The Santa Clarita Valley Sanitation District of Los Angeles County (SCVSD) provides wastewater conveyance and treatment for residential, commercial, and industrial users in theSanta Clarita Valley. The SCVSD sewage system consists of an interconnected network of approximately 42 miles of trunk sewers, one pumping plant, and two interconnected water reclamation plants (WRPs), the Valencia WRP (VWRP) and the Saugus WRP (SWRP). The system achieves operating efficiencies by diverting solids and excess wastewater from the SWRP to the VWRP for treatment and disposal. The total permitted treatment capacity of the SCVSD is 28.1 million gallons per day (mgd), and the existing combined flow is approximately 20.8 mgd. The Regional Water Quality Control Board Los Angeles (RWQCB-LA) established a Total Maximum Daily Load (TMDL) of 100 mg/L for chloride that can be discharged to the Santa Clara River (SCR) by the SCVSD’s two wastewater treatment plants. To identify the most costeffective and environmentally sound method of meeting the chloride limit, the Santa Clarita Valley Sanitation District Chloride Compliance Facilities Plan (Facilities Plan) and Environmental Impact Report were prepared. The Facilities Plan identified the need for a new advanced wastewater treatment facility (AWTF) and the approved project includes:· An ultraviolet disinfection (UV) system at VWRP and SWRP that will eliminate the need for chlorination of the effluent discharge to the river. · An AWTF at VWRP consisting of membrane filtration (MF), nanofiltration (NF), and reverse osmosis (RO). The AWTF will produce “product” water with low chloride concentration to blend with the higher chloride plant effluent and achieve a blended concentration below the 100 mg/L limit. In the initial Facilities Plan, an AWTF using MF, RO and a “second pass of RO” would have produced approximately 0.5 mgd of brine byproduct. Due the VWRP’s location that is 40 miles from the ocean, brine disposal was a very challenging component of the project. After considering a variety of options including a pipeline to the ocean and deep well injection, the SCVSD selected enhanced brine concentration and limited trucking of concentrated brine (an average of 6 truckloads per day, 10 maximum) to an existing industrial facility.
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