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Desalination of Sundays River Irrigation Return Flows .

Proposed scheme utilizing irrigation return flows for desalination to enhance water quality, supply, and estuarine health. Feasibility and pre-feasibility studies cover environmental and technical aspects for optimal implementation.

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Desalination of Sundays River Irrigation Return Flows .

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  1. Desalination of Sundays River Irrigation Return Flows. Lay-out of Proposed Scheme

  2. Positives – • Well located for integration into both NMBM Potable and Industrial supply infrastructure • Can supplement either potable or industrial demand of IDZ • Utilisation of a waste stream in a water scarce area • Unit cost of raw water will be minimal • Reduction of unwanted nutrients & fresh water transfers into estuary (falls within the Estuarine Management Plan of Sanparks & will improve health classification status of estuary) • Low pressure RO more cost effective than seawater desalination (unit cost to consumers more affordable) • Once blended at Olifantskop Reservoirs, improved quality to consumers Desalination of Sundays River Irrigation Return Flows.

  3. Negatives – • No detailed data base of water quality variabilities at point of abstraction (> 2 years Conductivities & flow at Poplar Grove (DWA data records for Addo Bridge – random sampling data available up to 2008) • Full data set of chemical and biological analysis required for pre treatment and RO design purposes (a priority action item) • Value of land close to river is high – treatment plant and off-channel storage to be positioned some distance away • Long brine discharge pipeline required (to river mouth) • If tidal discharge not environmentally acceptable, sea outfall will be expensive alternative Desalination of Sundays River Irrigation Return Flows.

  4. Desalination of Sundays River Irrigation Return Flows.

  5. Desalination of Sundays River Irrigation Return Flows.

  6. Desalination of Sundays River Irrigation Return Flows • Scheme Capacity – • .A HYDROLOGICAL STUDY OF THE SUNDAYS RIVER ESTUARY -  WRC PROJECT NO. K8/780/2 by NinhamShand (2008) based Scenario 5 of the study on 45 Mm3/a (123 Ml/day) as “ return flow” scheme to PE. • Poplar flow measurements – minimum values = 130 Ml/day • Studies showed that Scenario 5 will improve SR Health Status classification from a C to a B. • Assumption for average abstraction = 80-90 Ml/day • based on utilisation rate of 80%, final water = 64-72 Ml/day, and brine discharge stream = 16-18 Ml/day

  7. Desalination of Sundays River Irrigation Return Flows

  8. Desalination of Sundays River Irrigation Return Flows • FEASIBILITY or PRE-FEASIBILITY STUDY • Environmental • Proposed methodology to investigate the potential impacts : • Identify all possible engineering solutions that may be considered and the associated areas that may be impacted from infrastructure; • Understand the technical components proposed to identify secondary impacts (such as increased energy requirements) and predict level of significance from a strategic/cumulative perspective; • Map the vegetation types that will be affected and identify the conservation status of affected areas and the potential impact of the loss in terms of the vegetation remaining. Liaise with specialist botanists in the field to determine the significance of the loss, if required. • Get specialist opinion from a scientist with estuarine ecological experience to identify areas of concern related to release of brine within the estuary • Get specialist opinion from a scientist with coastal marine ecological experience to identify areas of concern related to release of brine in the sea; • Predict the nature and magnitude of social impact from examples of similar projects in Southern Africa and especially in the Eastern Cape. • Identify any factors that would be considered fatal flaws to development. • Provide a clear indication of legal requirements for project detailed study.

  9. FEASIBILITY or PRE-FEASIBILITY STUDY • 2. Technical • Proposed methodology for investigation & data gathering: • Finalise chemical & biological quality data required and put in place a bi- monthly sampling and analysis programme for Poplar Grove / Barkley Bridge • Optimize the scheme abstraction capacity based on flow records and environmental requirements of Estuary • Investigate alternate river abstraction points and methods /structures (1 in 100 year floodline determination) • Investigate alternate treatmentprocesses • Investigate alternate treatment works and off-channel balancing sites, alternate pipeline routes and sea discharge methods and points • Develope initial operating rules for integration with NMBM bulk infra-structure • Preliminary costing (Capital, operating, etc.) and project funding options Desalination of Sundays River Irrigation Return Flows

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