project at Nooitgedacht entails construction of an additional box culvert next to an existing one so
that larger flows can be passed through the structure, rather than over-topping the road and causing
wash-aways and erosion. The existing culvert will be extended on the on upstream side and there will be a
slight realignment of the existing road to improve road safety at the crossing. Embankment protection will
be provided upstream and downstream. Heavy stone rip-rap will be emplaced at the end of downstream
apron slab to prevent scouring.
Proposed flood damage repair projects in the western Overberg (C958.5)
v
2. Invitation to comment
The Draft BAR has been distributed for a 40-day review / comment period from xyz to xyz 2012 in order to provide
Interested and Affected Parties (I&APs) and authorities with an opportunity to comment on any aspect of the Basic
Assessment process and the proposed project. Copies of the full report have been made available at the following
locations:
1. Plek A
2. Plek B
3. Plek C.
Any written comments on the Draft BAR must be submitted to:
BolandEnviro cc
Attn: Marizanne Vos
PO Box 250
WORCESTER
6849
Ph 023 347-0336
Fax 023 347-5336
Please ensure that you have included the DEA&DP reference number in your comment: 16/3/1/1/E4/5/2031/14
3. Legislation
A Basic Assessment is required in accordance with the 2010 Environmental Impact Assessment (EIA) 2010 Regulations
promulgated in terms of Sections 24(5), 24M and 44 of the National Environmental Management Act (No. 107 of 1998)
(NEMA), as amended (Government Notice (GN) No. R.543).
Water Use Licences may be necessary in terms of subsections 21(c) and (i) of the National Water Act 36 of 1998 (to be
clarified with the Breede-Gouritz Catchment Management Agency). A 'Notice of Intent to Develop' has been submitted
to Heritage Western Cape in order to determine if the proposed projects are subject to the heritage assessment
requirements of the National Heritage Resources Act 25 of 1999.
The proposed projects triggers the following activities listed in GN No. R544 and R546:
Listing Notice 1 (GN R. 544) Aspects of the road repairs that relate to the
applicable listed activity.
11(xi) Construction of infrastructure ≥50 m2 in size within 32
m of a watercourse
This activity applies to sites OB1 and OB3 where
damaged bridges are to be replaced with new
structures.
18 (i) In-filling, removal etc of any material >5 m3 in a
watercourse …
This activity relates to all earth-moving and
excavation that may be necessary during
construction or, in the case of site OB6, to build a
temporary bypass.
39(iii) Expansion of bridges within a watercourse or within
32 m of a watercourse
This activity applies to the proposed works at sites
OB5 and OB6. It is triggered by the addition of
concrete approaches, outlets and scour protection
to existing bridges. .
40(iv) Expansion of infrastructure by >50 m2 within a
watercourse or within 32 m of a watercourse
This activity also applies to sites OB5 and OB6. It
relates to the provision of additional or redesigned
elements, e.g. wing walls, scour protection and
culverts that may increase the extent of existing
structures.
Proposed flood damage repair projects in the western Overberg (C958.5)
vi
Listing Notice 3 (GN R. 546) Aspects of the road repairs that relate to the
applicable listed activity.
16(d)(ii)(hh) Construction of infrastructure ≥10 m2 within 32 of a
watercourse outside urban areas within 5 km from
any other protected area identified i.t.o. NEMA
Protected Areas Act 57/2003
Two of the sites where 'construction'-related
activities are triggered (OB1 and OB3), are located
within 5 km of proclaimed Mountain Catchment
Areas or provincial nature reserves managed by
CapeNature.
24(d)(ii)
and (iii)(gg)
Expansion of infrastructure by ≥10 m2 in or within 32
m of a watercourse in all watercourses in the
Western Cape, and outside urban areas in the
Western Cape within 5 km from any protected
areas (other than a National Park or World Heritage
Site) proclaimed in terms of the NEM: Protected
Areas Act 57 of 2003
Three of the projects, at OB4, OB5 and OB6, entail
'expansion' as defined in LN3.
4. The environmental context
The study domain is in the Western Overberg, an agricultural region that support cereal and deciduous fruit production,
as well as sheep farming. The sites lie at the base of the Groenlandberge, between Bot River and the Theewaterskloof
Dam, and the Riviersonderend Mountains respectively. The sites are within a 20 km radius of Caledon; OB1 and OB3 to
the north-west of the town, and the remainder to the north. The closest settlement to any of the sites is a Bereaville,
which is about 5.5 km by road from OB6.
The Helderstroom Maximum Security Prison is about 8.5 km west of site OB3. The Moravian mission settlement at
Genadendal and Greyton are located some six and 13 km respectively from the easternmost site, OB6.
There are two regionally important rivers in the study area: the Bot River and the Riviersonderend. Sites OB1 and OB2 are
located on the former, whereas OB3 to OB6 are located on watercourses that drain from the Riviersondernend
Mountains into the Riviersonderend itself.
All the sites in question fall within mapped Crtiical Biodiversity Areas or Ecological Support Areas. The Ecological
Importance and Sensitivity (EIS), Present Ecological State (PES) of each river or wetland and condition of terrestrial
habitat are also provided (cf. Day, 2014). Sites OB3 to OB6 were ground-truthed as valley bottom wetland FEPAs
(Freshwater Water Ecosystem Priority Areas).
Site CBA ESA Condition and importance of
aquatic ecosystems (rivers, wetlands)
Condition of terrestrial habitat
within a c. 100 m radius of each
site** Ecological
Importance and
Sensitivity (EIS)
Present
Ecological State
(PES*)
OB1 Yes Yes Moderate D D = 80; T = 20
OB2 Yes Yes Moderate D NN = 10; D = 60; T = 30
OB3 Yes Yes Low E D = 80; T = 20
OB4 No Yes Low C NN = 60; D = 40
OB5 No Yes Moderate C NN = 30; D = 50; T = 20
OB6 No Yes Low D/E NN = 20; D = 50; T = 30
*A = Unmodified/natural B = Largely natural C = Moderately modified D =
Largely Modified E = Seriously modified F = Critically/extremely modified
** NN = Near Natural D =
Degraded T = Transformed
Proposed flood damage repair projects in the western Overberg (C958.5)
vii
The basic assessment, supported by a specialist aquatic assessment undertaken by Dr Liz Day, provisionally concluded
that the following aspects of the receiving environment could be affected by the proposed projects and related
activities:
Hydrological aspects
− Flow regimes
− Water quality
Hydro-geomorphological aspects
− Scouring, erosion and sediment movement
− Physical structures and stability of watercourse
Biodiversity aspects
− In-stream and riparian habitat
Biodiversity conservation priorities
− Critical Biodiversity Areas and Ecological Support Areas
− Freshwater Ecosystem Priority Areas
− Listed threatened ecosystems
Socio-economic aspects
− Employment opportunities
− Sense of place and wellbeing
− Integrity of road network (safety and reliability)
The overall significance of impacts during the construction phase was evaluated as follows:
Table 1: Impacts during the construction phase Potential (negative) significance of impacts
Before mitigation After mitigation
Biophysical environment
Erosion and sedimentation Low to Very Low Very Low
Water quality (turbidity) Low to Very Low Very Low
Water quality (contamination) Medium to Very Low Very Low
Channel stability Low to Very Low Very Low
Critical Biodiversity Areas Medium Very Low
Socio-economic environment
Inconvenience to road users Low Low
Sense of wellbeing
Noise Medium to Very Low Very Low
Dust Medium to Very Low Very Low
Socio-cultural environment
Sense of place Medium Very Low
The overall significance of impacts during the post-construction, operational phase was evaluated as follows:
Table 2: Impacts during the operational phase:
Potential (negative) significance of impacts
Before mitigation After mitigation
Biophysical environment
Improved hydraulic capacity Medium Low (positive)
Erosion and sedimentation High to Low Very Low (positive)
Aquatic CBAs Medium to High Very Low
Terrestrial CBAs Low to Very Low Very Low
Proposed flood damage repair projects in the western Overberg (C958.5)
viii
Socio-economic environment
Improved road safety High to Medium High (positive)
No negative cumulative impacts were conclusively identified a site-specific scale. Generally, it is assumed that improved
culvert design, particularly by the introduction of increased flow space and/or scour protection, could be expected to
reduce flow concentration and the risk of downstream erosion and habitat degradation, which would be a positive
impact. Conversely, if erosion is allowed to persist, it will almost certainly result in further damage to agricultural land and
road infrastructure, as well as having a cumulative, negative, impact on aquatic habitats, biota and ecological
processes.
However, as with other flood repair projects in the Overberg area, any environmental benefits issuing from the new or
upgraded structures would largely be annulled by the impacts of intense floods and heavy sediment burdens that are
directly linked to the degraded and destabilised condition of most of the affected catchments in this intensively-farmed
region. Similarly, failure to keep channels clear of invasive alien plants will mean that the structures remain vulnerable to
the impacts of down-cutting, erosion and enhanced sediment transport.
One of the most evident positive cumulative impacts relates to the improvement and maintenance of a high quality
rural road network which holds manifest benefits across the socio-economic spectrum.
From a socio-economic point of view, the road repairs would be both necessary and desirable. Any long-term
environmental benefit would, however, be contingent upon the degree to which these highly degraded and
destabilised watercourses can be rehabilitated. It is for the latter reason that mitigation has to be addressed
strategically, at an ecosystem or catchment scale, if the environmental benefits of the repaired and rebuilt structures are
to materialise.
5. Recommendations
The Draft Basic Assessment Report recommends that environmental authorisation be granted for all six projects, subject
to the following conditions that apply:
(A) Generically to all construction;
(B) To ecological mitigation and post-construction rehabilitation and maintenance at each of the respective sites;
and
(C) To farm and catchment-scale interventions.
(A) GENERIC, CONSTRUCTION-RELATED MITIGATION THAT APPLIES TO ALL SITES
The key mitigation measure is impact avoidance, failing which disturbance of watercourses and other wetlands must be
minimised and remedied.
Where adverse impacts cannot reasonably be prevented, construction should be managed through the effective
implementation of the Construction Environmental Management and Maintenance Programme (EMP) with a strong
emphasis on post-construction rehabilitation and channel maintenance.
Construction-related impact avoidance and mitigation must address activities that may:
− Cause disturbance to river banks;
− Result in potential pollution of the water course as a result of allowing the passage (direct, or by seepage,
surface spillage or overflow) of pollutants such as sediment, cement, fuels, litter or other waste into
watercourses;
− Increase the likelihood of invasion by alien plants;
− Increase disturbance as a result of human access to river / wetland areas; and/or
− Negatively affect the success of planned river bank rehabilitation activities.
Timing of construction
Proposed flood damage repair projects in the western Overberg (C958.5)
ix
− Construction activities within watercourses should not take place during the wet season (i.e. any activities
requiring the diversion of flows should take place between October and April only), and construction schedules
should preferably be managed within these time frames.
Delineation of construction sites and access to watercourses
− Obtain the landowner's written permission if sites must be accessed across farmland
− Only use existing access roads to undertake the proposed activities
− The physical extent of construction-related impacts must be minimised and securely contained within an area
demarcated by RoadQuip® 'Express Net' or a similar highly visible and durable barrier device. This particularly
applies to those points where vehicles obtain access into watercourses.
− Limiting activities and vehicle movement to disturbed sections of river channels
− Clearly mark vegetation that may not be damaged
− All areas outside of the demarcated construction zone should, within reason, be regarded as no-go areas
during construction, with the exception of personnel engaged in required alien clearing and bank
rehabilitation activities outside of construction disturbance zones.
Removal of indigenous vegetation
− Only remove reeds and other riparian vegetation in the channel and along river banks if access to structures or
construction areas would otherwise be impeded by indigenous vegetation – this applies specifically to Site OB5,
which still retains natural in-stream vegetation and habitat types.
De-watering of construction sites
− Where de-watering is required as part of construction activities, provision must be made for the settlement of
sediment in temporary sediment ponds or other areas of containment. These must be managed so as to
prevent the passage of sediment-rich water into the watercourse
− De-watering systems must be designed so that they do not result in the passage of concentrated flow into
watercourses, thereby promoting erosion.
− Ensure that flows that are routed around or discharged downstream of construction areas do not result in scour
downstream of construction sites
− Ensure that the impact of pumped water that is discharged under pressure is dissipated by placing pipe outlets
in rocky parts of the stream bed that are not susceptible to scour.
Removal and stockpiling of topsoil for post-construction rehabilitation
− Fill sourced for construction purposes must be free of alien seed.
− Remove topsoil to a depth of 150 mm and stockpile it locally for re-vegetation.
− Grade banks to a slope of at least 1:4, but preferably flatter, between the repaired structures and the
boundary of the road reserve.
− Grade slopes downwards, towards the watercourses, with reducing the width or depth of the channel
− Re-plant disturbed areas directly upstream and downstream of each structure with indigenous, locally-
occurring pioneer species at the level of base flow.
− Using bagged plants rather than seeds or cuttings to achieve rapid stabilisation of particularly lower banks.
Storage and preparation of construction materials
− Construction sites must be managed so that construction material (especially cement and fuel products) is not
washed or blown into watercourses during storm events or strong winds.
− Store and contain all materials on the construction sites at least 40 m from the nearest water resource.
− Concrete batching must take place at least 40 m from the edge of channel in a secure, bunded area (e.g.
wooden boards placed over heavy plastic sheeting within a bund of sandbags).
− Keeping stockpiled spoil and recently disturbed areas moist.
Proposed flood damage repair projects in the western Overberg (C958.5)
x
Refuelling of vehicles and other machinery
− Vehicles must be refuelled at least 40 m away from rivers, in securely bunded areas
− Fuel bowsers and other forms of fuel storage must be kept at least 40 m away from any watercourse
− Check vehicles daily for oil leaks and repair leaks immediately
− Maintain all construction machinery and vehicles in good working order.
General site maintenance
− Inspect sites daily for litter and remove all rubble and waste material from the river channels and riparian zones
after construction is completed.
− No open fires are permitted at any of the construction sites – fires for cooking or heating purposes must be
made in 'konkas' within a cleared area within the construction site
− Provide and regularly service ablution facilities for construction staff on site.
− Toilets must be located at least 40 m from watercourses.
− No tools, packaging, empty containers or other construction materials may be washed in watercourses
− Water used for washing must be managed such that it does not contaminate any watercourse;
Noise abatement
− Ensure construction machinery and especially silencers are in good working order.
− Limit construction to the hours of daylight, on weekdays only.
Dust abatement
− Vehicles must not exceed 40 km/hr on gravel roads in the vicinity of human habitation or vineyards or
orchards with ripening fruit.
Road safety
− Provide sufficient signage to warn motorists of the presence of construction works and detours.
Post-construction rehabilitation
− Rehabilitation activities specified in mitigation measures, including rehabilitation of temporary bypasses or
defunct structures should take place outside of the wet season, and immediately after the completion of
construction activities.
− All waste generated by construction activities (including rubble, litter etc.) is to be removed from the site and
disposed of at an appropriate approved site.
− Remove invasive species such as black wattle Acacia mearnsii and beefwood Casuarina sp as they contribute
to channel restriction, down-cutting and erosion, and displace indigenous biodiversity.
− Post-construction alien management must be ongoing at all sites.
− Alien clearing procedures should be carried out in accordance with species-specific guidelines outlined by
Working for Water documentation, or as recommended by an experienced alien clearing specialist;
− Bank rehabilitation activities should make provision for input by a river ecologist or the Western Cape Department of Agriculture into the final shaping and planting of these areas.
− Any area accidentally disturbed during construction should be rehabilitated after construction, with input from
a riverine specialist ecologist or the Western Cape Department of Agriculture where such areas lie within a
watercourse or other wetland.
Post-construction channel maintenance
− Keeping watercourses upstream of the structures (at least as far as the edge of the road reserve) clear of flood
debris (particularly ‘spoelklippe’, branches and uprooted bushes and trees) to prevent premature over-topping
and back-flooding in floods ≤1:5-year return period.
Proposed flood damage repair projects in the western Overberg (C958.5)
xi
− Keeping channels downstream, at least as far as the fenced edge of the road reserve, clear of branches and
other obstacles that may deflect flows into the banks of watercourses.
− Where excavations have taken place upstream of structures, ensure that potential nick-points and benches in
the channel are removed so as to prevent head-cut erosion from developing upstream of these locations.
− Monitor the first reach/first 150 m of the watercourse downstream for signs of new erosion.
− Monitor changes to sediment patterns (deposition and erosion) up- and downstream of repaired structures to
assess recovery and reinstatement of the general slope of the watercourse.
− Obtaining timeous ecological advice on how best to repair and, if feasible, provide additional venting, to
gravel approaches that may be washed away as a result of floods.
− Maintain roads to reduce the concentration and/or intensity of run-off so as to dissipate energy and erosion
potential.
(B) Measures relating to site-specific mitigation and ecological rehabilitation
OB1: Kanaan The following measures need to be implemented upon completion of construction:
− All concrete and other debris associated with the present road crossing should be removed from the river bed and banks as
soon as the requirement for a construction-phase bypass road is over, and disposed of outside of the 1:50 year flood line for the river;
− The existing road, which will be replaced by a new alignment, should be ripped, all artificial debris removed, and the river bank and riparian zone thus created should be shaped to resemble a natural system, in a band at least 15m wide on either side of the river – a river ecologist should oversee / sign off on this aspect of mitigation;
− The river bank must be rehabilitated according to Environmental Specification C1008; and − The small tributary directly to the east should be addressed as part of the latter process, and re-shaped as a broad open
channel, planted in destabilised areas to prevent erosion;
OB3: Meerlustkloof
− Additional pipes must be installed in the existing causeway to improve its capacity to accommodate high flows during construction, after which this structure must be demolished and its disturbed footprint rehabilitated as specified below. The installation of the extra pipes must be supervised by the project engineer and an aquatic ecologist.
− All concrete and other debris associated with the present road crossing should be removed from the river bed and banks as soon as the requirement for a construction-phase bypass road is over, and disposed of outside of the 1:50 year flood line for the river; and
− The existing road, which will be replaced by a new alignment, should be ripped, all artificial debris removed, and the river bank rehabilitated according to Environmental Specification C1008.
Site OB6: Nooitgedacht
− The wetland head-cut must be addressed, as a matter of great urgency, and prior to the start of any construction activities on this overall project, through the installation of a gabion weir, located at the head-cut point, and appropriately designed to prevent further erosion caused by a change in gradient between the wetland channel and the excavated channel upstream of the low-lying culvert.
(C) General, post-construction ecological rehabilitation
These recommendations relate to long-term rehabilitation and channel maintenance and do NOT apply to construction
phase activities as specified in the Construction Environmental Management Programme for project C958.5
Alien clearance and monitoring − Keep channels upstream and downstream – and at least as far as the first bend and/or for 150 m – clear of large branches
and other debris that may deflect flows into the banks of watercourses. − Clear invasive alien plants from river banks and the floodplain at least 200 m downstream of the structures, in a corridor at
least 30 m wide and replant with locally-occurring indigenous pioneer plant species.
Proposed flood damage repair projects in the western Overberg (C958.5)
xii
− Species-appropriate alien clearing methods should be employed – Working for Water guidelines should be used in this regard;
− Cleared areas should be stabilised by a combination (as appropriate) of bank shaping and planting with locally indigenous plant species
− Monitor the first reach/first 150 m of the watercourse downstream on an annual basis for signs of new erosion. − Maintain a photographic record of the monitored reaches. − In all cases, alien clearance needs to be co-ordinated by an authority such as the Western Cape Department of Agriculture
and local landowners should be encouraged to participate in such clearance programmes.
Site OB1: Kanaan
− The eroding bank upstream of the bend must be addressed, through removal of alien vegetation, reshaping of the bank and
replanting; hard stabilisation techniques (e.g. bank lining with gabions) should not be used, although it is understood that gabions will be used immediately up- and possibly downstream of the new structures.
Site OB2: Doringkloof
− All invasive woody alien vegetation and the seedlings of such species should be cleared from a zone extending at least 30 m upstream and 30 m downstream of the present crossing point, as well as 30m upstream along the inflowing minor stream, in a swathe at least 15m wide on either side of the river channel, or less if alien invasion is within a narrower zone – the final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner;
− The design for this structure must include an additional or extended culvert or other ecologically cognisant measure that allows for the free flow of the minor stream through the structure, without being diverted along the road edge. The mechanism for this would need to address the fact that the stream appears to enter the system at a higher level than the existing culvert.
Site OB3: Meerlustkloof
− The DTPW should liaise with the Western Cape Department of Agriculture regarding the proposed installation of a groyne field in the Elandskloof River, and ensure that bank erosion and channel migration in the reaches at least 50 m upstream and downstream of the crossing are controlled by groynes, designed in keeping with the objectives of the broader WCDA flood and erosion control programme.
− Such structures ideally need to be in place before the start of the present proposed activities – in the event that delays in their authorization through WCDA are considered likely, it is recommended that the DTPW either work with WCDA to prioritise approval and construction of the structures that would affect the present road, or design and obtain authorization for such structures separately.
− Note that the proposed design at OB3 already assumes implementation of the groyne field, and allows for a lower invert level in the crossing than that required at present, given that the river would be down-cut by concentration of flood flows.
− The extensive eroded area to the east of the existing bermed river channel downstream of OB3 must be addressed, and returned to a vegetated floodplain condition.
− This rehabilitation measure, which should only take place after construction of the groynes and new road and bridge, would require:
o Liaison with the WCDA regarding the implications of the proposed groyne field for this area – ideally, the groyne field itself should allow for widening of the river in these disturbed reaches
o Removal of the berm (berm material may be spread on the eroded floodplain)
o Removal of the beefwood trees lining the channel downstream of the road
o Landscaping / shaping the floodplain area such that it comprises a mosaic of depressions and raised areas, mirroring natural conditions;
o Establishment of indigenous floodplain vegetation on the rehabilitated area – note that while planting or seeding of the area would be positive, it is likely that appropriate plants will establish themselves in the rehabilitated area over time, provided that weeding is allowed for in the establishment phase. This has been the case with disturbed areas upstream (Day 2013).
− Allowance must be made for the establishment of a continuous swathe of appropriate, locally indigenous vegetation along
Proposed flood damage repair projects in the western Overberg (C958.5)
xiii
at least the wetted bottom of the bank of the river, but ideally up the bank as well, for a distance of 30m up- and downstream of the proposed structure, to prevent erosion. It is strongly recommended that dense stands of Palmiet reeds (Prionium serratum) should be utilised for this purpose. Other plant species used should be selected in consultation with a botanist and/or river ecologist, to ensure they meet the required criteria of being hardy, locally indigenous and suited to the conditions in which they are planted;
− The final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner;
Site OB5: Tarentaalkraal
In order to address the issue of concentrated flows and at times the passage of large debris through the road culvert, exacerbating the problems experienced in the scour hole: − The alien-invaded channel upstream of the road must be cleared of all woody aliens and the seedlings of such species,
across the entire riverine zone, extending upstream for a distance of at least 40 m upstream of the road – the final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner
− Species-appropriate alien clearing methods should be employed – Working for Water guidelines should be used in this regard;
− Cleared areas should be stabilised by a combination (as appropriate) of bank shaping and planting with locally indigenous plant species;
− Local landowners should ideally be required to participate in long-term alien maintenance clearing activities in the cleared reach and upstream;
− Branches and other material that become entangled in the fence across the culvert should be cleared before the onset of winter in order to prevent debris-build-up;
− Consideration should be given to the creation of attenuation depressions / wetlands in the area to the west of the channel, upstream of the road, to manage flood velocities and volumes; and
− Also, alien vegetation should be cleared to a distance of 30 m downstream of the road (i.e. to just past the riffle at the end of the pool).
OB6: Nooitgedacht
− The eroding banks downstream of the culvert must be addressed as a matter of urgency, bearing in mind their proximity to the Riviersonderend wetlands downstream. The following measures are regarded as minimum requirements:
o The need for the installation of energy-control weirs in the channel should be considered, to prevent further
down-cutting and allow the re-establishment over time of wetland vegetation – where considered necessary by an engineer, working with a river ecologist, such weirs should be constructed;
o The river banks must be graded (during low flow periods) to establish banks that have slopes no steeper than 1:5 and preferably less steep;
o Allowance must be made for the planting of at least the lower bank with hardy locally indigenous plant species, approved by a botanist or river ecologist, that will play a role ion lower bank stabilisation; the use of Palmiet in this regard would be encouraged;
o The passage of flows into the channel from the west must be investigated and addressed, such that it does not
constitute a threat to the long-term rehabilitation of the channel.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR xiv
TABLE OF CONTENTS
PROJECT INFORMATION i
DEPARTMENTAL REFERENCE NUMBERS ii
PROJECT TITLE ii
DETAILS OF THE ENVIRONMENTAL ASSESSMENT PRACTITIONER (EAP) ii
DETAILS OF EAP'S EXPERTISE TO CARRY OUT BASIC ASSESSMENT PROCEDURES iii
EXECUTIVE SUMMARY iv
TABLE OF CONTENTS x
A. ACTIVITY INFORMATION 1
1. Project description 1
2. Physical size of the activity 4
3. Site access 5
4. Description of the property on which the activity is to be undertaken 5
5. Site photographs 7
B. DESCRIPTION OF RECEIVING ENVIRONMENT 8
1. Gradient of the site 8
2. Location in landscape 8
3. Groundwater, soil and geological stability of the site 9
4. Surface water 10
5. Biodiversity 11
6. Land use of the site 13
7. Land use character of surrounding area 14
8. Socio-economic aspects 16
9. Historical and cultural aspects 16
10. Applicable legislation, policies and/or guidelines 17
C. PUBLIC PARTICIPATION 19
D. NEED AND DESIRABILITY 21
E. ALTERNATIVES 24
F. IMPACT ASSESSMENT, MANAGEMENT, MITIGATION AND MONITORING MEASURES 27
1. Manner in which the development will impact on various aspects 27
2. Waste and emissions 28
3. Water use 29
4. Power supply 30
5. Energy efficiency 30
6. Description and assessment of the significance of impacts prior to and after mitigation 30
7. Specialist inputs/studies and recommendations 41
8. Impact summary 42
9. Other management, mitigation and monitoring measures 43
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR xv
G. ASSESSMENT METHODOLOGIES AND CRITERIA, GAPS IN KNOWLEDGE, UNDERLYING ASSUMPTIONS
AND UNCERTAINTIES 44
H. RECOMMENDATION OF THE EAP 45
I. APPENDICES 47
DECLARATIONS 48
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 16
SECTION A: ACTIVITY INFORMATION
1. PROJECT DESCRIPTION
2.1 Is the project a new development? See below
All projects relates to the repair or replacement of existing culverts and related infrastructure on public roads in the north-
western Overberg. In two cases, flood-damaged bridges are to be replaced with equivalent structures (OB1 and OB3). In
one case (OB6), an additional box culvert is to be added to a crossing. A small gabion weir would also have to be installed
in the eroding channel upstream of Site OB6 in order to prevent a head-cut from forming. Activities at the remainder of the
sites will be limited to the repair and/or refurbishment of existing infrastructure (OB2, OB4 and OB6) within their current
alignment (i.e. April 2014).
(b) Provide a detailed description of the development project and associated infrastructure.
Essential repairs to flood-damaged rural road infrastructure in the Theewaterskloof Municipality
The Western Cape Government: Department of Transport and Public Works (DTPW) proposes to undertake essential flood
damage repairs to road infrastructure at various locations in the western parts of the Overberg, in an area spanned by
Villiersdorp, Bot River, Caledon and Greyton in the Theewaterskloof Municipality (cf. Fig 1). The work entails two contracts:
− C958.5 (Bergstan) – To which this application for environmental authorisation applies; and
− C960.4 (Hatch Goba) – This contract is subject to a separate but parallel application for environmental
authorisation.
Contact C958.5
The proposed works entail repairs and/or maintenance to flood-damaged causeways, culverts and drifts at six different sites
in the Theewaterskloof Municipality. The sites are located on the Bot River (OB1 and OB2) and northerly tributaries of the
Riviersonderend (OB3-OB6). The damage – which originally stemmed from floods in August 2012 – has been exacerbated by
subsequent floods in October 2012 and November 2013.
Two of the structures (OB1 at Kanaan, and OB3 at Meerlustkloof) will be replaced with new crossings. These bridges need to
be rebuilt owing to the extent of damage and the adverse implications this holds for road safety and maintaining
serviceable public road infrastructure. Redundant structures will be demolished and their former footprints rehabilitated.
Rubble is to be conveyed to municipal waste dumps. The redundant structures will serve as bypasses during construction of
the new bridges.
*** Access to the Helderstroom Prison: High priority ***
The repairs relating to the four damaged structures over the northern tributaries of the Riviersonderend (OB3-OB6) are
particularly urgent, because these crossings on the DR1313 provide the only road access to the Helderstroom Prison when
the Riviersondernd is in flood and cuts off the prison from the DR1311 (the main road linking the R43 (Caledon-Villiersdorp)
with Greyton. This has potentially grave security and humanitarian consequences and interferes with the effective
functioning of the justice system.
Environmental factors influencing repairs
All the structures, barring those at OB3 and OB4 (which are both vented by pipes; the rebuilt bridge at OB3 is to be equipped
with box culverts), constitute concrete box culverts of various dimensions that carry either single or double lane decks. The
use of precast box culverts is generally recommended where riverbeds carry a high boulder load and high energy flood
events are common in winter and early summer. All the rivers in question are degraded as a result of alien infestation, and
cultivation and development in former floodplains and the surrounding catchments that, cumulatively, promote channel
confinement, down-cutting, lateral erosion and mobilisation of large quantities of sediment during floods. Boulders are less
likely to block rectangular portal units than pipe culverts, which are prone to being clogged by uprooted or felled trees and
high loads of debris that are generated as a result of chronic channel destabilisation. Box culverts are also more easily
cleared than pipe culverts. In the light of the boulder load in the affected systems, gabions have been largely avoided.
Flood capacity of structures
The structures are designed to cater at least for a one-in-two-year design flood and in most cases entail increasing the
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 17
hydraulic capacity of the portals, which also has the effect of improving sediment movement underneath the crossings. The
structures would be designed to be over-topped by larger floods. Where deemed necessary, protection works such as cut-
off walls, apron slabs and approach slabs have been designed to cater for larger flow volumes. In this way, structural
damage during large floods should be reduced even if the road becomes temporarily unpassable. In some cases, splash
aprons would be extended to prevent scouring at outlets which, if not controlled, can undermine the structure and
contribute to erosion of the downstream channel. See Appendix B1 for an overview of the proposed repairs and
maintenance-related activities.
(c) List all the activities assessed during the Basic Assessment process:
Listing Notice 1 (GN R. 544) Aspects of the road repairs that relate to the
applicable listed activity.
11(xi) Construction of infrastructure ≥50 m2 in size within 32
m of a watercourse
This activity applies to sites OB1 and OB3 where
damaged bridges are to be replaced with new
structures.
18 (i) In-filling, removal etc of any material >5 m3 in a
watercourse …
This activity relates to all earth-moving and
excavation that may be necessary during
construction or, in the case of site OB6, to build a
temporary bypass.
39(iii) Expansion of bridges within a watercourse or within
32 m of a watercourse
This activity applies to the proposed works at sites
OB5 and OB6. It is triggered by the addition of
concrete approaches, outlets and scour protection
to existing bridges. .
40(iv) Expansion of infrastructure by >50 m2 within a
watercourse or within 32 m of a watercourse
This activity also applies to sites OB5 and OB6. It
relates to the provision of additional or redesigned
elements, e.g. wing walls, scour protection and
culverts that may increase the extent of existing
structures.
Listing Notice 3 (GN R. 546) Aspects of the road repairs that relate to the
applicable listed activity.
16(d)(ii)(hh) Construction of infrastructure ≥10 m2 within 32 of a
watercourse outside urban areas within 5 km from
any other protected area identified i.t.o. NEMA
Protected Areas Act 57/2003
Two of the sites where 'construction'-related
activities are triggered (OB1 and OB3), are located
within 5 km of proclaimed Mountain Catchment
Areas or provincial nature reserves managed by
CapeNature.
24(d)(ii)
and (iii)(gg)
Expansion of infrastructure by ≥10 m2 in or within 32
m of a watercourse in all watercourses in the
Western Cape, and outside urban areas in the
Western Cape within 5 km from any protected
areas (other than a National Park or World Heritage
Site) proclaimed in terms of the NEM: Protected
Areas Act 57 of 2003
Three of the projects, at OB4, OB5 and OB6, entail
'expansion' as defined in LN3.
If the application is also for activities as per Listing Notice 2 and permission was granted to subject the application to
Basic Assessment, also indicate the applicable Listing Notice 2 activities:
GN No. R. 545
Activity No(s):
If permission was granted in terms of Regulation
20, describe the relevant Scoping and EIA
Activity(ies) in writing as per Listing Notice 2 (GN
No. R. 545)
Describe the portion of the development as per the
project description that relates to the applicable
listed activity.
N/A
Waste management activities in terms of the NEM: WA (Government Gazette No. 32368):
GN No. 718 - Category A Activity
No(s): Describe the relevant Category A waste management activity in writing.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 18
N/A
If the application is also for waste management activities as per Category B and permission was granted to subject the
application to Basic Assessment, also indicate the applicable Category B activities:
GN No. 718 – Category B Activity No(s): Describe the relevant Category B waste management activity in writing.
N/A
Atmospheric emission activities in terms of the NEM: AQA (Government Gazette No. 33064):
GN No. 248 Activity No(s): Describe the relevant atmospheric emission activity in writing.
N/A
(d) Please provide details of all components of the proposed project and attach diagrams (e.g. architectural
drawings or perspectives, engineering drawings, process flow charts etc.).
Buildings YES NO �
Provide brief description:
N/A
Infrastructure (e.g. roads, power and water supply/ storage) YES � NO
Provide brief description:
See Section 1(b) above for an overview of the projects, as well as the plans and project descriptions in Appendices B and
C.
Two of the projects (OB1 and OB3) will entail building new bridges in close proximity to the alignment of the damaged
structures (<20 m will separate the new structures from the old ones, which are to be demolished and removed upon
completion of the works).
The remainder of the projects entail repairing and upgrading existing bridges on public thoroughfares. Only OB6 requires a
bypass. It also entails installation of an additional box culvert to double the hydraulic capacity of the culvert.
In all cases, structures are to be equipped with either new or additional anti-scour protection and road surfaces may be
sealed with concrete to protect approaches against erosion.
Most of this work will take place within the existing road prism or with minimal expansion within watercourses. Only one
temporary bypass is required, namely at site OB6.
More detailed descriptions follow below.
3.1 OB1 This project entails the complete replacement of a damaged bridge (C10765) over the Bot River at the
farm Kanaan. The site is about 10 km north of the Bot River village. The new bridge would be repositioned
approximately 15 m upstream of the existing crossing, which requires realignment of the DR1288. The bridge
consist of a single span portal concrete structure with an opening of c. 12 m wide x 4.5 m high with
concrete invert slabs. The upstream and downstream banks will receive gabion mattress protection.
3.2 OB2 This project is located about 3 km north of OB1, on the DR1288, where the southern approaches to structure
C10768 are vulnerable to wash-aways. The site is at the confluence of the Bot River and a seasonal tributary
that flows in from the east, via the farm Doringkloof. New concrete slabs are required on the road
approaches which will also be equipped with side slope protection.
3.3 OB3 This site is located on the DR1313 where it spans the Elandskloof River by means of a severely damaged
pipe culvert crossing adjacent to the farm 'Meerlustkloof'. A new two-lane causeway is required,
comprising six 3.0 m wide x 1.6 m high openings along a new alignment approximately 12 m downstream of
the existing crossing. Road slabs will be provided. The Western Cape Department of Agriculture is due to
construct groynes in the Elandskloof River, which are designed to control the severe destabilisation and
erosion that periodically contributes to damage of the bridge at this site.
3.4 OB4 This project entails placing gabion 'mattresses', each about 12 m2 in extent, upstream and downstream of a
small pipe culvert crossing about 140 m to the east of OB3. The top surface of the mattresses will receive a
thin concrete slab. The main object of this work is to control the growth of reeds that trap sediment and
cause the pipes underneath the road to become blocked. Flood water is then forced upwards on to the
road surface where it causes damage. The mattresses will contain the growth of reeds while permitting low
flows through the gabions, thereby maintaining the hydraulic functioning of this minor flood channel. This
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 19
small side channel of the Elandskloof River also skirts the farm 'Meerlustkloof'.
3.5 OB5 This project entails providing new scour protection downstream of a box culvert at Tarentaalkraal, some 700
m east of OB4 on the DR1313. An apron slab at the culvert outlet has become undermined and needs to
be repaired and under-pinned. The damaged apron slab will be replaced with a stepped structure of three
gabions that are designed to break the fall of water. The base of the latter 'cascade' will be extended into
a reinforced gabion 'mattress' that will prevent scour downstream of the culvert. The gabion 'mattress' will
be 14.84 m wide, and the entire protective structure will extend 8 m from the culvert outet into the
watercourse below. The difference in height between the base of the culvert outlet and the base of the
gabion 'mattress' is 2.7 m. The top surfaces of the stepped gabions and the gabion 'mattress' will be
protected with concrete screed panels which allow water to infiltrate the structures and permit some
flexibility to accommodate settling of the scour protection.
3.6 OB6 This project at Nooitgedacht entails construction of an additional box culvert next to an existing one so that
larger flows can be passed through the structure, rather than over-topping the road and causing wash-
aways and erosion. The additional culvert will be 12.68 m long, by 1.8 m wide and 1.2 m high. The existing
culvert will be extended by 3.68 m on the upstream side and there will be a slight realignment of the
existing road to improve road safety at the crossing. Embankment protection will be provided upstream
and downstream. A gabion 'mattress' will be placed downstream of the outlet. It will have a width of 12 m
extend 4 m downstream. As with the scour protection at OB5, the surface of this gabion 'mattress' will also
protected with concrete screed panels.
Processing activities (e.g. manufacturing, storage, distribution) YES NO �
Provide brief description:
N/A
Storage facilities for raw materials and products (e.g. volume and substances to be stored)
Provide brief description YES NO �
N/A
Storage and treatment facilities for solid waste and effluent generated by the project YES NO �
Provide brief description
N/A
Other activities (e.g. water abstraction activities, crop planting activities) YES NO �
Provide brief description
N/A
2. PHYSICAL SIZE OF THE ACTIVITY
Size of the property
(a) Indicate the size of the property (cadastral unit) on which the activity
is to be undertaken.
The new causeways at OB1 and OB3, and the rebuilt scour protection at
OB5, will extend beyond the boundaries of the road reserve. The gabion
check-weir at OB6 and the temporary by-pass at this site will also be built
outside the road reserve. All other work will be confined to the road
reserve.
OB1
Farm 246/1 CALEDON
435.7770 ha
OB3
Farm 59/4 CALEDON
408.5953 ha
OB5
Farm 59/2 CALEDON
368.617 ha
OB6
Farm 58/6 CALEDON
85.3723 ha
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 20
Size of the completed structures (m2)
(extent of expansion relative to existing extent of
structure in brackets)
(b) Indicate the size of the facility (development area) on which
the activity is to be undertaken.
See Appendix B2 for the physical surface area of the respective
works in terms of their existing extent, the area of expansion and,
in the case of OB6, the footprint of the temporary by-pass (280
m2).
OB1 1 050 (600)
OB2 245
OB3 750 (250)
OB4 83 (32)
OB5 367 (112)
OB6 522 (322)
Site number (c) Indicate the physical size
(footprint) of the activity
together with its associated
infrastructure
Total extent of repairs plus by-
passes
(m2)
(d) Indicate the physical size
(footprint) of the activity
This represents the extent to
which structures may be
extended as a result of the
repairs and refurbished scour
protection and approach slabs
(m2)
(e) Indicate the physical size
(footprint) of the associated
infrastructure
This relates to the bypasses that
will be in place for the duration
of the repairs
(m2)
OB1 1050 600 0
OB2 245 0 0
OB3 750 250 0
OB4 82 32 0
OB5 367 112 0
OB6 522 322 280
and, for linear activities:
(f) Indicate the length of the activity: Length of the activity:
N/A m
3. SITE ACCESS
(a) Is there an existing access road? YES � NO
(b) If no, what is the distance over which a new access road will be built? m
(c) Describe the type of access road planned:
N/A
4. DESCRIPTION OF THE PROPERTY ON WHICH THE ACTIVITY IS TO BE UNDERTAKEN AND THE LOCATION OF THE
ACTIVITY ON THE PROPERTY
(a) Provide a description of the property on which the activity is to be undertaken and the location of the activity on
the property.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 21
All the sites in question are located on relatively isolated gravel rounds in rural landscapes in which farming (intensive and
extensive) is the predominant land use. The DR1288 carries, on average, fewer than 100 vehicles per day, and the DR1313
fewer than 200 vehicles per day (Bergstan South Africa, 2013).
(b) Please provide a location map (see below) as Appendix A to this report which shows the location of the property
and the location of the activity on the property; as well as a site map (see below) as Appendix A1 to this report; and
if applicable all alternative properties and locations.
Locality map:
The following GoogleEarth images and locality maps are included in Appendix A. The location map
is based on the 1:250 000 topocadastral sheet 3319 WORCESTER (Chief Directorate: Surveys and
Mapping, 1997). It is not to scale.
− Location map for sites OB1-OB6
− GoogleEarth image: OB1, Kanaan
− GoogleEarth image: OB2, Doringkloof
− GoogleEarth image: OB3, Meerlustkloof
− GoogleEarth image: OB4, Meerlustkloof
− GoogleEarth image: OB5, Tarentaalkraal
− GoogleEarth image: OB6, Nooitgedacht
Site Plans: See Appendix A1
(c) For a linear activity, please also provide a description of the route.
N/A
Indicate the position of the activity using the latitude and
longitude of the centre point of the site. Latitude (S): Longitude (E):
N/A
(d) Location of sites (degrees-minutes-seconds)
Site reference Lat Long 1:50 000 sheet Place reference
OB1
34° 9'3.83"S
19°14'9.29"E
3419AA
Kanaan
OB2
34° 7'27.84"S
19°14'21.78"E
3419AA
Doringkloof
OB3
34° 3'44.29"S
19°26'10.56"E
3419AB
Meerlustkloof (1)
OB4
34° 3'44.26"S
19°26'16.51"E
3419AB
Meerlustkloof (2)
OB5
34° 3'43.33"S
19°26'43.34"E
3419AB
Tarentaalkraal
OB6
34° 3'31.66"S
19°27'50.85"E
3419AB
Nooitgedacht
5. SITE PHOTOGRAPHS
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 22
Interpreted photographs of all the sites are represented in Appendix C. Depending on local circumstances and the
availability of vantage points, the photographic record depicts the condition of watercourses up- and downstream of
the respective causeways, surrounding land uses and the general state of riparian vegetation. Observations that are
relevant to the environmental assessment are also provided in summary.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 23
SECTION B: DESCRIPTION OF RECEIVING ENVIRONMENT
Site/Area Description
1. GRADIENT OF THE SITE
Indicate the general gradient of the site (highlight the appropriate box). NOTE Gradients represent slope profiles.
Sites Flat Flatter than 1:10 1:10 – 1:4 Steeper than 1:4
OB1 �
OB2 �
OB3 �
OB4 �
OB5 �
OB6 �
2. LOCATION IN LANDSCAPE
For ease of reference, the sites are clustered into two geographical groups, broadly arranged from west to east, namely:
The Bot River sites
The Riviersonderend sites
OB1 and OB2
OB3, OB4, OB5 and OB6
(a) Indicate the landform(s) that best describes the site (highlight the appropriate box(es).
NB: All sites lie inland of the coast, and references to coastal landforms or locations are therefore omitted.
The Bot River sites
Sites Ridge-
line Plateau
Side slope of hill,
mountain and/or
foothill
Closed
valley
Open
valley Plain
Undulating
plain/low hills
OB1 � �
OB2 � �
The Riviersonderend sites
Sites Ridge-
line Plateau
Side slope of hill,
mountain and/or
foothill
Closed
valley
Open
valley Plain
Undulating
plain/low hills
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 24
OB3 � �
OB4 � �
OB5 � � �
OB6 � � �
(b) Please provide a description of the location in the landscape.
The Bot River sites
OB1 This site is located on the Bot River, about 10 km north of the Bot River village and some 18 km from Caledon,
and just over 100 m south of out-buildings on the farm 'Kanaan', to the north-west. The river channel
upstream of the damaged bridge is densely infested with black wattle Acacia mearnsii.
Downstream of the bridge, the channel widens into a highly disturbed area denuded of vegetation, except
for black wattle along the fringes of the main channel and a smaller stream that enters the Bot River directly
downstream of the bridge, from the south-east.
The topography is dominated by the Groenlandsberg, directly west (Mount Lebanon: 1 201 mamsl), and hilly
terrain to the east. The site is about 200 m due west of the main connector between the R45 and R43 routes
south of the Theewaterskloof Dam. The landscape is intensively farmed with wheat and sheep.
OB2 The bridge at 'Doringkloof' is also located on the Bot River, about 4 km north of OB1, on the DR1288. The
damaged (southerly) approaches to the bridge skirt a minor seasonal watercourse, the Doringkloof River,
which joins the Bot River directly upstream of the bridge from the east.
An informal turn-off to 'Quaggaskloof' veers off the DR1288 to the east, about 50 m from the confluence of
the two watercourses. The latter track crosses the Doringkloof River directly upstream of the DR1288.
Upstream of the bridge, the Bot River is heavily infested with black wattle which continues downstream
along the banks of the channel. There is a dense stand of black wattle in the channel.
Downstream, the channel traverses a broad expanse of exposed shale with heaped piles of woody debris
against both banks, and in the channel itself. The flatter, low-lying areas in the vicinity of this site are
cultivated, and two dams lie to the south-east, alongside the DR1288. The terrain is similar to that at OB1.
The Riviersonderend sites (NOTE that all these sites are located on tributaries that join the Riviesonderend from the north,
i.e. these sites are not located on the main stream of the latter river).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 25
OB3 This site is located on the lower reaches of the Elandskloof River, where the DR1313 skirts the farm
'Meerlustkloof'.
The damaged bridge is located in a cultivated floodplain about 500 m upstream of the
Riviersonderend. The Elandskloof River runs through a relatively open valley, after dropping sharply
from the Riviersonderend Mountains into foothill reaches that start about 5 km upstream of the
damaged bridge. An extensive berm has been bulldozed between the left bank of Elandskloof River,
directly downstream of the bridge, and an eroded salient that intrudes into the floodplain, east of the
channel.
The DR1313 makes a wide bend to the north at the damaged bridge. Upstream of the structure, the
cobble-dominated channel is massively disturbed and denuded of vegetation, except for black
wattle along its edge. There is an extensive patch of kikuyu grass and ’fluitjiesriet' Phragmites australis
on the left bank of the river, upstream of the bridge. The latter area appears to mark the point at
which a minor flood channel branches off the Elandskloof River to the east (site OB4 is located on this
channel).
Downstream of the bridge, the Elandskloof River is separated from the DR1313 by a grassed meadow
that makes way for orchards directly to the south. The only infrastructure in this meadow is a former
evaporation tank, which is fenced but no longer in use.
A major irrigation pipe crosses the Elandskloof River just north of the point where it enters the
orchards, en route to the Riviersonderend (it has been suggested that this pipeline, which links the
remainder of the farm with two pump stations near the Riviersonderend, be routed via the new road
bridge to protect it from flood damage).
The floodplain extends east of the river, and is also occupied by orchards to the south. The area
directly north of the road is currently not cultivated and hosts scattered stands of alien acacias. A
row of six cottages extends along the northern side of the DR1313, to the west of the bridge. The
nearest cottage is about 70 m from the Elandskloof River.
The Helderstroom Prison is located on the DR1313, about 9 km to the west. This is primarily a fruit-
producing area, and the farm 'Meerlustkloof' (which is owned by Agrisouth Orchards SA (Pty) Ltd),
exports about 60% of its produce.
OB4 This minor pipe culvert lies about midway between the damaged bridge over the Elandskloof River
(site OB3) and the main entrance to 'Meerlustkloof', north of the DR1313. The distance between OB3
and OB4 is about 140 m. The channel at OB4 hosts 'fluitjiesriet' and dense stands of acacia north of
the DR1313. The surrounds are very similar to those described for OB3.
OB5 Sites OB4 and OB5 are separated by about 700 m. OB5 is a box culvert on an unnamed tributary of
the Riversonderend which drains through the farm 'Elandskloof' 59/2, directly east of 'Meerlusktloof'.
The 'Tarentaalkraal' recreational camp is situated directly north-west of OB5. It constitutes an
expansive grassed area, some 2 000 m2 in extent, that grades gently uphill towards the
Riviersonderend Mountains.
The watercourse in question is densely infested with black wattle upstream of the culvert, and
marginally less so downstream of structure, which drains into a wide open pool fringed by palmiet
Prionium serratum against its left bank. There is a depression upstream and west of the culvert that
seems to be considerably damper than the adjacent lawn on 'Tarentaalkraal'; this may serve as a
flood channel during elevated flows.
The only buildings in the vicinity of the site are a shed in a ploughed field to the north-west, and an
unoccupied building at the northern edge of the 'Tarentaalkraal' lawn. Otherwise, there do not
appear to be any permanently occupied buildings within a 500 m radius of the site.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 26
OB6 This site is located just east of the apex of a relatively tight northern bend in the DR1313, about 1 km
before it joins the DR1298. The Riviersonderend is about 600 m to the south.
This is open countryside with a rolling topography dominated by the Riviersonderend Mountains to
the north and typical 'Rûens'-type hills to the south. A homestead lies directly south of the DR1313, on
the right bank of the unnamed channel that is spanned by a single box culvert at this point. Besides
the farmhouse, the most distinctive built feature in the landscape is an earth dam that is situated
west of the homestead, between the DR1313 and the Riviersonderend.
Facing upstream from the culvert, there is a steep clay bank to the right (east), topped by indigenous
thicket-type vegetation, whereas the area west of the channel is occupied by bulrush Typha
capensis. There is an elevated bench in the channel several meters upstream of the culvert, which
may indicate a head-cut precipitated by excavations between this point and the culvert inlet. A
fence spans the channel here, and appears to trap debris, which may exacerbate plunge-induced
scour downstream of the obstruction during elevated flows.
The homestead is roughly equidistant from the road and the channel (about 70 m). Several mature
willows grow in and around the channel, directly below the road crossing. The banks of the channel
downstream of the culvert appear to be actively eroding, and flood overflow from the west has
scoured a donga between the road and a fenced-off orchard about 20 or 30 m to the south.
3. GROUNDWATER, SOIL AND GEOLOGICAL STABILITY OF THE SITE
(a) Is the site(s) located on or near any of the following (highlight the appropriate boxes)?
Bot River sites
Site Water
table <
1.5 m
deep
Season-
ally wet
soils
Un-
stable
rocky
slopes or
steep
slopes
with
loose
soil
Dis-
persive
soils
Soils with
high
clay
content1
Any
other un-
stable
soil or
geo-
logical
feature
An area
sensitive
to
erosion
An area
next to
or above
an
aquifer
An area
≤ 100m
of a
source
of sur-
face
water
OB1 No Yes No No Yes No No Unsure Yes
OB2 No Yes No No Yes No No Unsure Yes
Riviersonderend sites
Site Water
table <
1.5 m
deep
Season-
ally wet
soils
Un-
stable
rocky
slopes or
steep
slopes
with
loose
soil
Dis-
persive
soils
Soils with
high
clay
content
Any
other un-
stable
soil or
geo-
logical
feature
An area
sensi-
tive to
erosion
An area
next to
or above
an
aquifer
An area
≤ 100m
of a
source
of sur-
face
water
OB3 Potent-
ially
Yes No No Clays
overlaid
with
sand
No Yes Unsure Yes
OB4 Potent-
ially
Yes No No Clays
overlaid
No Yes Unsure Yes
1 Soil types derived from Mucina and Rutherford (Eds)(2006)
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 27
with
sand
OB5 Potent-
ially
Yes No No Clays
overlaid
with
sand
No Yes Unsure Yes
OB6 Potent-
ially
Yes No No Humic
soils,
clays
overlaid
with
sand
No Yes Unsure Yes
(b) If any of the answers to the above are “YES” or “unsure”, specialist input may be requested by the Department.
(Information in respect of the above will often be available at the planning sections of local authorities. Where it
exists, the 1:50 000 scale Regional Geotechnical Maps prepared by Geological Survey may also be used).
NOTE that the 'Groundwater Vulnerability Map of South Africa' (Council for Geoscience, 2011) describes groundwater
resources in the study area as being of 'Moderate' to 'Insignificant' vulnerability, with depth to groundwater ranging
from five to 30 m.
http://www.geohazard.org.za/images/docs/subsection_downloads/Groundwater_vulnerability.pdf
(accessed 5 April 2014).
(c) Please indicate the type of geological formation underlying the site.
Granite Shale � Sandstone � Quartzite � Dolomite Dolerite Other
(describe) �
Please provide a description
The rocks of the Groenlandberg and Riviersonderend Mountains are composed of auartzitic sandstones associated with
the formations of the Table Mountain Group. The more rolling, lower-lying relief between the sandstone ranges (i.e. the
Western Rûens that extend from Bot River towards Swellendam) is explained by the presence of shales within the
Bokkeveld Group. These formations consist of thick shale bands that alternate with sandstone units and are therefore
more susceptible to erosion than rocks in the underlying TMG sequence (Rebelo et al., 2006).
The type of parent material is reflected in the sediment that occurs in the different watercourses. The Bot River appears
to carry a relatively higher proportion of finer sediments (gravels and clay-rich silt) than the rivers that drain the
Riviersonderend Mountains to the east. Alluvial deposits in the high energy reaches of the latter channels are generally
coarser, with bed load being dominated by sandstone cobbles and rocks upstream of the DR1313. However, as the
vertical profile of channels flattens towards the Riviersonderend, hydrogeomorphologial sorting results in generally finer,
sand or gravel-dominated deposits as would be expected from dissipated flows.
There is no evidence of dispersive, soluble soils at any of the sites.
4. SURFACE WATER2
(a) Indicate the surface water present on and or adjacent to the site and alternative sites (highlight the appropriate
boxes)?
NB The following has bearing on reporting with respect to surface water and associated ecosystems:
− No coastal wetlands are presents as all the sites are inland of the Cape Fold Belt.
2 (cf Day, 2014; Table 3.2, and pp 15-26)
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 28
− The classification of river and wetland types follows the definitions provided by the National Wetland
Classification System (Ollis et al., 2013).
− Please see Section 5 ('Biodiversity') for a summary of freshwater features, their status as biodiversity conservation
priorities, and condition as observed during a site visit on 3 February 2014.
Bot River sites
Site River type Wetland type
OB1 Lower foothill river None present
OB2 Lower foothill river None present
Riviersonderend sites
Site River type Wetland type
OB3 Lower foothill river Channelled valley bottom wetland
OB4 Floodplain channel Channelled valley bottom wetland
OB5 Channelled valley bottom wetland
OB6 Channelled valley bottom wetland
(b) Please provide a description.
See Day (2014) for a comprehensive description of the types and condition of aquatic ecosystems at each site.
Department of Water Affairs 'ecoregions'
Sites OB1 and OB2 are located in the Bot River, which falls in Ecoregion 19 (Southern Folded Mountains), which is
characterised as follows:
− Closed hills and mountains, of moderate and high relief;
− A range of highly diverse vegetation types;
− Includes sections of the Riviersonderend, and Breede and Bot rivers – along which sites OB1 and OB2 are
located;
− Varied annual precipitation, between 100 and 1 500 mm MAP with a moderate to high Coefficient of
variation of annual precipitation;
− Rainfall falling mainly in very late summer to winter;
− Mean annual temperature of 10 to 20°C; and
− The Bot River is classified as a lower foothill river at sites OB1 and OB2.
Sites OB3-OB6 are located in Ecoregion 22 (Southern Coastal Belt Ecoregion). This ecoregion encompasses the rivers
in the southern portion of the Breede River Basin, and is characterised by:
− Terrain comprising low plains, closed hills with moderate relief, open hills with high relief, and low mountains
with high relief;
− Altitude that varies from 0 to 600 mamsl;
− Rock types include quartzitic sandstone, shale, sand and biotite granite overlain by sand-clay, sand-clay-
loam, loam-sand, clay-loam and sand-loam soils;
− Natural terrestrial vegetation that is dominated by a variety of thicket, fynbos and renosterveld, with patches
of forest in the Riversonderend range (in the present study area, NEFEPA vegetation data, based on the
Vegetation Map of South Africa, Lesotho and Swaziland (Mucina et al. (eds), 2005) classifies natural wetland
vegetation at the sites as Southwest Shale Fynbos); and
− Moderate rainfall (400 to >1 200 mamsl) and mean annual temperatures between 18 and 22 °C. Rainfall
ranges from winter to all year; heavy downpours associated with cut-off lows can be expected between
September and November.
− In terms of the NWCS (Ollis et al., 2013),
o the Elandskloof River at OB3 is a lower foothill river, associated with a valley bottom wetland
o the watercourse at OB4 is a floodplain channel, associated with a valley bottom wetland
o OB5 and OB6 are located in channelled valley bottom wetlands.
5. BIODIVERSITY
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 29
Refer to Appendix D1 for the Critical Biodiversity Area and NFEPA maps of the study domain.
This section requires that information be provided with respect to;
a) The applicable biodiversity planning categories of all areas on site and the reasons for their selection;
b) The condition of habitat on site, and the percentage natural, near natural, degraded and transformed habitat
present;
c) (i) The type of vegetation present, and its ecosystem status
(ii) Whether an aquatic ecosystem is present on site; and
d) A description of the vegetation type and/or aquatic ecosystem present on site, including any important
biodiversity features/information identified on site (e.g. threatened species and special habitats)
Note: Appendix D2 provides a tabulated summary of all the required biodiversity features, as well as a brief synopsis of
their implications for the proposed repairs. These aspects are considered in more depth in the impact assessment
(Section F). See Appendix G for a comprehensive ecological assessment of the proposed repairs (Day, 2014).
The biodiversity implications of the proposed repairs are presented below. The concluding section discusses how these
findings would inform the combined basic assessment.
(a) Critical Biodiversity Areas and Ecological Support Areas
The biodiversity plan for the Overberg District Municipality (Holness and Bradshaw, 2010) depicts Critical Biodiversity
Areas (CBAs) and Ecological Support Areas (ESAs) that represent the most spatially efficient network of sites for achieving
biodiversity conservation targets, maintaining ecosystem function and securing ecological connectivity across the
landscape in terms of ‘best design’ principles.
As indicated by the table below, all the sites in question fall within mapped CBAs or ESAs. The Ecological Importance
and Sensitivity (EIS), Present Ecological State (PES) of each river or wetland and condition of terrestrial habitat are also
provided (cf. Day, 2014). These findings are based on a site visit on 3 February 2014, i.e. in mid-summer.
Site CBA ESA Condition and importance of
aquatic ecosystems (rivers, wetlands)
Condition of terrestrial habitat
within a c. 100 m radius of each
site** EIS PES*
OB1 Yes Yes Moderate D D = 80; T = 20
OB2 Yes Yes Moderate D NN = 10; D = 60; T = 30
OB3 Yes Yes Low E D = 80; T = 20
OB4 No Yes Low C NN = 60; D = 40
OB5 No Yes Moderate C NN = 30; D = 50; T = 20
OB6 No Yes Low D/E NN = 20; D = 50; T = 30
*A = Unmodified/natural B = Largely natural C = Moderately modified D =
Largely Modified E = Seriously modified F = Critically/extremely modified
** NN = Near Natural D =
Degraded T = Transformed
See Appendix Dfor maps of the CBA status of the respective sites.
All the ESAs have been selected as being important supporting areas for maintaining hydrological processes. The CBAs,
in turn, have been selected with regard to the following criteria (cf Holness and Bradshaw, 2010; http://bgis.sanbi.org):
− Habitat required as part of the CBA network (i.e. critical for maintaining corridors, linkages and ecological
processes);
− Critical areas for maintaining hydrological processes;
− Areas with potential occurrences of (unspecified) threatened species or habitat;
− Potential occurrence of CR or EN habitat; and
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 30
− Areas important for protected habitats, such as wetlands and forests.
Loss of habitat and ecological functioning in CBAs must, as a first principle, be avoided. Alternatively, if degradation has
already occurred and may be perpetuated, steps must be taken to stem and rehabilitate the affected habitat to a
'natural' or 'near-natural' condition. Habitat loss can be contemplated with respect to ESAs, but without compromising
ecological processes, which would include maintaining a desired standard of water quality and the appropriate flow
regimes (in terms of volumes and seasonality) for the affected watercourses. Similarly, degradation or loss of both
terrestrial and aquatic habitats should not compromise the effective functioning of ecological and hydrological
processes.
(b) Freshwater Priority Ecosystem Areas
Maps produced for South Africa’s National Freshwater Ecosystem Priority Areas (NFEPA) project depict areas that have
been prioritised for conserving freshwater ecosystems and supporting sustainable use of water resources (Nel et al., 2011;
Day, 2014).
The NFEPA project has produced maps for seven types of priority freshwater ecosystems:
− River FEPAs and associated sub-quaternary catchments: Areas that are essential for achieving targets for river
ecosystems and threatened or near-threatened fishes and in a ‘natural’ (A) or ‘largely natural’ (B) ecological
condition; the sub-catchment must be managed to maintain an A or B condition;
− Wetland or estuary FEPAs:;
− Wetland clusters: These are groups of wetlands in relatively natural landscapes that must be managed in
support of maintaining ecological processes;
− Fish sanctuaries and associated sub-catchments: Rivers in an A or B condition that are essential for protecting
threatened and near-threatened indigenous freshwater species;
− Fish support areas and associated sub-catchments: Rivers with an ecological condition lower than A and B that
are important for conserving and supporting the migration of threatened or near-threatened indigenous fish
species
− Upstream management areas: These are sub-quaternary catchments that need to be managed to prevent
degradation of downstream FEPAs and fish support areas
− Free-flowing rivers: These are represented by 19 rivers nationally that, due to their rarity as unimipounded
systems, should never be dammed.
The following findings were made regarding the FEPA status of rivers and wetlands at each site (cf Day, 2014, Table 3.2):
River FEPAs or
Associated sub-
quaternary catchments
None of the sites are located in Phase 2 FEPAs, or mapped as River FEPAs or Associated sub-
quaternary catchments
Wetland FEPAs All of the sites are depicted as Wetland FEPAs (note, however, that no wetlands were
identified by aquatic ecologist with respect to sites OB1 and OB2).
FEPA attributes Threatened crane species have been sited at wetlands in the respective sub-quaternary
catchments
As with CBA maps, FEPA maps promote an ecosystem perspective in environmental assessment in that they introduce a
broader scale to impact identification than is often the case with site or property-specific impact assessment. These
maps emphasise the functional attributes of biodiversity by providing spatial or geographic surrogates for ecological
processes that may otherwise not be readily evident if an assessment were limited to a particular site or property
(Cadman et al., 2013).
FEPAs are often tributaries or rivers that support “hard working” rivers downstream (that is, rivers that are heavily utilised or
impacted by agricultural, industrial or other human activities) (Driver et al., 2011; Day, 2014). They need to stay (or get
into) good condition to manage and conserve freshwater ecosystems and to protect downstream water resources for
human use. Driver et al (2011) stress however that FEPAs do not necessarily need to be protected from all human use.
Rather, they should be supported by good planning, decision-making and management to ensure that human use does
not impact on their condition or on the important resources they may protect downstream.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 31
The extent of degradation of wetlands and rivers in South Africa means that even systems considered in the best relative
condition for a particular ecosystem type may be highly degraded. Nevertheless, the recommended condition for all
river and wetland FEPAs is an Ecological Category A or B, indicative of a system that is in an unmodified/natural to
largely natural condition respectively (Driver et al 2011).
None of the affected rivers have been identified as FEPAs. Sites OB3 to OB6 are located in channelled valley bottom
wetlands mapped as wetland FEPAs. From an NFEPA perspective, mitigation and rehabilitation at the latter four sites
should aim to guide recovery towards a PES of A or B.
(c) Wetland types
Following the South African Wetland Classification System (Ollis et al., 2013), the respective sites have been found to
occur in proximity to the following river and wetland types (Day, 2014, Table 3.2, pp 15-26):
Sites River/watercourse River/wetland type
(Ollis et al., 2013)
Findings
(Day 2014, Table 3.2)
OB1 & OB2 Bot
Valley floor floodplain wetlands
No wetlands identified at OB1 and
OB2
OB3 Elandskloof
All other sites ground-truthed as
channelled valley bottom wetlands
OB4 Elandskloof (flood channel)
OB5 Unnamed watercourse
OB6 Unnamed watercourse
(d) Vegetation types and ecosystem status
According to the Vegetation Map of South Africa, Lesotho and Swaziland (Mucina et al. (eds), 2005): the sites may
correspond with the following vegetation types (the 2011 ecosystem status of each is also provided):
Sites Vegetation type
Ecosystem status
(CR = Critically
Endangered EN =
Endangered)
OB1 Western Rûens Shale Renosterveld (FRs 11) CR
OB2 Western Rûens Shale Renosterveld (FRs 11) CR
OB3 North of DR1313: Greyton Shale Fynbos (FFh 7) EN
South of DR1313: Central Rûens Shale Renosterveld (FRs 12) CR
OB4 North of DR1313: Greyton Shale Fynbos (FFh 7) EN
South of DR1313: Central Rûens Shale Renosterveld (FRs 12) CR
OB5 North of DR1313: Greyton Shale Fynbos (FFh 7) EN
South of DR1313: Central Rûens Shale Renosterveld (FRs 12 CR
OB6 Greyton Shale Fynbos (FFh 7) EN
(e) Habitat condition at the respective sites
The table at 5(a) provides three measures of ecosystem or habitat condition, two of which directly address the
ecological importance and condition of aquatic ecosystems (Ecological Importance and Sensitivity, and Present
Ecological State respectively) and, more broadly, the condition of terrestrial habitat within a roughly 100 m radius of
each site (cf Day (2014, pp 11-14) for a comprehensive explanation of methods for ascertaining the importance and
condition of aquatic ecosystems). To this must be added the evaluation of habitat condition reflected in the Critical
Biodiversity Areas Map for the Overberg District Municipality (Holness and Bradshaw, 2010).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 32
Ecological Importance and Sensitivity (EIS) defines the ecological importance of a river as an expression of its
importance to the maintenance of ecological diversity and functioning on local and wider scales, while ecological
sensitivity refers to the system’s ability to resist disturbance, as well as its resilience. Both abiotic and biotic components of
the system are taken into consideration in the assessment of ecological importance and sensitivity. EIS ratings are
strongly biased towards the potential importance and sensitivity of particular system under unimpaired conditions. This
means that the present ecological status or condition (PES) is generally not considered in determining the ecological
importance and sensitivity per se (Day, 2014).
Present Ecological State (PES) describes a river according to its ecological status or health compared to natural or
'reference' conditions. Determining the PES of a river constitutes one of three components of the EcoClassification
process recommended by the Department of Water Affairs (the other two components of EcoClassification are the EIS
and reference condition of a river). PES is expressed by a scale ranging from 'A' (i.e. a river or reach is in a natural,
unmodified condition) to 'F' (which reflects critical or extreme modification), relative to the 'reference' or natural
condition of the river or reach subject to assessment.
The condition of terrestrial habitat was estimated visually, on site.
None of the aquatic features of the respective sites is in a natural or near-natural condition and their PES is either
'moderately', 'largely' or 'seriously modified'. This is attributed inter alia to:
− Infestation of channels and riparian areas by woody alien plants (specifically black wattle) (sites OB1, OB2, OB3
and OB6);
− Erosion and/or sedimentation (OB1, OB2, OB3 and OB6);
− Loss of indigenous vegetation (OB1, OB2, OB3 and OB6); and
− Channel constriction and confinement of flows (OB1, OB2, OB3 and OB4) (Day, 2014).
Only two sites – OB4 and OB5 – have a PES of 'C' (moderately modified); the remainder are 'largely' to 'seriously'
modified. OB5 has the highest overall rating in terms of its EIS and PES (Moderate, and 'C' respectively).
Woody alien plants contribute significantly to poor PES scores and habitat degradation beyond the immediate channel
margins of the respective watercourses. This is reflected in the condition of terrestrial habitat which has been
fundamentally transformed by cultivation (as would be expected in this particular region of the Western Cape where
shale-based soils have supported cereal cultivation for many decades). Greyton Shale Fynbos, an EN vegetation type, is
almost exclusively restricted to the foothills of the Riviersonderend Mountains. No occurrences of CR Western and Central
Rûens Shale Renosterveld were evident at any of the sites. The road reserves in the immediate vicinity of all of the sites
are in a highly disturbed condition and do not, at least locally, appear to serve as vegetation refugia or ecological
corridors in what is a highly transformed and fragmented landscape (cf. Esler and Milton, 2006).
The respective, freshwater and terrestrial, assessments of terrestrial habitat quality are supported by the CBA Map for the
Overberg District Municipality (Holness and Bradshaw, 2010) which described all the CBAs and ESAs at the six sites as
being either degraded or transformed (chiefly by road infrastructures and farmland).
(f) Potential biodiversity significance of the respective sites and related ecosystems
As indicated above at Section B(5)(a), (b) and (d), all of the sites in question have been mapped as coinciding with
priority features for biodiversity conservation and the potential occurrence of habitat in threatened ecosystems. All the
sites are either within CBAs or ESAs, or both, FEPA wetlands (excluding sites OB1 and OB2), and Critically Endangered or
Endangered ecosystems. Contextually, therefore, all these sites and their environs must be viewed as having high
biodiversity significance.
At the same time, however, all the sites and their associated catchments are moderately to seriously modified as a result
of channel constriction, alien infestation, erosion, infrastructure development and cultivation. Only two sites (OB4 and
OB5) have an observed (current) PES of 'C' or 'moderately modified'; the observed PES of the remainder of site ranges
from 'D' ('largely modified' to 'E' or 'seriously' modified. This not to say that the sites are not conservation-worthy; that is
clearly not the case. However, if the ecological condition of the sites remains unchanged – or worsens – their current
contribution to the achievement of the Overberg CBA network and national targets for wetland conservation is limited.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 33
6. LAND USE OF THE SITE
(a) Land use
All the sites constitute integral, established components of the provincial rural road network. The proposed works entail
repairing established road infrastructure that was damaged by floods in August 2012. All the roads involved in this
application (the DR1288 and DR1313) are gravelled.
The structures in question (bridges and box or pipe culverts) are per definition located within watercourses. In some
cases, approaches are shored up or supported by raised embankments. All sites are rural in character with agriculture
(both intensive and extensive) and privately-owned conservation areas being the dominant land uses. Most of the sites
are within 5 to 10 km of mountains. One site (OB3) is located 3 km from a provincial nature reserve and another (OB1)
within 3 km of a Mountain Catchment Area. In neither case would the proposed repairs have any impact on the values
that assign significance to mountain catchment areas or the integrity of provincial nature reserves.
The Groenlandberg and Riviersonderend Mountains in the west and north respectively provide a bold topographical
backdrop to the study domain, which is located between the latter features and the wheat lands of the Western Rûens.
The Bot River and Riviersonderend are important regional rivers which, owing to dense infestations by particularly black
wattle Acacia mearnsii are largely hidden from view. Other than being associated with rural landscapes and farms,
none of the sites has particular heritage value. See Appendices A and B for locality maps and photographs of the sites
respectively.
(b) Description.
All six sites form part of the existing provincial road network at the specified locations and adjacent to specified rivers.
7. LAND USE CHARACTER OF SURROUNDING AREA
(a) Highlight the current land uses and/or prominent features that occur within +/- 500m radius of the site and
neighbouring properties if these are located beyond 500m of the site.
The Bot River sites
Untransformed area Low density residential Medium density
residential High density residential Informal residential
Retail Commercial &
warehousing Light industrial Medium industrial Heavy industrial
Power station Office/consulting room
Military or police
base/station/com-
pound �
Casino/entertainment
complex
Tourism & Hospitality
facility �
Open cast mine Underground mine Spoil heap or slimes
dam
Quarry, sand or borrow
pit Dam or reservoir �
Hospital/medical
centre School
Tertiary education
facility Church Old age home
Sewage treatment
plant
Train station or shunting
yard Railway line
Major road (4 lanes or
more) Airport
Harbour Sport facilities Golf course Polo fields Filling station
Landfill or waste Plantation Agriculture � River, stream or Nature conservation
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 34
treatment site wetland � area �
Mountain, koppie or
ridge � Museum Historical building Graveyard Archaeological site
Other land uses
(describe):
Sites OB1 and OB2 are situated in the Vanderstel Pass, about 4 km apart by road. They are both
surrounded by farmland. The 'Porcupine Hills Guest Farm' (Ph 028 284 9066) is located about 1 km
north of OB2, on the far side of a ridge. OB1 is situated about 3 km from the Hottenots Holland MCA,
to the west. There are two earth dams that lie parallel to the DR1288, immediately to the south-east
of the approaches to the site.
The Riviersonderend sites
Untransformed area Low density residential Medium density
residential High density residential Informal residential
Retail Commercial &
warehousing Light industrial Medium industrial Heavy industrial
Power station Office/consulting room Prison � Casino/entertain-ment
complex
Tourism & Hospitality
facility �
Open cast mine Underground mine Spoil heap or slimes
dam
Quarry, sand or borrow
pit Dam or reservoir �
Hospital/medical
centre School
Tertiary education
facility Church Old age home
Sewage treatment
plant
Train station or shunting
yard Railway line
Major road (4 lanes or
more) Airport
Harbour Sport facilities Golf course Polo fields Filling station
Landfill or waste
treatment site Plantation Agriculture �
River, stream or
wetland �
Nature conservation
area �
Mountain, koppie or
ridge � Museum Historical building Graveyard Archaeological site
Other land uses
(describe):
As with the Bot River sites, the four bridges/culverts on the DR1313 traverse an agricultural landscape
in a corridor between the Riviersonderend and the mountains that bear its name. The Helderstroom
Maximum Security Prison (Tel 028 215 1000) is situated about 9 km to the west of OB3, just north of the
Riviersonderend. This correctional services facility is entirely dependent on the DR1313 for access to
the outside world when the main road bridge over the Riviersonderend is flooded – and when the
bridge at OB3 has been put out of action owing to flood damage (as in October 2012), staff and
prisoners have had to be routed to and from the prison via an emergency crossing over the
Elandskloof River on the farm 'Meerslustkloof'. There is a campsite at 'Tarentkraal', directly north-west
of OB5 and an earth dam about 100 m west of the 'Nooitgedacht' site, OB6.
(b) Please provide a description, including the distance and direction to the nearest residential area and industrial area.
There are no residential areas within 5 km of any of the sites. The nearest settlement to OB1 and OB2 is Bot River, next to
the N2 and about 10 km to the south by road. The other sites are roughly 20 km due north of Caledon, but further by
road. OB6 is some 15 km by road from Greyton, which lies to the east.
8. SOCIO-ECONOMIC ASPECTS
Describe the existing social and economic characteristics of the community in order to provide baseline information.
All the sites are located within the Theewaterskloof (TWK) Local Municipality, which falls under the Overberg District
Municipality. The TWK Municipality spans the N2 national road between Grabouw and Stormsvlei. Its northern boundary
coincides with the Riviersonderend Mountains, while the Kleinrivierberge and the northern exent of the Agulhas Plain
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 35
broadly delineate its southern aspects. The TWK Local Municipality is based in Caledon, and the Oberberg District
Municipality in Bredasdorp.
The total population of the TWK Municipality was about 106 000 in 2009, representing some 44% of the total population of
the Overberg District Municipality. The official unemployment rate (using the broader definition) in the TWK Municipality was
just under 40%. Local estimates of out-of-season unemployment are even higher. There is extensive poverty in the area, with
20% of households registered as indigent.
Agricultural production generates 36.47% of the local economy, making this the predominant economic activity???? in the
TWK Municipality.
The TWK Municipality is responsible for local roads which lie within the boundaries of the towns. Roads outside the town area
are the responsibility of the Overberg District but TWK acts on an agency basis for the District. Other than the pass through
freight on the N2, the road based freight transport in the region is almost entirely related to agricultural activity. Roads
Division receives grant-funding from the Provincial Department of Transport and Public Works and acts as a Provincial Agent
for the maintenance of the network of main, divisional and minor roads. This includes all activities relating to the
maintenance of 3 685 km of proclaimed roads in the Overberg District, of which more than 70% are unpaved.
The functions of the Road Division of the Overberg District Municipality include:
− Maintaining, repairing, protecting and managing the proclaimed Provincial Roads in the Overberg area;
− Resealing of surfaced roads;
− Regravelling of gravel roads; and
− Effecting initial repairs of flood damage to road infrastructure.
Sources:
Theewaterskloof Municipality, Third Generation IDP (2012-2017)
Overberg District Municipality, Third Generation IDP (2012-2016).
9. HISTORICAL AND CULTURAL ASPECTS
Is section 38 of the National Heritage Resources Act, 1999, applicable to the development? YES NO �
UNCERTAIN
If YES, explain: N/A. None of the projects trigger any of the thresholds prescribed in s 38 of the NHRA, 25 of1999.
Will the development impact on any national estate referred to in section 3(2) of the National
Heritage Resources Act, 1999?
YES NO �
UNCERTAIN
If YES, explain: N/A
Will any building or structure older than 60 years be affected in any way? YES NO � UNCERTAIN
If YES, explain: N/A
10. APPLICABLE LEGISLATION, POLICIES AND/OR GUIDELINES
(a) Please list all legislation, policies and/or guidelines that have been considered in the preparation of this Basic
Assessment Report.
LEGISLATION ADMINISTERING
AUTHORITY
TYPE
Permit / license / authorisation /
comment / relevant consideration
DATE
(if already obtained):
National
Environmental
Management Act
Department of
Environmental Affairs
& Development
Environmental Authorisation Pending
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 36
(107 of 1998) (NEMA),
as amended
Planning (DEA&DP)
EIA Regulations 2010
promulgated in terms
of Section 24(5) of
NEMA as amended
DEA&DP Environmental Authorisation Pending
National Water Act
(No. 36 of 1998)
Department of Water
Affairs (DWA)
The General Authorisation that
potentially exempts water users
from having to obtain a water use
licence in terms of sections 21(c)
and (i) of the National Water Act
may be applicable. Such
‘permissible use' does, however,
have to be registered (cf. GN
1199 of 18 Dec 2009), unless works
constitute an existing lawful use.
The Draft Combined BAR will be
sent to the Breede-Overberg
CMA and the Department of
Water Affairs for this
consideration.
POLICY/ GUIDELINES ADMINISTERING AUTHORITY
Guideline on interpretation of listed activities (June 2010) Department of Environmental Affairs (DEA)
Guideline on public participation (October 2013) DEA&DP
Guideline on alternatives (October 2013) DEA&DP
Guidelines for involving specialists in EIA processes (2005) DEA&DP
Guideline on need and desirability (October 2013) DEA&DP
CBA Map for the Overberg District Municipality (2010)
Atlas of National Freshwater Ecosystem Priority Areas (2011)
DEA&DP/CapeNature
SANBI
(b) Please describe how the legislation, policies and/or guidelines were taken into account in the preparation of this
Basic Assessment Report.
LEGISLATION / POLICY /
GUIDELINE
DESCRIBE HOW THE LEGISLATION / POLICY / GUIDELINE WERE TAKEN INTO ACCOUNT
(e.g. describe the extent to which it was adhered to, or deviated from, etc).
NEMA, EIA Regulations 2010
This Draft Combined Basic Assessment Report (BAR) was compiled in terms of Reg 14 of
the NEMA EIA Regulations 2010 (Government Notice No. R543). The applicable
requirements of the EIA Regulations 2010 were adhered to during the compilation of this
report.
National Water Act (No 36 of
1998)
The Draft Combined BAR will be submitted to BOCMA and the DWA for consideration in
accordance with the National Water Act. Also see Section 10(a) above.
National Heritage Resources
Act (No. 25 of 1999)
The Draft Combined BAR will be sent to HWC for consideration. Also see Section 10(a)
above.
Guidelines associated with
2010 NEMA EIA Regulations as
listed under 10 (a) above
These guidelines were consulted in the undertaking of the Basic Assessment process
(including public participation) and the preparation of the Draft Combined BAR and
associated specialist studies
CBA map (2010)and NFEPA
atlas (2011)
The CBA Map for the Overberg District Municipality and Atlas of Freshwater Ecosystem
Priority Areas were consulted to determine the strategic biodiversity importance of the
respective sites, the reasons for their selection as CBAs or ESAs, and whether the proposed
projects would have a significant detrimental effect on the achievement of biodiversity
conservation objectives in these areas.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 37
SECTION C: PUBLIC PARTICIPATION
Please highlight the appropriate box to indicate whether the specific requirement was undertaken or whether there was
a deviation that was agreed to by the Department.
1. Were all potential interested and affected parties notified of the application by –
(a) fixing a notice board at a place conspicuous to the public at the boundary or on the fence of -
(i) the site where the activity to which the application relates is to be
undertaken; and YES � DEVIATED
(ii) any alternative site mentioned in the application; N/A* YES DEVIATED
(b) giving written notice to –
(i) the owner or person in control of that land if the applicant is not the owner or
person in control of the land; YES N/A �
(ii) the occupiers of the site where the activity is to be undertaken and to any
alternative site where the activity is to be undertaken; YES � DEVIATED
(iii) owners and occupiers of land adjacent to the site where the activity is to be
undertaken and to any alternative site where the activity is to be undertaken; YES � DEVIATED
(iv) the municipal councillor of the ward in which the site and alternative site is
situated and any organisation of ratepayers that represent the community in
the area;
YES � DEVIATED
(v) the municipality which has jurisdiction in the area; YES � DEVIATED
(vi) any organ of state having jurisdiction in respect of any aspect of the activity;
and YES � DEVIATED
(vii) any other party as required by the competent authority; YES � DEVIATED
(c) placing an advertisement in -
(i) one local newspaper; and YES � DEVIATED
(ii) any official Gazette that is published specifically for the purpose of providing
public notice of applications or other submissions made in terms of these
Regulations;
YES DEVIATED N/A �
(d) placing an advertisement in at least one provincial newspaper or national
newspaper, if the activity has or may have an impact that extends beyond
the boundaries of the metropolitan or local municipality in which it is or will
be undertaken.
YES DEVIATED N/A �
* No alternative sites are available as the activity entails upgrading and repairs to existing road infrastructure.
2. Provide a list of all the state departments that are to be consulted:
• Breede-Overberg Catchment Management Agency
• CapeNature
• Department of Agriculture, Forestry and Fisheries
• Department of Correctional Services
• Department of Water Affairs;
• Heritage Western Cape;
• Overberg District Municipality.
• Theewaterskloof Local Municipality; and
• Western Cape Department of Agriculture
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 38
3. Please provide an overall summary of the Public Participation Process that was followed. (The detailed outcomes of
this process must be included in a comments and response report to be attached to the final Basic Assessment Report
(see note below) as Appendix F).
A list of steps undertaken as part of the public participation process is presented below. All supporting information is
presented in Appendix F.
• A preliminary list of I&APs was compiled consisting of landowners of properties adjacent to road infrastructure,
authorities (local and regional), ward councillors, agricultural associations and other key stakeholders (see
Appendix F1).
• Site notices (in Afrikaans and English) were erected at each site on 11 April 2014. Interested and affected parties
were invited to register as I&APs before 10 May 2014. Photographs of the site notices in situ have been included as
an appendix.
• The Draft BAR was released for a 40-day period of public comment (which included an additional day to
compensate for a public holiday) from xxx to xxxx
• A notice announcing the availability of the DBAR for public comment was published in xyz on xyz (see Appendix
F3).
• Copies of the DBAR were made available at the following locations:
1. xxx
2. Offices of BolandEnviro cc;
3. On the BolandEnviro website, www.bolandenviro.co.za;
• Copies of the Draft BAR were also sent to: CapeNature; the Western Cape Department of Agriculture; the
Department of Agriculture, Forestry and Fisheries; the Department of Water Affairs; the Theewaterskloof
Municipality and the Overberg District Municipality for comment.
• I&APs have been requested to submit comment on the Draft BAR by.
• All comment received by BolandEnviro from I&APs will be captured in a comments and responses report to be
circulated with the Final Combined BAR. The latter and I&AP comment will be be forwarded directly to DEA&DP
for consideration.
• After DEA&DP has reached a decision, all I&APs on the project database will be notified of the outcome of the
application, the reasons for the decision and the associated appeal process.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 39
SECTION D: NEED AND DESIRABILITY
1. Is the activity permitted in terms of the property’s existing land use rights? YES � NO Please explain
The proposed projects would entail upgrading and maintenance of existing infrastructure as part of a provincial road network.
2. Will the activity be in line with the following?
(a) Provincial Spatial Development Framework (PSDF) YES � NO Please explain
The PSDF refers to the provision of well-maintained and safe road networks, which matches the Basic Services and
Infrastructure KPA of the Overberg District Municipality, insofar as it commits the district municipality to "(keeping) the
proclaimed Provincial Roads in a safe and reliable condition within the legal framework of the various Ordinances, Acts and
Regulations..."
Source:
Overberg District Municipality, Third Generation IDP (2012-2016).
(b) Urban edge / Edge of Built environment for the area YES � NO Please explain
All the projects are outside the urban edge.
(c) Integrated Development Plan (IDP) and Spatial Development Framework of
the Local Municipality (e.g. would the approval of this application
compromise the integrity of the existing approved and credible municipal
IDP and SDF?).
YES � NO Please explain
The proposed project entails road maintenance and upgrading of existing road infrastructure, which is compatible with the
IDP of the Overberg District Municipality.
(d) Approved Structure Plan of the Municipality YES � NO Please explain
The proposed project entails essential maintenance and upgrading of existing road infrastructure which does not require any
decisions pertaining to changes in land use rights, departures or zoning.
(e) An Environmental Management Framework (EMF) adopted by the
Department
(e.g. Would the approval of this application compromise the integrity of the
existing environmental management priorities for the area and if so, can it
be justified in terms of sustainability considerations?)
YES NO Please explain
N/A. There is no approved Environmental Management Framework for the study area.
(f) Any other Plans (e.g. Guide Plan) YES NO � Please explain
No other plans are applicable to the respective projects or the decisions that is the object of this application.
3. Is the land use (associated with the activity being applied for) considered
within the timeframe intended by the existing approved Spatial Development
Framework (SDF) agreed to by the relevant environmental authority (i.e. is
the proposed development in line with the projects and programmes
identified as priorities within the credible IDP)?
YES NO Please explain
N/A. The proposed project entails essential maintenance and upgrading of existing provincial road infrastructure.
4. Should development, or if applicable, expansion of the town/area
concerned in terms of this land use (associated with the activity being
applied for) occur here at this point in time?
YES � NO Please explain
The repairs and maintenance work have been prioritised to improve the safety of the affected public roads, to prevent
potential further damage to this infrastructure, and to curb further degradation of the affected watercourses. Repairs to the
bridge over the Elandskloof River (OB3) are particularly urgent owing to its crucial strategic importance to the Helderstroom
Maximum Security Prison.
5. Does the community/area need the activity and the associated land use
concerned (is it a societal priority)? (This refers to the strategic as well as local
level (e.g. development is a national priority, but within a specific local
context it could be inappropriate.)
YES � NO Please explain
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 40
The structures on the DR1288 provide a direct link, via Bot River, between the N2 and the Vyebom-Villiersdorp areas, and from
Vyeboom to Caledon via the R43. South-bound traffic diverted at OB2 will have to drive an additional 33 km if headed for the
N2 via the DR1288 and R43. The structures on the DR1313, in turn, provide an important route for farms and communities north
of the Riviersonderend River, but at certain times of the year are also of great importance to the Helderstroom Maximum
Security Prison. This is because the prison’s primary access (via the tarred section of DR1313 south of the prison) is sometimes
impassable for several weeks as a result of flooding. During such periods, the gravel portion of DR1313 serves as the prison’s
only access (and, when the bridge over the Elandskloof River is out of order, an emergency drift on the farm 'Meerlustkloof'
provides the only connection with the prison and the outside world).
Source:
Bergstan, 2013
6. Are the necessary services with adequate capacity currently available (at
the time of application), or must additional capacity be created to cater for
the development? (Confirmation by the relevant Municipality in this regard
must be attached to the final Basic Assessment Report as Appendix E.)
YES NO Please explain
N/A: The repairs fall within the exclusive legislative mandate and powers of the Provincial Government of the Western Cape,
which is responsible for designing, managing and repairing provincial roads. The Executive Manager: Provincial Roads and
Transport Management Branch in the Department of Transport and Public Works has the authority and capacity to undertake
the works that are the subject of this application for environmental authorisation.
7. Is this development provided for in the infrastructure planning of the
municipality, and if not what will the implication be on the infrastructure
planning of the municipality (priority and placement of services and
opportunity costs)? (Comment by the relevant Municipality in this regard
must be attached to the final Basic Assessment Report as Appendix E.)
YES NO Please explain
N/A. The relevant road sections form part of the existing provincial road infrastructure under the management control of the
Provincial Department of Transport and Public Works: Roads Infrastructure Branch and fall outside of the urban edge of the
local municipalities. The Overberg DM manages these roads on behalf of the provincial transport department on an agency
basis.
8. Is this project part of a national programme to address an issue of national
concern or importance? YES NO Please explain
N/A. The proposed projects entail either rebuilding or repairing and refurbishing existing provincial road infrastructure.
9. Do location factors favour this land use (associated with the activity applied
for) at this place? (This relates to the contextualisation of the proposed land
use on this site within its broader context.)
YES � NO Please explain
The proposed projects entail rebuilding, repairing and refurbishing existing public transport infrastructure.
10. How will the activity or the land use associated with the activity applied for, impact on sensitive natural and cultural areas
(built and rural/natural environment)?
There are six projects of which two entail rebuilding damaged bridges (OB1 and OB3), and variously repairing and refurbishing
the remainder of the structures. Anticipated biophysical and other impacts are addressed in the impact assessment (Section
F). Enhanced flow capacity, improved sediment throughput and additional scour protection will have the effect of preventing
or at least mitigating the type and extent of environmental degradation that may have been associated with the structures
prior to their repair and/or refurbishment.
11. How will the development impact on people’s health and well-being (e.g. in terms of noise, odours, visual character and
sense of place, etc)?
The proposed projects would, overall, result in a positive impact on people’s health and well-being as they would contribute
to the safety and utility of road infrastructure at all the proposed project sites. In the short term (during construction), there may
be some inconvenience to traffic, and noise and dust levels may increase locally (it may be necessary to temporarily close
the crossing at OB2 for up to three weeks to accommodate construction activities at the site). The temporary disruption of
traffic would be offset by the fact that none of these roads is a major thoroughfare, and that the repairs would probably be
viewed favourably by most motorists (and especially local residents). The total annual average daily traffic at sites OB1 and O2
is less than 100 vehicles per day, and that at sites OB3 to OB6 less than 200 vehicles per day (Bergstan, 2013).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 41
14. Is the development the best practicable environmental option for this
land/site? YES � NO Please explain
The 'best practicable environmental option' is the option or alternative that provides the most benefit or causes the least
damage to the environment as a whole, at a cost acceptable to society, in the long term as well as the short term (cf s 1(1)(iii)
of NEMA 107/1998).
The proposed projects would entail repairing and maintaining existing infrastructure as part of the provincial road network. In
the case of OB1, the new, single-span culvert is designed to pass the 1:10-year flood. At OB3, significantly enlarged culvert
openings, embankment slope protection and scour aprons have been designed to accommodate 1:2-year floods with
frequent over-topping. Besides reducing the vulnerability of these structures to flood damage, increased hydraulic capacity
will allow larger flows and debris loads to move through the structures which will help to promote the stability of the affected
channels.
Although adverse, long-term impacts on aquatic ecosystems in the direct vicinity of the structures cannot be conclusively
discounted, the repaired and refurbished structures represent a significant improvement on their predecessors in terms of
minimising adverse impacts on flows and erosion and, over time, should contribute to measurable improvements to the
condition and stability of in-stream habitats.
Overall, the proposed road repairs would bring about a reduction in long-term environmental damage that, even if were
residual negative impacts to persist, would be of considerably less significance than had prevailed previously at the respective
sites. The repairs represent an indisputable contribution to public wellbeing that can be achieved and maintained at a
minimal detrimental cost to the environment.
12. Will the proposed activity or the land use associated with the activity applied
for, result in unacceptable opportunity costs? YES NO � Please explain
The proposed projects entail repairing and maintaining existing provincial road infrastructure to improve the safety and
lifespan of the structures, and to prevent further degradation to the affected aquatic ecosystems. The public participation
process is aimed at inter alia identifying such opportunity costs, if raised as concerns by interested and affected parties.
13. What will the cumulative impacts (positive and negative) of the proposed land use associated with the activity applied for
be?
No negative cumulative impacts related to the proposed activities have been conclusively identified a site-specific scale.
Generally, it is assumed that improved culvert design, particularly by the introduction of increased flow space and/or scour
protection, is expected to reduce flow concentration and the risk of downstream erosion and habitat degradation, which
would be a positive impact.
Conversely, if erosion is allowed to persist, it will almost certainly result in further damage to agricultural land and infrastructure,
as well as having a cumulative, negative, impact on aquatic habitats, biota and ecological processes.
As with other flood repair projects in the Overberg area, any environmental benefits issuing from the new or upgraded
structures will largely be annulled by the impacts of intense floods and heavy sediment burdens that are directly linked to the
degraded and destabilised condition of most of the affected catchments in this intensively-farmed region. Similarly, failure to
keep channels clear of invasive alien plants will mean that the structures remain vulnerable to the impacts of down-cutting,
erosion and enhanced sediment transport.
One of the most evident positive cumulative impacts relates to the improvement and maintenance of a high quality rural
road network which holds manifest benefits across the socio-economic spectrum.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 42
15. What will the benefits be to society in general and to the local communities? Please explain
The proposed projects would improve road safety and prevent potential further damage or eventual collapse of the road
infrastructure in future flood events (which is potentially imminent in the case of the damaged structures at OB1 and OB3). As
explained above, the DR1313 represents the only link between the maximum security Heldestroom Prison and the outside
world when the bridge across the Riviersonderend is made impassable by floods.
The maintenance of robust rural transport infrastructure is essential to ensure the continued viability of particularly agricultural
activities, which represent the mainstay of the rural economy. A safe and effective road network is also exceedingly important
for farming and rural communities who rely on health and welfare facilities in local towns such as Villiersdorp and Caledon.
It is anticipated that employment opportunities would be available to a limited number of people from the local communities
during the construction phase. The Contractor would also contribute to the local economy for the duration of the contract
period.
16. Any other need and desirability considerations related to the proposed activity? Please explain
None.
17. Please describe how the general objectives of Integrated Environmental Management as set out in section 23 of NEMA
have been taken into account.
The general objectives of IEM have been given effect as follows:
− The National Environmental Management Principles (specifically those relating to the primacy of human need in
environmental management and the prevention of environmental degradation) are key informants to this application;
− The impact assessment has been informed by the consideration of feasible and reasonable alternatives in support of
selecting the best practicable environmental option for each of the repaired structures;
− The combined basic assessment process has aimed to inform, where feasible, amendments to the engineering designs
so as to proactively accommodate and respond to particularly ecological concerns. Construction-related impacts have
been anticipated and would be mitigated by means of an Environmental Management Programme, which also
doubles as a management plan for post-construction maintenance of the immediate environs of the respective
structures;
− Interested and affected parties have been involved in the environmental assessment by means of a robust consultation
process;
− The environmental assessment has sought, inasmuch as it is reasonably possible to do so, to identify and analyse all
significant environmental factors that are relative to the decision that is being sought; and
− Established techniques for identifying, assessing and avoiding significant residual environmental harm and promoting
environmental and societal benefits arising from the project have been pursued throughout.
18 Please describe how the principles of environmental management as set out in section 2 of NEMA have been taken into
account
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 43
The proposed projects would contribute to the maintenance of essential provincial road infrastructure and have a positive
impact on road safety and the security of the rural road network in the western Overberg. This directly addresses reasonable
human needs.
Adverse impacts associated with the current, damaged, crossings at OB1 and OB3 included road approaches being washed
away, major erosion downstream, physical damage to the causeway in the case of the pipe culvert crossing at OB3, and
disrupted road transport. The repaired and refurbished bridges and culverts would contribute substantially to reducing
environmental degradation by improving the hydraulic capacity of the structures and the unimpeded passage of high
volumes of sediment during floods. Although a residual element of degradation to aquatic habitats and ecosystems can
never be entirely dispelled, reasonable measures have been pursued to anticipate and prevent negative impacts from arising
in the first place and, where such impacts cannot be avoided by positive planning, to ensure that environmental change that
may be associated with post-construction lifespan of the repaired structures is monitored and responded to.
In summary, it is believed that the proposed projects would be sustainable in terms of socio-economic and environmental
(primarily ecological) considerations and where negative effects may persist, these would – provided that all recommended
mitigation measures are implemented – be within limits that are acceptable to society at large as well as in terms of the
management objectives for CBAs, ESAs and FEPAs.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 44
SECTION E: ALTERNATIVES
NOTE that the Department of Transport and Public Works has agreed to adapt the initial engineering designs to
accommodate concerns raised by the specialist aquatic ecologist, Dr Liz Day (Day, 2014). Agreement on these changes
was obtained at a meeting between Mr Harry Viljoen, representing the DTPW, Mr Mick Latimer of Bergstan South Africa
(consulting engineers), and the project EAP, Mr Charl de Villiers, on 25 April 2014. The engineering drawings appended to
this Draft BAR (Appendix A2) incorporate these changes, which are recorded below.
1. In the sections below, please provide a description of any identified and considered alternatives and alternatives
that were found to be feasible and reasonable.
(a) Property and location/site alternatives to avoid negative impacts, mitigate unavoidable negative impacts and
maximise positive impacts, or detailed motivation if no reasonable or feasible alternatives exist:
The proposed project entails either re-building, repairing or refurbishing flood-damaged provincial road infrastructure at
six sites in the western parts of the Overberg, in the Theewaterskloof Municipality.
No location or site alternatives are available or necessary with regard to the works at OB2, OB4, OB5 and OB6. In the
case of the damaged bridges that are to be rebuilt with larger openings – and, therefore, increased hydraulic capacity
and less long-term environmental impact –, the structures at sites OB1 and OB3 will be parallel to their predecessors.
The centre lines of the new bridges at OB1 and OB3 will be about 12 m from the centre lines of the current, damaged,
structures, which are to be demolished once the new structures have been built. At OB1, the new bridge is to be placed
upstream from the current crossing, whereas at OB3 the new structure will span the watercourse downstream of the
current pipe culvert.
Site OB6 is the only one that will require a by-pass, primarily because the road at this point is too narrow to simultaneously
accommodate construction work and traffic (i.e. 'half-width construction'). Owing to difficult terrain upstream of the
works (including a wetland, a deeply cut channel, and a heavily bushed clay outcrop), traffic will have to be routed via
by-pass around the downstream aspect of the construction site. This would necessitate removing one or more willow
trees. Owing to the restrictions imposed by the terrain, this by-pass cannot be placed anywhere else.
(b) Activity alternatives to avoid negative impacts, mitigate unavoidable negative impacts and maximise positive
impacts, or detailed motivation if no reasonable or feasible alternatives exist:
Activity alternatives refer to different means of achieving a particular objective (such as different response to flood
hazards, waste disposal or mass transit of commuters) (cf. Preston et al., 1996; DEADP, 2013). Knowing the purpose or
desired outcome of the activity is therefore crucial when considering the feasibility and reasonableness of different
activity alternatives.
In this regard, changes to designs that would meet the objectives of the proposed activities have been addressed under
this head.
The objectives of the activities
Overall, the objective that guides the activities that must be undertaken to execute the proposed projects relate to the
repair, reinstate or maintain flood-damaged provincial road infrastructure according to prescribed design specifications.
The 'do nothing' option, insofar as it implies abandoning the damage infrastructure, would be unconscionable unless the
Provincial Government of the Western Cape intends de-proclaiming the DR1288 and DR1313 as public roads and
divesting itself and its agents of any responsibility towards the upkeep of the affected road infrastructure and its safe use
by the motoring public. This is patently not the case and therefore does not merit further consideration
Activity alternatives to the proposed flood-related repairs
− There is no reasonable or feasible alternative to replacing the badly damaged bridges at OB1 and OB3 and
equipping the new structures with sufficient hydraulic capacity to prevent over-topping in a 1:2-year flood and
allowing sediment to pass unimpeded through the structures (Bergstan 2013).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 45
− Originally, it was proposed that concrete scour protection be provided upstream and downstream of the pipe
culvert at OB4 in order to control the growth of reeds that contributed to blockages, over-topping of the road
during floods, and subsequent erosion. The freshwater specialist (Day, 2014) instead recommended that gabion
mattresses be used as an alternative to concrete slabs as this would allow low flows to seep through the gabion
mattresses. There would still be some opportunity for reeds to be established, but at far low densities than is currently
the case. At higher volumes of flow, water would simply pass over the gabion mattresses. This alternative has been
implemented in the designs for the works at OB4.
− Originally, it was proposed that the undermined scour apron at OB5 be under-pinned, equipped with a secondary
outlet slab and cut-off wall, and protected on its downstream aspect by placing rocks in the plunge pool to
prevent further scour. These plans have been amended on Dr Day's advice. Instead, the damaged apron slab is to
be replaced with three tiers of gabions, founded on a gabion 'mattress'. This design will still allow the velocity of
water to be broken, and the structure to be protected against scour and undermining, while permitting vegetation
to be gradually re-established in and around the gabions. The roughed surface and cavities provided by the
gabions also contribute to the establishment of micro-habitats that can be occupied by aquatic organisms.
− The works at OB6 entail adding a second box culvert to this crossing as the existing structure does not have
sufficient capacity to carry 1:2-year flows. Ongoing over-topping and wash-aways can be expected at this site if
the flood conveyance capacity of the structure cannot be improved. The freshwater ecologist (Day 2014) has also
recommended that a weir be constructed to control a head-cut a short distance upstream of the crossing, and
that the eroding banks downstream of the crossing be addressed as a matter of urgency. The DTPW has agreed to
include the construction of a gabion check-weir and 'mattress' as recommended by Dr Day. Erosion downstream of
the expanded culvert at OB6 would be countered by the addition of more lateral flow space, which will prevent
down-cutting and erosion around the edges of the outlet structures.
Activity alternatives: Construction of bypasses
In order to maintain functionality of roads during repairs and maintenance work, traffic must, where possible, be allowed
to pass through sites under construction. Activity alternatives with respect to bypasses are as follows:
− Only one site, OB6, will have to be equipped with a temporary bypass outside of the current road alignment as the
road width here is inadequate to accommodate half-width construction. The by-pass would have to be placed
immediately downstream of the structure (i.e. to the south) as the northern option would be impracticable owing to
the depth of the channel and steepness of its sides. Installing a bypass upstream of the construction sites would also
mean having to destroy a substantial stand of indigenous vegetation and, potentially, intrude into a valley bottom
wetland north-west of the road. A bypass at the latter location would also entail considerably more excavation
than would the case with regard to the preferred alignment, which would run through a seriously disturbed section
of channel that needs to be stabilised. The bypass will have a low profile and be laid as close to the existing shape
of the bed of the watercourse as possible. It will be built with commercially-sourced material. The bypass will be
demolished and the disturbed footprint rehabilitated immediately after construction. The residue of the
decommissioned bypass will be used to ‘tie in’ the expanded box culvert crossing with the adjacent gravel road
approaches.
− The narrowness of the road and difficult terrain at OB2 precludes half-width construction and laying of a bypass,
which means that this road will have to be closed to traffic for an estimated three weeks while construction takes
place.
− The existing bridges at sites OB1 and OB3 will be used to route traffic past the latter construction sites. The old,
damaged, bridges are to be demolished and all debris is to be removed. The sites will be rehabilitated.
(c) Design or layout alternatives to avoid negative impacts, mitigate unavoidable negative impacts and maximise
positive impacts, or detailed motivation if no reasonable or feasible alternatives exist:
The basis of the design brief set by the DTPW is that all the repaired structures must be trafficable, with no over-topping
for a 1:2-year flood, except for the structure at OB1 which is designed to pass the 10-year flood. Designs are based on
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 46
two specifications: the PGWC Standard Drawings and Details for Culverts and Causeways and the South African
National Roads Agency Drainage Manual (5th edition).
In three instances, road crossings are to be equipped with substantially improved hydraulic capacity, namely OB1, OB3
and OB6. The new bridges that are planned for the Botrivier and Elandskloofrivier will replace the existing structures,
which have experienced repeated wash-aways to their approaches because of blocked pipes or culverts which
deflects high flows to the side and into the gravel road embankments. The single culvert at OB6 is too small to convey
floods underneath the road, which are either deflected into the upstream embankments or over the road surface, which
causes erosion to the embankment on the southern side of the road. A narrow outlet structure at this site has also
apparently contributed to significant down-cutting of the channel below this point.
Besides reducing blockages and scour, and the ensuing risk of damage to the structures, less erosion means that less
sediment would enter the affected watercourses. This holds benefits with respect to reducing the overall hydrological
instability of these systems, and lessening undesirable impacts on in-stream habitat.
The most significant changes to the proposed engineering designs that have been recommended by the specialist
aquatic ecologist (Day, 2014) are summarised below. The responses by the DTWP are also recorded.
Design-related questions raised by the aquatic ecologist: OB1
At the farm 'Kanaan' (site OB1), blockages caused by trees and debris have periodically caused flood waters to back up
to such an extent that fields upstream of the bridge have been eroded when the floods subside (pers comm., Mr Kobus
van Zyl, owner of 'Kanaan', 11.04.2014). The channel of the Botrivier downstream of the bridge at 'Kanaan' is massively
eroded and has cut so deeply into the peat substrate that large 'blocks' within the embankment of the DR1288 have
slumped towards the base of the channel. The banks of the river are also heavily infested with black wattle.
The new bridge at 'Kanaan' is to consist of a single span portal structure, some 12 m wide and 4.5 m high. In comparison,
the current, damaged, bridge consists of two portals, each of which is 4 m wide and 1.8 m high. This structure is
supported on a former drift equipped with six 600 mm pipes. The new bridge is designed to accommodate 10-year
floods without over-topping and will substantially reduce the build-up of debris during floods. It will also be protected by
wing walls and gabion 'mattresses'.
The aquatic ecologist (Day, 2014, pp 29-31) supported the assertion that the new bridge at OB1 would be better able to
reduce the frequency of significant flood disturbance. Ecological recovery would, however, depend on removing alien
trees both upstream and downstream of the structure.
The aquatic ecologist raised the following concerns about the new bridge at OB1:
− Failure to address the present constricted alignment of the small stream that enters the river on its left bank
downstream of the existing structure means that this system will probably play a long-term role in disturbance of the
downstream channel and banks. The small stream has been directly impacted by the existing road alignment.
− Medium to long-term likelihood of structural failure, as a result of erosion and bank collapse at the bend some 20 m
upstream of the proposed structure. If this erosion (triggered by constriction of alien trees along the channel, and
blockage of flows in the channel by fallen trees) is left unchecked, it is likely to result in significant widening of the
channel over time, and potential bypassing of the bridge structure on the left hand bank.
The DTPW has indicated that, in response to the first concern regarding the tributary that enters the Botrivier from the
east, downstream of the crossing, the problem of restricted flow space will be resolved once the damaged bridge is
demolished, and alien trees are removed from the site. The eroding left bank of the Botrivier upstream of the crossing will
be evaluated by the project engineers. It is, however, outside the road reserve and its stabilisation has not been factored
into the contract for the repairs in question (pers comm., Mr Harry Viljoen, DTPW, 25.04.2014).
Design-related questions raised by the aquatic ecologist: OB2
The specific practical challenges that arise at this site on the Botrivier include:
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 47
− The skew alignment of the existing culvert relative to the course of the Botrivier, which is forced into an 'S'-bend
where it passes through the structure;
− The seasonal Doringkloof stream which joins the Botrivier at a sharp angle, directly at the upstream edge of the
culvert, from the east;
− An informal track that crosses the Doringkloof stream just above its confluence with the Botrivier; and
− Heavily infested river banks up- and downstream of the DR1288 which contribute to channel constriction and
erosion.
One of the effects of this state of affairs is that the southern approach to the existing crossing are highly vulnerable to
erosion damage that occurs when the road is over-topped by floods.
Currently, the repairs planned for OB2 would entail installing concrete road slabs on the approaches to the existing
culvert over the Botrivier, namely a 7 m slab on the northern approach, and another one of about 30 m on the southern
approach. The latter, longer slab, would taper from an initial width of 6 m to about 4.1 m where it abuts the southern
facie of the culvert. The latter design would have the purpose of protecting the road surface against flood-related scour
on the upstream side of the structure, as well compelling motorists to slow down when approaching the single-lane
crossing. The works would also include repairing or extending existing masonry walls to protect the sides of the road.
New, concrete, side cut-off walls would be built along the upstream aspect of the southern approaches. Eroded fill at
the south-eastern edge of the culvert, where it meets the upstream edge of the concrete road slag, will be replaced
with compacted material.
The aquatic ecologist (Day, 2014, pp 31 and 32), raised the following concerns about the proposed repairs at site OB2:
− The proposed construction measures at OB2 did not attempt to address the problem of the small tributary (which
issues from Doringkloof, to the south-east of the main culvert) that was currently diverted along the upstream edge
of the concrete structure, increasing flood pressure and erosion damage on the right hand side of the Bot River
channel, and contributing to the high levels of erosion damage observed in the river downstream of the structure.
− Contextually, invasion of the riparian zone and banks by woody aliens, which constricted the channel and
contributed to high levels of disturbance (erosion) during floods, with felled or fallen aliens blocking the bridge and
causing high levels of scour even in relatively small flood events, increased the frequency of disturbance;
− The existing culverts were inadequately sized for the unstable river, characterised in floods by sediment and tree
debris; furthermore, the small stream is not catered for at all by the culverts, with the result that flows from the
stream were deflected off the structure, flowed parallel with the road, and then passed under the culvert with the
main Bot River. This system was likely to have contributed to erosion and undercutting of the right hand river bank
downstream of the road. As with all the other structures, however, it deserves noting that the adequacy of the
culverts may have been compromised over the years as a result of long-term changes to run-off patterns in
catchments, channel modification and the invasion of riparian areas by woody alien plants.
− The existing access road off DR1288 interrupted flows along the minor stream. However, this informal road crossing
was less damaging than the bridge structure, because it did not result in debris dams and associated bank erosion.
− These impacts would be perpetuated by repairs to the new structure, which did not take the foregoing factors into
account.
The aquatic specialist recommended that the designs for the repairs at OB2 be amended to:
− Make provision for an additional or extended culvert or other ecologically cognisant measure that allowed for the
free flow of the minor stream through the structure, without being diverted along the road edge; and
− The mechanism for this would need to address the fact that the small stream appeared to enter the system at a
higher level than the existing culvert.
These issues were raised in discussion with the DTWP, its consulting engineers and EAP on 25.04.2014.
In short, Mr Harry Viljoen (DTPW) indicated that Dr Day's observations and concerns were valid. However, contract
C960.4 only provided for essential repairs to flood-damaged road infrastructure or, where crossings had been so badly
damaged, that they needed to be replaced (e.g. at OB1 and OB3). The interventions proposed by Dr Day were
extensive, had not been budgeted for, and could not be implemented in the 2104/2015 financial year. Dr Day's
recommendations would, however, be seriously considered if the crossing at OB2 had to be replaced. Planning to this
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 48
end would probably necessitate specialist input by a fluvial geomorphologist and hydrological surveys to better
understand flow dynamics at this point, and how engineering designs could best respond to this complex state of affairs.
The upshot is that the current designs for the refurbishment of the damaged road and crossing at OB2 will not be
amended in the course of the contract in questionC960.5????
The Applicant has implemented recommended amendments to the initial designs at the following sites:
OB4: See above, 'Activity alternatives';
OB5: See above, 'Activity alternatives; and
OB6: See above, 'Activity alternatives'.
(d) Technology alternatives (e.g. to reduce resource demand and resource use efficiency) to avoid negative impacts,
mitigate unavoidable negative impacts and maximise positive impacts, or detailed motivation if no reasonable or
feasible alternatives exist:
N/A.
(e) Operational alternatives to avoid negative impacts, mitigate unavoidable negative impacts and maximise positive
impacts, or detailed motivation if no reasonable or feasible alternatives exist:
N/A. The most critical operational alternatives would relate to (a) post-construction maintenance of the channels
upstream of and downstream of the structures, combined with (b) the removal of invasive plants and stabilisation of
degraded watercourses with groynes (as in the case of the Elandskloofrivier), controlling excavations in the affected
watercourses, and landscaping and revegetation of river banks with appropriate indigenous plants. The latter
alternatives are beyond the object or scope of this application for environmental authorisation.
(f) The option of not implementing the activity (the No-Go Option):
In all cases, pursuit of the ‘no go option’ would be counter to the Duty of Care with respect to road safety, ensuring the
integrity and availability of well-functioning regional road transport infrastructure, and prevention of environmental
degradation in highly dynamic and important ecosystems. Where such the integrity and safety of provincial roads are at
stake, failure to undertake the planned repairs is not a credible or desirable alternative and would hold no benefits to
society or the environment and is therefore not considered to be a feasible or reasonable option deserving of further
assessment.
(g) Other alternatives to avoid negative impacts, mitigate unavoidable negative impacts and maximise positive
impacts, or detailed motivation if no reasonable or feasible alternatives exist:
The freshwater assessment (Day 2014) includes specific management recommendations that represent key elements in
an integrated 'package of measures' to prevent erosion and destabilisation that may expose the respective structures
for future flood damage. These are addressed in detail in Section H, which deals with mitigation measures.
Because the recommendations are, in effect, integral to the long-term ecological sustainability and structural viability of
the structures, they are also presented as crucial, 'high-level' means to prevent ongoing degradation and destabilisation
of the affected watercourses and their associated road infrastructure.
In the case of the new crossing over the Elandskloofrivier at OB3, the proposed construction of groynes by the Western
Cape Department of Agriculture was an essential intervention to stabilise the high rates of erosion and sedimentation in
this system. If these soil conservation works were not to be erected, the damage associated with even a new, better-
designed causeway at OB3 would persist, compounding an already "ecologically catastrophic situation" (Day, 2014, p
34).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 49
In all cases, invasive alien vegetation had to be removed from channels as this infestation was a major driver of structural
failure of the affected watercourses (Day, 2014, p 42) and, by implication, damage to provincial road infrastructure.
(h) Please provide a summary of the alternatives investigated and the outcomes of such investigation:
− The ‘no go’ alternative is regarded as neither feasible nor reasonable with regard to any of the projects, and is
therefore not subject to further consideration or assessment.
− Activity or design-related concerns that could be remedied by adapting engineering designs have been
addressed in the course of this environmental assessment, through interactions with the aquatic ecologist, the
DTPW, its consulting engineers and the project EAP.
− The projects where these concerns could be positively addressed by means of amendments to the respective
engineering designs, are the proposed works at OB4, OB5 and OB6 (see above). No alternatives will therefore be
assessed with regards to activities at the latter sites.
− At OB1, on the Botrivier, the most important additional intervention, which does not form part of the current
contract, would be to investigate methods for stabilising the left bank of the Botrivier upstream of the crossing. If the
DTPW were, at a later stage, to proceed with stabilising the river bank at this point, this would require environmental
authorisation and a basic assessment that should inter alia consider various options for preventing erosion at this
point.
− At OB2, major investigations and expenditure would be needed to address the concerns raised by the ecological
assessment. The DTPW has indicated its readiness to take these recommendations into account in the event of this
crossing having to be replaced. This work cannot, however, be implemented in the course of the current contract.
No alternatives will be investigated at this site.
− At OB3, the potential environmental advantages of the new causeway are contingent upon the stabilisation of the
Elandskloof River by means of soil conservation works that are in the process of being planned by the Western
Cape Department of Agriculture. Execution of the latter project is beyond the responsibilities or powers of the
DTPW. It has, however, been emphasised that the ecological benefits of the new causeway at this site will not be
realised unless extensive erosion and sedimentation in this system are addressed, failing which the new crossing will
perpetuate an unstable system that has resulted in catastrophic degradation. No major issues were identified with
regard to the alignment and design of the new causeway, and it is therefore not necessary to consider any other
options for a crossing at this site.
− At OB6, there is only one feasible route to accommodate a by-pass around the construction site, namely
downstream of the DR1313. Short of retaining a single, under-capacitated culvert at this crossing, there is no
feasible alternative available to improve the flood conveyance of this structure besides adding an extra box
culvert as proposed. No alternatives will therefore be investigated. The same applies to the proposed construction
of a small gabion weir to restrain the development of a head-cut upstream from site OB6. This is viewed as essential
and urgent from a wetland and river management perspective, and failure to address erosion at this point would
perpetuate degradation of the channelled valley bottom wetlands upstream of the culvert.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 50
SECTION F: IMPACT ASSESSMENT, MANAGEMENT, MITIGATION AND MONITORING MEASURES
N O T E
PROBLEMS ARISING FROM THE IDENTIFICATION AND ASSESSSMENT OF MULTIPLE, SYNERGISTIC IMPACTS
AND HOW TO FORMULATE MANAGEMENT RESPONSES AT A FUNCTIONAL OR ECOSYSEM SCALE
1) It is a fundamental, internationally-recognised precept that environmental assessment and management must
(a) focus on the functional relationships and processes within ecosystems and (b) carry out management
actions at the scale appropriate for the issues being addressed (cf. Annex B and C, Decision V/6 'Ecosystem
Approach', Sixth meeting of the Conference of Parties of the Convention on Biodiversity, 15-26 May, 2000,
Nairobi).
2) It is also common cause that activity-specific environmental impact assessment is generally poorly suited to
predicting and assessing cumulative impacts on ecosystems and ecological functioning, and often fails to
situate project-specific impacts within a broader landscape, regional or functional – ecological – perspective
(cf. Le Maitre et al., 1998; Treweek, 1998; Brownlie et al., 2005; Treweek et al., 2005; DEA, 2005).
3) The assessment of impacts resulting from listed activities is required by law, and represents a non-negotiable
mandatory cornerstone of the prescribed environmental assessment process (cf. sections 24(2)(a) and (b) of
NEMA, and Regulation 22 of the NEMA EIA regulations). Competent authorities, when reviewing applications for
environmental authorisation, must among others take into account any environmental or environmental
degradation likely to be caused if the application were to be authorised or refused (NEMA s 24O). Likewise, the
authorities must take into account measures to protect the environment from harm as a result of the activity
(ies) being applied for, as well as measures to prevent or mitigate substantially detrimental environmental
impacts, or degradation of the environment.
4) It is less clear, however, if the potential impacts of activities subject to compulsory environmental authorisation
must be analysed and understood in relation to the effects of environmental degradation and ecosystem
instability that may, in origin, be entirely independent to the activities subject to environmental scrutiny but,
unless prevented or mitigated, could substantially and negatively amplify what would otherwise be relatively
benign or acceptable impacts if these are defined in isolation of broader contextual factors.
5) Such an approach to environmental assessment, which is attuned to the condition and changed dynamics of
surrounding ecosystems, and how these may influence the impacts generated by a particular project at a
particular site, can certainly be motivated on the basis of EIA best practice. Its legal foundations can be readily
inferred from particularly those national environmental management principles that require that environmental
management must avoid disturbance to ecosystems, or pay specific attention to planning and management
in vulnerable or stressed ecosystems that are subject to specific human resource usage and development
pressure.
6) The difficulty faced by this environmental assessment (and, potentially the decision maker), is that the
environmental impacts associated with the listed activities subject to this application would, from a strict
activity and site-specific perspective, be relatively insignificant. In some cases, the impacts on the affected
watercourses may even be positive.
7) However, this state of affairs is effectively turned on its head if the environmental implications of the proposed
projects are recast in relation to their interaction with the highly modified flood and erosion dynamics that have
resulted from intensive agricultural use of the surrounding catchments and floodplains which, in turn, have
been compounded by alien infestation and, in the case of the Meulrivier at Site OB1, extensive bulldozing of
the river channel.
8) The specialist aquatic assessment (Day, 2014) undertaken in support of this combined application for the
environmental authorisation of activities 'triggered' by repairs, refurbishment of rebuilding of flood-damaged
provincial road infrastructure has been closely guided by a functional, scale-sensitive approach to biodiversity
assessment. The latter assessment has considered construction-related impacts, and post-construction
management/maintenance of the immediate environs of the respective structures. In addition, the specialist
aquatic assessment has also highlighted the mutually-reinforcing and environmentally damaging interactions
between destabilised aquatic ecosystems and the impacts of the affected river crossings.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 51
9) Of crucial importance, however, is the finding by the aquatic specialist assessment that the environmental
advantages of the proposed works will effectively be annulled if erosion, channel instability and alien
infestation – which, synergistically, are driving negative environmental change in the affected catchments,
outside the proclaimed road reserve – are not actively addressed and remedied by the responsible
landowners.
10) As indicated, this state of affairs poses a serious conundrum to both the applicant, as well as the competent
authority, as the impacts of the proposed works could, if analytically divorced from any extraneous factors, be
mitigated to environmentally (specifically ecologically) acceptable levels. In fact, construction of new bridges
at OB1 and OB3 would potentially represent a significant improvement upon the poor environmental
performance of its predecessor. The specialist ecological assessment has, however, found that the
management of potential impacts arising from the proposed works cannot be divorced from the synergistic
and cumulative effects of land use practices in the respective catchments – which means that this suite of
problems needs to be addressed in an integrated and co-ordinated manner at a catchment or ecosystem
scale. Failure to do so would perpetuate the continued degradation and destabilisation of especially the
Elandskloofrivier, and effectively obliterate most of the environmental advantages that would be achieved by
implementing the proposed repairs.
11) It is recognised, however, that environmental decision-making in terms of section 24 of NEMA is primarily
concerned with controlling listed or specified activities which applicants (i.e. project proponents) may not
commence with without environmental authorisation. In this respect, individual project proponents cannot be
held accountable for managing or mitigating the impacts of listed activities that are pursued, independently,
by other persons or parties. Likewise, it is difficult to see how an individual or entity can be expected to exercise
the 'duty of care' towards preventing or remedying environmental degradation that is entirely the making of
someone else. This line of reasoning is less clear-cut, however, in the context of ecosystem management where
multiple independent actors may, through a variety of pressures and land uses, have a combined impact on
the condition and functioning of the affected ecosystem, such as a foothill river and its floodplains and
wetlands on the southern slopes of the Riviersonderend Mountains. This, in fact, is the situation that prevails with
regard to all of the projects in question – the environmental concerns associated with the proposed repairs are
relatively trivial compared to those arising from the highly modified condition of the affected catchments and
watercourses, but the latter has a direct, negative, effect on the significance of the former. The only realistic
method for addressing this state of affairs requires defining the environmental degradation in question as a
case of ecosystem failure, and responding at an equivalent scale. Exclusively focusing on controlling individual
listed activities and their impacts will not, unfortunately, yield sustainable outcomes for the affected rivers.
12) Given this complexity, and the activity-specific focus of the environmental regulatory system, impact
identification and assessment will be presented as two distinct but inter-related components:
a) The first will focus exclusively on impacts attributable to the proposed activities for which authorisation is
being sought; whereas
b) The second component will situate and analyse the potential consequences of the proposed works in a
broader, ecosystem context.
13) This is an artificial device designed to assist the decision making process by distinguishing between:
a) Impacts that are clearly activity-related, and therefore within the ambit of authority and responsibility of
the Western Cape Department of Transport and Public Works, its duty of care towards the environment,
and obligations under environmental legislation and the EIA regulations – as the applicant; and
B) Broader problems of environmental management that need to be addressed in conformity with the
national environmental management principles, the objectives of integrated environmental
management, and the duty of care, but are not the responsibility of the Department of Transport and
Public Works and therefore fall outside the ambit of this application.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 52
1. PLEASE DESCRIBE THE MANNER IN WHICH THE DEVELOPMENT WILL IMPACT ON THE FOLLOWING ASPECTS:
The draft basic assessment has provisionally concluded that the proposed projects will have an impact on the following
aspects of the affected environment (which are discussed in detail below):
ENVIRONMENTAL ASPECTS THAT MAY BE AFFECTED BY THE P ROPOSED PROJECTS AND RELATED ACTIVITIES
Phase of project when environmental aspects may be
affected by impacts
A–D = Biophysical aspects
E = Biodiversity conservation priorities
F = Socio-economic aspects
Construction Operation
A. Hydrological aspects − Flow regimes − Water quality
� �
B. Hydro-geomorphological aspects
− Scouring, erosion and sediment movement − Physical structures and stability of watercourse
� �
C. Biodiversity aspects
− In-stream and riparian habitat � �
D. Biodiversity conservation priorities
− Critical Biodiversity Areas and Ecological Support
Areas − Freshwater Ecosystem Priority Areas − Listed threatened ecosystems
� �
E. Socio-economic aspects
− Employment opportunities − Sense of place and wellbeing − Integrity of road network (safety and reliability)
� �
(1)(a) The biophysical context, biophysical impacts and evaluation criteria
The biophysical context and definition of biophysical impacts
The impacts identified by this Draft Combined Basic Assessment relate virtually exclusively to the biophysical environment
which, to recapitulate, is broadly characterised by:
− The Southern Folded Mountains (late summer to winter rainfall) and Southern Coastal Belt Ecoregions (winter
rainfall), both of which form part of the Cape Floristic Region, a global biodiversity hotspot;
− Threatened shale fynbos and shale renosterveld ecosystems, which are reduced to a fraction of their original
extent with respect to the latter vegetation types;
− Lower foothill rivers and valley bottom wetlands (the former are either CBAs or ESAs, and the latter are wetland
FEPAs which as with CBAs, should be managed in support of an unmodified or largely natural condition).
Two of the sites have a PES of 'C' ('moderately modified'); the remainder are 'largely' to 'seriously' modified. Half of the
rivers are rated as having 'moderate' ecological importance and sensitivity; the EIA of the remainder is 'low'. Rivers with
an EIS of 'moderate' are usually not sensitive (in terms of habitat and biota) to flow modifications, and may have a
substantial capacity for use (Day 2014, p 12). Sites OB3 to OB6 are associated with wetland FEPAs.
Classification of biophysical impacts
The classification of biophysical impacts distinguishes between:
− Construction-related impacts, including those arising from the proposed by-pass at OB6 (which are generic to
all sites); and
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 53
− Impacts that may persist after construction, into the operational lifespan of the structures, at a site-specific and
ecosystem scale.
Impacts that may result if specific aspects of the affected environment are not adequately managed will be dealt with
separately as these considerations fall outside the scope of this application (see 'Note' above).
This section is, unless otherwise indicated, exclusively based on the findings of the specialist freshwater ecological
assessment (Day, 2014).
Aspects of the biophysical environment to undergo review and impact assessment
As indicated above, each of the projects will be assessed for impacts on:
− Hydrological aspects, i.e. flow regimes and water quality;
− Hydro-geomorphological aspects, i.e. scour, erosion and sediment movement;
− The physical structure and stability of the watercourse; and
− Biodiversity aspects, i.e. aquatic CBAs as surrogates for biodiversity pattern (in -stream and riparian habitats)
and ecosystem function (flows and sediment dynamics).
The projects will be assessed generically against this set of impacts, using the 'extent-duration-magnitude' formula. The
method of impact evaluation (i.e. determination of impact 'significance') is explained below. Impacts that are specific
to a particular structure or situation will be highlighted and dealt with independently.
Impacts on hydrological and hydro-geomorphological aspects (flow regimes and erosion)
Whereas the impact assessment in Section F will allow for a focused scrutiny of the environmental implications of the
proposed works, relative to the ecological management objectives of foothill rivers as summarised above, it also needs
to be recognised that the new or repaired and refurbished structures may represent a net improvement on the condition
of affected ecosystems that is more usefully expressed in the language of 'need and desirability' than impact
significance.
The latter statement must, however, be qualified by the caveat that such improvements in the ecological condition of
the respective watercourses are virtually entirely contingent upon implementing mitigation measures in the reaches
directly up- and downstream of all the sites, except OB4, and, in the case of OB3, at the scale that it would take in order
to stabilise the seriously degraded Elandskloof River (cf. Day, 2014).
Nonetheless, it must be recognised that the proposed works also represent a deliberate attempt on the part of the
project engineers to design structures to standard specification that are not only capable of withstanding floods of a
specified magnitude, but are also equipped to prevent flow restriction and minimise scour and erosion which would
otherwise result in loss of agricultural land, channel destabilisation and degradation of in-channel habitats.
The bridges at OB1 and OB3 are to be rebuilt. In both cases, the new structures will be equipped with significantly
improved hydraulic capacity that will permit 1:2-year floods to pass through the structures without being impeded by
blockages caused by driftwood or sediment.
The new bridge at OB1 will be vented by a single opening, 12 m wide x 4.5 m high and the directly abutting
embankments will be secured with gabion 'mattresses'. The bridge spans a relatively deep channel and has therefore
not been designed for over-topping.
At OB3, where the DR1313 crosses the Elandskloof River, the new causeway is designed to be over-topped by floods
exceeding the 1:2-year return period. The new causeway will have three twin box culverts, each consisting of cells 3 m
wide x 2.05 m high. The approaches at either end will be protected by concrete road slabs, and the embankments by
gabion 'mattresses'.
From an environmental perspective, the major design shortcomings of river crossings in the study area relate to culverts
or pipes that cannot accommodate the passage of floods through the structures, especially when insufficiently-sized
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 54
openings are blocked by waterborne debris. This has the effect of causing water to back up, upstream, and to break
around the edge of structures which often causes approaches to be washed away. This undesirable deflection of flows
away from active channel can also result in significant lateral erosion into cultivated floodplains, as evident at OB3.
These physical shortcomings can be exacerbated when culverts are not aligned perpendicular to flows. Culverts that do
not have adequate scour protection at their outlets may also be vulnerable to undermining due to the development of
plunge pools that erode the underside of outlets slabs and aprons. Concrete wing walls and/or gabion protection at
inlets may be absent or damaged, which also contributes to erosion and eventual instability of the crossings.
There may be some disruption of flows down the watercourses in question during the establishment of temporary
diversions or coffer structures to route water around the construction sites. 'Local' impacts may arise during the initial
establishment of diversionary structures (such as sandbagged coffers) and flows (depending on water levels) are
temporarily prevented from reaching the Riviersonderend.
Impacts on flows in the Bot River cannot be altogether avoided as the works will be taking place either within or in close
proximity to this watercourse.
Overall, these will be short-lived interruptions, not lasting more than a few minutes in any instance. Flows may be
interrupted intermittently during construction which, except for the construction of the bridges at OB1 and OB3, is not
expected to exceed more than five months in toto. The aim of mitigation would be to maintain natural flow regimes
during the full period of construction. Overall, the drier the watercourse at the time of construction, the less impact there
will be on flows.
The site at 'Nooitgedacht' (OB6) is the only one where a temporary by-pass will be required owing to the narrowness of
the road at the point. Impacts that may typically be associated with by-passes include:
− Changes to the structure and condition of the bed and banks of watercourses;
− A potential increase in local scour and erosion caused by the passage of water over the by-pass, or as a result
of channel constriction;
− Impeded flows if water cannot pass through over the by-pass;
− Flow diversion if bypasses are vented by pipes;
− An increase in downstream turbidity and sedimentation; and
− Development of eroding head-cuts at the downstream edge of the by-pass and which thereafter may migrate
upstream.
These impacts can be effectively countered by ensuring that the by-pass has a low profile, laid as close to the existing
shape of the bed of the watercourse as possible.. It will be necessary to lay pipes through the by-pass in order to
accommodate low flows. The by-passes will be demolished and the disturbed footprint rehabilitated immediately after
construction. Close attention needs to be given to evening out any residual 'benches' across the watercourse that may
precipitate head-cut erosion after the by-pass has been demolished. The residue of the decommissioned by-pass will be
used to ‘tie in’ the enlarged culvert structure with the adjacent gravel road approaches.
Changes to flows, especially in terms of the availability and quality of water, can have a deleterious effect on aquatic
organisms and riparian vegetation in the lower, wetted zone of the watercourses. Where flows have to be disrupted for
operational reasons, interruptions must be kept as short as possible. High flows during winter, or as a result of cut-off low
pressure events in early summer can swamp construction sites, exacerbate erosion, damage works and lead to
contamination of water by building materials and fuel. These are all factors that need to be taken into account by the
Construction Environmental Management Programme and Maintenance Plan for these works.
Unless prevented or mitigated to acceptable levels, erosion and sedimentation can reduce in-stream habitat diversity,
contribute to turbidity and, cumulatively, result in simplification and destabilisation of aquatic ecosystems and their biotic
communities. The prevention and control of erosion and sediment release into watercourses is therefore a key
consideration in the design of watercourse crossings.
Engineering best practice w.r.t. bridge and culvert design in rural conditions
In this regard see, for example, the DTPW‘s Standard Drawings and Details for Culverts and Causeways (2012), DEA&DP
guideline on planning off-road routes (2006), the KwaZulu Natal Department of Transport’s design standards for local
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 55
roads (1997) and the US Environmental Protection Agency (EPA) manual on best practice for low-volume roads’
engineering (2003). The EPA recommends that vented crossings must be designed to occasionally be over-topped by
floods and have an erosion-resistant deck and approaches. Outlet structures must be equipped with scour protection
(‘splash aprons’).
According to a major Australian manufacturer of concrete box culverts, 'Humes', box culverts are "ideal" for flows where
hydraulic head is limited. For an equivalent waterway, box culverts can be configured to have less impact on upstream
water levels and downstream flow velocities than equivalent pipe structures (http://www.humes.com.au accessed 23
April 2014).
These best practice requirements have been met with regard to the majority of the proposed projects. The exception is
OB2, where time and cost constraints do not permit a fundamental review and re-assessment of the effectiveness of the
culvert crossing over the Botrivier at 'Doringkloof'.
Impacts on CBAs and ESAs
All of the structures are located in either CBAs or ESA, or combinations thereof, and will have an impact on the
achievement of the ecological management objectives for these features. These impacts can be either positive or
negative, depending on the scale at which impacts are assessed. This is explained below.
Potential impacts on CBAs and ESAs can be defined as:
− Impact on biodiversity pattern thresholds or targets (chiefly relating to focal species, priority catchments,
important aquatic habitats and threatened ecosystems); and/or
− Impacts that may result in the degradation of areas or features that are important for maintaining ecological
processes (i.e. areas selected on the basis of ‘best design’ considerations).
CBAs can be selected for their contribution to both pattern and process targets or thresholds, whereas ESAs mostly only
apply to areas or features that are important for maintaining ecosystem function (such as ecological corridors or
hydrological processes).
CBAs and ESAs are treated as a surrogate for biodiversity pattern and process at a site-specific scale, i.e. representing
localised impacts on flows, sediment processes and habitat within approximately 100 m up-and downstream of each
structure. CBAs and ESAs will also be used to evaluate the potential significance of impacts by:
− Defining the 'magnitude' of impacts in relation to loss of habitat in CBAs and ESAs; and
− Contextualising the overall environmental benefits or costs of the projects in relation to the extent to which the
repairs may either contribute to, or detract from, the achievement of the management objectives for CBAs
and ESAs.
Potential impacts on FEPAs
'Wetland FEPAs' refer to wetlands that must be maintained or rehabilitated to a good ecological condition (i.e. 'A' or 'B'
ecological category). The aquatic ecologist has confirmed that Sites OB3-OB6 coincide with channelled valley bottom
wetlands that have been identified as Wetland FEPAs (cf. Driver et al., 2011). None of the wetlands at the four sites in
question are in a 'good', 'natural' or 'near-natural' condition (Day 2014, p 14).
The specialist aquatic assessment has summarised the present ecological state (PES) and ecological importance and
sensitivity (EIS) of these respective Wetland FEPAs as follows (Day, 2014, p 14):
Site PES Explanation EIS
OB3 E River severely degraded – no associated wetland habitat. Very high levels of disturbance,
extensive sedimentation, loss of indigenous vegetation, alien invasion.
Low
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 56
OB4 C River degraded – but large areas of floodplain wetland upstream of road. Confined
downstream and channelised
Low
OB5 C River degraded – but areas of floodplain wetland upstream of road. High levels of alien
invasion but river channel retains good quality instream habitat including palmiet
vegetation.
Moderate
OB6 D/E River highly degraded – but areas of valley bottom wetland upstream of road. Very high
levels of erosion; loss of indigenous vegetation; channelisation.
Low
A = Unmodified/natural B = Largely natural C = Moderately modified D = Largely Modified E = Seriously
modified F = Critically/extremely modified
SANBI's Implementation Manual for Freshwater Ecosystem Priority Areas (Driver et al., 2011, p 46) recommends that
potential impacts on FEPAs must be dealt with as follows in the course of environmental assessments:
− Anticipated impacts on FEPAs that may result in an ecological condition lower than A or B should be ranked as
having medium to high significance.
− Any activity that will have an overall residual impact on wetland or river FEPAs and their immediate surrounds
greater than a low negative significance, is not acceptable from the point of view of managing and
conserving freshwater ecosystems, and must be avoided.
− Unavoidable development must require special mitigation measures that would reduce the overall impact of
the activity or development to low negative significance, or must require a biodiversity offset....
If the potential impacts on wetland FEPAs at sites OB3-OB6 are reviewed in terms of the preceding considerations, the
following emerges:
− None of the wetlands in question is in a natural (A) or near-natural (B) condition. In all instances, however, the
proposed works would contribute to local or at least site-specific improvements to flood conveyance and
lower levels of erosion and sediment transport. However, improvements to the ecological condition of the
affected watercourses would only be accomplished if the full suite of 'high level' mitigation measures were to
be implemented (Day, 2014, p 38). Even so, the specialist aquatic assessment predicted that "full mitigation"
(i.e. on-, and off-site) would have a very limited positive effect on the PES of the affected watercourses as
illustrated below:
Site
Pre-
construction
PES (February
2014)
Estimated post-construction PES
With full
mitgation
Without
mitigation
OB3 E D/E E A = Unmodified/natural
B = Largely natural
C = Moderately modified
D = Largely Modified
E = Seriously modified
F = Critically/extremely
modified
OB4 C C C
OB5 C C C
OB6 D/E C E
Given the 'moderately' to 'seriously' modified condition of these watercourses, which is a culmination of land
use practices in the adjacent catchments and upstream reaches, alien invasion and the local effects of the
respective structures on the aquatic environment, the impacts of the works will be relatively trivial – even if a
comprehensive programme of ecosystem rehabilitation were to take place at the appropriate functional and
geographical scales. In the circumstances, it is understood that the proposed activities will have a negligible
impact on the condition of FEPA wetlands. Also, there appears to be little prospect that any of these
watercourses, wetlands and catchments can be restored to the desired ecological condition for FEPAs. Small,
incremental improvements may be possible, but can certainly not be initiated or registered at the scale of
individual sites and their immediate environs. Impacts on FEPAs will therefore not be assessed.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 57
− There are two basic ways in which impacts on FEPAs and CBAs can be assessed: assessing impacts on
surrogates for the biodiversity that is represented by FEPAs and by means of which FEPAs are maintained (e.g.
habitats, flows, erosion and channel stability), or by assessing the consistency of predicted impacts with the
management objectives for FEPAs (or CBAs). The results of these two assessments are reported at Sections
F(8(a) and (c) respectively. With regards to site-specific impacts on biodiversity pattern and process, none of
the impacts would, provided that mitigation takes place as recommended, exceed 'Low' negative
significance, and most would be of 'Very Low' negative significance. The section below assesses the impacts of
the proposed works for consistency with the management objectives for FEPAs, CBAs and ESAs.
− Following from the latter point, there are no impacts that are directly associated with the proposed activities
that cannot be mitigated to at least 'Low' negative significance. However, if the works are re-evaluated in a
broader spatial and functional context, it is recognised that site-specific mitigation cannot have its desired
effect unless causes of widespread ecological degradation and instability of the respective watercourses are
addressed at source, and at the appropriate scale. The uncontested environmental benefits of the works will,
unfortunately, come to nought as long as they are undermined by the cumulative damage that arises from the
structural instability of the affected ecosystems. That is not, however, a problem that can be addressed by the
DTPW. Answers to these issues lie elsewhere, and will certainly not be found in the course of project-specific
environmental assessments relating to the repair of flood-damaged road bridges.
Evaluating the compatibility of projects with respect to the management objectives for CBAs, FEPAs and Phase 2 FEPAs
In terms of general practice and approaches, environmental assessment sets out to identify, assess and evaluate
impacts against criteria of magnitude, duration and extent, with the view of determining if impacts can be mitigated to
acceptable environmental levels, in which case projects should or should not be allowed to proceed.
Here, an attempt is made to establish if the proposed projects can be reconciled with the ecological management
objectives of CBAs and FEPAs which, if so, can indicate that a project may be able to make a substantial contribution to
ecosystem resilience and the maintenance of functionally viable and spatially efficient network of priority conservation
sites.
The conservation management objectives for CBAs are, in summary, to maintain natural areas in a natural condition or,
where habitat in CBAs may have become degraded, to prevent further deterioration and rehabilitate the CBA to a
near-natural or natural condition (cf. Holness and Bradshaw, 2010). Management in Ecological Support Areas, in turn,
must be aimed at maintaining ecological processes.
The management objectives for foothill rivers designated as aquatic CBAs (Job et al., 2008) provide a clear standard
against which to evaluate the ecological implications of proposed activities in such systems. Ideally, management of
foothill rivers and channelled valley bottom wetlands (where these are present) should:
− Aim to maintain flow regimes as natural as possible in terms of magnitude, frequency and variability of flow;
and
− Not result in modification to the bed and banks of watercourses or constriction of flow through pipes and
culverts as this can promote erosion, excessive mobilisation of sediments, habitat destruction and
destabilisation of the affected channel.
It can also be presumed that, historically, the damaged structures would have individually and cumulatively contributed
to environmental degradation owing to designs that did not necessarily take the abovementioned management
considerations into account. Added to this, the structures were possible designed in response to physical conditions that
have subsequently changed and now exceed the capacity of the pipe and culvert crossings to convey floods and high
sediment burdens.
Such change can be attributed to catchment 'hardening', accelerated run-off, loss of wetlands, floodplains and flood
attenuation capacity, down-cutting and alien encroachment that accelerates flows and erosion. In fact, flood damage
in the study area over the past several years suggests that floods seem to be causing damage that is disproportionately
greater than what previously had been predicted for an equivalent-sized flood. Changing rainfall patterns may also be
contributing to these phenomena (King, 2012).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 58
Where the projects may – in a site-specific context, isolated from broader catchment-related problems -- contribute to
the achievement of the management objectives for aquatic CBAs (and, therefore, FEPAs), this is regarded as a positive,
site-specific impact. Viewed from a local or regional scale, the impacts of the projects will, at best, be neutral owing to
the overall, negative, cumulative impacts arising from intensive agricultural modification of the respective catchments
(which is most severe in the case of the Elandskloofrivier).
The remainder of this section is, unless otherwise indicated, exclusively based on the findings of the specialist freshwater
ecological assessment (Day, 2014).
(1)(b) Impacts on hydrological (flow regimes and water quality) and hydro-geomorphological aspects (scouring,
erosion and sediment movement; and physical structure and stability of watercourses)
NOTE
Excavations in river beds, vehicle movements in and out of watercourses, and the type of trampling and compaction that
can be expected with construction sites anywhere will, to a lesser or greater extent, occur at all sites – and, added to this,
disturbances to flow regimes that can contribute to erosion and sediment transport which, in turn, may affect the stability
of channels, compromise water quality, degrade aquatic habitats and amplify flood-related risks to the structures in
question. All these impacts, as are their causes, inter-related. In the context of managing human interactions with
dynamic watercourses, it is critical to understand the causes of adverse environmental change, and to know at what
scale the ensuing instability and degradation take place and, therefore, at what scale they need to be addressed.
Will the development have an impact on flow regimes? YES
� NO
If yes, please describe:
OB1 During construction, flows may be temporarily diverted around the construction area to keep it dry. This will
be a temporary disturbance, largely confined to the construction footprint. Alternatively, flows may be fed
through the construction area. There will be no impoundment.
In the long-term, the single, larger culvert will assumingly reduce the frequency of significant flood
disturbance, with an enhanced likelihood of ecological recovery between flood events. The new structure
should also improve ecological connectivity by passing flows through a large portal instead of narrow
pipes as is currently the case. The new bridge over the Bot River should pose no impediment to base flows
provided that the base of the culverts is low enough to convey water under low conditions.
OB2 As previously noted, the proposed construction measures do not attempt to address the problem of the
small, seasonal tributary that joins the Botrivier from Doringkloof. The latter tributary is diverted along the
edge of the concrete structure, increasing flood pressure and erosion damage on the right hand side of
the Bot River channel, and contributing to the high levels of erosion damage observed in the river
downstream of the structure. These impacts will thus be perpetuated by repairs to the new structure.
The aquatic ecologist (Day, 2014) has recommended that structure must include an additional or
extended culvert or other ecologically cognisant measure that allows for the free flow of the minor stream
through the structure, without being diverted along the road edge. The mechanism for this would need to
address the fact that the stream appears to enter the system at a higher level than the existing culvert.
Amendment of the proposed design to address the issue of diversion of flows from the small tributary into
the Bot River is considered essential mitigation. Assuming that this and the other recommended mitigation
measures are implemented at this site, the proposed activities would be considered to have a net positive
ecological impact. In the absence of this aspect being addressed, it is likely that erosion and disturbance
will remain significant sources of disturbance to the river. Further expenditure on perpetuating these
conditions is not considered ecologically sustainable, and thus approval of this project without the
specified mitigation measures would not be recommended.
NOTE that these concerns raised by Dr Day have been discussed with the DTPW and its consulting
engineers, and that the DTPW's responses are recorded in the discussion of alternatives at Section E(1)(c)..
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 59
OB3 Widening of the existing culverts and their extension across the full width of the (now bermed and
channelised) river in these reaches as proposed, so as to allow the passage of cobbles and sand beneath
the structure and to allow the passage of flows up to a 1:2 year flood through the structure is regarded as a
positive impact, likely to promote longer-term stability of the river channel.
Provision to cater for the irrigation pipelines at the outlet to the bridge structure is also considered a
positive impact, as its relocation away from the river bed will reduce the ongoing disturbance to the river,
resulting in the past from the frequent need to repair infrastructure, subject to frequent flood damage.
However, in the absence of ensuring control over erosion at the level of the river or at least the upstream
reach, it is very unlikely that such positive outcomes will be achieved, with significant damage occurring on
a 1:2 year basis considered a disturbance regime too great to allow for ecological recovery between
disturbance events.
Flows may also have to be diverted temporarily in order to allow work to take place in the active channel.
Any disruption to flows will be of short duration and localised in extent.
Owing to the disturbed state of the river and the level of damage to the existing river crossing structure
means that there is some likelihood that further flooding will result in the current road being unusable as a
bypass without intervention during construction, resulting in the need for additional earthworks and
probable diversion of flows.
In the event of damage to the existing crossing being such that it cannot be used as a bypass during
construction, it is recommended that construction phase mitigation measures include allowance for the
short-term repair of the existing bridge, using pipe culverts if necessary to minimize disruptions to flows.
OB4 Installation of gabion 'mattresses' at the inlet and outlet structures along this secondary flood channel of
the Elandskloofrivier would, at most, have an impact of 'Very Low' negative significance on the hydraulic
functioning of this watercourse. There would consequently be no reason to motivate against the project
going ahead – specifically given that gabions would be used instead of concrete apron slabs.
The positive aspects of gabions are that, besides meeting the project objective to constrain the growth of
reeds that contribute to the pipe culvert being blocked, their rough surface will not accelerate flows to the
extent that concrete surfaces would, reducing erosion potential. Also, gabions would support sub-surface
seepage during the flow season which would help to prevent wetland vegetation from drying out.
As with all the other projects, flows may also have to be diverted temporarily in order to allow work to take
place in the active channel. This channel seems to be highly seasonal, only carrying water that overflows
from the Elandskloofrivier during floods. If work is confined to the dry season (January to March), there
would be minimal dispruption of flows – which, in any event, will be of short duration and highly localised in
extent.
OB5 The installation of improved scour protection downstream of this culvert will not have any influence on
flows passing through the structure. Flows may, however, be temporarily disrupted during construction,
when it may be necessary to divert water around the construction site. This will be of short duration and
localised.
OB6 The additional box culvert at this site will improve the passage and management of high flows under the
road. Flows may be disrupted during construction of the extra culvert, and a check-weir just upstream of
the crossing (see above). Such disruptions in flows may be exacerbated by the construction of a
temporary by-pass downstream of the culvert where work is to take place. Again, if work is timed to
coincide with the dry season, the management and diversion of water will be considerably less
problematic than under wetter conditions. If effectively managed, any disruptions or diversions will have a
localised and relatively short-term impact on water movement down this channel.
NOTE that in all cases, it is important to keep flows as natural as possible as the rivers at sites OB3-OB6 all drain into the
Riviersonderend, which an aquatic CBA and Wetland FEPA.
Will the development have an impact on water quality? YES
� NO
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 60
If yes, please describe:
OB1 The Botrivier is already prone to sediment loading and turbidity due to the effects of high erosion. During
construction, there may be increased turbidity arising from unavoidable disturbances to the bed and
banks of the river. The river may also be contaminated by the receipt of construction-associated materials
such as cement, fuel or lubricants. These impacts, were they to occur, would be of high intensity but
localised in extent. The risk of these impacts occurring beyond the construction phase is effectively nil.
OB2 If construction takes place in late summer or autumn, there should be a negligible risk of water resources
being contaminated in the manner described above for Site OB1. The vulnerability of the resource to
contamination would, however, be less than at site OB1 because considerably less work is to take place at
the 'Doringrivier' site. Turbidity may increase under wetter conditions, when more erosion of areas disturbed
by construction may be expected. Although, the risk of contamination of water resources would cease
once construction has been concluded, erosion would probably continue with varying intensity around the
confluence of the two watercourses, across the southerly road approaches, and against the right bank of
the Botrivier downstream of the culvert. This would only be preventing by completely redesigning the river
crossings at this difficult site.
OB3 Impacts on water quality in the bottom reaches of the Elandskloof River would be as closely associated
with the proposed construction of a new bridge, as well as the large volume of unstable sediments in the
channel and along eroded reaches of river bank that become mobilised and transported downstream
during floods. The bed and banks of the Elandskloof River are actively eroding along much of its length
and the river is, overall, in a highly destabilised and degraded condition. It is therefore essential that the
destabilised river channel and its margins be stabilised by means of groynes and adequate plant cover.
The same construction phase impacts on water quality are likely as outlined for OB1. Their net effect would
however be relatively low, given the level to which the river is already disturbed. Additional sediment and
bank disturbance, for example, would probably have a negligible additional effect, given the current rates
of disturbance.
OB4 The proposed works at this minor pipe culvert are relatively far more limited in extent than those planned
for the other sites and, provided that construction takes place during dry weather, the risks of erosion,
contamination and turbidity of downstream reaches are understood to be low.
OB5 The pool below the culvert at 'Tarentaalkraal' is in a 'moderate' ecological condition and supports relatively
intact wetland vegetation along its margins (including palmiet Prionium serratum). Construction-phase
impacts may include contamination of the watercourse by construction-associated materials such as
cement and sediments, resulting in a short-term increase in turbidity and pH, in a watercourse in which
water quality is probably only mildly impacted. These impacts would all be exacerbated if construction
took place during the wet season when the water table was high, or during a period when a storm event
occurred. Great caution must be therefore be exercised in order to protect this watercourse from any
contamination and excessive disturbance or deposition of sediments.
OB6 The major source of turbidity at this site would be associated with erosion caused by disturbances to the
bed and banks of the watercourse at, respectively, the site where the check-weir has to be built, the main
construction site itself (i.e. parallel to the existing box culvert underneath the DR1313), and downstream
when the by-pass is built and de-commissioned. The erection of a temporary coffer or barrier to divert
water away from the construction site may also contribute to disturbance and turbidity, albeit of short
duration. As it is, this system is probably already vulnerable to these effects owing to existing, high levels of
disturbance and erosion. In the long-term, however, the works at OB6 would probably lead to a significant
reduction in erosion at the site and, with that, a far less severe impact on water quality downstream of the
structure. However, the active erosion and loss of river bank downstream of the crossing needs to be
controled in order to prevent ongoing deterioration of the watercourse and water quality.
NOTE that in all cases, the above impacts would be exacerbated if construction took place during the wet season when the
water table was high, or during a period when a storm event occurred.
Will the development have an impact on scouring, erosion and sediment movement?
YES
� NO
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 61
NOTE
In all cases, changes to flows coupled with disturbances to the beds and banks of the affected watercourses may
precipitate scouring, erosion and sediment transport and deposition. The proposed works at sites at OB1 and OB3 entail the
construction of two new bridges and realigning the road approaches to these structures. It would take at least six months to
complete these works, and to demolish and remove the redundant structures. Not only will there be more physical
disturbance at these sites, but it will continue for foreseeably longer than at any of the other sites with, maybe, the exception
of the extra culvert that is to be installed at OB6. With disturbance to the beds and banks of watercourses, arises the risk of
increased scour, erosion, downstream sediment transport, turbidity and even destabilisation of watercourses – particularly so
where construction may entail temporarily constricting flows around coffer structures, or flows are diverted by earthworks
(such as by-passes), excavators loosen or dislodge otherwise consolidated materials, or when water is pumped back into
rivers under pressure. These risks are generic to all sites, and need to be mitigated and managed accordingly – and
particularly so at OB1, OB3 and OB6 where disturbances are to be more sustained than elsewhere and, following from that,
would have commensurately increased prospects for erosion-related damage to the affected water resources and their
biodiversity. The proposed groynes in the Elandskloofrivier would play a critical role in mitigating the impacts of the new
causeway at OB3 as they would control bank erosion and channel migration in the reaches directly up- and downstream of
the crossing. Flows and erosion would need to controlled at least 50 m upstream and downstream of the crossing and,
ideally, the groynes should be in place before construction starts on the new causeway at OB3. Currently, however, this
seems unlikely.
OB1 As with the works at sites OB3 and OB6, major improvements to the flood conveyance capacity of this and
the structures at the latter sites will help to reduce the frequency of significant flood disturbance, ease the
passage of debris through the structure, and potentially promote more rapid ecological recovery
between floods because of the reduced rates of disturbance and erosion. However, alien trees would
have to be cleared from the channel (60 m x 15 m on each bank upstream, and 30 m x 15 m on each
bank downstream) for these improvements to have demonstrable effect. Furthermore, cleared areas
would have to be stabilised otherwise they will be vulnerable to erosion. This can be achieved by bank
shaping and planting cleared areas with indigenous plants that occur naturally in watercourses in the
western parts of the Overberg. The eroding and collapsed right bank of the Botrivier upstream of OB1 also
needs to be stabilised against further erosion. If not, the erosion may develop to the extent that it
threatens the structural stability of the new bridge. Key factors driving this erosion include dense infestation
of black wattle along the river banks, and fallen trees which block and deflect flows in the channel.
OB2 See above. This site is subject to severe erosion that appears to be caused be, among others, the
misalignment of the culvert to the direction of flow within the Botrivier, flows from a small, seasonal tributary
that are deflected across the upstream face of the culvert into the right bank of the Botrivier, and flooding
of the southern approaches to the culvert which causes road material to be scoured away and washed
into the channel. These erosive processes are exacerbated by dense stands of alien trees that need to be
cleared from the two watercourses – in swathes of 30 m x 15 m on both sides of the Botrivier, up-and
downstream of the culvert, and at least 30 m upstream along the minor stream that flows in from
Doringkloof, to the east.
OB3 See above. Little can be achieved in terms of stabilising the Elandskloofrivier in the vicinity of the crossing
at OB3 unless a comprehensive strategy of channel stabilisation is implemented along the heavily farmed
length of this severely destabilised river. The Western Cape Department of Agricultural is currently
undertaking planning to this end, with the support of national disaster relief funding. As indicated above,
the new causeway would have considerably widened culverts, extending across the full width of the
channel which would allow 1:2-year floods and their sediment load to pass unimpeded through the
structure. It will be over-topped by larger floods. Gabion protection along the approaches, and an
extensive concrete scour apron at the outlets, will help to prevent erosion of the approaches as well as
the channel downstream of the causeway.
OB4 See above. This pipe culvert on a minor flood channel of the Elandskloofrivier is to be equipped with
gabion mattress on its upstream and downstream sides. This will help to curtail the growth of reeds that
contribute to blockages and over-topping of the road during floods, as well as prevent scouring at the
outlet and when floods overtop the culvert.
OB5 See above. The stepped series of gabions and a gabion mattress at the base of the refurbished anti-scour
structure are specifically designed to prevent erosion and undermining of the culvert at 'Tarentaalkraal'.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 62
OB6 See above. The single culvert at 'Nooitgedacht' can currently convey only 50% of flows during 1:2-year
floods, which causes the river to back up, rise and erode the gravel road embankments, over-top the
road, and inflict erosion damage on the other side of the culvert. The single culvert also causes flows to be
concentrated, which appears to have precipitated severe and active erosion of the channel bed and
banks downstrearm of this structure. A head-cut just upstream of the crossing is an additional source of
erosion and sedimentation. Besides adding a second culvert, and stabilising the head-cut, construction at
this site will also have to manage the temporary by-pass, downstream of the crossing so that it does not
precipitate erosion both during and after completion of the works.
NOTE that in all cases, the above impacts would be exacerbated if construction took place during the wet season when the
water table was high, or during a period when a storm event occurred.
Will the development have an impact on the physical structure and stability of the watercourse? YES
� NO
OB1 The comments about the synergistic interaction between modified flows, erosion and the effects of
exacerbated sediment transport apply equally to questions of channel structure and instability. In short,
the potential environmental benefits associated with the rebuilt bridge at OB1 (improved food
conveyance capacity and sediment throughput) must be combined with measures to stabilise erosion
and slumping of the left bank of the Botrivier upstream of the new bridge, as well as the removal of alien
vegetation both upstream and downstream of the structure, as recommended above. Extra diligence is
required with regard to reshaping the channel following the removal of the now-defunct, original, bridge.
This is because residual disturbances to the bed and banks of the river may precipitate erosion at nick-
points or discontinuities (benches') in the bed of channel. All rubble must be removed for the same
reasons.
OB2 There is little prospect that the current instability and degradation of the Botrivier downstream of the
current culvert can be effectively managed and mitigated by the repairs that are proposed for this site. As
indicated above, the entire configuration of the crossing and related infrastructure at the confluence of
the minor watercourse and Botrivier needs to be revisited to resolve erosion and channel instability that
are contributing to environmental degradation as well as damage to the road.
OB3 The comments above relating to the potential impacts on channel instability at OB1 apply equally to the
works at OB3. Additional measures at this site that are necessary to forestall long-term changes to the
morphology and stability of the Elandskloofrivier include the construction of groynes to prevent rampant
erosion, as well as removing the berm along the left side of the channel downstream of the new
causeway.
OB4 Minor works are proposed at this point which, if executed as recommended and in accordance with the
Construction EMP, should not affect the structure or stability of this secondary channel.
OB5 The re-designed anti-scour measures downstream of this culvert are intended to curb erosion and under-
cutting of the outlet structure and would therefore prevent destabilisation of the channel as a result of
excessive scour.
OB6 As noted above, the current culvert at this site is a major contributor to erosion and channel instability.
With improved flow capacity, and the construction of a weir to contain the head-cut upstream of the
culvert, these problems should be largely resolved. However, as with OB1 and OB3, special care must be
taken to prevent the demolished by-pass from precipitating erosion. The aquatic ecologist has also
recommended that the severely eroded channel downstream of the culvert must be stabilised with weirs
or similar structures.
NOTE that in all cases, the above impacts would be exacerbated if construction took place during the wet season when the
water table was high, or during a period when a storm event occurred. Achieving long-term stability for particularly the
Meulrivier can only be achieved by stemming and reversing degradation in the river's intensively farmed catchment, which
lies outside the scope of this application and the decision that must be made.
(1)(c) Biodiversity aspects:
Will the development have an impact on (a) Critical Biodiversity Areas and Ecological Support Areas,
(b) Freshwater Ecosystem Priority Areas, and (c) habitat in listed threatened ecossytems?
YES
� NO
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 63
NOTE that impacts on CBAs and ESAs are defined and assessed in relation to the criteria that informed the selection
of an area or feature for inclusion in a CBA network, as well as the implications that loss of habitat would hold for
achieving the management objectives for these two types of priority conservation areas. The CBAs and ESAs at the
respective sites were selected according to the following criteria:
− Habitat required as part of CBA network OB1 and OB2
− Potential area of important of nationally listed CR or EN habitat OB1 and OB2
− Critical area for maintaining hydrological processes All sites
− Critical area for maintaining ecological processes All sites
If yes, please describe:
OB1 CBAs/ESAs
Marginally
positive to
neutral
impact
The CBA map for the Overberg District Municipality states that the ESA at this site is
transformed, and the CBA is characterised as degraded. This is reflected by the
'largely modified' PES (D) of the site as described by the aquatic ecologist (Day,
2014). Currently, habitat at this site, and the maintenance of hydrological
functioning/ecological processes in support of the affected biodiversity features,
do not contribute to keeping the affected features in their desired ecological
condition. The impacts of the proposed works, and structure, on CBAs or ESAs will
therefore be negligible owing to their degraded condition. Any ecological or
biodiversity benefits arising from the new bridge would only materialise if the full
suite of mitigation measures recommended by the aquatic ecologist were to be
implemented.
FEPAs
No impact
No FEPAs are present.
Threatened
habitat
No impact
The site is mapped as falling within Western Rûens Shale Renosterveld, a CR
ecosystem. It is severely degraded and there are no evident occurrences of
renosterveld at the site.
OB2 CBAs/ESAs
Negative
impact
The site has a PES of E, or 'seriously modified'. The CBA is also described as
'degraded' by the Overberg biodiversity plan. As with site OB1, no positive changes
can be forecast with regard to improving the ecological condition, and
biodiversity value, of the site unless the current drivers of erosion and channel
instability are conclusively addressed as recommended by the aquatic ecologist.
FEPAs
No impact
No FEPAs are present.
Threatened
habitat
No impact
The site is mapped as falling within Western Rûens Shale Renosterveld, a CR
ecosystem. Riparian vegetation is in a poor condition, with high levels of alien
infestation.
OB3 CBAs/ESAs
Marginally
positive to
neutral
impact
Habitat at the site is 'degraded', according to the Overberg biodiversity plan, and
it has a PES of 'E' or 'seriously modified'. Indigenous vegetation against the steep
western bank of the Elandskloofrivier, upstream of the current pipe culvert crossing,
will not be affected by work at the site. The remainder of the site constitutes a
grassy meadow, the severely disturbed channel and banks of the watercourse, a
bulldozed berm running downstream, left of the channel, and an area of extensive
erosion behind it. The new causeway, viewed in isolation of the heavily degraded
and destabilised condition of the Elandskloofrivier, would have a positive impact
on flood conveyance and sediment transport. However, these positive attributes
would be erased by the structural intstabiity and poor condition of habitat in the
remainder of this aquatic ecosystem.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 64
FEPAs
Neutral
Structurally, the Elandskloofrivier coincides with a channelled valley bottom
wetland that is designated as a FEPA wetland (Day, 2014). Impacts arising from the
proposed new causeway would, if assessed locally and in isolation from the
condition of the broader system, potentially contribute to the rehabilitation of the
affected river reaches towards a less degraded ecological state. However, as with
all the other watercourses that are subject to a high degree of habitat
modification and structural instability, the full benefits of improved flood and
sediment conveyance capacity would only materialise if coupled with a
concerted programme of rehabilitation at the appropriate hydrological and
ecological scales.
Threatened
habitat
No impact
South of the DR1313, this site is mapped as coinciding with the distribution range of
Central Rûens Shale Renosterveld, a CR ecosystem. Endangered Greyton Shale
Fynbos potentially occurs north of the DR1313. As indicated above in the discussion
of impacts on CBAs and ESAs, the terrain around site OB3 is degraded and reflects
'very high' levels of disturbance. This is inter alia attributed to the massively eroded
and destabilised condition of the Elandskloofrivier, orchards and grassed areas
downstream of the damaged causeway, and severe erosion into fields to the
south-east which is currently hemmed in from the channel by a bulldozed berm.
OB4 CBAs/ESAs
Neutral
The site is mapped as an ESA which must be managed in support of maintaining
hydrological and ecological processes. It has a PES of 'C' ('moderately modified').
Provided that the recommended mitigation measures are implemented at this site,
the installation of protective gabion mattresses to contain reed growth should not
affect flows along this seasonal flood channel.
FEPAs
Neutral
Whereas the installation of gabion mattresses will not contribute to improving the
ecological condition of the affected channel, they will help to prevent blockages
that contribute to erosion damage to the road embankments and, by implication,
the condition of the small flood channel.
Threatened
habitat
No impact
The vegetation here is identical to that mapped for site OB3. The landscape south
of site OB4 is also mapped as falling within the range of Central Rûens Shale
Renosterveld, a CR ecosystem. Greyton Shale Fynbos (EN) occurs on the rounded
spurs that flank the valleys between the Riviersonderend Mountains and the
Riviersonderend. There are no vestiges of intact renosterveld or fynbos within 100 m
of the site. Upstream and downstream of the DR1313, the flood channel is choked
by 'fluitjiesriet' P. australis. Weeping willows Salix sp. occur downstream of the
culvert.
OB5 CBAs/ESAs
Neutral
Site OB5 coincides with an ESA in a channelled valley bottom wetland. It has a PES
of 'C' ('moderately modified'). The banks of this watercourse are heavily infested by
alien wattle species, but the channel retains good quality in-stream habitat,
including palmiet P. serratum. The proposed scour protection, which is to be
constructed with gabions, will intrude about 8 m into the pool below the culvert
and occupy a surface area of some 120 m2. The new measures against scour will
prevent erosion downstream of the culvert while preventing the outlet structure
from being under-mined. The gabion structure will contribute to habitat loss but, by
the same measure, will also prevent habitat degradation associated with the
culvert.
FEPAs
Neutral
The proposed works will not have a significant impact on the FEPA status of this
section of the affected watercourse. As explained above, the works will contribute
to some loss of habitat, but will also prevent erosion that would otherwise lead to
habitat degradation and potential long-term instability of the river. In the
circumstances, the refurbished anti-scour protection would represent the best
practicable option from a biodiversity and socio-economic perspective.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 65
Threatened
habitat
No impact
As with the preceding works between the Riviersonderend and the adjacent
mountains to the north, vegetation in this area is mapped as constituting Greytone
Shale Fynbos EN north of the DR1313, and CR Central Rûens Shale Renosterveld
below the road. Neither vegetation types occur in the vicinity of the site. The works
will also not intrude into relatively intact habitat around the margins of the pool
and, in the long term, will contribute to protecting this habitat against erosion
damage.
OB6 CBAs/ESAs
Potentially
positive
This 'largely' to 'seriously' modified (PES = D/E) site spans a watercourse that has
been identified as an ESA which must be managed in support of maintaining
hydrological processes. The proposed works will represent a substantial
improvement on flood and sediment conveyance, and would therefore have a
positive impact by reducing erosion. Stabilisation of the head-cut upstream of the
culvert would also stem erosion and protect the vegetated valley bottom wetland
against degradation. A by-pass would represent a temporary source of
disturbance to the bed and banks of the channel downstream of the road.
However, the channel here is actively eroding and needs to be stabilised. The
proposed addition of another box culvert would, however, reduce the impact of
flood discharge from the culvert on the downstream environment. With stabilisation
of the channel, the proposed works may, in the long term, have a net positive
effect on riparian habitat and hydrological functioning.
FEPAs
Potentially
positive
As above.
Threatened
habitat
No impact
According to the national vegetation map, this site falls within the range of
Greyton Shale Fynbos EN. The site is substantially degraded and rates 'low' in terms
of its ecological importance and sensitivity. There is some intact vegetation on the
rise directly north-east of the culvert, as well as in the wetland to the north-west of
the road. Neither of these habitats will be affected by construction.
(c)(i) Socio-economic aspects (capital costs and employment opportunities, etc):
What is the expected capital value of the activity on completion?
What is the expected yearly income or contribution to the economy that will be generated by or
as a result of the activity?
N/A
Will the activity contribute to service infrastructure? YES � NO
How many new employment opportunities will be created in the construction phase of the
activity?
What is the expected value of the employment opportunities during the construction phase?
What percentage of this will accrue to previously disadvantaged individuals?
How will this be ensured and monitored (please explain):
The appointed main contractor would implement the applicant’s standard Procurement Policy. Specific targets have
been set in the contract documentation and will be monitored by the applicant.
How many permanent new employment opportunities will be created during the operational
phase of the activity?
None
What is the expected current value of the employment opportunities during the first 10 years? N/A
What percentage of this will accrue to previously disadvantaged individuals? N/A
How will this be ensured and monitored (please explain):
N/A.
Any other information related to the manner in which the socio-economic aspects will be impacted:
None.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 66
(c)(ii) Socio-economic impacts
Will the development have an impact on:
− Sense of place
− Human wellbeing (noise and dust)
− The integrity and safety of the road network?
YES
� NO
If yes, please describe:
Impacts on 'sense of place' (potentially applies to the construction phase at all the sites).
‘Genius loci’ or the 'spirit of place is a subjective but important consideration for individuals who attach particular
meanings or values to specific places or landscapes.
It is hard to pin down as a concern of general application, but there may be individuals who take issue with factors such
as visual or aural disturbances or detraction from perceived aesthetic qualities. Sense of place is emotionally charged,
entails idealised expectations, and can provides grounds for strong reactions to environmental change.
However, the social necessity and temporary nature of the works and rehabilitation of disturbed areas should contribute
to ameliorating people’s concerns about infringements on their sense of place and impacts on 'sense of place' will
therefore not be subject to more rigorous assessment.
− Impacts on sense of place: Marginally negative to neutral
Impacts on human wellbeing (potentially applies to the construction phase at all the sites).
Dust and noise would be generated during construction.
Particular care is needed to suppress and minimise dust near homesteads and orchards that are ready for harvesting,
specifically at OB3, which is adjacent to orchards and employee accommodation, and OB6, which is within 60 m of a
farm house. Contractors must ensure that the generation of dust is minimised and controlled in terms of the prescriptions
of the Construction EMP.
Construction-related noise may be experienced as a nuisance to people living in the vicinity of the sites. However, the
sound of heavy machinery forms part of the aural 'landscape' in farming areas and would be confined to weekdays. The
impact of noise is viewed as an unavoidable but transient nuisance and will not be assessed any further. The mitigation
of noise-related impacts is addressed in the CEMP.
− Impacts on human wellbeing: Potentially negative to neutral
The integrity and safety of the road network in the Theewaterskloof Municipality
The need and desirability of the proposed repairs and replacement of the existing bridges at sites OB1 and OB3 are
addressed favourably in detail in Section D and will not be assessed further.
Road safety has two aspects: Safety to pedestrians and motorists during construction, and the long-term contribution
that the repaired or rebuilt structures will make to safe use of the affected road network.
Whereas daily vehicle usage is heaviest on the DR1313 (annual average daily traffic count = 200 vehicles), the DR1288
negotiates a small pass with relatively tight corners and impeded visibility, and traffic control measures would therefore
be advisable at all the construction sites.
The contribution of the repaired and rebuilt structures is dealt with under the discussion of need and desirability, which
underscores the public benefits of the works and therefore will not be assessed any further.
− Impacts on the Overberg rural roadwork: Positive
2. WASTE AND EMISSIONS
(a) Waste (including effluent) management
Will the activity produce waste (including rubble) during the construction phase? YES � NO
If yes, indicate the types of waste (actual type of waste, e.g. oil, and whether hazardous or not) and
estimated quantity per type?
Rubble generated by the demolition of the damaged bridge at site OB1. The estimated volume is: 70 m3
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 67
Rubble generated by the demolition of the damaged bridge at site OB3. The estimated volume is: 65 m3
Construction waste in the form of used cement bags, broken material, etc. The estimated volume is: 6 m3
Hazardous waste in the form of spilled fuel and/or oil spills collected in drip trays and contaminated soil
resulting from accidental spills. The estimated quantity is: 2 m3
Will the activity produce waste during its operational phase? YES NO �
If yes, indicate the types of waste (actual type of waste, e.g. oil, and whether hazardous or not) and
estimated quantity per type? N/A NIL m3
Where and how will the waste be treated / disposed of (describe)?
− The demolished remains of the bridge at sites OB1 and OB3 will be removed for disposal at at the nearest license
waste collection facility.
− The Contractor would be responsible for the establishment of a solid waste control and removal system. Construction
waste would be disposed of at an approved landfill site. Hazardous waste in the form of fuel/oil and contaminated soil
would also be disposed at a registered hazardous waste site (see Construction EMP in Appendix H).
Has the municipality or relevant authority confirmed that sufficient capacity exist for treating / disposing
of the waste to be generated by this activity(ies)? If yes, provide written confirmation from Municipality or
relevant authority. N/A
YES NO
Will the activity produce waste that will be treated and/or disposed of at another facility other than into a
municipal waste stream? YES NO �
If yes, has this facility confirmed that sufficient capacity exist for treating / disposing of the waste to be
generated by this activity(ies)? Provide written confirmation from the facility and provide the following
particulars of the facility: N/A
YES NO
Does the facility have an operating license? (If yes, please attach a copy of the license.) N/A YES NO
Describe the measures that will be taken to reduce, reuse or recycle waste:
During the construction phase the Contractor shall be responsible for the establishment of a solid waste control and
removal system (see Construction EMP in Appendix H). An integrated waste management approach shall be used,
based on the principles of waste minimisation, reduction, reuse and recycling of materials.
(b) Emissions into the atmosphere
Will the activity produce emissions that will be disposed of into the atmosphere? YES � NO
If yes, does it require approval in terms of relevant legislation? YES NO �
Describe the emissions in terms of type and concentration and how it will be treated/mitigated:
Dust and noise would be generated as a result of construction activities. The Contractor shall ensure that the generation
of dust is minimised and shall implement a dust control programme (e.g. wetting of areas being disturbed) to maintain a
safe working environment and minimise nuisance to road users and residents in the area. Particular care is needed to
suppress and minimise dust near homesteads and orchards that are ready for harvesting. The Contractor shall ensure that
exposed soil and material stockpiles are adequately protected against the wind (e.g. covering of material stockpiles,
etc.).
These activities would be managed in terms of the requirements of the Construction EMP (see Appendix H).
The Contractor shall also be familiar with and adhere to any regulations and by-laws regarding the generation of noise
and hours of operation. Permits shall be required if the contractor deviates from local by-laws and/or regulations of the
local authority.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 68
3. WATER USE
Please indicate the source(s) of water for the activity by ticking the appropriate box(es)
Municipal Water board Groundwater River, Stream,
Dam or Lake Other �
The activity will not
use water
A minimal volume of water would be required for road construction activities. The appointed Contractor would be
responsible for finding suitable water sources, which may be from local farm dams. This would be discussed with the
relevant farmers, as appropriate. Extraction of water directly from the river for construction activities is not allowed.
If water is to be extracted from a groundwater source, river, stream, dam, lake or any other natural feature,
please indicate the volume that will be extracted per month: N/A m3
Please provide proof of assurance of water supply (eg. Letter of confirmation from municipality / water user associations,
yield of borehole) N/A
Does the activity require a water use permit / license from DWA? YES NO �
A copy of the Draft BAR and freshwater assessment specialist report will be submitted to the DWA for comment and to
confirm whether the proposed project would be exempted from water use licensing in terms of GN 1199 of 18 December
2009.
If yes, please submit the necessary application to Department of Water Affairs and attach proof thereof to this application.
N/A
Describe the measures that will be taken to reduce water demand, and measures to reuse or recycle water:
Only a minimal volume of water would be required for construction activities. If water is to be used for dust suppression
measures, areas should only be wetted during windy days and/or when dust may become a nuisance to surrounding
residents and farms. All water tanks and water trucks must be maintained in a good working condition to ensure that no
unnecessary water leaks occur.
4. POWER SUPPLY
Please indicate the source of power supply e.g. Municipality / Eskom / Renewable energy source
Generators would be used at the construction sites to power drills, pumps and other machinery.
If power supply is not available, where will power be sourced from?
See above.
5. ENERGY EFFICIENCY
Describe the design measures, if any, that have been taken to ensure that the activity is energy efficient:
N/A.
Describe how alternative energy sources have been taken into account or been built into the design of the activity, if any:
N/A.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 69
6. DESCRIPTION AND ASSESSMENT OF THE SIGNIFICANCE OF IMPACTS PRIOR TO AND AFTER MITIGATION
Note:
− All impacts are systematically assessed and presented according to the ‘Convention for assigning significance
ratings to impacts’.
− The status of all impacts should be considered to be negative unless otherwise indicated.
− Only the preferred design alternative for each project component is assessed in this section. This is in line with the
outcome of the investigation of alternatives (see Section E1(h)). The ‘no go’ option is not assessed (see Section
C1(f)).
− Owing to the common objective of the proposed repairs (repair or refurbishment of flood-damaged causeways
and culvert crossings on provincial roads), the shared functional characteristics of the affected ecosystems
(seasonal/perennial foothill rivers draining sandstone and/or shale-dominated catchments in the fynbos biome),
and generally degraded condition of most sites, impacts on the biophysical environment are assessed
generically, with specific reference to site-specific issues identified by the aquatic and terrestrial ecologists during
the initial screening process.
− Most of the sites are located within CBAs and/or ESAs. Impacts on CBAs and ESAs are assessed separately to
impacts on the actual, affected ecosystem in order to distinguish between identifiable and predictable
ecological impacts, and impacts on habitat or ecosystem functioning that may compromise the integrity of the
biodiversity features that informed the selection of the affected CBAs.
− Impacts on degraded habitat in CBAs or ESAs are treated as 'neutral'. Impacts that may hold localised, site-
specific benefits with respect to improving the condition or functioning of CBAs or ESAs are treated as having
'marginal' positive significance. The biodiversity sector plan guidelines (Holdness and Bradshaw, 2010) for
development in aquatic CBAs in the Overberg District Municipality applies a ‘restricted’ status to infrastructure
development in these features, which means that development can be entertained in these situations as long as
it is demonstrably consistent with the management objectives for CBAs. The ‘restriction’ in question would appear
to apply to new development, not repairs to existing infrastructure as is the case with the projects subject to this
Basic Assessment. The impact assessment and recommendations for impact management have nonetheless
been guided by the management objectives for CBAs.
6.1 CONSTRUCTION PHASE
Construction phase impacts are likely to be of high intensity but locally confined, and readily managed through
implementation of standard impact mitigation measures, which are provided below.
Selection of issues for impact assessment on the basis of screening
Impacts arising from the construction phase of the repairs have, for the sake of ease of analysis, been separated into
several broad environmental contexts. It is important to note, however, that this is in many respects an artificial distinction
as many of these classes of impact are integrated and mutually reinforcing. For example, a biophysical impact on
biodiversity in the form of indigenous vegetation can also be experienced as an impact on human wellbeing and sense
of place.
The following construction-phase impacts have been identified for the purpose of impact assessment and evaluation:
− Impacts on the biophysical environment, i.e.,
o Hydrological aspects, i.e. flow regimes and water quality;
o Hydro-geomorphological aspects, i.e. scour, erosion and sediment movement;
o The physical structure and stability of the watercourse; and
o Biodiversity aspects, i.e. aquatic CBAs as surrogates for biodiversity pattern (in -stream and riparian habitats)
and ecosystem function (flows and sediment dynamics).
− Impacts on the socio-economic environment, i.e.,
o Sense of place
o Human wellbeing (noise and dust)
o Inconvenience to road users
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 70
No assessment has been undertaken of potential impacts relating to cultural heritage or the national estate as this did
not emerge as an area of concern during the environmental screening process.
Impacts on employment are viewed as positive, albeit of temporary duration. Besides the benefits of direct income
generated by the projects, employment also entails a measure of capacity-building and skills’ transfer that can enhance
the future employability and livelihood prospects of beneficiaries.
NOTE that where there are inconsistencies between significance ratings reported here, and in any of the appended
specialist reports, the more conservative rating is reflected in the impact evaluation tables (Sections 6.1 and 6.2).
6.1.1 POTENTIAL IMPACTS ON BIOPHYSICAL ENVIRONMENT: HYDROLOGICAL ASPECTS AT SITES OB1, OB3, OB5 AND OB6
Flow regimes
Nature of impact:
Temporary changes to stream flows as a result of diversions and coffer
structures to de-water construction areas at sites OB1, OB3, OB5 and
OB6.
Before mitigation After mitigation
Extent of impact: Local Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Low to very low Very low
Probability of occurrence: Probable Possible
Degree to which the impact can be
reversed: Fully reversible Fully reversible
Cumulative impact Low Minimal
Significance rating LOW to VERY LOW (-) VERY LOW (-)
Additional remarks
There may be some disruption of flows down the watercourses in question during the establishment of temporary
diversions or coffer structures to route water around the construction sites. 'Local' impacts may arise during the initial
establishment of diversionary structures (such as sandbagged coffers) and flows (depending on water levels) are
temporarily prevented from reaching the Riviersonderend or, in the case of the Bot River sites, the visible effects of flow
modification exceed the length of the nearest downstream reaches. These will be short-lived interruptions, not lasting
more than 48 hours in any instance. Flows may be interrupted intermittently during construction which may in toto
extend to six months at sites OB1, OB3 and OB6, i.e. where the most substantial works are to take place. Construction is
expected to be concluded more rapidly at sites OB2 and OB4. The aim of mitigation would be to maintain natural flow
regimes during the full period of construction. The risk that flows would be significantly impacted at site OB4 is viewed as
marginal owing to the seasonal character and small size of this channel. Overall, the drier the watercourse at the time of
construction, the less impact there will be on flows.
Mitigation measures
− Construction activities within watercourses must not take place during the wet season (i.e. any activities
requiring the diversion of flows must take place between October and April only), and construction schedules
should be managed within these time frames
− Where de-watering is required as part of construction activities, provision must be made for the settlement of
sediment in temporary sediment ponds or other devices, managed so as to prevent the passage of sediment-
rich water into the watercourse
− De-watering systems must be designed so that they do not result in the passage of concentrated flow into
watercourses, thereby promoting erosion.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 71
6.1.2 POTENTIAL IMPACTS ON BIOPHYSICAL ENVIRONMENT: HYDROLOGICAL ASPECTS AT ALL SITES
Water quality (turbidity)
Nature of impact:
− Release of sediments into watercourses may result in episodes of
increased turbidity, particularly when excavations take place to
establish foundation structures. This impact applies to all sites, but is
expected to be most significant at OB1, OB3 and OB6 owing to the
extent and duration of works arising from the construction of the
new bridge and an additional culvert and temporary by-pass in the
case of site OB6.
Before mitigation After mitigation
Extent of impact: Local (OB1, OB3 and OB6) to site-
specific (other sites) Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Low (OB1, OB3 and OB6) to very
low (other sites) Very low
Probability of occurrence: Probable Possible
Degree to which the impact can be
reversed: Fully reversible Fully reversible
Cumulative impact Low Minimal
Significance rating LOW (OB1, OB3 & OB6) to VERY
LOW (-) VERY LOW (-)
Additional remarks
None.
Mitigation
− Construction activities within watercourses must not take place during the wet season, i.e. between May and
September.
− Where de-watering is required as part of construction activities, provision must be made for the settlement of
sediment in temporary sediment ponds or other devices, managed so as to prevent the passage of sediment-rich
water into the watercourse;
− De-watering systems must be designed so that they do not result in the passage of concentrated flow into
watercourses, thereby promoting erosion.
6.1.2 POTENTIAL IMPACTS ON BIOPHYSICAL ENVIRONMENT: HYDROLOGICAL ASPECTS AT ALL SITES
Water quality (contamination by construction materials)
Nature of impact:
− De-watered material, cement and diesel may contaminate water
resources.
− Site OB5 is particularly vulnerable to excessive sediment inputs and
contamination owing to the extent and quality of habitat fringing
the pool below the culvert.
Before mitigation After mitigation
Extent of impact: Local (OB5) to site-specific (other
sites) Site-specific
Duration of impact: Short term Short term
Magnitude of impact: High (OB5) to very low (other sites) Very low
Probability of occurrence: Possible Possible
Degree to which the impact can be
reversed: Fully reversible Fully reversible
Cumulative impact Low Minimal
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 72
Significance rating MEDIUM (OB5) to VERY LOW (-) VERY LOW (-)
Additional remarks
None
Mitigation
− Construction activities within watercourses must not take place during the wet season, i.e. between May and
September.
− Construction sites must be managed so that construction material (especially cement and fuel products) is not
washed into watercourses during storm events. Contamination of water resources can be avoided, or where
unavoidable, mitigated by:
o Storing and containing all materials on the construction sites at least 40 m from the nearest water resource.
o Protecting cement and other water-soluble substances against rainfall and wind.
o If there is any risk that concrete or contaminated water may enter a watercourse, concrete batching must
take place at least 40 m from the edge of channel in a secure, bunded area (e.g. wooden boards placed
over heavy plastic sheeting within a bund of sandbags)
o Inspecting sites daily for litter and remove all rubble and waste material from the river channels and riparian
zones after construction is completed.
o Taking precautions to prevent soil and chemical materials, including waste cement and concrete, from being
released into downstream drainage areas.
o Refueling vehicles at least 100 m away from rivers, in securely bunded areas, preferably at sites already uses
for refueling by farmers
o Only using existing access roads to undertake the proposed activities
o Maintaining all construction machinery and vehicles in good working order.
o Provide and regularly service ablution facilities for construction staff on site; toilets must be located at least 30
m from watercourses.
6.1.3 POTENTIAL IMPACTS ON BIOPHYSICAL ENVIRONMENT: HYDRO-GEOMORPHOLOGICAL ASPECTS AT ALL SITES
Scour, erosion and sediment movement
Nature of impact:
− Construction-related disturbance (excavations, trampling, removal
of reeds, etc) may contribute to erosion of the beds and banks of
the affected watercourse.
− Restriction of flows as a result of diversions or coffer outlets may also
contribute to scouring and erosion.
Before mitigation After mitigation
Extent of impact: Local (OB1, OB3 & OB6) to site-
specific (other sites) Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Low (OB1, OB3 & OB6) to very low
(other sites) Very low
Probability of occurrence: Probable Possible
Degree to which the impact can be
reversed: Fully reversible Fully reversible
Cumulative impact Low Minimal
Significance rating LOW (OB1, OB3 & OB6) to VERY
LOW (-) VERY LOW (-)
Additional remarks
Mitigation
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 73
− Construction activities within watercourses must not take place during the wet season, i.e. between May and
September.
− The physical extent of construction-related impacts must be minimised and securely contained within an area
demarcated by RoadQuip® 'Express Net' or a similar highly visible and durable barrier device. This particularly
applies to those points where vehicles obtain access into watercourses.
− All areas outside of this zone should, within reason, be regarded as no-go areas during construction, with the
exception of personnel engaged in required alien clearing and bank rehabilitation activities outside of
construction disturbance zones.
− Ensure that flows that are routed around or discharged downstream of construction areas do not result in scour
downstream of construction sites
− Ensure that the impact of pumped water that is discharged under pressure is dissipated by placing pipe outlets in
rocky parts of the stream bed that are not susceptible to scour.
− Limiting activities and vehicle movement to disturbed sections of river channels.
− Limit the removal of reeds and other riparian vegetation in the channel and along river banks.
− Apply all the mitigatory measures relating to the prevent and mitigation of impacts on water quality.
6.1.4 POTENTIAL IMPACTS ON BIOPHYSICAL ENVIRONMENT: CHANGES TO THE PHYSICAL STRUCTURE AND STABILITY OF
WATERCOURSES
Cumulative effects of interaction between modified flows, physical disturbance and erosion
Nature of impact:
− The destabilisation of river channels is closely related to constricted
or diverted flows, physical disturbances to the bed and banks of
watercourses, scour and the ensuing transport and deposition of
sediment that may precipitate further iterative changes to patterns
of flow and erosion that undermine channel stability.
− Whereas measures can be adopted to minimise these impacts from
developing at a site-specific or local extent, the drivers of river
destabilisation must be addressed at source which means doing so
at the appropriate hydro-geomorphological and ecological scales.
− The cumulative impacts of the respective projects would be
negligible relative to the wholesale destabilisation and degradation
of the affected watercourses as a result of catchment hardening,
agricultural encroachment into floodplains, physical manipulation
of watercourses and flood processes by bulldozing, and infestation
of riparian areas by invasive alien plants.
Before mitigation After mitigation
Extent of impact: Local (OB1, OB3 & OB6) to site-
specific (other sites) Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Low (OB1, OB3 and OB6) to very
low (other sites) Very low
Probability of occurrence: Probable Possible
Degree to which the impact can be
reversed: Fully reversible Fully reversible
Cumulative impact Low Minimal
Significance rating LOW (OB1, OB3 & OB6) to VERY
LOW (-) VERY LOW (-)
Additional remarks
Channel destabilisation and ensuing loss of functional resilience and riparian habitat are 'driven' and occur at physical
and geographical scales that exceed the scope of activity- and project-specific impact assessment. If effectively
mitigated (as set out above), the impacts of the respective projects on the watercourses in question can be limited to
acceptably low levels of significance. However, as previously emphasised, any environmental benefits that may be
associated with the implementation of the proposed repairs will be neutralised by the degraded and destabilised
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 74
condition of the affected ecosystems. NOTE that without 'high level' mitigation, the respective structures will have a
considerably greater impact on the affected watercourses than is predicted above.
Mitigation measures
Measures aimed at modifying agricultural land-uses that contribute to the degradation and destabilisation of aquatic
ecosystems are set out in Section G.
6.1.5 POTENTIAL IMPACTS ON BIOPHYSICAL ASPECTS: CRITICAL BIODIVERSITY AREAS
Nature of impact:
− The most severe impacts would result from loss of habitat or species
that are either irreplaceable, essential for the achievement of
biodiversity targets, or threatened. There is no evidence, however,
that any of the sites support threatened vegetation, i.e. Western
and Central Rûens Renosterved CR or Greyton Shale Fynbos EN. It is
concluded construction will not have any impacts on biodiversity
pattern that has been identified as having regional or national
conservation importance.
− Given the highly degraded condition of the immediate surrounds of
all the sites, there is little likelihood that construction-related
activities would adversely affect the functioning of ecological
corridors or any spatial surrogates of ecological processes that may
have a role in maintaining threatened ecosystems.
− Construction-related impacts may, however, temporarily affect
hydrological processes (chiefly the availability and quality of water,
and seasonal flows) maintain aquatic biodiversity and, at a regional
scale, contribute to the maintenance of biodiversity pattern and
process in the Riviersonderend.
− In conclusion, the chances that the proposed works – provided that
the stipulated mitigation measures are implemented – will
precipitate impacts that compromise the integrity of CBAs is viewed
as exceedingly remote.
− However, without addressing ecological degradation and the
instability of the affected watercourses at an effective functional
scale, site-specific mitigation will have little impact on contributing
the recovering of the affected watercourses. Impacts in the latter
regard must be viewed as of HIGH negative significance.
Before mitigation After mitigation
Extent of impact: Local Site-specific
Duration of impact: Long term Short term
Magnitude of impact: Medium Low
Probability of occurrence: Highly probable Probable
Degree to which the impact can be
reversed: Potentially irreversible
Partially reversible, but best
avoided.
Degree to which the impact may cause
irreplaceable loss of resources: Medium Low to medium
Cumulative impact Potentially significant if long-term
integrity of CBAs is compromised Minimal
Significance rating MEDIUM (-) VERY LOW (-)
Additional remarks
See Appendix D2 for a summary of the Critical Biodiversity Areas that apply to the respective sites, and Sections B(5)(a)
and F(1)(b) for an explanation of CBAs and their implications for project planning and impact assessment.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 75
Impacts on the values that informed the selection of river reaches, wetlands or terrestrial habitats as CBAs and ESAs
would be a direct consequence of interactions between modified flows, physical disturbance and erosion and the
effect that this may have on in-stream and riparian habitat.
The prospects for complete ecological restoration of eroded and degraded watercourses and riparian areas are
viewed as slim but, as indicated previously, rehabilitation can aim to prevent further degradation and initiate – at least
at site level – beneficial ecological functions such as localised soil and bank stabilisation.
However, actions to prevent further degradation of aquatic and terrestrial CBAs, and to initiate their restoration to a
natural or at least near-natural state, will have to be undertaken at a far broader scale. This is beyond the scope of this
application.
Mitigation measures
Adverse impacts that may compromise the integrity of CBAs and ESAs, or where unavoidable, can be mitigated by
implementing all the mitigation measures pertaining to:
− Hydrological aspects, i.e. flow regimes and water quality;
− Hydro-geomorphological aspects, i.e. scour, erosion and sediment movement;
− The physical structure and stability of the watercourse
Adverse impacts on terrestrial habitats within CBAs and ESAs can be avoided, or where unavoidable, mitigated by:
− Implementing, insofar as these are relevant, all the mitigation measures pertaining to erosion and
sedimentation and aquatic ecosystems.
− Fill sourced for construction purposes must be free of alien seed.
− Where possible – and definitely at Site OB5 -- actively aiming to reduce as far as practicable the removal of
existing natural vegetation in the channel and riparian zone.
− Retaining topsoil to a depth of 150 mm and stockpiling locally for revegetation.
− Grading banks to a slope of at least 1:4, but preferably flatter, between the repaired structures and the
boundary of the road reserve.
− Grading slopes downwards, towards the watercourses.
− Revegetating disturbed areas directly upstream and downstream of each structure with indigenous, locally-
occurring pioneer species at level of base flow.
− Using bagged plants rather than seeds or cuttings to achieve rapid stabilisation of particularly lower banks.
− Fast-growing pioneer plant species, and other plants that would facilitate post-construction rehabilitation (such
as xxx), should be collected beforehand, bagged and kept in good condition for replanting.
− Plant lists must be approved by CapeNature.
Degradation and loss of aquatic habitats within CBAs and ESAs can be avoided, or where unavoidable, mitigated by:
− Implementing all the mitigation measures relating to flows, erosion and sedimentation;
− Fill sourced for construction must be free of alien seed.
− The removal of invasive species such as black wattle Acacia mearnsii and beefwood Casuarina sp as they
contribute to channel restriction, down-cutting and erosion, and displace indigenous biodiversity.
− Post-construction alien management must be ongoing at all sites.
6.1.9 POTENTIAL IMPACTS ON SOCIO-CULTURAL ENVIRONMENT: SENSE OF PLACE
Nature of impact:
Construction activities in relatively remote and scenically attractive
landscapes may detract from some individuals’ expectations regarding
‘sense of place’ and ‘naturalness’. This is taken to include potential
visual impacts, and impacts on valued heritage landscapes.
Before mitigation After mitigation
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 76
Extent of impact: Local Local
Duration of impact: Short term Short term
Magnitude of impact: Medium Low
Probability of occurrence: Probable Probable
Degree to which the impact can be
reversed: Entirely Entirely
Degree to which the impact may cause
irreplaceable loss of resources: Low Low
Cumulative impact Negligible Negligible
Significance rating MEDIUM (-) VERY LOW (-)
Additional remarks
‘Genius loci’ or the sense of place is potentially a highly subjective but important consideration for individuals who
attach particular meanings or values to specific places or landscapes. It is hard to pin down as a concern of general
application, but there may be individuals who take issue with factors such as visual or aural disturbances or detraction
from perceived aesthetic qualities. Sense of place is emotionally charged, entails idealised expectations, and can
provides grounds for strong reactions to environmental change. The social necessity and temporary nature of the works
and rehabilitation of disturbed areas should, however, contribute to ameliorating people’s concerns about infringements
on their sense of place.
Mitigation measures
Adverse impacts that may compromise individuals’ sense of place can be avoided, or where unavoidable, potentially
mitigated by implementing all foregoing mitigation measures.
6.1.7 POTENTIAL IMPACTS ON THE SOCIAL ENVIRONMENT AND WELLBEING: NOISE
Nature of impact: Construction activities (e.g. construction vehicles, etc.) would increase
noise levels, which could be a nuisance for local residents.
Before mitigation After mitigation
Extent of impact: Local (OB3 & OB6) to site-specific Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Medium (OB3 & OB6) to low Very low
Probability of occurrence: Highly probable Highly probable
Degree to which the impact can be
reversed: Entirely Entirely
Degree to which the impact may cause
irreplaceable loss of resources: Low Low
Cumulative impact Negligible Negligible
Significance rating MEDIUM (OB3 & OB6) to
VERY LOW (-) VERY LOW (-)
Additional remarks
Noise is unlikely to be of concern at most of the sites which are located in relatively remote rural areas. Construction-
related noises could be experienced as more of a nuisance closer to farm houses and other habitation. However, if work
is limited to week days and daylight hours, this would probably not be cause for much concern, especially given that
these are primarily agricultural areas where heavy machinery (tractors, trucks and excavators) constitutes a familiar
feature of the socio-economic landscape.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 77
Mitigation measures
Adverse impacts relating to noise can be avoided or, where unavoidable, mitigated by;
− Ensuring construction machinery is in good working order.
− Limiting construction to the hours of daylight.
− Limiting construction to weekdays.
6.1.8 POTENTIAL IMPACTS ON THE SOCIAL ENVIRONMENT AND WELLBEING: DUST
Nature of impact: Construction activities (e.g. construction vehicles, etc.) would increase
noise levels, which could be a nuisance for local residents.
Before mitigation After mitigation
Extent of impact: Local (OB3 & OB6) to site-specific Site-specific
Duration of impact: Short term Short term
Magnitude of impact: Medium (OB3 & OB6) to low Zero to very low
Probability of occurrence: Probable Improbable
Degree to which the impact can be
reversed: Entirely Entirely
Degree to which the impact may cause
irreplaceable loss of resources: Low Low
Cumulative impact Negligible Negligible
Significance rating MEDIUM (OB3 & OB6) (-) to
VERY LOW (-) VERY LOW (-) to INSIGNIFICANT
Additional remarks
If dust suppression measures are applied (reducing vehicle speeds close to inhabited areas and crops, covering and
and sprinkling stockpiles and recently disturbed spoil), dust is unlikely to feature as an issue of concern. Specific attention
needs to be paid to suppressing the generation of dust near sensitive crops such as grapes and fruit.
Mitigation measures
Adverse impacts relating to dust can be avoided, or where unavoidable, mitigated by:
− Reducing vehicle speeds close to inhabited areas and fruit-bearing vineyards and orchards (i.e. from
November onwards, depending on the crop) – a limit of 40 km/hr is recommended for roads near homes or
settlements, and 20 km/hr adjacent to orchards or vineyards during the harvest season;
− Covering stockpiled sand and soil (especially during the dry, windy summer months); and
− Keeping stockpiled spoil and recently disturbed areas moist.
6.1.6 POTENTIAL IMPACTS ON SOCIO-ECONOMIC ASPECTS: INCONVENIENCE TO ROAD USERS
Nature of impact: During construction there may be delays or detours in order to route
traffic through the various sites.
Before mitigation After mitigation
Extent of impact: Local Local
Duration of impact: Short term Short term
Magnitude of impact: Low Low
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 78
Probability of occurrence: Highly probable Highly probable
Degree to which the impact can be
reversed: Entirely Entirely
Degree to which the impact may cause
irreplaceable loss of resources: Low Low
Cumulative impact Negligible Negligible
Significance rating LOW (-) LOW (-)
Additional remarks
Temporary inconvience to road users who may be held up or required to undertake short detours around construction
sites is of little environmental consequence and would probably be viewed as a tolerable and unavoidable nuisance by
the affected public, especially given the future benefits of improved crossings.
Mitigation measures
Adverse impacts that may inconvience road resures can be mitigated by:
− Providing sufficient signage to warn motorists of the presence of construction works and detours.
− Executing individual projects as speedily and expeditiously as possible.
6.2 OPERATIONAL PHASE
Impacts that may result from the operational phase (briefly describe and compare the potential impacts (as
appropriate), significance rating of impacts, proposed mitigation and significance rating of impacts after mitigation that
are likely to occur as a result of the operational phase.
The supposition is that none of the construction-phase impacts (which, by their nature, are temporary) would persist
beyond the duration of work at the respective sites, and consequently not assessed any further.
However, three distinct sets of residual impacts that may extend into the operational phase of the respective projects
have been identified, namely:
− Impacts arising from increased hydraulic capacity, from a site to local scale (i.e. within 100 m the structures or,
alternatively, extending as far as the Riviersonderend);
− Impacts on aquatic ecosystems arising from erosion and sedimentation precipitated the structures (scale of
impacts above); and
− Impacts on road safety.
Potential residual impacts on environmental flows, erosion and sedimentation, and the effects that this potentially holds
for aquatic habitats, biota and ecological processes are closely inter-related. Erosion can contribute to turbidity, which is
both a water quality as well as an ecological concern. They are separated for the sake of ‘unpacking’ the different
types of impacts that may result from the operational lifespan of the repaired structures. In effect, however, they are
integrated and potentially mutually reinforcing.
Added to this is the over-riding problem, which has been repeatedly referred to above, of not being able to decouple
the generally localised impacts (both positive and negative) of the repaired or rebuilt structures, from the question of
broader ecosystem degradation and instability, and the implications that the latter holds for the operational phase
impacts of the respective completed works. Failure to contextualise the potential impacts of the respective projects with
reference to the condition and stability of the river systems in their totality would amount to a significant and
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 79
unacceptable 'blind spot' in this environmental assessment, and the decision that it is intended to inform. This problem is
dealt with in Section 7 below.
6.2.1 POTENTIAL POST-CONSTRUCTION IMPACTS ON BIOPHYSICAL ASPECTS: INCREASED HYDRAULIC CAPACITY
Nature of impact:
Three of the structures – at OB1, OB3 and OB6 – are to have
considerably improved hydraulic capacity over that of their
predecessors. This is predicted to substantially curtail flow concentration
downstream of these structures. Sediment movement will also be vastly
improved. Advantages include:
− Preventing sediment build-up upstream of the causeway;
− Minimising the risk of scouring and erosion downstream (thereby
preventing and mitigating impacts on aquatic habitats and
biodiversity);
− Contributing to the recovery of the longitudinal slope profile of the
affected watercourses; and
− Protecting the approaches against erosion damage.
− The benefits of the enlarged culverts will be, however, reduced if
the channels upstream of the causeways, and the culverts
themselves, are not kept clear of accumulated sediment and
debris. Mitigation refers to such maintenance.
NOTE The provision of additional hydraulic capacity is treated as a
POSITIVE impact. Mitigation equates to increased hydraulic capacity.
Before mitigation After mitigation
Extent of impact: Local Long tem
Duration of impact: Long term Long term
Magnitude of impact: Medium (-) Low (+)
Probability of occurrence: Probable Probable
Degree to which the impact can be
reversed: Potentially irreversible
Partially reversible (assuming some
flow restriction)
Degree to which the impact may cause
irreplaceable loss of resources: Medium to high Very low
Cumulative impact
Potentially significant if restriction
and concentration of flows is
allowed to persist because of
blockages.
Significantly limited if restriction
and concentration of flows is
avoided or at least minimised by
effective maintenance.
Significance rating MEDIUM (-) LOW (+)
Additional remarks
The risk of environmental degradation at sites OB1, OB3 and OB6 is proportional to the degree in which the new,
enlarged culverts either exacerbate or reduce the impact of altered flow regimes on the aquatic environment and
habitats. In general, increased flow capacity is therefore considered to be positive as it would prevent or significantly
slow down the rate of erosion that contributes to degradation of the aquatic environment. The approaches to the
crossings will also be less vulnerable to flood damage and there would less risk to lateral erosion downstream of the
structures as high flows would be conveyed through the crossing, rather than around them.
However, environmental benefits may be compromised by floods that exceed the specified conveyance capacity of
the new or refurbished structures. The bridge at OB1 has been designed to accommodate floods of up to the 1:10-year
return period without over-topping. The structures at OB3 and OB6 are designed to accommodate 1:2-year floods
without over-topping. In both cases, substantially enlarged openings will reduce the build-up of debris during floods.
Mitigation measures
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 80
Mitigation in this instance is defined by the addition of substantially improved hydraulic capacity to the crossings at OB1,
OB3 and OB6.
6.2.2 POTENTIAL IMPACTS ON BIOPHYSICAL ASPECTS: EROSION AND SEDIMENTATION
Nature of impact:
Adverse changes to environmental flows and/or erosion and
sedimentation (these impacts are linked to insufficient hydraulic
capacity that may also translate into impaired sediment transport
through the structure). If culverts and the adjacent channel are cleared
of sediments, the impact would be positive.
Before mitigation After mitigation
Extent of impact: Regional Local
Duration of impact: Medium to long term Short term
Magnitude of impact: Low to medium Low
Probability of occurrence: Probable Improbable
Degree to which the impact can be
reversed: Potentially irreversible Partially to fully avoidable
Cumulative impact
Potentially significant if long-term
integrity of Riversonderend is
compromised as a result of
erosion, sedimentation and
habitat loss
Minimal
Significance rating LOW to HIGH (-) VERY LOW (+)
Additional remarks
Potential long-term impacts associated with changes to flow restriction, erosion and the impacts that this may have on
the integrity of in-stream habitats and ecological functioning constitute the single most important area of concern
relating to the operation of the repaired and refurbished causeways.
These issues, insofar as they pose demonstrable risks to the wellbeing of the affected environment, have been addressed
‘up front’ in the design phase of the projects as degradation resulting from erosion, once it has occurred, is effectively
impossible to repair. In the case of the crossings at OB1, OB3 and OB6, the increased flood conveyance capacity of the
structures plus wing walls and scour protection will help to reduce the contribution of these structures to erosion.
The other structures are to be equipped with concrete road slabs and side protection (OB2), gabion aprons (OB4) and
improve downstream scour protection (OB5). All of these works are designed to protect the structures and immediate
aquatic environments against erosion. The aquatic ecologist (Day, 2014) has found the structural hydraulic
arrangements at OB2 to be inadequate, and has recommended that the road crossing at this site be reviewed in its
entirety.
Mitigation measures
Adverse impacts arising from erosion and sedimentation can be avoided, or where not avoidable, mitigated by:
− Keeping watercourses upstream and downstream of the structures (at least as far as the edge of the road
reserve) clear of flood debris (particularly ‘spoelklippe’, branches and uprooted bushes and trees) to prevent
premature over-topping and back-flooding in floods ≤1:5-year return period.
− Keeping channels downstream, at least as far as the fenced edge of the road reserve, clear of branches and
other obstacles that may deflect flows into the banks of watercourses.
− Where excavations have taken place in watercourses, ensure that potential nick-points and benches in the
channel are removed so as to prevent head-cut erosion from developing upstream of these locations.
− Removing alien plants at least as far as the boundary of the road reserve, and re-planting disturbed areas with
locally-occurring indigenous pioneer plant species.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 81
− Monitoring the first reach/first 150 m of the watercourse downstream for signs of new erosion.
− Monitoring changes to sediment patterns (deposition and erosion) up- and downstream of repaired structures
to assess recovery and reinstatement of the general slope of the watercourse.
− Obtaining timeous ecological advice on how best to repair and, if feasible, provide additional venting, to
gravel approaches that may be washed away as a result of floods; and
− Obtaining agreement with the Western Cape Department of Agriculture on how to best to manage the farm-
channel interface up- and downstream of the repaired structures on privately-owned land.
− Maintain roads to reduce the concentration and/or intensity of run-off so as to dissipate energy and erosion
potential.
6.2.3 POTENTIAL IMPACTS ON BIOPHYSICAL ASPECTS: ECOSYSTEM FUNCTIONING AND HABITAT IN AQUATIC CBAs
Nature of impact:
Adverse, long-term changes arising from altered environmental flow
regimes, erosion and sedimentation can translate into loss of in-stream
habitats, reduced habitat and community diversity, local loss of species,
and impeded ecological processes. Impacts of 'HIGH ' magnitude are
predicted if CBAs in the Riviersonderend were to be adversely
impacted.
Before mitigation After mitigation
Extent of impact: Local to regional Local
Duration of impact: Medium to long term Short term
Magnitude of impact: High Low
Probability of occurrence: Probable Improbable
Degree to which the impact can be
reversed: Potentially irreversible
Avoidance most desirable from of
mitigation
Degree to which the impact may cause
irreplaceable loss of resources: Medium to high Low
Cumulative impact Potentially significant if long-term
integrity of CBAs is compromised Minimal
Significance rating MEDIUM to HIGH (-) VERY LOW (-)
Additional remarks
See above.
Mitigation measures
In the long-term, degradation of CBAs and FEPAs can only effectively be addressed through rehabilitation of
watercourses, floodplains and wetlands an ecosystem or catchment scale.
6.2.4 POTENTIAL IMPACTS ON BIOPHYSICAL ASPECTS: ECOSYSTEM FUNCTIONING AND HABITAT IN TERRESTRIAL CBAs
Nature of impact:
Construction-related impacts (i.e. direct disturbance and degradation)
on terrestrial vegetation and habitats designed as CBAs will probably
extend into the operational phase and therefore need a measure of
management attention. Full restoration of disturbed sites is unlikely but
rehabilitation with locally occurring indigenous plants and limited
landscaping that focuses on the reinstatement of basic environmental
regulatory functions is feasible and desirable, e.g. bank stabilisation, soil
retention, and initiation of successional processes. Former construction
sites must be kept clear of aliens.
Before mitigation After mitigation
Extent of impact: Local Site-specific
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 82
Duration of impact: Medium to long term Medium to long term
Magnitude of impact: Very low to low (-) Very low to low (+)
Probability of occurrence: Highly probable Probable
Degree to which the impact can be
reversed: Potentially irreversible Partially reversible
Cumulative impact Insignificant at a local scale but
significant if assessed at the scale of the farming-river interface
Significance rating VERY LOW to LOW (-) VERY LOW to LOW (+)
Additional remarks
Complete restoration of the disturbed sites is unlikely and probably an unrealistic goal given the highly degraded and
even transformed condition of most of the affected sites. Post-construction rehabilitation should aim to re-establish basic
environmental regulatory functions such as bank stabilisation, soil retention and conditions that are suitable for initiating
vegetation succession. Active management of alien plants is essential.
Mitigation measures
Adverse impacts on terrestrial vegetation and habitats can be avoided, or where not avoidable, mitigated by
implementing all the above-mentioned mitigation measures. Pay specific attention to alien clearance and curtailing
erosion that may result from damage to gravel approaches during floods.
6.2.5 POTENTIAL IMPACTS ON SOCIO-ECONOMIC ASPECTS: ROAD SAFETY
Nature of impact:
The causeways and culvert crossings in question serve traffic that uses a
network of gravelled roads in the broad vicinity of Bot River,
Helderstroom, Genadendal and Greyton. Left unrepaired, these
structures are bound to deteriorate and they would potentially
represent an increasingly dangerous hazard to road users. The safety of
these structures is among others compromised by wash-aways, road
verge that cave in and general deterioration of the structures with use,
over time. One of the chief objectives of the repairs is to eliminate these
types of hazards. Securing an alternative route to the Helderstroom
Maximum Security Prison during floods is of major regional importance
and must be achieved as rapidly as possible. NOTE Improved road
safety is treated as a POSITIVE impact. Mitigation equates to such
improvement.
Before mitigation After mitigation
Extent of impact: Regional Regional
Duration of impact: Medium to long term Long-term
Magnitude of impact: High (-) High (+)
Probability of occurrence: Probable Probable
Degree to which the impact can be
reversed: Potentially irreversible Partially to fully avoidable
Cumulative impact
Difficult to predict or quantify, but
any increase in traffic accidents
must be viewed as significant from
a cumulative perspective.
Overall positive.
Significance rating MEDIUM to HIGH (-) HIGH (+)
Additional remarks
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 83
Providing a safe and efficient integrated transport system is a key priority of the Western Cape Government: DTPW,
which aims to reduce road fatalities by 50% by the end of 2014.
Mitigation measures
Repairing the damaged drifts and causeways to a sufficiently high standard of road safety constitutes a highly significant
mitigation measure and motivation for the projects to go ahead as planned.
7. SPECIALIST INPUTS/STUDIES AND RECOMMENDATIONS
Specialist inputs/studies and recommendations:
(a) Specialist inputs/studies and recommendations:
Dr Liz Day of the Freshwater Consulting Group conducted the specialist aquatic ecological assessment (Day, 2014).
In broad, this entailed:
− Describing the condition of aquatic ecosystems in the vicinity of the respective sites, and the impacts of the
existing structures on the aquatic environment;
− Describing the affected freshwater ecosystems in terms of: distinctive environmental factors such as location,
topography, climate and vegetation (i.e. 'ecoregions'); wetland and river types; biodiversity conservation
priorities (Freshwater Ecosystem Priority Areas); the present ecological states of the respective sites; and their
ecological importance and sensitivity;
− Assessing the environmental impacts of the existing structures and the proposed works respectively, proposing
mitigation measures, and providing an overall ecological assessment and recommendation with respect to the
different works;
− Reporting on the implications of the proposed works for overall river PES;
− Making recommendations on construction-phase mitigation; and
− Assessing the proposed mitigation and management measures for consistency with the conditions specified by
the General Authorisation pertaining to sections 21(c) and (i) of the National Water Act 36 of 1998 (GN1199, 12
December 2009).
Dr Day's report is appended as Appendix G. She undertook the site visit 3 February 2014, under dry, late summer
conditions. Her findings are presented with respect to:
− Construction-related impacts, their significance and mitigation; and
− The overall effectiveness of site-specific mitigation if the degradation and destabilisation of the affected rivers is
not addressed at source, at the appropriate spatial and functional scales.
Please note that in some instances (specifically with regard to the works at sites OB4, OB5 and OB6), Dr Day revised her
initial findings on the potential significance of the long-term, operational phase impacts of the latter projects following
the implementation of some of the key mitigation measures that she had recommended in her report, dated March
2014. These revised specialist findings are recorded below.
(b) Revised specialist findings following recommended amendments to project plans
As previously indicated, the findings and recommendations of Dr Day's aquatic assessment were subsequently taken up
with the consulting engineers, Bergstan South Africa (Pty) Ltd, and Mr Harry Viljoen, of the Department of Transport and
Public Works.
It was on the basis of the latter discussions, held in Cape Town on 25 April, 2014, that the Department of Transport and
Public Works agreed – in response to some of Dr Day's recommendations – to implement a number of changes to the
plans that would contribute to further mitigating potential adverse impacts associated with, specifically, the structures at
sites OB4, OB5 and OB6. These amendments are further elucidated below, as are Dr Day's revised findings on the
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 84
potential contribution that the respective changes to the project plans would make towards mitigating adverse impacts
on the aquatic environment.
Dr Day has confirmed that the summary of her feedback on the revised plans to the project EAP accurately represents
her revised conclusions about the potential impacts of the proposed works at sites OB4, OB5 and OB6 (Appendix G1).
(c) Specialist assessment of construction-related impacts, and impact mitigation
See pages 15 of 26 of the specialist aquatic assessment (Day, 2014) for an illustrated assessment and explanation of the
current ecological condition of each site.
The findings of the specialist aquatic assessment with regard to the works at each of the six sites are summarised below.
Changes to the plans that were initiated in response to Dr Day's concerns are also recorded, plus her revised assessment
of the potential impacts that could arise from implementation of the adopted changes.
OB1: BOTRIVIER, DR1288
(Construction of a new bridge)
Positive aspects of the new structure w.r.t. flood and sediment conveyance
• A single, wider culvert (12 m wide x 4.5 m high) and slightly longer span
of the structure are proposed for this site. This would be more
appropriate to the disturbed river upstream, with its high sediment and
woody debris load, than the present system, which is to be
demolished. The new structure may therefore reduce the frequency of
significant flood disturbance, such that recovery between flood events
is likely.
• Real recovery and improved ecological function is however only likely
if invasion by woody alien plants is addressed both up- and
downstream of the crossing, and as long as alien trees dominate the
river banks, flood damage as a result of blockages to flow by debris
dams is likely to be a feature of the system.
• The new structure should improve ecologically connectivity, by passing
low flows through the wide culverts, rather than through narrow pipes,
as per the previous structure.
Construction phase impacts
Construction phase impacts are likely to be of high intensity but locally
confined, and readily managed through implementation of standard
impact mitigation measures. Impacts are likely to include:
• Increased downstream sediment and turbidity from bank and bed
disturbance (the river is however already prone to these effects as a
result of high erosion)
• Increased risk of erosion as a result of alien clearing
• Contamination of the river as a result of receipt of construction-
associated materials
• Trampling and disturbance to the (already disturbed) river bed and
banks in the vicinity of the existing and new structures.
• These impacts would all be exacerbated if construction took place
during the wet season or during a period when a storm event
occurred.
Mitigation requirements: Construction
• A Construction Phase Environmental Management Programme
Overall ecological assessment and
recommendations
• Assuming full implementation of
the mitigation measures outlined
above, the proposed change in
structural design and its
implementation is considered
likely to be a positive impact
from a freshwater ecosystems
perspective.
• However, if the requirements for
the long-term stabilisation and
management of an alien-free
river corridor immediately up-
and downstream of the
structure, and the requirement to
address concerns around
existing erosion of the river bank
upstream of the new crossing
and at the minor tributary, are
not implemented, rates of flood-
associated disturbance are still
expected to be high.
• In the event of the latter
scenario, in terms of which the
recommended mitigation
measures are not implemented,
no net positive impacts would be
expected as the existing –
destabilised – system would be
actively maintained by floods.
Without the recommendation
measures being implemented,
the impacts would therefore be
negative.
• NB The applicant has undertaken
to investigate the potential risks
associated with the eroding river
bank upstream of the structure.
If, however, this area of instability
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 85
(CEMP) must be implemented during construction (see Section H
below).
• The existing road should be ripped, all artificial debris removed, and
the river bank and riparian zone thus created should be shaped to
resemble a natural system, in a band at least 15m wide on either side
of the river – a river ecologist should oversee / sign off on this aspect of
mitigation.
• The small tributary should be addressed as part of this process, and re-
shaped as a broad open channel, planted in destabilised areas to
prevent erosion.
Residual negative aspects that need to be addressed
• Failure to address the present constricted alignment of the small
stream that enters the river on its left bank downstream of the existing
structure means that this system will probably play a long-term role in
disturbance of the downstream channel and banks. The small stream
has been directly impacted by the existing road alignment.
• Medium to long-term likelihood of structural failure, as a result of
erosion and bank collapse at the bend some 20 m upstream of the
proposed structure. If this erosion (triggered by constriction of alien
trees along the channel, and blockage of flows in the channel by
fallen trees) is left unchecked, it is likely to result in significant widening
of the channel over time, and potential bypassing of the bridge
structure on the left hand bank.
Mitigation requirements: Residual degradation
• The eroding bank upstream of the bend must be addressed, through
removal of alien vegetation reshaping of the bank and replanting;
hard stabilisation techniques (e.g. bank lining with gabions) should not
be used, although it is understood that gabions will be used
immediately up- and possibly downstream of the new structures.
is outside the road reserve, the
DTPW will not be able to readily
take any steps to secure this part
of the river bank against further
erosion and instability.
• The decommissioned bridge will
be demolished and all debris will
be removed. Demolition of the
latter structure, plus alien
clearance, would free up more
space – thereby promoting
improved stability – for the small
tributary to which Dr Day refers.
OB2: CONFLUENCE OF BOTRIVIER AND MINOR SEASONAL WATERCOURSE AT DORINGKLOOF, DR1288
(Installation of concrete road slabs and side slope protection)
Structural inadequacies of current culvert
• The proposed construction measures do not attempt to address the
problem of the small tributary that presently is diverted along the
edge of the concrete structure, increasing flood pressure and erosion
damage on the right hand side of the Bot River channel, and
contributing to the high levels of erosion damage observed in the
river downstream of the structure.
• These impacts will thus be perpetuated by repairs to the new
structure.
Need to re-assess culvert/crossing design
• The design for this structure must include an additional or extended
culvert or other ecologically cognisant measure that allows for the
free flow of the minor stream through the structure, without being
diverted along the road edge.
• The mechanism for this would need to address the fact that the
stream appears to enter the system at a higher level than the existing
culvert.
Pre-construction ecological remediation
Overall ecological assessment and
recommendations
• Amendment of the proposed
design to address the issue of
diversion of flows from the small
tributary into the Bot River is
considered essential mitigation.
• Assuming that this and the other
recommended mitigation
measures are implemented at this
site, the proposed activities would
be considered to have a net
positive ecological impact.
• In the absence of this aspect
being addressed, it is likely that
erosion and disturbance will
remain significant sources of
disturbance to the river, i.e. have a
negative impact.
• Further expenditure on
perpetuating these conditions is
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 86
To address the significant ecological damage caused by the combined
impacts of the present road structure, inadequate control of alien
invasion and poor clearing practices, the following aspects must be
addressed at this site, prior to the start of construction:
• All invasive woody alien vegetation and the seedlings of such
species should be cleared from a zone extending at least 30 m
upstream and 30 m downstream of the present crossing point, as well
as 30 m upstream along the inflowing minor stream, in a swathe at
least 15 m wide on either side of the river channel, or less if alien
invasion is within a narrower zone;
• Species-appropriate alien clearing methods should be employed –
Working for Water guidelines should be used in this regard;
• Cleared areas should be stabilised by a combination (as
appropriate) of bank shaping and planting with locally indigenous
plant species
• Local landowners should be required to participate in long-term alien
maintenance clearing activities.
Construction phase impacts
• The same construction phase impacts as outlined for OB1 would be
anticipated at OB2, albeit taking place at a lower magnitude, given
that less work is required at this site.
Mitigation requirements: Construction
• As in the case of OB1, the requirements of a comprehensive CEMP
must be met during construction. Issues relevant to the reduction of
construction-associated impacts on watercourses that need to be
addressed in a CEMP are outlined in Section H.
not considered ecologically
sustainable, and thus approval of
this project without the specified
mitigation measures would not be
recommended
• NB The applicant has
acknowledged the validity of
these concerns. Its current budget
for the projects being undertaken
in terms of contract C958.5 does
not, however, provide for the
scope and technical complexity
of the interventions recommended
by Dr Day.
• The DTPW has indicated that, in the
event that the crossing at OB2 has
to be re-built owing to irreparable
damage, the new structure will be
designed to accommodate the
above-mentioned issues.
OB3: ELANDSKLOOFRIVIER, DR1313
(Construction of new causeway)
Positive aspects of the new structure w.r.t. flood and sediment
conveyance
• Widening of the existing culverts and their extension across the full
width of the (now bermed and channelized) river in these reaches
as proposed, so as to allow the passage of cobbles and sand
beneath the structure and to allow the passage of flows up to a 1:2
year flood through the structure is regarded as a positive impact,
likely to promote longer-term stability of the river channel.
• If the recommended mitigation measures are implemented, the
ecological disturbance caused by floods greater than 1:2 year
events should be much less than at present, with only large floods
likely to result in severe perturbation.
• Inclusion of the ('Meerlustkloof') irrigation pipelines in the bridge
structure is also considered a positive impact, as its relocation away
from the river bed will reduce the ongoing disturbance to the river,
resulting in the past from the frequent need to repair infrastructure,
subject to frequent flood damage.
• In the absence of ensuring control over erosion at the level of the
river or at least the upstream reach, it is very unlikely that such
Overall ecological assessment and
recommendations
• Implementation of the proposed
structure at OB3 would, in the
absence of any mitigation
measures aimed at stabilizing the
high rates of erosion and
sedimentation taking place in the
Elandskloof River, simply
perpetuate an unstable system
and would thus, considering the
lost opportunity to rectify an
ecologically catastrophic situation,
be considered a negative impact
of at least medium-high
significance.
• Implementation of the proposed
mitigation measures, along with the
planned improved road structure,
would be considered a positive
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 87
positive outcomes will be achieved, with significant damage
occurring on a 1:2 year basis considered a disturbance regime too
great to allow for ecological recovery between disturbance events.
Construction phase impacts
• The same construction phase impacts are likely as outlined for OB1
and OB2. Their net effect would however be relatively low, given
the level to which the river is already disturbed.
• Additional sediment and bank disturbance, for example, would
probably have a negligible additional effect, given the current rates
of disturbance.
• The disturbed state of the river and the level of damage to the
existing river crossing structure means that there is some likelihood
that further flooding will result in the current road being unusable as
a bypass without intervention during construction, resulting in the
need for additional earthworks and probable diversion of flows.
Mitigation requirements
• As for of OB1 and OB2, the requirements of a comprehensive CEMP
must be met during construction (see Section H).
• The above impacts would however be exacerbated if construction
took place during the wet season when the water table was high, or
during a period when a storm event occurred.
• In the event of damage to the existing crossing being such that it
cannot be used as a bypass during construction, it is recommended
that construction phase mitigation measures include allowance for
the short-term repair of the existing bridge, using pipe culverts if
necessary to minimize disruptions to flow.
• Such measures should be considered temporary only, to ensure that
construction of the new road and crossing can proceed as fast as
possible.
Residual negative Impacts
• Ongoing erosion of the destabilised river channel and its margins, as
a result of lack of adequate plant cover;
• In the event that existing concrete and other waste associated with
the present channel is not removed, its persistence in the channel
would constitute an ongoing potential trigger for erosion as a result
of diversion of flows off the hard structure, as well as being visually
displeasing
Post-construction ecological remediation (including groyne fields)
• Allowance must be made for the establishment of a continuous
swathe of appropriate, locally indigenous vegetation along at least
the wetted bottom of the bank of the river, but ideally up the bank
as well, for a distance of 30 m up- and downstream of the proposed
structure, to prevent erosion.
• Dense stands of palmiet reeds (P. serratum) should be utilised for this
purpose. Other plant species used should be selected in
consultation with a botanist and/or river ecologist, to ensure they
meet the required criteria of being hardy, locally indigenous and
suited to the conditions in which they are planted;
• All concrete and other debris associated with the present road
crossing should be removed from the river bed and banks as soon as
the requirement for a construction-phase bypass road is over, and
impact, of low to medium
significance, with the low level of
significance reflecting the risk that
the degree of impact to date is too
high to reflect high levels of
improvement.
• NOTE that this application has been
amended to include the installation
of pipes in the existing (damaged)
bridge for the duration of
construction. This causeway is
severely damaged and there is a
high risk that the structure would
not be able to withstand even a
relatively minor flood. Additional
venting in the form of pipes may
help to secure the structure against
such failure. See figures 8 and 10,
Appendix C, for photographs of the
causeway in February 2014.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 88
disposed of outside of the 1:50 year flood line for the river;
• The existing road, which will be replaced by a new alignment,
should be ripped, all artificial debris removed, and the river bank
treated as outlined above;
• Planted areas should be subjected to a maintenance programme
that includes where necessary, weeding, plant replacement and
irrigation, over at least one full annual cycle.
• Bank erosion and channel migration in the reaches at least 50 m
upstream and 50 m downstream of the crossing must be controlled
by groynes. Such structures should ideally be in place before
construction at OB3 commences. NOTE that the construction of river
stabilisation works falls within the purview of the Western Cape
Department of Agriculture (WCDA), and not that of the DTPW. The
WCDA is undertaking planning to construct groynes in the
Elandskloofrivier, but it is not possible to predict when this work will
commence.The groyne field should allow for widening of the river in
the disturbed reaches downstream of the crossing at OB3.
• The invert levels at the new causeway at OB3 must be designed to
account for greater channel incision than is current the case, and
which will be caused by down-cutting once the groynes are in
place and concentrate flood flows.
• The extensive eroded area to the east of the existing bermed river
channel downstream of OB3 must be returned to a vegetated
floodplain after completion of the groyne field.
• The berm east of the Elandskloofrivier must be removed. Berm
material may be spread on the eroded floodplain)
• Remove the beefwood trees lining the channel downstream of the
road
• Landscape/shape the floodplain area such that it comprises a
mosaic of depressions and raised areas, mirroring natural conditions;
• Establish indigenous floodplain vegetation on the rehabilitated area
– note that while planting or seeding of the area would be positive,
it is likely that appropriate plants will establish themselves in the
rehabilitated area over time, provided that weeding is allowed for in
the establishment phase. This has been the case with disturbed
areas upstream (Day 2013).
OB4: SECONDARY FLOOD CHANNEL OF ELANDSKLOOFRIVIER, DR 1313
(Installation of gabion mattress at in- and outlets of minor pipe culvert)
NOTE that the aquatic ecologist questioned the need for apron slabs up-
and downstream of this pipe culvert, as well as the ecological desirability
of such refurbishment (cf. Day, 2014, pp 34-35). The Applicant has
subsequently agreed to use gabion mattresses to support the concrete
apron slabs. This will help to control the proliferation of reeds that
contribute to blockages, while permitting low flows to pass unimpeded
through the porous gabion structures.
Construction phase impacts
• Disturbance of the wetland
• Potential infilling of portions of wetland with excess spoil
Overall ecological assessment and
recommendations
• The need for this specific
intervention seems unfounded as
flows over the road at this point
seem to issue from overflows of the
Elandskloofrivier, and not because
of blockages to the culvert at
OB4).
• Nonetheless, the use of concrete
apron slabs in conjunction with
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 89
• Passage of dewatered material into the watercourse
• Contamination of the watercourse by construction associated
materials such as cement.
• These impacts would all be exacerbated if construction took place
during the wet season when the water table was high, or during a
period when a storm event occurred.
Mitigation requirements: Construction
• The requirements of a comprehensive CEMP must be met during
construction.
gabion mattresses would reduce
the negative significance of
impacts associated with these
works to 'low', as opposed to 'low'
to 'medium' without the proposed
mitigation.
• In this context, it would not be
necessary to motivate for the
project not to go ahead as the
negative impacts of the proposed
refurbishment of this culvert were
of limited ecological
consequence.
OB5 UNNAMED WATERCOURSE AT 'TARENTAALKRAAL', DR1313
(Addition of gabion scour protection downstream of culvert)
NOTE that the aquatic ecologist revised her initial findings about the
desirability of the proposed works at this site following revisions, on her
recommendation, to the project plans. Instead of reinforcing the outlet
structure with concrete apron slabs and the dumping of rocks to prevent
scour, the new outlet structure and scour protection will be built from
gabions. As a result, it will no longer be necessary to armour the base of
the gabion protected with rocks, as initially recommended by the project
engineers.
The revised layouts and designs
The engineering activities included in this project aim to address the
formation of a deep scour hole downstream of the road and repair an
undermined apron slab.
This is to be achieved by building a stepped (three-tier) gabion structure
and protective gabion mattress at the base of the refurbished scour
protection. The gabions will be surfaced with a protective layer of
concrete, 10cm thick. The new structure will extend 8 m into the pool,
measured from the edge of the culvert outlet to the outer edge of the
gabion mattress. The gabion mattress will be 14.84 m wide. The edge
furthest from the culvert will be sunk 0,.5 m into the river bed to stabilise
the structure. There is a 2.4 m drop between the outlet invert and the bed
of the pool. The undermined scour protection will demolished and
removed prior to the commencement of construction.
Mitigation requirements
• “Sausage gabions” or similar mechanisms should be used to allow
stabilisation of steep, deep undercut banks, and to dissipate energy
downstream of the culvert;
• In order to address the issue of concentrated flows and at times the
passage of large debris through the road culvert, exacerbating the
problems experienced in the scour hole:
o the alien-invaded channel upstream of the road must be
cleared of all woody aliens and the seedlings of such
species, across the entire riverine zone, extending upstream
for a distance of at least 40m upstream of the road
o Species-appropriate alien clearing methods should be
employed – Working for Water guidelines should be used in
this regard;
o Cleared areas should be stabilised by a combination (as
appropriate) of bank shaping and planting with locally
Overall ecological assessment and
recommendations
• Assuming implementation of the
recommended mitigation
measures, the overall impact of
the proposed project at this site
would probably be of very low
negative significance.
• Without implementation of the
recommended mitigation
activities, the significance would
increase to at least medium
negative significance.
• Any activities taking place at this
site should however take
cognizance of the fact that the
watercourse still retains natural in-
stream vegetation and habitat
types, and should be considered
a locally sensitive habitat type, of
some value in determining local
reference conditions.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 90
indigenous plant species
o Local landowners should ideally be required to participate
in long-term alien maintenance clearing activities in the
cleared reach and upstream
o The fence across the culvert should be removed – it
appears likely to contribute to debris-build-up;
o Consideration should be given to the creation of
attenuation depressions / wetlands in the area to the west
of the channel, upstream of the road, to manage flood
velocities and volumes;
• Alien vegetation should be cleared to a distance of 30 m
downstream of the road (i.e. to just past the riffle at the end of the
pool).
OB6 UNNAMED WATERCOURSE AT 'NOOITGEDACHT', DR1313
(Additional box culvert, inlet and outlet protection, gabion anti-scour mattress and temporary by-pass)
NOTE that the DTWP has agreed to install a gabion check-weir to stabilise
head-cut erosion upstream of the culvert at this site, as recommended by
the aquatic ecologist. It is, however, beyond the scope of this contract to
address channel erosion downstream of the culvert. The latter
interventions would be outside the road reserve, on privately-owned land.
Negative impacts
• The head-cut erosion in the wetland upstream of the existing culvert
was identfied as a matter of 'serious concern' which, if left
unaddressed, would threaten the whole valley bottom wetland
upstream.
• The DTPW has agreed to stabilise the head-cut with a gabion weir, as
part of the overall project to improve the culvert design.
• In addition, significant erosion has occurred downstream of the road,
and although the exact source of the flows from the west were not
identified in this study, the road clearly plays a pivotal causal role in
the degradation witnessed downstream.
Mitigation measures
• The wetland head-cut must be addressed, as a matter of great
urgency, and prior to the start of any construction activities on this
overall project, through the installation of a gabion weir, located at
the head-cut point, and appropriately designed to prevent further
erosion caused by a change in gradient between the wetland
channel and the excavated channel upstream of the low-lying
culvert.
• The eroding banks downstream of the culvert must be addressed as
a matter of urgency, bearing in mind their proximity to the
Riviersonderend wetlands downstream.
• The following measures are regarded as minimum requirements with
regard to stemming further erosion downstream of the culvert:
o The need for the installation of energy-control weirs in the
channel should be considered, to prevent further down-
cutting and allow the re-establishment over time of wetland
vegetation – where considered necessary by an engineer,
working with a river ecologist, such weirs should be
constructed;
Overall ecological assessment and
recommendations
• Implementation of the proposed
culvert designs with the
recommended, additional,
mitigation measures would result in
(limited) positive outcomes from a
freshwater ecosystem perspective.
• Importantly, this would prevent
further degradation to the
wetlands upstream of the culvert
• However, implementation of this
project without inclusion of the
specified mitigation measures
would serve only to perpetuate
the unacceptably high levels of
ecological degradation that are
occurring on an ongoing basis as
a result of the existing road culvert
and watercourse management at
OB6.
• As such, implementation without
mitigation measures would be
accorded a high level of negative
significance, form the perspective
of freshwater ecosystems.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 91
o The river banks must be graded (during low flow periods) to
establish banks that have slopes no steeper than 1:5 and
preferably less steep;
o The passage of flows into the channel from the west must
be investigated and addressed, such that it does not
constitute a threat to the long-term rehabilitation of the
channel.
Impacts associated with layout and design
• If the mitigation measures are implement, the proposed layout and
design would have positive impacts only as the design allows for
stabilisation of the eroding toe of the road, and improved
management of flows under the road.
(d) Mitigation of high-level (supra-site) impacts on aquatic ecosystems
As previously indicated, this basic assessment is obliged to distinguish between:
(a) Impacts that can be demonstrably attributed to the proposed activities for which environmental
authorisation is being applied for, and are therefore fall within the Applicant's sphere of responsibility and
duty of care towards the environment; and
(b) Impacts that cannot be attributed to the Applicant but are nonetheless closely related to the effectiveness
of the proposed, activity-specific mitigation measures, and the overall (degraded) state of the affected
watercourses and their terrestrial margins.
Besides recommending mitigation measures that apply specifically to construction, the aquatic specialist (Day, 2014)
has identified measures to counter 'high-level' impacts that have evolved from site-specific impacts being
compounded by ecological degradation at an ecosystem scale. Poor land-use practices are the primary cause of
such broad-scale degradation – and specifically the failure by local landowners to control or properly remove,
invasive alien vegetation along watercourses.
The following 'high level' mitigation measures have been recommended with respect to the management and
rehabilitation of the Elandskloofrivier, in the broad vicinity of Site OB3:
Background to degradation associated with the existing causeway over the Meulrivier (cf. Day, 2014, pp 32-34)
Any activities planned for the Elandskloof River at OB3 need to address the significant damage that has accrued to the
river ecosystem, as a result, at least in part, of structures that have been inadequate for the flows, sediment and debris
loads passing through them. It is acknowledged that in the case of the Elandskloof River, these have changed
dramatically as a result of large-scale destabilisation in the upstream system (Day 2013), rather than because of
significant original design inadequacies at OB3. Nevertheless, without addressing the broader issues of destabilisation of
the river, at least in the reaches immediately up- and downstream of the road, it is very unlikely that sufficient stability will
be attained to prevent frequent high levels of flood damage in the vicinity of the road.
High level mitigation strategy
Following from the foregoing, it is strongly recommended that:
− The DTPW should liaise with the Western Cape Department of Agriculture regarding the proposed installation of
a groyne field in the Elandskloof River, and ensure that bank erosion and channel migration in the reaches at
least 50 m upstream and downstream of the crossing are controlled by groynes, designed in keeping with the
objectives of the broader flood and erosion control programme of the WC Department of Agriculture. Such
structures ideally need to be in place, at least 50 m up- and downstream of the alignment of the new
causeway, before the start of the present proposed activities.
− In the event that the authorisation of the groynes may be delayed, it is recommended that the DTPW either
works with the Western Cape Department of Agriculture to prioritise approval and construction of the structures
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 92
that would affect the present road, or design and obtain authorisation for such structures separately. It is noted
in this regard that the proposed design at OB3 already assumes implementation of the groyne field, and allows
for a lower invert level in the crossing than that required at present, given that the river would be downcut by
concentration of flood flows.
− The extensive eroded area to the east of the existing bermed river channel downstream of OB3, must be
addressed, and returned to a vegetated floodplain condition. This rehabilitation measure, which should only
take place after construction of the groynes and new road and bridge, would require:
o Liaison with the DA regarding the implications of the proposed groyne field for this area – ideally, the
groyne field itself should allow for widening of the river in these disturbed reaches
o Removal of the berm (berm material may be spread on the eroded floodplain)
o Removal of the beefwood trees lining the channel downstream of the road
o Landscaping / shaping the floodplain area such that it comprises a mosaic of depressions and raised
areas, mirroring natural conditions;
o Establishment of indigenous floodplain vegetation on the rehabilitated area – note that while planting
or seeding of the area would be positive, it is likely that appropriate plants will establish themselves in
the rehabilitated area over time, provided that weeding is allowed for in the establishment phase.
This has been the case with disturbed areas upstream (Day 2013).
Dr Day's assessment concludes as follow (Day, 2014, p 42):
"With the inclusion of rehabilitation measures, none of the (activities subject to this application for
environmental authorisation) were considered unacceptable from a freshwater ecology perspective, although
the need for activities proposed at OB4 was questioned (and have been subsequently addresed – C de V).
Mitigation measures required for the rehabilitation of the crossing at OB2 require, however, that the proposed
structure be substantially reconsidered to take cognisance of a small stream.
"Included in mitigation measures at several sites is the need to address impacts resulting from the existing
structures. Such measures are considered crucial elements relating to the successful implementation of the
proposed structures, to prevent ongoing, frequent disturbance to the river channel as a result of flood damage
that is not only ecologically devastating but is financially expensive as well. It is noted however that in many
cases (particularly at OB1 and OB2) one of the major drivers of structural failure is the impact of alien invasion
along the river. It is recommended in this regard that stringent measures should be set in place to ensure that
local landowners address this issue, using best practice clearing and rehabilitation measures, to avoid ongoing
damage to the watercourses and road infrastructure, considering that while aliens appear to be kept out of
agricultural areas, they are allowed to spread (uncontrolled) along riparian zones, with the resource value of
these channels seemingly being disregarded, until severe damage accrues along access points..."
8. IMPACT SUMMARY
Please provide a summary of all the above impacts.
Significance of potential construction-phase impacts
Adverse impacts associated with construction would, if effectively mitigated, be of ‘Very Low’ significance.
Disturbances to the socio-economic and socio-cultural facets of the environment would of necessity be of limited
duration and, if effectively mitigated, would have a negligible effect on the affected public. Impacts arising from loss
of habitat and ecological function in CBAs may be of ‘Very low’ to ‘Medium‘negative significance, if not effectively
mitigated.
Significance of impacts during the operational phase
All the factors that may adversely affect socio-economic and socio-cultural facets of the receiving environment
during construction would no longer be of any consequence during the operational lifespan of the roads in question.
Residual negative impacts on CBAs would, unless timeously identified and pre-empted by appropriate engineering
designs, persist into the operational phase and cumulatively result in impacts of ‘Very Low’ to ‘Medium’ negative
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 93
significance (see above). Assuming effective, broad-scale mitigation, the provision of additional hydraulic capacity
at sites OB1, OB3 and OB6 will entail a positive impact of ‘Low’ significance. If erosion cannot be controlled at the
latter sites, it could have an impact of 'High' negative significance; if mitigation is effective, the impacts of the
structures on erosion may be marginally positive. Improved road safety will be of ‘High’ positive significance.
Table 1: Impacts during the construction phase Potential (negative) significance of impacts
Before mitigation After mitigation
Biophysical environment
Erosion and sedimentation Low to Very Low Very Low
Water quality (turbidity) Low to Very Low Very Low
Water quality (contamination) Medium to Very Low Very Low
Channel stability Low to Very Low Very Low
Critical Biodiversity Areas Medium Very Low
Socio-economic environment
Inconvenience to road users Low Low
Sense of wellbeing and biophysical environment
Noise Medium to Very Low Very Low
Dust Medium to Very Low Very Low
Socio-cultural environment
Sense of place Medium Very Low
Table 2: Impacts during the operational phase:
Potential (negative) significance of impacts
Before mitigation After mitigation
Biophysical environment
Improved hydraulic capacity Medium Low (positive)
Erosion and sedimentation High to Low Very Low (positive)
Aquatic CBAs Medium to High Very Low
Terrestrial CBAs Low to Very Low Very Low
Socio-economic environment
Improved road safety High to Medium High (positive)
9. OTHER MANAGEMENT, MITIGATION AND MONITORING MEASURES
(a) Over and above the mitigation measures described in Section 6 above, please indicate any additional
management, mitigation and monitoring measures.
See Section 7(d) for measures that are needed to address the instability and degraded condition of the affected
watercourses beyond the scale of the individual sites. The effectiveness of site-specific mitigation is contingent upon
these 'high level' measures being put in place.
(b) Describe the ability of the applicant to implement the management, mitigation and monitoring measures.
− The single most important mitigation strategy is impact avoidance, which has been largely achieved by the
introduction of substantially improved flow volumes with respect to the structures at OB1, OB3 and OB6.
− Furthermore, the DTPW has reacted positively to recommendations by the specialist aquatic ecologist that the
designs for the proposed works at OB4, OB5 and OB6 be amended to accommodate ecological considerations.
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 94
− Some of the recommendations by the aquatic ecologist do, however, entail interventions that are either not
catered for in the current contract, would be too expensive implement, or entail works outside the road reserve
and therefore would be beyond the official purview of the DTPW.
− All construction-related mitigation measures proposed are deemed realistic and feasible to implement (see the
Construction EMP, Appendix H).
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 95
SECTION G: ASSESSMENT METHODOLOGIES AND CRITERIA, GAPS IN KNOWLEDGE, UNDERLYING ASSUMPTIONS AND
UNCERTAINTIES
(a) Please describe adequacy of the assessment methods used.
The assessment of potential impacts related to the proposed project and compilation of this Draft BAR were undertaken
in compliance with the requirements of the NEMA EIA Regulations, 2010. The NEMA EIA Regulations Guideline Series
(DEADP, March 2013) was also consulted for guidance on the assessment and public participation process to be
followed. The identification and assessment of impacts was also informed by the IAIA best practice guideline on
‘Biodiversity in Impact Assessment’ (IAIA, 2005), and the DEADP guideline on involving biodiversity specialists in EIA
(Brownlie, 2005).
This combined basic assessment was closely informed by the principles of positive planning (cf McDonald and Brown,
1995; The World Bank, 1999; IAIA, 2005; Brownlie, 2005), in that the aquatic ecologist engaged directly with the project
engineers and the DTPW with the objective of motivating for designs to be amended to accommodate ecological
concerns. This interactive process, conducted in tandem with the basic assessment, proved to be very effective: in the
case of the projects at sites OB4, OB5 and OB6, the engineering plans were revised in response to ecological concerns
raised by Dr Day. The DTWP also indicated that, in the event that the culvert and/or approaches at OB2 being
irreparably damaged as a result of flooding, it would review the configuration of road infrastructure at this site with the
view of implementing designs that took into account the concerns raised by the specialist aquatic assessment. Bank and
anti-erosion measures recommended at sites OB1 and OB6 entailed locations outside the road reserve which would
have to be addressed in consultation with private landowners and, potentially, the Western Cape Department of
Agriculture.
Charl de Villiers Environmental Consulting is confident that all significant environmental impacts have been identified
and adequately assessed in the course of this combined basic assessment process, and that this draft report provides a
sound basis for informed public and authority comment that will be incorporated in the final BAR and environmental
management programme.
(b) Please describe the assessment criteria used.
A standard convention for assigning significance ratings to impacts was used in the assessment. A copy of this
convention is attached in Appendix J.
(c) Please describe the gaps in knowledge.
Limitations regarding the aquatic assessment
No new biophysical data were collected by the specialist aquatic ecologist. The latter report relied primarily on a visual
assessment of issues of ecological concern and existing conservation planning data (e.g. NEFEPA datasets). No floral or
faunal analysis or ground-truthing (besided a site visit in February 2014) were conducted. Nonetheless, given the extent
to which the affected sites have been disturbed, these were not considered significant limitations (Day, 2014, p 4).
Uncertainty regarding the implementation high level, ecosystem-scale mitigation
It is beyond the scope and capacity of this basic assessment process to predict whether the crucial high-level mitigation
measures that have been recommended by the aquatic specialist will, in fact, be implemented. The DTPW is equally in
the dark in this regard, and cannot reasonably be held responsible for environmentally detrimental activities on land
beyond its jurisdiction. To achieve this the level of intervention in support of river rehabilitation will require co-operation
between a variety of state agencies and the affected landowners, who are primarily farmers.
Monitoring of the long-term environmental impacts of the repaired and rebuilt structures
In view of the prevailing uncertainties about the long-term ecological effects of the repaired and refurbished structures,
it is recommended that post-construction monitoring be undertaken to determine if the structures are:
Proposed flood damage repair projects in the western Overberg (C958.5)
Charl de Villiers Environmental Consulting & BolandEnviro Draft BAR 96
− Contributing to recovery or ongoing degradation of the river channels; or
− Simply maintaining the existing levels of degradation that have resulted from past flooding (i.e. there is no
indication that the affected watercourses in the reaches affected by the crossing are on a trajectory of
recovery from the effects of past flooding).
− Watercourses should also be monitored for build-up of sediment upstream of structures and scouring
downstream (this is necessary to test the hypothesis that improved hydraulic capacity and sediment movement
will promote recovery of the longitudinal slope profile of watercourses).
(d) Please describe the underlying assumptions.
The following assumptions apply:
− The project engineers provided the EAP with all relevant, correct and valid project description information;
− The biodiversity specialist had sufficient information on which to base a defensible assessment of the respective
sites and their local ecological context and condition, and to make recommendations on impact avoidance
and mitigation at the relevant spatial and functional scales;
− There will be no significant changes that could substantially influence findings and recommendations with
respect to mitigation and management; and − The DTPW will ensure, within the confines of its jurisdiction and resources, that all recommended mitigation
measures that apply exclusively to the activities subject to this application will be implemented.
(e) Please describe the uncertainties.
As indicated, the most over-riding uncertainty is whether the high-level mitigation measures recommended by the
aquatic specialist will be implemented. Key in this regard are the:
− Proposed bank stabilisation measures upstream of OB1
− Construction of groynes in the Elandskloofrivier, up- and downstream of OB3;
− Anti-erosion works downstream of OB6;
− Clearance of alien vegetation at sites; and
− Need to control agricultural activities that contribute to erosion, channel instability and degradation of aquatic
habitats and ecological processes.
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 97
SECTION H: RECOMMENDATION OF THE EAP
In my view (EAP), the information contained in this application form and the documentation
attached hereto is sufficient to make a decision in respect of the activity applied for. YES � NO
If “NO”, list the aspects that should be further assessed through additional specialist input/assessment or whether this
application must be subjected to a Scoping & EIR process before a decision can be made:
No further specialist assessments are deemed necessary as the basic assessment report provides sufficient information on
which to base an informed decision about this application – subject to the proviso that operational phase impacts need
to be monitored (see recommended mitigation measures below), and high level mitigation takes place. The aquatic
ecologist will be invited to review future iterations of the basic assessment with the view of ensuring that all pertinent
biodiversity-related considerations have been identified and addressed as recommended.
If “YES”, please indicate below whether in your opinion the activity should or should not be authorised:
Activity should be authorised: YES � NO
Please provide reasons for your opinion
It is recognised that authorisation can only follow once the final basic assessment report has been submitted to the
DEA&DP. At this stage of the process, it is possible to recommend authorisation on the following grounds:
− The repairs and, in the case of the structures at OB1 and OB3, which are to be replaced with new culvert
crossings, are essential for road safety and the maintenance of an effective rural transport network in the
western Overberg.
− The DTPW has emphasised the urgency for the repairs, given the vulnerability of the Helderstroom prison to
floods that periodically cut it off from the outside world.
− Socially and economically, this basic assessment has demonstrated both the need for the repairs, as well as
their desirability.
− There are no adverse impacts at an activity or site-specific level that are sufficiently severe to warrant refusing
the authorisation of the proposed repairs.
− If all the recommended mitigation measures were to be implemented, the environmental impacts of the
repairs will range from 'very low' negative significance, to impacts of 'low' positive significance in terms of
improved flood conveyance capacity and reduced erosion and channel instability.
− However, this presupposes that all the recommended high level mitigation measures will be implemented for, if
not, the proposed activities are liable to contribute to further environmental degradation of the Bot River, and
the affected tributaries of the Riviersonderend.
− Residual uncertainties about long-term operational phase impacts must therefore be subject to monitoring and
review.
− Furthermore, it is crucial that the watercourses be kept free of invasive alien plants and that the channels at the
different crossings be cleared regularly of sediment deposits and debris that may clog culverts during floods.
If you are of the opinion that the activity should be authorised, then please provide any conditions, including mitigation
measures that should in your view be considered for inclusion in an authorisation.
NOTE that recommendations are provided for:
A. Generic mitigation of construction-related impact at all sites;
B. Measures relating to site-specific mitigation and ecological rehabilitation; and
C. General, post-construction ecological rehabilitation.
(A) Generic measures for mitigating construction-related impacts at ALL sites
− Construction activities within watercourses should not take place during the wet season (i.e. any activities
requiring the diversion of flows should take place between October and April only), and construction schedules
should preferably be managed within these time frames.
Delineation of construction sites and access to watercourses
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 98
− Obtain the landowner's written permission if sites must be accessed across farmland
− Only use existing access roads to undertake the proposed activities
− The physical extent of construction-related impacts must be minimised and securely contained within an area
demarcated by RoadQuip® 'Express Net' or a similar highly visible and durable barrier device. This particularly
applies to those points where vehicles obtain access into watercourses.
− Limiting activities and vehicle movement to disturbed sections of river channels
− Clearly mark vegetation that may not be damaged
− All areas outside of the demarcated construction zone should, within reason, be regarded as no-go areas
during construction, with the exception of personnel engaged in required alien clearing and bank
rehabilitation activities outside of construction disturbance zones.
Removal of indigenous vegetation
− Only remove reeds and other riparian vegetation in the channel and along river banks if access to structures or
construction areas would otherwise be impeded by indigenous vegetation – this applies specifically to Site OB5,
which still retains natural in-stream vegetation and habitat types.
De-watering of construction sites
− Where de-watering is required as part of construction activities, provision must be made for the settlement of
sediment in temporary sediment ponds or other areas of containment. These must be managed so as to
prevent the passage of sediment-rich water into the watercourse
− De-watering systems must be designed so that they do not result in the passage of concentrated flow into
watercourses, thereby promoting erosion.
− Ensure that flows that are routed around or discharged downstream of construction areas do not result in scour
downstream of construction sites
− Ensure that the impact of pumped water that is discharged under pressure is dissipated by placing pipe outlets
in rocky parts of the stream bed that are not susceptible to scour.
Removal and stockpiling of topsoil for post-construction rehabilitation
− Fill sourced for construction purposes must be free of alien seed.
− Remove topsoil to a depth of 150 mm and stockpile it locally for re-vegetation.
− Grade banks to a slope of at least 1:4, but preferably flatter, between the repaired structures and the
boundary of the road reserve.
− Grade slopes downwards, towards the watercourses, with reducing the width or depth of the channel
− Re-plant disturbed areas directly upstream and downstream of each structure with indigenous, locally-
occurring pioneer species at the level of base flow.
− Using bagged plants rather than seeds or cuttings to achieve rapid stabilisation of particularly lower banks.
Storage and preparation of construction materials
− Construction sites must be managed so that construction material (especially cement and fuel products) is not
washed or blown into watercourses during storm events or strong winds.
− Store and contain all materials on the construction sites at least 40 m from the nearest water resource.
− Concrete batching must take place at least 40 m from the edge of channel in a secure, bunded area (e.g.
wooden boards placed over heavy plastic sheeting within a bund of sandbags).
− Keeping stockpiled spoil and recently disturbed areas moist.
Refuelling of vehicles and other machinery
− Vehicles must be refuelled at least 40 m away from rivers, in securely bunded areas
− Fuel bowsers and other forms of fuel storage must be kept at least 40 m away from any watercourse
− Check vehicles daily for oil leaks and repair leaks immediately
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 99
− Maintain all construction machinery and vehicles in good working order.
General site maintenance
− Inspect sites daily for litter and remove all rubble and waste material from the river channels and riparian zones
after construction is completed.
− No open fires are permitted at any of the construction sites – fires for cooking or heating purposes must be
made in 'konkas' within a cleared area within the construction site
− Provide and regularly service ablution facilities for construction staff on site.
− Toilets must be located at least 40 m from watercourses.
− No tools, packaging, empty containers or other construction materials may be washed in watercourses
− Water used for washing must be managed such that it does not contaminate any watercourse;
Noise abatement
− Ensure construction machinery and especially silencers are in good working order.
− Limit construction to the hours of daylight, on weekdays only.
Dust abatement
− Vehicles must not exceed 40 km/hr on gravel roads in the vicinity of human habitation or vineyards or
orchards with ripening fruit.
Road safety
− Provide sufficient signage to warn motorists of the presence of construction works and detours.
Post-construction rehabilitation
− Rehabilitation activities specified in mitigation measures, including rehabilitation of temporary bypasses or
defunct structures should take place outside of the wet season, and immediately after the completion of
construction activities.
− All waste generated by construction activities (including rubble, litter etc.) is to be removed from the site and
disposed of at an appropriate approved site.
− Remove invasive species such as black wattle Acacia mearnsii and beefwood Casuarina sp as they contribute
to channel restriction, down-cutting and erosion, and displace indigenous biodiversity.
− Post-construction alien management must be ongoing at all sites.
− Alien clearing procedures should be carried out in accordance with species-specific guidelines outlined by
Working for Water documentation, or as recommended by an experienced alien clearing specialist;
− Bank rehabilitation activities should make provision for input by a river ecologist or the Western Cape Department of Agriculture into the final shaping and planting of these areas.
− Any area accidentally disturbed during construction should be rehabilitated after construction, with input from
a riverine specialist ecologist or the Western Cape Department of Agriculture where such areas lie within a
watercourse or other wetland.
Post-construction channel maintenance
− Keeping watercourses upstream of the structures (at least as far as the edge of the road reserve) clear of flood
debris (particularly ‘spoelklippe’, branches and uprooted bushes and trees) to prevent premature over-topping
and back-flooding in floods ≤1:5-year return period.
− Keeping channels downstream, at least as far as the fenced edge of the road reserve, clear of branches and
other obstacles that may deflect flows into the banks of watercourses.
− Where excavations have taken place upstream of structures, ensure that potential nick-points and benches in
the channel are removed so as to prevent head-cut erosion from developing upstream of these locations.
− Monitor the first reach/first 150 m of the watercourse downstream for signs of new erosion.
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 100
− Monitor changes to sediment patterns (deposition and erosion) up- and downstream of repaired structures to
assess recovery and reinstatement of the general slope of the watercourse.
− Obtaining timeous ecological advice on how best to repair and, if feasible, provide additional venting, to
gravel approaches that may be washed away as a result of floods.
− Maintain roads to reduce the concentration and/or intensity of run-off so as to dissipate energy and erosion
potential.
(B) Measures relating to site-specific mitigation and ecological rehabilitation
OB1: Kanaan The following measures need to be implemented upon completion of construction:
− All concrete and other debris associated with the present road crossing should be removed from the river bed and banks as
soon as the requirement for a construction-phase bypass road is over, and disposed of outside of the 1:50 year flood line for the river;
− The existing road, which will be replaced by a new alignment, should be ripped, all artificial debris removed, and the river bank and riparian zone thus created should be shaped to resemble a natural system, in a band at least 15m wide on either side of the river – a river ecologist should oversee / sign off on this aspect of mitigation;
− The river bank must be rehabilitated according to Environmental Specification C1008; and − The small tributary directly to the east should be addressed as part of the latter process, and re-shaped as a broad open
channel, planted in destabilised areas to prevent erosion;
OB3: Meerlustkloof
− Additional pipes must be installed in the existing causeway to improve its capacity to accommodate high flows during construction, after which this structure must be demolished and its disturbed footprint rehabilitated as specified below. The installation of the extra pipes must be supervised by the project engineer and an aquatic ecologist.
− All concrete and other debris associated with the present road crossing should be removed from the river bed and banks as soon as the requirement for a construction-phase bypass road is over, and disposed of outside of the 1:50 year flood line for the river; and
− The existing road, which will be replaced by a new alignment, should be ripped, all artificial debris removed, and the river bank rehabilitated according to Environmental Specification C1008.
Site OB6: Nooitgedacht
− The wetland head-cut must be addressed, as a matter of great urgency, and prior to the start of any construction activities on this overall project, through the installation of a gabion weir, located at the head-cut point, and appropriately designed to prevent further erosion caused by a change in gradient between the wetland channel and the excavated channel upstream of the low-lying culvert.
(C) General, post-construction ecological rehabilitation
T
These recommendations relate to long-term rehabilitation and channel maintenance and do NOT apply to construction phase activities as specified in the Construction Environmental Management Programme for project C958.5
Alien clearance and monitoring − Keep channels upstream and downstream – and at least as far as the first bend and/or for 150 m – clear of large branches
and other debris that may deflect flows into the banks of watercourses. − Clear invasive alien plants from river banks and the floodplain at least 200 m downstream of the structures, in a corridor at
least 30 m wide and replant with locally-occurring indigenous pioneer plant species. − Species-appropriate alien clearing methods should be employed – Working for Water guidelines should be used in this
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 101
regard; − Cleared areas should be stabilised by a combination (as appropriate) of bank shaping and planting with locally indigenous
plant species − Monitor the first reach/first 150 m of the watercourse downstream on an annual basis for signs of new erosion. − Maintain a photographic record of the monitored reaches. − In all cases, alien clearance needs to be co-ordinated by an authority such as the Western Cape Department of Agriculture
and local landowners should be encouraged to participate in such clearance programmes.
Site OB1: Kanaan
− The eroding bank upstream of the bend must be addressed, through removal of alien vegetation, reshaping of the bank and
replanting; hard stabilisation techniques (e.g. bank lining with gabions) should not be used, although it is understood that gabions will be used immediately up- and possibly downstream of the new structures.
Site OB2: Doringkloof
− All invasive woody alien vegetation and the seedlings of such species should be cleared from a zone extending at least 30 m upstream and 30 m downstream of the present crossing point, as well as 30m upstream along the inflowing minor stream, in a swathe at least 15m wide on either side of the river channel, or less if alien invasion is within a narrower zone – the final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner;
− The design for this structure must include an additional or extended culvert or other ecologically cognisant measure that allows for the free flow of the minor stream through the structure, without being diverted along the road edge. The mechanism for this would need to address the fact that the stream appears to enter the system at a higher level than the existing culvert.
Site OB3: Meerlustkloof
− The DTPW should liaise with the Western Cape Department of Agriculture regarding the proposed installation of a groyne field in the Elandskloof River, and ensure that bank erosion and channel migration in the reaches at least 50 m upstream and downstream of the crossing are controlled by groynes, designed in keeping with the objectives of the broader WCDA flood and erosion control programme.
− Such structures ideally need to be in place before the start of the present proposed activities – in the event that delays in their authorization through WCDA are considered likely, it is recommended that the DTPW either work with WCDA to prioritise approval and construction of the structures that would affect the present road, or design and obtain authorization for such structures separately.
− Note that the proposed design at OB3 already assumes implementation of the groyne field, and allows for a lower invert level in the crossing than that required at present, given that the river would be down-cut by concentration of flood flows.
− The extensive eroded area to the east of the existing bermed river channel downstream of OB3 must be addressed, and returned to a vegetated floodplain condition.
− This rehabilitation measure, which should only take place after construction of the groynes and new road and bridge, would require:
o Liaison with the WCDA regarding the implications of the proposed groyne field for this area – ideally, the groyne field itself should allow for widening of the river in these disturbed reaches
o Removal of the berm (berm material may be spread on the eroded floodplain)
o Removal of the beefwood trees lining the channel downstream of the road
o Landscaping / shaping the floodplain area such that it comprises a mosaic of depressions and raised areas, mirroring natural conditions;
o Establishment of indigenous floodplain vegetation on the rehabilitated area – note that while planting or seeding of the area would be positive, it is likely that appropriate plants will establish themselves in the rehabilitated area over time, provided that weeding is allowed for in the establishment phase. This has been the case with disturbed areas upstream (Day 2013).
− Allowance must be made for the establishment of a continuous swathe of appropriate, locally indigenous vegetation along at least the wetted bottom of the bank of the river, but ideally up the bank as well, for a distance of 30m up- and
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 102
downstream of the proposed structure, to prevent erosion. It is strongly recommended that dense stands of Palmiet reeds (Prionium serratum) should be utilised for this purpose. Other plant species used should be selected in consultation with a botanist and/or river ecologist, to ensure they meet the required criteria of being hardy, locally indigenous and suited to the conditions in which they are planted;
− The final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner;
Site OB5: Tarentaalkraal
In order to address the issue of concentrated flows and at times the passage of large debris through the road culvert, exacerbating the problems experienced in the scour hole: − The alien-invaded channel upstream of the road must be cleared of all woody aliens and the seedlings of such species,
across the entire riverine zone, extending upstream for a distance of at least 40 m upstream of the road – the final extent of alien clearance must be clarified in consultation with the Western Cape Department of Agriculture and the responsible landowner
− Species-appropriate alien clearing methods should be employed – Working for Water guidelines should be used in this regard;
− Cleared areas should be stabilised by a combination (as appropriate) of bank shaping and planting with locally indigenous plant species;
− Local landowners should ideally be required to participate in long-term alien maintenance clearing activities in the cleared reach and upstream;
− Branches and other material that become entangled in the fence across the culvert should be cleared before the onset of winter in order to prevent debris-build-up;
− Consideration should be given to the creation of attenuation depressions / wetlands in the area to the west of the channel, upstream of the road, to manage flood velocities and volumes; and
− Also, alien vegetation should be cleared to a distance of 30 m downstream of the road (i.e. to just past the riffle at the end of the pool).
OB6: Nooitgedacht
− The eroding banks downstream of the culvert must be addressed as a matter of urgency, bearing in mind their proximity to the Riviersonderend wetlands downstream. The following measures are regarded as minimum requirements:
o The need for the installation of energy-control weirs in the channel should be considered, to prevent further
down-cutting and allow the re-establishment over time of wetland vegetation – where considered necessary by an engineer, working with a river ecologist, such weirs should be constructed;
o The river banks must be graded (during low flow periods) to establish banks that have slopes no steeper than 1:5 and preferably less steep;
o Allowance must be made for the planting of at least the lower bank with hardy locally indigenous plant species, approved by a botanist or river ecologist, that will play a role ion lower bank stabilisation; the use of Palmiet in this regard would be encouraged;
o The passage of flows into the channel from the west must be investigated and addressed, such that it does not constitute a threat to the long-term rehabilitation of the channel.
Duration and Validity:
Environmental authorisations are usually granted for a period of three years from the date of issue. Should a longer
period be required, the applicant/EAP is requested to provide a detailed motivation on what the period of validity
should be.
N/A
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 103
SECTION I: APPENDICES
The following appendices must be attached to this report:
Appendix
Tick the box if
Appendix is
attached
Appendix A Locality maps �
Appendix A1 Site plans
Appendix B Project summary �
Appendix C Photographs �
Appendix D1 Biodiversity overlay maps �
Appendix D2 Biodiversity summary �
Appendix E Permit(s) / license(s) from any other organ of state including service letters
from the municipality N/A
Appendix F
Public participation information including a copy of the register of interested
and affected parties, the comments and responses report, proof of notices,
advertisements and any other public participation information as required in
Section C above.
�
Appendix G1 Rapid biodiversity screening report: Mr Jan Vlok, botanist �
Appendix G2 Rapid biodiversity screening report: Dr Liz Day, aquatic ecologist �
Appendix G3 Freshwater assessment: MsToni Belcher, aquatic ecologist
Appendix H Draft Construction Environmental Management Programme �
Appendix I Application Form �
Appendix J Convention for Assigning Significance Ratings to Impacts �
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 104
DECLARATIONS
THE APPLICANT
I …………………………………., in my personal capacity or duly authorised (please circle the applicable
option) by …………….................………………… thereto hereby declare that I:
• regard the information contained in this report to be true and correct, and
• am fully aware of my responsibilities in terms of the National Environmental Management Act of 1998 (“NEMA”) (Act
No. 107 of 1998), the Environmental Impact Assessment Regulations (“EIA Regulations”) in terms of NEMA
(Government Notice No. R. 543 refers), and the relevant specific environmental management Act, and that failure
to comply with these requirements may constitute an offence in terms of the environmental legislation;
• appointed the environmental assessment practitioner as indicated above, which meet all the requirements in terms
of regulation 17 of GN No. R. 543, to act as the independent environmental assessment practitioner for this
application;
• have provided the environmental assessment practitioner and the competent authority with access to all
information at my disposal that is relevant to the application;
• will be responsible for the costs incurred in complying with the environmental legislation including but not limited to –
o costs incurred in connection with the appointment of the environmental assessment practitioner or any person
contracted by the environmental assessment practitioner;
o costs incurred in respect of the undertaking of any process required in terms of the regulations;
o costs in respect of any fee prescribed by the Minister or MEC in respect of the regulations;
o costs in respect of specialist reviews, if the competent authority decides to recover costs; and
o the provision of security to ensure compliance with the applicable management and mitigation measures;
• am responsible for complying with the conditions that might be attached to any decision(s) issued by the
competent authority;
• have the ability to implement the applicable management, mitigation and monitoring measures;
• hereby indemnify, the government of the Republic, the competent authority and all its officers, agents and
employees, from any liability arising out of, inter alia, the content of any report, any procedure or any action for
which the applicant or environmental assessment practitioner is responsible; and
• am aware that a false declaration is an offence in terms of regulation 71 of GN No. R. 543.
Please Note: If acting in a representative capacity, a certified copy of the resolution or power of attorney must
be attached.
Signature of the applicant:
Name of company:
Date:
THE INDEPENDENT ENVIRONMENTAL ASSESSMENT PRACTITIONER (EAP)
I ……………………………………, as the appointed independent environmental practitioner (“EAP”) hereby declare that I:
• act/ed as the independent EAP in this application;
• regard the information contained in this report to be true and correct, and
Proposed flood damage repair projects in the western Overberg (C958.5)
CCA Environmental (Pty) Ltd Draft BAR 105
• do not have and will not have any financial interest in the undertaking of the activity, other than remuneration for
work performed in terms of the NEMA, the Environmental Impact Assessment Regulations, 2010 and any specific
environmental management Act;
• have and will not have no vested interest in the proposed activity proceeding;
• have disclosed, to the applicant and competent authority, any material information that have or may have the
potential to influence the decision of the competent authority or the objectivity of any report, plan or document
required in terms of the NEMA, the Environmental Impact Assessment Regulations, 2010 and any specific
environmental management Act;
• am fully aware of and meet the responsibilities in terms of NEMA, the Environmental Impact Assessment Regulations,
2010 (specifically in terms of regulation 17 of GN No. R. 543) and any specific environmental management Act, and
that failure to comply with these requirements may constitute and result in disqualification;
• have ensured that information containing all relevant facts in respect of the application was distributed or made
available to interested and affected parties and the public and that participation by interested and affected
parties was facilitated in such a manner that all interested and affected parties were provided with a reasonable
opportunity to participate and to provide comments;
• have ensured that the comments of all interested and affected parties were considered, recorded and submitted
to the competent authority in respect of the application;
• have kept a register of all interested and affected parties that participated in the public participation process;
• have provided the competent authority with access to all information at my disposal regarding the application,
whether such information is favourable to the applicant or not; and
• am aware that a false declaration is an offence in terms of regulation 71 of GN No. R. 543.
Note: The terms of reference must be attached.
Signature of the environmental assessment practitioner:
Name of company:
Date:
THE INDEPENDENT PERSON WHO COMPILED A SPECIALIST REPORT OR UNDERTOOK A SPECIALIST PROCESS
See overleaf for declarations from relevant Specialist Studies.