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Emerging Contaminants & the Groundwater Replenishment System

This article discusses the Orange County Water District's Groundwater Replenishment System and its role in managing and protecting the Orange County groundwater basin. It explores the various components of the system and the need to address emerging contaminants in groundwater. The article also emphasizes the importance of understanding the risks associated with trace organics and the need for better treatment options. 8 Relevant

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Emerging Contaminants & the Groundwater Replenishment System

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  1. Emerging Contaminants & the Groundwater Replenishment System Shivaji Deshmukh April 18, 2007

  2. Orange County Water District • OCWD, formed in 1933, is responsible for managing and protecting the Orange County groundwater basin • OCWD encompasses 229,000 acres (925 km2) in the lower watershed of the Santa Ana River (SAR) • Orange County groundwater basin provides water for over 2.3 million people

  3. OCWD Functions: • Protect Water Quality • Manage Pumping • Replenish Basin Groundwater Basin Cross Section Drinking Water Wells Huntington Beach Recharge Area 0’ 1,000’ Santiago Pits 2,000’ NON-WATERBEARING FORMATION 3,000’ 0 miles 5 10 15 20

  4. Groundwater(OCWD) provides 69% of the water used in North and Central Orange County Imported Water (Metropolitan Water District) is water from the Colorado River and Northern California Sources of Water for Orange County

  5. OCWD Water Supply Reclamation 4% Santa Ana River 54% Imported Water 40% Local Runoff 2%

  6. Phase I GWR System Prado Dam Santa Ana River Facilities Operational Recharge Facilities

  7. Kraemer Basin Future Mid-BasinInjection/Recharge GWR Pipeline SeawaterIntrusion Barrier Pumping Facilities AdvancedWater PurificationFacility GWR System Components Santa Ana River Fullerton Santiago Creek Groundwater Basin HuntingtonBeach Pacific Ocean OCWD Irvine OCSDTreatmentFacilities N OceanOutfall

  8. OCSD - Wastewater Collection, Treatment and Disposal OCWD - Manage and Protect the Orange County Groundwater Basin First Partnership in 1972 for Wastewater Reclamation Agency Responsibilities Source Control OCSD OCWD Primary Treatment Secondary Treatment Advanced Water Purification Reuse Sewage

  9. GWR System Advanced Water Purification Microfiltration (MF) Reverse Osmosis (RO) Ultraviolet Light with H2O2 OCSD Secondary Effluent Barrier Recharge Basins Backwash OCSD Plant 1 Brine OCSD Outfall

  10. Microfiltration System • 86 Mgd US Filter CMF-S Microfiltration System • Removes bacteria, protozoa, and suspended solids • 0.2 micron pore size • In basin submersible system

  11. Reverse Osmosis System • 70 Mgd Reverse Osmosis System • Hydranautics ESPA-2 Membranes • Recovery Rate: 85% • Removes salts, viruses, organics and pharmaceuticals • Pressure range: 150 psi – 200 psi

  12. Ultraviolet/Advanced Oxidation System • 70 Mgd Trojan UVPhox System • Low Pressure – High Output lamp system • Removes trace organics • Uses Hydrogen Peroxide to form an Advanced Oxidation Process

  13. Why Are We Concerned About Trace Organics? • Some trace organics may contribute to health risks • THMs and HAAs - associated with bladder cancer and other risks • NDMA and other nitrosamines - powerful carcinogens • Endocrine disruption observed in fish and other aquatic animals • Traces of pharmaceuticals - any risk? • Effects of mixtures?

  14. What Have We Found In U.S. Waters? • THMs in most drinking water systems • VOCs - chlorinated solvents, MTBE in many groundwaters • Pesticides, herbicides in ag/urban runoff • Pharmaceuticals traces in wastewater discharges • USGS survey of water sources, NAWQA program • PPCPs, EPOCs, POPs, etc.

  15. SARWQH Study by OCWD • 1994-2004 Study of Santa Ana River recharge • Organics research by LLNL, USGS, Stanford, Berkeley, MWD • Examined DBPs, Total Organic Carbon, WW marker compounds • Scientific Advisory Panel by NWRI • Found no evidence of water quality or health threat from existing SAR recharge

  16. Water Factory 21 • Organics testing since 1970s by Stanford and OCWD – GAC and RO • No problems detected until NDMA in 2000 and 1,4-dioxane in 2001 • Treatment changed to control NDMA, dioxane • GAC eliminated • Flow limitedto 5 MGD RO • UV/AOP added

  17. ppm to ppt and beyond with ever more powerful tools Pesticides and VOCs Pharmaceuticals, personal care products European and US universities, USGS Lowest level detected becomes the new benchmark for testing Analytical Arms Race

  18. Where Is The Science Leading Us? • More testing for more chemicals at lower levels • Continuing analytical arms race • More PPCPs and PHACs • Nanoparticles and other persistent organics • Detection at ppq (pg/L) levels • Increasing public concern • Regulatory and legislative confusion

  19. What is Really Needed Now? • Understanding of risk needs to catch up with analytical capabilities • AWWARF project 3085 on Toxicological Relevance • Examination of what should we be testing and at what levels, based on risk • Better surrogates than TOC for assessing removal of trace organics • Better understanding of relative efficacy of treatment options – e.g. MBR, SAT, NF/RO, AOP

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