75E - PH - WATER MANAGEMENT PLAN

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2015 URBAN WATER MANAGEMENT PLAN The second step of the process consists of RO, semi - permeable polyamide polymer (plastic) membranes that water is forced through under high pressure. RO removes dissolved chemicals, viruses and pharmaceuticals in the water resulting in near - distilled - quality water that requires minerals be added back in to stabilize the water. This process was used by OCWD from 1975 to 2004 at their Water Factory 21 (W F -21) to purify treated wastewater from OCSD for injection into the seawater intrusion barrier. The third step of the process involves water being exposed to high- intensity UV light with hydrogen peroxide (H2O2) for disinfection and removal of any trace organic compounds that may have passed through the RO membranes. The trace organic compounds may include NDMA and 1 -4 Dioxane, which have been removed to the parts -per trillion level. UV disinfection with H2O2 is an effective disinfection /advanced oxidation process that keeps these compounds from reaching drinking water supplies. OCW D's GWRS has a current production capacity of 112,100 AFY with the expansion that was completed in 2015. Approximately 39,200 AFY of the highly purified water is pumped into the injection wells and 72,900 AFY is pumped to the percolation ponds in the city of Anaheim where the water is naturally filtered through sand and gravel to deep aquifers of the groundwater basin. The OC Basin provides approximately 72 percent of the potable water supply for north and central Orange County. The design and construction of the first phase (78,500 AFY) of the GWRS project was jointly funded by OCWD and OCSD; Phase 2 expansion (33,600 AFY) was funded solely by OCWD. Expansion beyond this is currently in discussion and could provide an additional 33,600 AFY of water, increasing total GWRS production to 145,700 AFY. The GWRS is the world's largest water purification system for indirect potable reuse (IPR). 6. 2 Wante ater Description and Disposal The City operates and maintains the local sewer system consisting of over 390 miles of pipeline, 7,630 manholes, and two lift stations that connect to OCSD's trunk system to convey wastewater to OCSD's treatment plants, OCSD has an extensive system of gravity flow sewers, pump stations, and pressurized sewers. Collected wastewater is sent to OCSD's plants located in the cities of Huntington Beach and Fountain Valley. OCSD's Plant No. 1 in Fountain Valley has a capacity of 320 million gallons per day (MGD) and Plant No. 2 in Huntington Beach has a capacity of 312 MGD. Both plants share a common ocean outfall, but Plant No. 1 currently provides all of its secondary treated wastewater to OCWD's GWRS for beneficial reuse. The 120 -inch diameter ocean outfall extends 4 miles off the coast of Huntington Beach. A 78 -inch diameter emergency outfall also extends 1.3 miles off the coast. Table 6 -1 summarizes the wastewater collected by the City and transported to OCSD's system in 2015. No wastewater is treated or disposed in the City's service area as OCSD treats and disposes all of the City's wastewater. arcadls.com 75E-78 6 -2