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<br />. <br /> <br />w <br />c.n <br />OJ <br />c:> <br /> <br />. <br /> <br />. <br /> <br />USBR/MWD SALINITY MANAGEMENT STUDY <br />FINAL REPORT <br /> <br />SECTION 2 <br />SALINITY PROBLEMS, <br />IMPACTS AND TECHNOLOGY <br /> <br />Salinity, or total dissolved solids (TDS), commonly expressed in milligrams per liter (mgIL), <br />are mineral salts dissolved in water. Typical constituents include calcium, magnesium, sodium, <br />sulfate, and chloride. Figure 2-1 is a breakdown ofTDS components found in Metropolitan' <br />water. At salinity levels of about 1,000 mgIL, potable and recycled water use is significantly <br />impaired, and alternate lower salinity supplies are typically sought. Technical Appendix 3 <br />provides detailed information on the regulations and physical impacts of salinity constituents. ~' <br /> <br />Hardness is a component of TDS and is a measure of certain dissolved salts (primarily calcium <br />and magnesium, see Table 2-1), which leave deposits in plumbing systems and appliances. <br />Hardness also inhibits the solubility of soap, which is noticeable when bathing or launderin <br />clothes. Water softening reduces hardness, but adds salt to the water and wastewater in the <br />process. <br /> <br />Table 2-1 Hardness Quality Characteristics <br />Hardness Range mglL (asCaCO ,) Description <br /> 0-75 Soft <br /> 75 - 150 Moderately Hard <br /> 150 - 300 Hard <br /> Over 300 Very Hard <br /> <br />There are numerous factors that contribute to high salinity in Metropolitan's service area. <br />Some factors are a result of the sources of imported Metropolitan water while others add salt <br />to water supplies as the water travels from the foothill areas to the ocean. Imported water <br />from the Colorado River perennially contains high salinity levels, primarily due to naturally <br />occurring minerals and agricultural runoff. In the arid southwestern states, there is little, if <br />any, surplus water to flush salts from the environment. <br /> <br />Salinity increases with each cycle of urban use for residential, commercial, or industrial <br />purposes. Such urban uses typically add 250 to 400 mgIL of salt to wastewater. Salt <br />increments higher than the typical 250 to 400 mgIL level indicate higher than normal salinity <br />contributions from industrial and commercial brines, residential water softeners, or brackish <br />groundwater infiltration into sewers. <br /> <br />BOOKMAN-EDMONSTON <br />ENGINEERING, INC. 2-1 <br />O:\LOCALRES\ANDYS\SALINITY\TUNE98-2\6SECT2.DOC Last printed 07120/98 10:17 AM <br /> <br /> <br /> <br /> <br /> <br />,. <br /> <br />" <br /> <br />,1;;""", <br />