uMWP: SSC 11 Sep 2012 1

The uMkhomazi Water Project Phase 1Strategy Steering Committee meeting of the 

Maintenance of the Water Reconciliation Strategy Study for the KwaZulu‐Natal Coastal Metropolitan 

Areas Study

11 September 2012

The uMkhomazi Water Project Phase 1

Purpose of presentation

• Share available information

E l i th th f• Explain the progress thus far

• Obtain and discuss relevant impacts on the project

2

Spring Grove Dam

Midmar Dam Albert Falls 

Dam Nagle Dam

Project area

Proposed Impendle Dam

Inanda Dam

1

Proposed Smithfield Dam

Baynesfield Dam

ProjectcomponentsPhase 2: 

Proposed Impendle Dam

Module 1: Raw water• Raw Water  

component• DWA contract• BKS appointed: 1 

Proposed conveyance infrastructure

Umlaas Road / Cato Ridge

Impendle Dam

Phase 1: d Baynesfield

Module 2: EIAModule 2: EIA•• Raw  and potable waterRaw  and potable water

•• DWA contractDWA contract

Dec 2011 to 30 Nov 2014

WTPCato Ridge reservoirProposed 

Smithfield Dam

Baynesfield Dam

4

Module 3: Potable water• Potable water component 

• Umgeni Water contract

• Knight Piésold appointed

uMWP: SSC 11 Sep 2012 2

Objective of the study

• Undertake a feasibility study to finalise planning of proposed uMWP at a very detailed level so that schemeproposed uMWP at a very detailed level so that scheme may be:

accurately compared with other possible alternatives  

ready for implementation (detail design & construction) on completion of study

Project Description:

• Develop Smithfield and Impendle dams with conveyanceDevelop Smithfield and Impendle dams with conveyance infrastructure transfer water to a balancing dam in the Baynesfield area. This will supply water  to a Water Treatment Plant, from where it is conveyed to a tie‐in point with the eThekwini distribution system

5

Governance of the project

The uMkhomazi River Water Project Phase 1

6

Environmental Screening

• Critical considerations for EIA:Damming one of the few “undammed” riversDamming one of the few  undammed  rivers

Biodiversity: presence of terrestrial fauna and flora• Loss of Southern KwaZula‐Natal Moist Grassland veld type

• Vulnerable species: Bald Ibis, Fire lilies, Millipedes

Biodiversity: impact on riverine and aquatic ecosystems• Potential sensitive fish species 

l l f f• Potential loss of water features 

Changes to water quality due to dam

Socio‐economic issues

7

Water resourcesWater resources(Hydrology, water requirements)

uMWP: SSC 11 Sep 2012 3

Water Resource Focus Area

Proposed Impendle Dam

Proposed Smithfield 

Dam

Baynesfield Dam

19

53%33%

I dl

Water resources(Hydrology)

14%

Impendle

Smithfield

Remainder

16%

1 078 million m1 078 million m33/a/a

6%ForestrynMAR

35%

31%

27%

6%Industrial (SAPPI)

Irrigation

Other170 million170 million

mm33/a/a*

*Include Domestic of 1%

Spring Grove DamSpring Grove Dam Additional Yield 

(Pumpstation)

Re‐use of Treated Effluent

Mkomazi River Development(Smithfield Dam)

1370

1507

1644

1781

500

550

600

650

Mgeni System water balance

Existing Total Mgeni (including Growth in Darvill Return Flows)

548

685

822

959

1096

1233

200

250

300

350

400

450

Volum

e (M

ℓ/d)

Volume (106

m³/a)

emen

tation

plem

entation

Deficit

137

274

411

50

100

150

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

2022

2023

2024

2025

2026

2027

2028

2029

2030

2031

2032

2033

2034

2035

2036

2037

2038

2039

2040

Actual historic water use (Source: KZN Reconciliation Strategy)

Water requirement scenario ‐ September 2011 (Source: KZN Reconciliation Strategy)

Total AADD required at Umlaas Road (Source: BKS,GIBB, Umgeni Water)

Total AADD required at Umlaas Road (Source: Umgeni water, KNIGHT PIESOLD)

Total SDD required at Umlaas Road (Source: BKS,GIBB, Umgeni Water)

Earliestre‐use im

ple

EarliestMkomazi imp

11

Phase 1: Smithfield, Average 4.6 m³/s; If 1.25 peak, 5.8 m³/sPhase 2: Impendle added with 1.25 peak = 14.9 m³/s

12

uMWP: SSC 11 Sep 2012 4

uMWP PROPOSED SUPPLY AREA

13

Engineering investigation

1

Proposed Smithfield Dam• 58 m high composite dam• Dam wall length 1.1km• Storage capacity = 140 million m³/a (0.19 MAR)• Historic firm yield = 119 million m³/a

(Information from Pre-feasibility Study)

Investigated Dam Positions

Site A

Site B

16

Site C

uMWP: SSC 11 Sep 2012 5

Site B, Option 3

Preferred option:Main wall : ECRF 67m highSaddle wall: ECRF 13 m highSpillway at Saddle embankment

17

Proposed Impendle Dam

• Proposed clay core rockfill dam

1

• Proposed clay core rockfill dam• Maximum size = 830 million (1.5 MAR)• 92 m high• Historic firm yield with Smithfield Dam 

= 388 million m³/a(Information from Pre-feasibility Study)

Tunnel from Smithfield Dam to Baynesfield

• Tunnel length = 32,5 km• 2 x 3,5 m diameter

19

Long section through conveyance system

Preferred:

Twin phased pressure tunnel from Smithfield position B to Baynesfield

20

To be confirmed:1. Firm yields and storage provided;2. Transfer capacity factor;3. Storage state exceedance relationship;4. Power generation at the outlet of the tunnel;5. Necessity to line tunnels – geotechnical investigation;

uMWP: SSC 11 Sep 2012 6

Proposed Balancing Dam –Latest option : New Mbangweni Dam

21

Cato Ridge reservoir

Western Aquaduct

Umlaas Road reservoir

1

Date

Feasibility studies

h i l ‘ ‘

Project programme

Technical – Raw water Dec ‘11 to Nov ‘14

Environmental Impact Assessment (EIA) Jan ‘13 to Dec ’15

Technical – Potable water Aug ‘12 to Oct ‘13

Implementation

Decision Support Phase 2015 to 2017

Design/Documentation Phase 2017 to 2019Design/Documentation Phase 2017 to 2019

Construction/Implementation Phase

Smithfield Dam and tunnel 4 years

Estimated water delivery 2023Impendle Dam                                                           (incl. decision support phase, design & construction) 9 years

23

Key current tasks• Geotechnical investigation

Tender document completed, ready to advertise

• Yield modelSetup completed, ready to run different scenarios

Obtain new Reserve figures, including reserve for estuary 

Establish dam size 

• Coordination and collaboration with Module 3: Potable Water PSP

Finalise water requirements

Determine balancing dam size and position 

• Appointment of EIA PSP24

uMWP: SSC 11 Sep 2012 7

Thank you www.dwa.gov.za/Projects/uMkhomazi

25