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primarily east-southeast. Large regional irrigation withdrawals from aquifers <br /> below 250 feet have affected the water table elevation, encouraged a high <br /> downward gradient despite the low permeabilities of_clay and silt layers, and en- <br /> couraged the encroachment of saline water from the San- Joaquin River delta. <br /> Wells that were used historically for water supply in.the M&B area have been j <br /> abandoned because of the high TDS and chloride levels from encroaching saline <br /> water (CDWR, 1967; Bertoldi and Sun, 1986). <br /> Table 2-1 lists groundwater wells within a 1-mile radius of the site-and their <br /> current use. The well locations are depicted- in Figure 2-3. All wells within the <br /> 1-mile radius are used for nonpotable industrial-purposes. Potable water is <br /> i <br /> supplied by local water,companies to both industries and residences. <br /> Groundwater pumped for industrial use is from the deep aquifer and generally <br /> of poor quality because of high chloride concentrations, high. TDS, and high pH. <br /> Chloride content in the Gold Bond wells ranges from 50 to 660 mg/l, well <br /> beyond the average concentration of 100 mg/1 found in groundwater in the . <br /> I <br /> United States and above the objectionable taste threshold of 250 mg/l (NAS, <br /> 1980). Concentrations as low as 96 mg/l chloride have been determined to <br /> produce an objectionable taste (NAS, 1980). .TDS concentrations above <br /> 500 mg/l tend to increase corrosion, thereby reducing the service life of pumps, <br /> piping, etc. (NAS, 1980). Groundwater TDS concentrations range from, 410 to <br /> 1,800 mg/l in the area. The high chloride, TDS, and pH are the result of <br /> encroaching saline waters and are not influenced by the M&B site. <br /> Surface material at the site is very powdery, most probably because of the use <br /> of heavy machinery. Water is used for dust suppression at.the site. This is only j <br /> somewhat effective because of the climatic conditions of the area. The Stockton <br /> area receives about 14 inches of rainfall per year with only 9 percent falling <br /> from May through October. Winds are primarily out of the west. -Wind speed <br /> is relatively constant year :round with a slight .increase from December to April <br /> I <br /> GLT909/040.50 2-3 <br />