Managed Aquifer Recharge for Drinking Water, Atlantis, South Africa

Transcription

1 Contents Managed Aquifer Recharge for Drinking Water, Atlantis, South Africa Gideon Tredoux, Bettina Genthe, Maronel Steyn, Nebo Jovanovic, Sumaya Israel, Richard Bugan Maronel Steyn WISA 7 June 2016

2 Contents What is MAR? Examples globally History of Atlantis Overview of MAR at Atlantis Management Tools Way forward 2

3 WHAT is MAR? Managed aquifer recharge (MAR) = Intentionally enhancement of groundwater recharge building infrastructure and/or modifying landscape Benefits of MAR include : storing water for future use, stabilising or recovering groundwater levels in over-exploited aquifers, reducing evaporative losses, managing saline intrusion or land subsidence, and enabling reuse of waste or storm water. MAR is among the most significant adaptation opportunities for developing countries seeking to reduce vulnerability to climate change and hydrological variability. 3

4 Artificial Recharge 4

5 Different methods and examples 5

6 6

7 Global examples IGRAC, Netherlands and University of Dresden, Germany global MAR inventory is made available free of charge on a web-based GIS platform that can be accessed at the following address: Started November

8 Historic overview of Atlantis Town of Atlantis 50 km north of CT Planned around 1977 by the apartheid government as an industrial centre Huge coloured development to house people by 2010 Have very high unemployment growth Hisense factory opened in 2013 and now have > people in area 8

9 R27 Highway Scale: km Waste site Residential N W E S South Africa Atlantis CAPE TOWN Atlantis Dunes Dunes Silwerstroom Industrial Wellfield WWTW Basin 12 Witzand Wellfield Alternate Outfall Basin 7 Coastal Donkergat Basins River Dunes 9

10 SCHEMATIC LAYOUT OF THE ATLANTIS WATER RESOURCE MANAGEMENT SCHEME RESIDENTIAL AREA DS 6 DONKERGAT RIVER DS DOMESTIC WASTE WATER TREATMENT PLANT (DWWTP) 1 st flush INDUSTRIAL AREA 9 10 VELD ARTIFICIAL RECHARGE BASIN 12 ARTIFICIAL RECHARGE BASIN 7 INDUSTRIAL WASTE WATER TREATMENT PLANT (IWWTP) VELD WELLFIELD(S) WATER TREATMENT & SOFTENING PLANT MELKBOS PIPELINE PUMP STATION COASTAL RECHARGE BASINS Catchment, Stormwater and Rivers Bulk Water Waste Water 10 Potable water 4 Stormwater detention basin DS Treated effluent ex DWWTP & higher quality stormwater runoff Diversion structure Treated effluent ex IWWTP, diluted softening brines ex WT&SP & poorer quality stormwater runoff Proposed re-routing Proposed re-routing Raw waste water Responsibility area

11 EU RECLAIM study 11

12 Overview of project Monitored over three years 4 times a year Physical, chemical and microbiological analyses Contaminants of emerging concern (CECs) Risk Management HACCP Risk Assessment 12

13 Atlantis scheme Domestic WWTP SA1 Maturation ponds Industrial WWTP SA13 Final effluent SA2 Stormwater system SA3 Basin 6 Reed Bed Base flow Peak flow SA8 SA6 SA4 SA5 SA7 SA9 Witzand W/field South Recharge Basin 7 Recharge Basin 12 Witzand W/field North Softening SA10 SA11 Chlorinator SA12 Plant To Town supply 13

14 Multiple barrier approach risk management 14

15 Chlorination 15

16 S1 S2 S3 S4 S5 S6 Concentration [ng/l] SMX CMZ DHC IOP IOH IBU DIC SMX Sulphamethoxazole CMZ Carbamazepine DHC Dihydrodihydroxy- Carbamazepine IOP Iopromide IOH Iohexol IBU Ibuprofen DIC Diclofenac All Sampling-Points: Traces of psychoactive Drugs < 50 ng/l (Temazepam, Codeine, Oxazepam, Diazepam) LOQ [ng/l]

17 Oestrogenic activity EEQ ng/l ng/l EEQ SA1 SA2 SA3 SA4 SA6 SA7 SA9 SA10 SA11 SA12

18 HACCP Risk Management team Bulk Water Drinking water and Reticulation External Consultant (CSIR) Pollution Control Atlantis Recharge Scheme Roads and Stormwater conveyance and catchment management Wastewater Scientific services Environmental Health Environmental Resource Management 18

19 Atlantis scheme - CCPs Domestic WWTP SA1 Maturation ponds Industrial WWTP SA13 Final effluent 2 SA2 1 Stormwater system SA3 Basin 6 Reed Bed Base flow Peak flow SA8 3 SA6 SA4 SA5 SA7 SA9 Witzand W/field South Recharge Basin 7 Recharge Basin 12 Witzand W/field North Softening SA10 SA11 Chlorinator SA12 Plant To Town supply 19 4

20 Main conclusions from EU The retention time within the aquifer is particularly important in reducing pathogenic organisms. This was originally initiated for the management of salinity. Stormwater (SA3) tended to have higher microbial counts than the treated wastewater effluent. This has implications for the management of the water scheme. Stormwater management to ensure integrity of the thin unsaturated zone confining the reduction capacity of the soil aquifer system during basin recharge will be important in the overall management of the artificial recharge system. 20

21 Way forward 21

22 Thank you