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<br />. <br /> <br />W <br /><:)1 <br />CO <br />0) <br /> <br />USBR/MWD SALINITY MANAGEMENT STUDY <br />FINAL REPORT <br /> <br />Regional brine lines are expensive and usually reqUire multiple agency cooperation and <br /> <br />financing. <br /> <br />Other sources of salts flowing into wastewater collection systems contribute to salinity in <br />wastewater treatment plant discharges. Leaky sewers can be infiltrated by brackish' <br />groundwater. Certain types of residential water softeners are controversial sources of salts in <br />wastewater. Industrial and commercial discharge to sewer systems are typically not regulated <br />for TDS by pretreatment programs. Water conservation efforts in recent years have prompted <br />many industries to increase internal recycling, which results in higher TDS concentrations in. <br />their waste streams. Long-term indoor water conservation measures reduce water use and <br />increase salinity concentrations of residential wastewater by 2 to 5 percent. Figure 2-6 depicts <br />the sources of salinity in the inflow stream of a coastal recycling water facility in <br />Metropolitan's service area. <br /> <br />Figure 2-6 <br /> <br />Sources of TDS at a Water Recycling Plant <br /> <br /> 1500 <br /> 1390 <br />. I <br /> I <br /> , <br /> I , , <br /> 1050 I , <br /> '~";~:".' I , <br /> 1000 ,. . <br />:::r , <br />;;, , <br />.5- <br />rJl <br />Q <br />I- <br /> SOD <br /> <br />. <br /> <br /> <br />o <br /> <br />Groundwater Infiltration <br />Industrial~Commercial Brines <br />Residential Water Softeners <br /> <br />1986 1992 1995 1997 <br />Low TOS DroughtIWater Mid Year Anticipated <br />Water Supply Conservation Condition Levels <br /> <br />Demineralization is needed to meet recycled water quality requirements (TD5 <1,000 mg/l) for intended uses. <br />Various sources contribute TDS to sewage coUection system. Example is San Diego North City Water <br />Recycling Plant. <br /> <br />Beginning in the mid-1980s, with the expansion of water recycling programs, concerns about <br />wastewater IDS have grown significantly. In general, TDS over 1,000 mg/L is a quality <br />problem for irrigation and industrial reuse customers. In addition to TDS, specific mineral <br /> <br />BOOKMAN-EDMONSTON Section 2 <br />ENGINEERING, INC. 2-7 Salinity Problems, Impacts, & Technology <br />O:\LOCALRES\ANDYS\SALlNITY\JUNE98-2\6SECTI.DOC Last printed 07120/98 10: 17 AM <br /> <br />'\1 <br /> <br /> <br /> <br /> <br /> <br />~ ..."':'""' <br />