engineering design report rangitane maritime …

ENGINEERING DESIGN REPORT

RANGITANE MARITIME DEVELOPMENT

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APPENDIX 10

20-0072 Rangitane Maritime Development Engineering Design Report P a g e | 1

Contents 1.0 INTRODUCTION ........................................................................................................................... 2

2.0 OTHER REPORTS .......................................................................................................................... 3

3.0 SITE DIMENSIONS ........................................................................................................................ 4

4.0 SITE DESCRIPTION AND SITE HAZARDS ....................................................................................... 5

5.0 IMPORTANCE LEVELS .................................................................................................................. 6

6.0 SEISMIC CRITERIA ........................................................................................................................ 6

7.0 GEOLOGY ..................................................................................................................................... 7

8.0 SITE INVESTIGATIONS ................................................................................................................. 7

9.0 RECLAMATION DESIGN ............................................................................................................... 8

10.0 EARTHWORKS ........................................................................................................................... 10

11.0 CONSTRUCTION DURATION ...................................................................................................... 10

12.0 REDUCTION OF EMISSIONS FOR EARTHWORKS ....................................................................... 11

13.0 ARMORING ROCK ...................................................................................................................... 12

14.0 LANDCSAPING AND PLANTING ................................................................................................. 13

15.0 STORMWATER DESIGN ............................................................................................................. 14

16.0 EROSION AND SILT CONTROL ................................................................................................... 14

17.0 RECLAMATION SURFACING ....................................................................................................... 15

18.0 CONCLUSIONS ........................................................................................................................... 15

APPENDIX A – PROPOSED PLANS ..............................................................................................................

APPENDIX B – PRELIMINARY STORMWATER CALCULATIONS ..................................................................

APPENDIX C – SITE PHOTOS .....................................................................................................................

This report has been prepared for the sole benefit of Far North Holdings for the purposes outlined in the introduction. Reliance on this report for any other purposes than that stated shall be done at the full risk of the user. This report shall not be reproduced in part or in full for any other purposes without the express written permission of Shorewise Engineering Consultants Limited.

Document Version Prepared By Date Released DRAFT Rob Brown 23-07-2021 Rev 0 Rob Brown 21-08-2021 Rev 1 Rob Brown 25-08-2021


ENGINEERING REPORT Rangitane Maritime Development

1.0 INTRODUCTION

Far North Holdings Limited (FNHL)seek to develop a reclamation and new boat ramp facility at Rangitane Loop Road in Kerikeri. The purpose of the new facility is to provide a substantial upgrade to the existing limited boat ramp facilities and provide for the recreational boating requirements of the wider community.

The proposed reclamation will service a new two lane (4 metres width per lane) concrete boat ramp and central floating pontoon providing deep water access 1 hour either side of low tide for larger motorised trailer boats, and all tide access for smaller dinghies, kayaks and paddle boards. The ramp is proposed to be constructed at the southern end of the reclamation.

A footpath around the perimeter of the site will provide direct public access to the CMA and will provide pedestrian linkages along Rangitane Loop Road. Pedestrians will be required to cross the top of the two lane boat ramp as they progress around the perimeter of the site. Public amenity will be provided along the pedestrian route.

The reclamation has been designed for the highest levels of sea level rise over a 100 year planning horizon and will provide for a relatively flat entrance off the existing road for the safety of users. The reclamation will be constructed of imported fill, up to 4.5 metres high in places, and will be protected with a layer of armoring rock to the perimeter.

Shorewise Engineering Consultants Ltd have been engaged by FNHL , to provide engineering design input and an engineering report to support the consent application for the proposed reclamation.

This application excludes any works associated with the jetty and pontoon (connected to the jetty) to the east of the proposed boatramp, these are covered under an existing resource consent.


2.0 OTHER REPORTS

The proposed reclamation design has been supported by a range of other reports from relevant technical specialists as below:

Subject Title Date Revision Company Coastal Hazards Coastal Hazard

Report 23-07-2021 Rev 1 Shorewise

Engineering Consultants

Geotechnical (Boat Ramp)

Geotechnical Report, Rangitane boat ramp

23-07-2021 Rev 1 Shorewise Engineering Consultants

Construction Management Plan (preliminary)

Construction Management Plan

23-07-2021 Rev 1 Shorewise Engineering Consultants

Geotechnical (reclamation)

Geotechnical assessment report

20-07-2021 Rev C Initia

Coastal processes Coastal processes assessment

May 2021 V 1.0 4 Sight Consulting

Noise effects Assessment of noise effects

14 May 2021 Marshall Day Acoustics

Ecology Ecological assessment

10 May 2021 V 1.0 4 Sight Consulting

Traffic Rangitane Boat Ramp Traffic Assessment

19 August 2021 Traffic Planning Consultants

Landscape Assessment of landscape, natural character, and visual effects

August 2021 Littoralis landscape architecture


3.0 SITE DIMENSIONS

The reclamation will measure roughly 151 metres long x 56.6 metres wide and will occupy a seabed area of approximately 7400m².

The 19 trailer boat parks will all measure 15 metres long x 3.2 metres wide, this is a generous dimension to accommodate large trailer boats up to 7.5 metres. The dimensioned width of the carpark at 33.9 metres, combined with the parking width, will allow vehicles to back up and turn the car and trailer within the carpark space without having to back the trailer through the whole carpark.

The 8 carparks are 2.5 metres wide to allow boat users to load supplies out of their vehicle with sufficient movement space.

Two dedicated spaces are allowed for boat preparation within the reclamation. The first, at the top of the ramp, on the eastern side, allows a space for a boat to be prepared and loaded for launching without inhibiting any movements on the ramp, and is intended as a 5 minute loading zone only. The second space is between the boat ramp and the carpark exit. This is a space for the boat to be tied down to the trailer and prepared for being towed, and is intended as a 5 minute loading zone only. This space is behind the carparks but the effects on the carpark users will be minor in terms of waiting for a car and trailer to leave to be able to exit the carpark.

Please refer to the traffic report for further details.


4.0 SITE DESCRIPTION AND SITE HAZARDS

The site of the proposed structures is within the CMA at Rangitane Loop Road, Kerikeri. The proposed reclamation is in an area of relatively shallow water that mostly dries at low tide, the boat ramp will extend down to mean low water springs and the proposed works do not require any dredging. The installation of the reclamation will have a less than minor effect on the coastal processes and the tidal flows in the area.

The site is not shown as being at risk of any coastal erosion on the FNDC GIS or the NRC GIS systems.

The existing foreshore has been lined with locally supplied rip rap rock and this has performed well, there are only signs of minor erosion around the existing structures.

The area is a relatively low energy environment and is generally only affected by local wind generated waves of up to 0.7m from the south west and 1.0 metre from the east in storm conditions. Tidal flows at the site are relatively minor.

The site is identified as Tsunami evacuation zone Orange.

There are no other risks associated to the site therefore we consider the site to be low risk from a geotechnical and coastal hazards perspective.

The coastal flood hazard zone heights are defined as below:

CFHZ 1 CFHZ 2 CFHZ 3 Height OTP 2.1 m 2.9 m 3.2 m Height CD 3.4 m 4.2 m 4.5 m

Refer to the coastal hazard report, geotechnical reports, and coastal processes report for further details.

Existing Jetty

(partially demolished)

Existing Boat Ramp


5.0 IMPORTANCE LEVELS

The boat ramp, jetty and new pontoon are Importance level 2 structures.

6.0 SEISMIC CRITERIA

The reclamation design life is 100 Years, the design life of the boat ramp structure is classified as Importance Level 2, the design life is 50 Years. The design seismic acceleration is derived using Standards NZS 1170.5, MBIE/NZGS Geotechnical engineering guidelines and the NZTA Bridge Manual (2004). The hazard factor (Z) for Kaitaia is 0.1 and the subsoil class is defined as Class C (firm material up to 25m depth and stiff material up to 40m depth). There are no known active faults within 20km of the site.

Based on the above information, the design horizontal Peak Ground Acceleration (PGA) for a 1 in 1000-year return period can be derived as follow.

C(0) = C0,1000 * R/1.3 * f*g

Based on these parameters the ULS and SLS factors for the subsoils are:

Case Return Period Peak Ground Acceleration ULS 1/1000 0.13g SLS 1/25 0.025g

The superstructure ULS and SLS seismic factors to NZS1170.5 are:

C(T) = Ch(T) * Z * Ru * N(T,D) g

Case Return Period Seismic coefficient

ULS 1/500 0.19g SLS 1/25 0.04g


7.0 GEOLOGY

The Geotechnical map of the Kerikeri area by GNS Science published on the GNS website identifies the site as basalt flows of the Kerikeri volcanic group, and described as Basalt lava, volcanic plugs, and minor tuff.

The description is consistent with the underlying soils identified at the site and our visual inspections of the site and its surrounds. Boreholes carried out at the site to support the reclamation design found silty deposits intermixed with cobbles and boulders overlying hard basalt at relatively shallow depths.

8.0 SITE INVESTIGATIONS

Detailed site investigations were undertaken by Shorewise and Initia. The testing by Initia consisted of 3 x machine drilled boreholes and 3 x hand augers from land to inform the reclamation design. The Initia investigation was complemented by a range of lab tests to confirm the soils properties. The testing by Shorewise consisted of 5 x Scala penetrometer tests from a boat in the location of the boat ramp, and the future location of the jetty and pontoon upgrade (not part of this application).

Please refer to the respective geotechnical reports for further details.

Basalt flows


9.0 RECLAMATION DESIGN

The reclamation has been designed to have a level of + 4.85m Chart Datum, this is above the Coastal Flood Hazard Zone 3 (CFHZ3) level, a new level that has been released in the latest version of the Tonkin and Taylor report entitled “Coastal Flood Hazard Assessment for Northland Region”, dated March 2021. The recommendations of this report have been adopted by the Northland Regional Council (NRC) and have been published in a series of maps on their GIS website.

The CHFZ3 level incorporates an extreme sea level rise allowance of 1.5m. The coastal hazard report has considered a range of scenarios to recommend a suitable design level, the design level proposed is just below the level of the existing Rangitane Loop Road to provide a relatively level entrance off the road, and the safest possible entry and exit from the new carpark.

The reclamation will be constructed of imported fill ranging from rock fill to clay type overburden materials. Rock fill will generally be used in the intertidal area, clay materials such as a quarry rotten rock overburden type soil may be used in the area above high tide to provide a cost effective, low permeability highly compactible fill, crushed and graded rock will be used in the top layers to form the base for the carpark. The reclamation batters will be protected with geotechnical fabric as appropriate and a layer of armouring rock around the perimeter to prevent erosion of the reclamation fill.

The following volumes are expected to be excavated at the site:

Area Volume Reclamation shear key 1500 m³ - 2000 m³ Boat Ramp 200 m³ – 400 m³

The shear key under the edge of the reclamation batters will require excavation on site, the excavated material from this shear key and from under the boat ramp is expected to be blended with imported fill on site so that the materials do not have to be carted off site.

The volume of unsuitable materials that will be cut to waste is expected to be a maximum of 1000m³, this volume is to be confirmed at site inspections. This material will be stockpiled on site to dewater and will be carted off site by backloading the trucks supplying the site fill, to minimize the number for truck movements required.

The material removed to form the reclamation batter shear key will be blended with the hardfill where possible, in non-critical areas.

Any unsuitable material under the boat ramp footprint will be reused or removed from the site as required.

The following volumes of materials are expected to construct the reclamation:

Material Type Volume Reclamation fill (total) 20750 m³ Rock armoring 2250 m³


The breakdown of expected reclamation volumes required:

Material Type Volume Min Volume Max Shear key hardfill 1500 m³ 2000 m³ Boat ramp base hardfill 200 m³ 400 m³ Reclamation fill 17500 m³ 21000 m³ Rock armoring 2000 m³ 2500 m³ Total Volumes 21200 m³ 25900 m³

The rock armoring will be sourced from local quarries where possible, the material will be a quarried basalt.

The following volumes of materials are expected for the surfacing works:

Material Type Volume Min Volume Max Carpark basecourse 1600 m³ 1800 m³ Boat Ramp Concrete 80 m³ 120 m³ Footpath Concrete 25 m³ 30 m² Kerb concrete 6 m³ 8 m³ Asphalt carpark surface 1700 m³ 2000 m³

The sealed carpark will have an area of approximately 4400m², it will be finished with an asphaltic concrete surface with kerb and channel edging. The carpark will fall from a high point in the centre towards the vegetated swale drains and will drain through gaps in the kerbing directly into the vegetated swales.

The boat ramp will have a slope of between 1 vertical to 8 horizontal (1:8) and 1 vertical to 9 horizontal (1:9), the ramp will be of reinforced concrete over a compacted rock subbase, minor removal of softer surface sediments will be required.

The boat ramp is expected to be cast in place as it is above the low tide mark, the lower edge of the ramp may consist of precast concrete panels lifted directly into place. The edges of the boat ramp will be protected by armouring rock, similar to the reclamation batter armoring rock. The toe of the boat ramp will be at the MLWS line, and the boat ramp surface will be grooved to provide a non-slip finish.

The boat ramp lane widths are 4 metres which is a generous boat ramp width for larger trailer vessels and less experienced operators.

The boat ramp pontoons will be 1800mm wide with approximately 100mm wide timber walers either side, giving a total width of 2000mm. The concrete pontoons will have a freeboard of approximately 400mm and will provide maximum stability for the users. The boat ramp pontoons will be designed by the manufacturer, the pontoons will sit on rubber buffers that protect the pontoons from impact on the concrete boat ramp.

The boat ramp pontoon piles will most likely be steel I beams protected with black polyethylene sleeves to prevent corrosion. The use of steel I beams will allow the piles to be driven into the underlying volcanic soils.


10.0 EARTHWORKS

The first layers of hardfill to be placed across the site, in the intertidal zone, will be a crushed quarry run rock, this material will be compacted in layers until a level above the high tide line is achieved.

Once filling operations are above the high tide mark a rotten rock quarry overburden, clay based type fill may be used to continue elevating the site, the thickness of this fill (if used in the detailed design) is not expected to exceed 1.5 metres thickness.

The top of the reclamation will be completed with crushed graded rock, such as Gap 65, to reach the subgrade level for the carpark.

All hardfill materials will be delivered to the site by truck, where possible, and where space on the reclamation allows the hardfill will be delivered by truck and trailer to reduce the number of truck movements to and from the site.

The earthworks will abut up to the edge of the existing roadway batter, a stormwater swale drain will be constructed at the connection between the reclamation and the existing roadway edge to minimise the works will be required to the existing roadway batters and keep construction works away from the existing Pohutukawa tree roots, where possible.

11.0 CONSTRUCTION DURATION

The construction works for the reclamation fill are expected to be completed within a five to six month period. This period is when the bulk of the truck movements will be generated for the delivery of the fill material to the site.

The filling movements will initially require trucks to back up to the north west corner of the development and tip the materials off the edge of the existing boat ramp until and area large enough for truck movements above the tide level can be established so that truck turning and backing movements can be moved off the existing roadway, this methodology is to be one of the focus areas of the tendering process and the construction methodology will be developed with the successful contractor.

The rock armoring of the slopes will take place during the recommended 3 month settlement duration. During this settlement period the reclamation will have a gravel finish. After the settlement period the final trimming of the surfaces will proceed before the surfacing works can commence and the landscaping features are constructed.

The construction of the boat ramp surfacing, carpark surfacing, footpaths and final landscaping are expected to occur over a 3 month duration.

The expected total construction duration is 12 months, this is to be confirmed in consultation with the construction contractors.

The Traffic Planning Consultants traffic report has calculated the number of trip movements based on the maximum volume of materials, limited number of truck and trailer movements and no backloading of materials and a compressed reclamation construction period of three months. This


results in a maximum construction trip generation of 10 trucks per hour, this is thought to be the worst case truck movement volume for the site. Truck movements will be planned around the tides in the initial stages of the reclamation construction.

Extract from Traffic Planning Consultants Report:

The reclamation bulk works (Stage 1) are anticipated to be completed over a three-month period, with the other works following. Over this approximate 65 working day period, a total of 3,486 SBT, or 1,742 TT are expected. This period would be the highest intensity period of truck activity and would result in approximately 54 SBT per day (5-6 per hour) or 27 TT per day (2-3 per hour on average). However, truck volumes will also be subject to the tides. During low tide periods, a higher truck volume can be expected, with fewer or potential none during high tide. It is noted that these truck volume estimates are subject to change based on the construction methodology and day-to-day variations due to peak periods during individual construction tasks. However, given the constraints of the site, it is likely that truck volumes will be no greater than 10 trucks per hour.

12.0 REDUCTION OF EMISSIONS FOR EARTHWORKS

The removal of unsuitable material from the site will be reduced to the minimum possible by dewatering the material and reusing it in non-critical parts of the reclamation as compacted fill where possible.

The dewatered unsuitable material to be carted off site will be removed by backloading in the trucks (and trailers where appropriate) that deliver the reclamation fill to site, to reduce the total travel distance for all truck movements.

The hardfill and rock for the reclamation construction will be sourced from the closest quarry possible. Quarries with suitable fill and armouring rock are located in Kerikeri.

Material will be carted to site with truck and trailer units where possible to reduce the emissions.

Tenderers for the project will be encouraged to use modern, low emission trucks and site plant. Tenderers will be required to provide details on the emission standards that their fleet meets.

Mitigation of the effects of the construction will be provided by the installation of new planting areas to the vegetated swales and trees on the site, these will absorb carbon over time.

Natural mitigation of the effects will be provided due to the fact that the boat ramp will be closer to the Kerikeri township than the existing nearest available Doves Bay and Opito Bay boat ramps, so the vehicle travel distances for people to use the ramps will be less.


13.0 ARMORUING ROCK The armouring rock required to protect the external batters of the site will be sourced to match the existing iron stained rock where possible, in agreement with Littorailis Landscape Architects and as per their report

Were the proposal to be for the reclamation and boat ramp structures alone, the related landscape effects would be elevated. Factoring in the selection of armouring rock type to better integrate with the hues of the neighbouring coast and the significant level of native coastal vegetation proposed for the margins of the reclamation, brings the potential adverse impact upon existing landscape values to an acceptable level. These measures also assist to link back to well-established themes of vegetation found in the immediate setting of the proposal.

This rock can be sourced locally in the form of paddock basalt rock or utilising the natural iron stained faces of the rock jointing found in a local basalt quarry, the look of a high percentage of natural stained rock facing can be achieved by carefully handling, sorting, and placing the outer rock armoring layers to display those natural staining features. The existing rocks at the site will be stockpiled and reused for the rock armouring where possible.

Natural staining features in nearby Stanners Road Basalt Quarry, Kerikeri

Natural staining features in blasted rocks at nearby Stanners Road Basalt Quarry, Kerikeri


14.0 LANDCSAPING AND PLANTING

The design will incorporate a number of landscaping features, selected, and developed alongside Littoralis Landscape Architects, to preserve and enhance the natural character and amenity of the development including:

• Preserving all of the existing roadside Pohutukawa trees. • Positioning the entry point between the existing Pohutukawa trees. • Preserving the existing beach to the west of the development. • Incorporating planted stormwater swale drains into the design • Incorporating trees and planting on the perimeter of the development

By incorporating a swale drain into the design where the reclamation abuts the existing roadside this will achieve a construction separation and will avoid damage to the roots of the existing Pohutukawa trees.

Other planting features will be developed alongside Littoralis Landscape Architects as per their report:

The proposal seeks to avoid and minimise wider adverse effects that would arise from a reclamation of the existing coastal margin and intertidal marine area. Shaping the broad form to run approximately parallel to the existing shore, conserving the adjacent beach, incorporating a strong frame of native planting, and preserving the nearby rank of pohutukawa are all measures that will assist the development to settle into its setting.


15.0 STORMWATER DESIGN

As per the 4 Sight Ecology report section 4.5.3 “The activities on the reclamation (car and trailer parking) are unlikely to generate more than small quantities of particulates and organic waterborne material. No specific or potentially significant contaminant sources or processes are likely to occur on the reclamation. Effects from stormwater discharges are considered to be minimal and contaminants such as oils and hydrocarbons are not expected to arise other than in minor quantities, as occurs off any paved road or parking surface in the region. Discharges from the car parking are not expected to raise issues of colour, clarity, odour, aesthetics or amenity or adverse effects on biota. It is concluded that the general water quality effects will be low arising from any discharge from the completed project.” The reclamation stormwater system will be designed for RCP 8.5 rainfall values, in line with the RCP 8.5 sea level rise scenario values that the reclamation height has been set to and suitable for the 100 Year life of the structure.

The first flush rainfall will be run into the vegetated swales for treatment, the vegetated swales will be designed as bioretention devices, for water quality treatment only, to Auckland Council GD01 guidelines, with permeable soils and underdrainage layers. The area of treatment surface, for water quality treatment only, is expected to be 3.4% of the total carpark sealed surface area, this exceeds the 2% of impermeable surface area guideline. The rainfall intensity used for the calculation is 10mm/hr for Auckland, corrected to 11.5 mm/hr for Bay of Islands as per NZBC E1 Appendix A, rainfall intensities.

The vegetated bioretention swale, on the roadway side, will fill the gap between the road edge/batter and the carpark edge and will form a continuation of the existing road berm and tree planting in this area, no effect is expected to the existing trees.

The design is expected to provide treatment to in excess of 90% of the first flush runoff from the carpark surface. Treatment of runoff water from the boat ramp surface and its immediate approach is neither achievable nor practical due to the intertidal nature of the zone. Contaminants from vehicles on the boat ramp surface will be very minor due to the very slow speed of operation and the very limited wheel turning associated with backing boat trailers.

The outlet pipes are expected to be approximately 200mm to 300mm in diameter, four outlets are expected to provide sufficient capacity. The outlets may be fitted with backflow prevention devices to prevent salt water ingress into the vegetated swales in times of high tides and storms.

The overland flow will be directed through slots in the perimeter kerbing as per the preliminary stormwater management plan.

16.0 EROSION AND SILT CONTROL

Erosion and silt control measures will be in use for the duration of the earthworks. Refer to the preliminary construction management plan for further details.


17.0 RECLAMATION SURFACING

The carpark will be bordered with a concrete kerb and channel, where appropriate, with gaps for stormwater flow as required.

The carpark will be approximately 4400m² and will be surfaced with an asphaltic concrete layer, of approximately 40mm thickness.

Wheel stops will be installed into the carparks as required.

The entrance way will be surfaced with an asphaltic concrete layer, of at least 50mm thickness.

The carpark and entranceway will be marked out with standard line marking paint.

The boat ramp will be surfaced with reinforced concrete, the boat ramp will have substantial grooves in the surface to provide a low slip surface, periodic cleaning of the boat ramp surface will be required to prevent a buildup of slippery slime and mud in the intertidal and low water zones.

The footpaths will all be surfaced with concrete.

The top edge of the reclamation rock armoring will be planted where possible and encouraged to establish suitable species of plants that will tolerate the environment, refer to the landscape design report for further details.

18.0 CONCLUSIONS

The structures proposed are suitable for the site and the reclamation can be constructed with only minor temporary effects on the local ecology and area generally.

The structure has been designed for a 100 year water level and the worst predicted effects of sea level rise.

The structure will provide a long term asset for the area and promote public access to the water, both for recreational trailer boating and users of kayaks and small craft alike.

Prepared By: Rob Brown

Chartered Professional Engineer Civil / Structural CPEng, CMEngNZ, IntPE(NZ)

APPENDIX A – PROPOSED PLANS

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• SEABED OCCUPATION AREAEXCLUDING ROCK ARMOURING: 6600 m2

• SEALED CARPARK AREA: 4400 m2

• BOAT RAMP AREA: 400 m2

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0 ISSUED FOR CONSENT 23/04/20211 REISSUED FOR CONSENT 27/04/2021

1 : 250PRE-RECLAMATION SECTION

1 : 250RECLAMATION SECTION

N

M3489M1235

M1236

PORT CHANNEL MARKER(RED RAILWAY IRON)

STARBOARD CHANNEL MARKER(GREEN POLE)


PROJECT

SHEET DESCRIPTION

STATUS


CLIENT

www.shorewise.co.nz

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A3

REV DETAILS DATE

1

24/0

8/20

21 4

:57:

54 p

m

CHANNEL VIEW

00420-0072


MW RB

0 ISSUED FOR CONSENT 21/05/20211 RE-ISSUED FOR CONSENT 02/07/2021

SCALE 1:3000

N

STORMWATER SWALE

OUTLET

STORMWATER CATCHPIT

STORMWATER SWALE

PEAK+5.0m

OVERLAND FLOW PATH

OVERLAND FLOW PATH

MHWS

OUTLET

OUTLET

+4.8m

+4.8m

+4.85m

+5.2m

OUTLET

OVERLAND FLOW PATH

+4.9m

STORMW

ATER SWALE


PROJECT

SHEET DESCRIPTION

STATUS


CLIENT

www.shorewise.co.nz

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REV DETAILS DATE

1

24/0

8/20

21 4

:57:

57 p

m

STORMWATER FLOW PATHS

00520-0072


MW RB


1 : 500FLOW PATHS

+2400 mmMHWS

MLWS

+5500 mm

⌀406mm STEEL PILES WITH PE SLEEVES

6000

ABUTMENT

HARDFILL AS REQUIRED

300mm GAP 65

200mm CONCRETE RAMP

81

RAMP SLOPE

+4850 mm

+400 mm

40000

9500

900

4000 2000 4000

2.51

200mm CONCRETE RAMP 300mm GAP 65HARDFILL AS REQUIRED


PROJECT

SHEET DESCRIPTION

STATUS


CLIENT

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2/07

/202

1 12

:51:

27 p

m

RAMP SECTIONS

00620-0072

FOR CONSENTRANGITANE LOOP RD RECLAMATION

MW RB


1 : 125RAMP LONGITUDINAL SECTION

1 : 50RAMP TRANSVERSE SECTION

APPENDIX B – PRELIMINARY STORMWATER CALCULATIONS

HIRDS V4 Intensity‐Duration‐Frequency Results

Sitename: Rangitane Loop Road

Coordinate system: WGS84

Longitude: 174.0029

Latitude: ‐35.1969

DDF ModelParameters c d e f g h i

Values: 0.002199 0.492235 ‐0.01926 ‐0.00293 0.255498 ‐0.01186 3.240721

Example: Duration (hARI (yrs) x y Rainfall Rate (mm/hr)

24 100 3.178054 4.600149 9.922337

Rainfall intensities (mm/hr) :: Historical Data

ARI AEP 10m 20m 30m 1h 2h 6h 12h 24h 48h 72h 96h 120h

1.58 0.633 60.6 43.8 36 25.5 17.8 9.5 6.14 3.81 2.26 1.63 1.27 1.05

2 0.5 66.4 48 39.5 28 19.5 10.4 6.75 4.19 2.49 1.79 1.4 1.15

5 0.2 86.2 62.3 51.3 36.5 25.5 13.7 8.84 5.5 3.27 2.36 1.85 1.52

10 0.1 101 72.9 60.1 42.8 29.9 16.1 10.4 6.48 3.86 2.78 2.18 1.8

20 0.05 115 83.6 69 49.2 34.4 18.5 12 7.49 4.46 3.22 2.53 2.08

30 0.033 124 90 74.3 53 37.1 20 13 8.09 4.83 3.48 2.73 2.25

40 0.025 130 94.6 78.1 55.7 39 21 13.7 8.52 5.09 3.67 2.88 2.37

50 0.02 135 98.1 81 57.8 40.5 21.8 14.2 8.86 5.29 3.82 3 2.47

60 0.017 139 101 83.4 59.5 41.7 22.5 14.6 9.14 5.46 3.94 3.1 2.55

80 0.012 145 106 87.2 62.3 43.6 23.6 15.3 9.58 5.72 4.13 3.25 2.67

100 0.01 150 109 90.2 64.4 45.1 24.4 15.9 9.92 5.93 4.28 3.36 2.77

250 0.004 169 123 102 72.9 51.2 27.7 18.1 11.3 6.77 4.89 3.85 3.17

Intensity standard error (mm/hr) :: Historical Data


1.58 0.633 7.6 4.7 3.6 2.4 1.7 1.1 0.75 0.61 0.37 0.27 0.22 0.19

2 0.5 8.3 5.2 3.9 2.6 1.9 1.2 0.83 0.68 0.41 0.3 0.25 0.21

5 0.2 12 7.4 5.7 3.7 2.7 1.6 1.1 0.93 0.55 0.41 0.34 0.29

10 0.1 15 9.8 7.6 4.9 3.5 2.1 1.4 1.1 0.65 0.49 0.41 0.34

20 0.05 19 13 10 6.5 4.6 2.6 1.8 1.3 0.77 0.58 0.48 0.4

30 0.033 22 15 12 7.6 5.5 3 2.1 1.5 0.85 0.64 0.53 0.44

40 0.025 24 17 13 8.6 6.1 3.4 2.3 1.6 0.9 0.69 0.57 0.47

50 0.02 26 19 15 9.4 6.7 3.7 2.5 1.7 0.95 0.72 0.6 0.49

60 0.017 28 20 16 10 7.2 4 2.7 1.7 0.99 0.75 0.62 0.51

80 0.012 31 22 18 11 8.1 4.4 3 1.9 1.1 0.81 0.66 0.55

100 0.01 33 24 19 12 8.8 4.8 3.3 2 1.1 0.85 0.7 0.58

250 0.004 46 34 27 18 12 6.8 4.6 2.5 1.4 1 0.86 0.71

Rainfall intensities (mm/hr) :: RCP2.6 for the period 2031‐2050


1.58 0.633 64.9 46.8 38.5 27.3 19 10 6.43 3.97 2.34 1.68 1.31 1.07

2 0.5 71.2 51.4 42.3 30 20.9 11 7.09 4.37 2.58 1.85 1.45 1.19

5 0.2 92.7 67 55.2 39.3 27.3 14.5 9.32 5.76 3.4 2.44 1.91 1.57

10 0.1 108 78.5 64.7 46.1 32.1 17.1 11 6.79 4.02 2.89 2.26 1.86

20 0.05 124 90.2 74.4 53 37 19.7 12.7 7.85 4.65 3.35 2.62 2.15

30 0.033 134 97.1 80.2 57.1 39.9 21.3 13.7 8.49 5.03 3.62 2.84 2.33

40 0.025 141 102 84.3 60.1 41.9 22.4 14.5 8.95 5.31 3.82 2.99 2.46

50 0.02 146 106 87.5 62.4 43.6 23.3 15 9.3 5.52 3.97 3.11 2.56

60 0.017 150 109 90.1 64.3 44.9 24 15.5 9.6 5.7 4.1 3.21 2.64

80 0.012 157 114 94.2 67.3 47 25.2 16.2 10.1 5.98 4.3 3.37 2.77

100 0.01 162 118 97.4 69.6 48.6 26.1 16.8 10.4 6.19 4.46 3.49 2.87

250 0.004 183 133 110 78.8 55.2 29.6 19.1 11.9 7.07 5.09 3.99 3.28



1.58 0.633 64.9 46.8 38.5 27.3 19 10 6.43 3.97 2.34 1.68 1.31 1.07

2 0.5 71.2 51.4 42.3 30 20.9 11 7.09 4.37 2.58 1.85 1.45 1.19

5 0.2 92.7 67 55.2 39.3 27.3 14.5 9.32 5.76 3.4 2.44 1.91 1.57

10 0.1 108 78.5 64.7 46.1 32.1 17.1 11 6.79 4.02 2.89 2.26 1.86

20 0.05 124 90.2 74.4 53 37 19.7 12.7 7.85 4.65 3.35 2.62 2.15

30 0.033 134 97.1 80.2 57.1 39.9 21.3 13.7 8.49 5.03 3.62 2.84 2.33

40 0.025 141 102 84.3 60.1 41.9 22.4 14.5 8.95 5.31 3.82 2.99 2.46

50 0.02 146 106 87.5 62.4 43.6 23.3 15 9.3 5.52 3.97 3.11 2.56

60 0.017 150 109 90.1 64.3 44.9 24 15.5 9.6 5.7 4.1 3.21 2.64

80 0.012 157 114 94.2 67.3 47 25.2 16.2 10.1 5.98 4.3 3.37 2.77

100 0.01 162 118 97.4 69.6 48.6 26.1 16.8 10.4 6.19 4.46 3.49 2.87

250 0.004 183 133 110 78.8 55.2 29.6 19.1 11.9 7.07 5.09 3.99 3.28



1.58 0.633 66 47.6 39.2 27.8 19.3 10.2 6.5 4.01 2.36 1.69 1.32 1.08

2 0.5 72.4 52.3 43 30.5 21.2 11.2 7.17 4.41 2.6 1.86 1.46 1.19

5 0.2 94.3 68.2 56.2 40 27.8 14.7 9.45 5.82 3.43 2.47 1.93 1.58

10 0.1 110 79.9 65.9 46.9 32.7 17.3 11.1 6.87 4.06 2.92 2.28 1.87

20 0.05 127 91.8 75.8 54 37.6 20 12.9 7.94 4.7 3.38 2.64 2.17

30 0.033 136 98.9 81.7 58.2 40.6 21.6 13.9 8.59 5.09 3.66 2.86 2.35

40 0.025 143 104 85.8 61.2 42.7 22.8 14.7 9.05 5.36 3.86 3.02 2.48

50 0.02 149 108 89.1 63.6 44.4 23.7 15.2 9.41 5.58 4.01 3.14 2.58

60 0.017 153 111 91.8 65.5 45.7 24.4 15.7 9.72 5.76 4.14 3.24 2.66

80 0.012 160 116 96 68.5 47.9 25.6 16.5 10.2 6.04 4.35 3.4 2.79

100 0.01 165 120 99.2 70.9 49.5 26.5 17.1 10.6 6.26 4.5 3.53 2.9

250 0.004 187 136 112 80.3 56.2 30.1 19.4 12 7.14 5.14 4.03 3.31



1.58 0.633 69.4 50.1 41.2 29.2 20.2 10.6 6.73 4.13 2.42 1.73 1.35 1.1

2 0.5 76.2 55 45.3 32.2 22.3 11.7 7.44 4.56 2.67 1.91 1.49 1.22

5 0.2 99.5 72 59.3 42.2 29.3 15.4 9.83 6.02 3.54 2.54 1.98 1.62

10 0.1 117 84.4 69.6 49.5 34.4 18.2 11.6 7.12 4.19 3 2.34 1.92

20 0.05 134 97.1 80.1 57.1 39.7 21 13.4 8.23 4.85 3.48 2.72 2.23

30 0.033 144 105 86.3 61.5 42.8 22.7 14.5 8.9 5.25 3.77 2.94 2.41

40 0.025 151 110 90.7 64.7 45.1 23.9 15.3 9.39 5.54 3.98 3.1 2.55

50 0.02 157 114 94.3 67.2 46.8 24.8 15.9 9.76 5.76 4.14 3.23 2.65

60 0.017 162 118 97.1 69.3 48.3 25.6 16.4 10.1 5.95 4.27 3.33 2.73

80 0.012 169 123 102 72.5 50.6 26.8 17.2 10.6 6.24 4.48 3.5 2.87

100 0.01 175 127 105 75 52.3 27.8 17.8 11 6.47 4.64 3.63 2.98

250 0.004 197 144 119 84.9 59.3 31.6 20.3 12.5 7.38 5.3 4.15 3.4



1.58 0.633 65.6 47.3 38.9 27.6 19.1 10.1 6.47 3.99 2.35 1.68 1.31 1.08

2 0.5 71.9 51.9 42.8 30.3 21.1 11.1 7.14 4.4 2.59 1.86 1.45 1.19

5 0.2 93.7 67.7 55.8 39.7 27.6 14.6 9.4 5.8 3.42 2.46 1.92 1.58

10 0.1 110 79.4 65.4 46.6 32.4 17.2 11.1 6.84 4.04 2.91 2.27 1.86

20 0.05 126 91.2 75.2 53.6 37.4 19.9 12.8 7.91 4.68 3.37 2.63 2.16

30 0.033 135 98.2 81.1 57.8 40.3 21.5 13.8 8.55 5.06 3.64 2.85 2.34

40 0.025 142 103 85.2 60.8 42.4 22.6 14.6 9.01 5.34 3.84 3.01 2.47

50 0.02 148 107 88.5 63.1 44.1 23.5 15.1 9.37 5.56 4 3.13 2.57

60 0.017 152 110 91.1 65 45.4 24.3 15.6 9.67 5.73 4.13 3.23 2.65

80 0.012 159 115 95.3 68 47.5 25.4 16.4 10.1 6.01 4.33 3.39 2.78

100 0.01 164 119 98.5 70.4 49.2 26.3 17 10.5 6.23 4.49 3.51 2.89

250 0.004 185 135 111 79.7 55.8 29.9 19.3 12 7.11 5.12 4.02 3.3



1.58 0.633 72.4 52.2 43 30.5 21 11 6.94 4.25 2.47 1.76 1.37 1.12

2 0.5 79.6 57.5 47.3 33.6 23.2 12.1 7.68 4.68 2.74 1.95 1.52 1.24

5 0.2 104 75.3 62.1 44.1 30.6 16 10.2 6.2 3.63 2.6 2.02 1.65

10 0.1 122 88.4 72.9 51.9 36 18.9 12 7.34 4.3 3.08 2.4 1.96

20 0.05 140 102 84 59.8 41.5 21.9 13.9 8.49 4.99 3.57 2.78 2.28

30 0.033 151 110 90.5 64.5 44.9 23.6 15 9.19 5.4 3.86 3.01 2.47

40 0.025 159 115 95.1 67.8 47.2 24.9 15.9 9.69 5.69 4.08 3.18 2.6

50 0.02 165 120 98.9 70.5 49.1 25.9 16.5 10.1 5.93 4.24 3.31 2.71

60 0.017 170 123 102 72.6 50.5 26.7 17 10.4 6.12 4.39 3.42 2.8

80 0.012 178 129 107 76.1 53 28 17.8 10.9 6.42 4.6 3.59 2.94

100 0.01 183 133 110 78.7 54.8 29 18.5 11.3 6.65 4.77 3.72 3.05

250 0.004 207 151 125 89.1 62.1 32.9 21 12.9 7.59 5.45 4.25 3.48



1.58 0.633 66.8 48.2 39.7 28.1 19.5 10.3 6.56 4.04 2.37 1.7 1.33 1.09

2 0.5 73.3 52.9 43.6 30.9 21.5 11.3 7.23 4.45 2.62 1.88 1.46 1.2

5 0.2 95.5 69.1 56.9 40.5 28.1 14.9 9.54 5.87 3.46 2.48 1.94 1.59

10 0.1 112 81 66.8 47.5 33.1 17.5 11.2 6.93 4.09 2.94 2.29 1.88

20 0.05 128 93.1 76.8 54.7 38.1 20.3 13 8.01 4.74 3.4 2.66 2.18

30 0.033 138 100 82.8 59 41.1 21.9 14 8.66 5.12 3.68 2.88 2.36

40 0.025 145 105 87 62 43.3 23 14.8 9.13 5.4 3.89 3.04 2.49

50 0.02 151 109 90.3 64.4 45 23.9 15.4 9.5 5.62 4.04 3.16 2.6

60 0.017 155 113 93 66.4 46.3 24.7 15.9 9.8 5.8 4.17 3.26 2.68

80 0.012 162 118 97.3 69.5 48.5 25.9 16.6 10.3 6.09 4.38 3.42 2.81

100 0.01 168 122 101 71.8 50.2 26.8 17.2 10.6 6.31 4.54 3.55 2.91

250 0.004 189 138 114 81.4 56.9 30.4 19.6 12.1 7.2 5.18 4.06 3.33



1.58 0.633 79.3 57.2 47.1 33.4 22.9 11.8 7.4 4.5 2.6 1.84 1.43 1.17

2 0.5 87.3 63.1 51.9 36.8 25.4 13.1 8.23 4.97 2.88 2.05 1.59 1.3

5 0.2 115 82.9 68.3 48.6 33.5 17.4 10.9 6.61 3.84 2.74 2.12 1.73

10 0.1 135 97.5 80.4 57.2 39.6 20.5 13 7.84 4.56 3.25 2.52 2.06

20 0.05 155 112 92.7 66 45.7 23.8 15 9.07 5.29 3.77 2.93 2.39

30 0.033 167 121 100 71.3 49.4 25.7 16.2 9.82 5.73 4.09 3.18 2.59

40 0.025 175 127 105 74.9 52 27.2 17.1 10.4 6.04 4.32 3.35 2.74

50 0.02 182 132 109 77.9 54.1 28.2 17.8 10.8 6.3 4.49 3.49 2.85

60 0.017 188 136 112 80.3 55.7 29.1 18.4 11.1 6.5 4.64 3.61 2.94

80 0.012 196 143 118 84.1 58.4 30.5 19.3 11.7 6.83 4.87 3.78 3.09

100 0.01 203 147 122 87 60.4 31.6 20 12.1 7.08 5.05 3.93 3.21

250 0.004 229 167 138 98.5 68.5 36 22.8 13.8 8.08 5.77 4.49 3.67

Page No.File No. 20-0072Calculated by RB

Main drainage pipes from vegitated swale drains Date

ProjectClient

Flow off Catchment 1a (Return Period 100 years)

Using Rational Formula => Q = CIA/360

I = From NIWA HIRDS 4.0 RCP 8.5Time of concentration = (0.87L³/H)0.385 (U.S. Soil Conservation Service)

L = 0.02 kmH = 0.1 m

TC = 0.018 Hours= 1.080 Minutes

= 135 mm/hr (Q10)

C = 0.96 From Building Code for Concrete Surfaces

A = 0.15 ha (Area of catchment)

Q100 = CIA / 360 = 0.1 m³/s

Flow Through Culvert 200 ømm

Using Mannings Formula => Q = A 1/n R2/3 s1/2

n = 0.011 From New Zealand Building Code

R = A / P = 0.03 / 0.628 = 0.050

s = 1 in 50

= 0.020 m/m

Q = 0.055 m³/s

<Flow through culvert

Therefore there is adequate capacity for a Q10 storm.Flow off catchment

0.053 0.055

I

Page No.File No. 20-0072Calculated by RB

OVERLAND FLOW KERB CUTOUTS Date

ProjectClient

Flow off Catchment 1 (Return Period 100 years )

Using Rational Formula => Q = CIA/360

I = From NIWA HIRDS 4.0 RCP 8.5Time of concentration = (0.87L³/H)0.385 (U.S. Soil Conservation Service)

L = 0.02 kmH = 0.1 m

TC = 0.03 Hours= 2 Minutes

= 203 mm/hr (Q100)

C = 0.96 From Building Code for Concrete Surfaces

A = 0.22 ha (Area of catchment) Half of total catchment

Q100 + 20% = CIA / 360 = 0.12 m³/s0.1 m

Approximate Flow Through Overland Flow Outlet 1 in 1

Using Mannings Formula => Q = A 1/n R2/3 s1/2 1.8 m

n = 0.03 From N.Z.B.C. for Rock Lined Channel

A = 0.19

R = A / P = 0.2 / 2.083 = 0.091

s = 1 in 100 = 0.010 m/m

Q = 0.13 m³/s

<Flow through stream

Therefore there is adequate capacity for a Q100 storm

0.13Flow off catchment

Therefore I

0.12

Stromwater Sump and Pipe Capacities.Job No 20-0072

Calculated by Rob BrownDate

ClientLocation

Number of Type 2 Sumps required

Type 2 sump capacity from Building Code 40000 /I m²Area feeding sump 600 m²

Intensity from NIWA HIRDS for 10 year event 10 min duration 135 mm/hrNumber Required = 600 /(40,000/ 135

= 2.0Use 2 Type 2 Sumps

Flow Into SumpsUsing Q = CIA/360

C = 0.96 From Building Code for Concrete SurfacesI = 135 mm/hr From WDC. E.E.S. using a 5 year event & Tc = 10 minutes

= 162 mm/hr 20% increase for climate chanceA = 0.030 ha Maximum area to feed a sump from calcs aboveQ = 0.96 * 162 * 0.02963 / 360

= 0.013 m³/s

Sump Outlet Pipe Capacityfor Concrete Stormwatwer Pipe with diameter of 200 mmUsing Mannings Q = A 1/n R2/3 s1/2

n = 0.011 From New Zealand Building Code

R = A / P = 0.03142 / 0.628 = 0.050

s = 0.02 1 in 50

Q = 1/ 0.011 * 0.050 2/3 * 0.02 1/2

= 0.055 m³/s

Inlet Flow 0.013 < Outlet Pipe Capacity 0.055 OK

APPENDIX C – SITE PHOTOS

engineering design report rangitane maritime …

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