Background Information
The existing Scheepersvlakte Balancing Dam, near to the town of Kirkwood in the Eastern Cape, is a balancing facility for water supply to the Lower Sundays River Water User Association (LSRWUA) and the Nelson Mandela Bay Municipality (NMBM), and for emergency supply. The capacity of the balancing dam is however not sufficient to meet the dual purpose of supplying the Nooitgedagt Water Treatment Works (WTW), as well as reducing the time of delivery to downstream irrigators. The lack of sufficient balancing capacity also negatively affects the maintenance of the canals.
The main purpose of the proposed new Coerney balancing dam is to eliminate the operational and balancing storage limitations imposed by Scheepersvlakte Dam.
After the investigation of several potential dam sites, the Coerney site was found to be the most favourable site for the proposed new balancing dam for emergency water supply to NMBM.
Locality Map
MAP
Technical Feasibility Study
The Technical Feasibility Study for the proposed Coerney Dam was undertaken as part of the Support of the Water Reconciliation Strategy for the Algoa Water Supply System study and was completed in June 2020.
The proposed Coerney Dam Project comprises a balancing dam and associated infrastructure to reduce the risk of failure of water supply to NMBM. The proposed dam will store water transferred from the Orange River to the lower Sundays River, which is diverted from Korhaansdrift Weir into the Kirkwood primary canal. The canal discharges freely into the existing Scheepersvlakte Dam, from where water is distributed further to irrigators and to NMBM.
The location of the proposed Coerney Dam is upstream of the Coerney Siphon outlet in a valley east of and adjacent to the existing Scheepersvlakte Dam. The proposed dam is an earthfill embankment dam with a side channel spillway. The dam is sited at a position with an elevation such that it can be filled under gravity via a new supply pipeline from the Kirkwood primary canal. It will also be able to supply the Nooitgedagt WTW under gravity via a new connecting pipeline to the existing Nooitgedagt WTW pipeline.
It is proposed that the WTW will be supplied from a combination of the proposed new intake at the Kirkwood canal and from the Coerney Dam. Flow to the WTW will still be controlled from the downstream end of the pipeline at the WTW.
A schematic layout of the proposed Coerney Dam and connecting pipelines is given below.
Reports
The following reports have been produced:
| Report Index | Report Number | Report Title |
| 1 | | Environmental Constraints Analysis |
| 2 | P WMA 15/N40/00/2517/1 | Topographical Survey |
| 3 | P WMA 07/N40/00/2619/2 | Lower Coerney Dam Geotechnical Survey |
| 4 | P WMA 07/N40/00/2619/3 | Lower Coerney Dam Supplementary Geotechnical Survey |
| 5 | P WMA 15/N40/00/2517/3 | Options Analysis Report |
| 6 | | RExisting Infrastructure and current agricultural developmentFeasibility-level Engineering Design - Balancing Dam |
| 7 | P WMA 09/E10/00/0417/6 | Feasibility-level Engineering Design - Conveyance Infrastructure |
| 8 | | Feasibility-level Cost and Implementation Analysis |
| 9 | | Implementation Support |
| 10 | P WMA 15/N40/00/2517/4 | Coerney Dam Feasibility Study Report |
| 11 | P WMA 15/N40/00/2517/5 | Stakeholder Participation: Feasibility Study |
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