COMPLIANCE INFO_1990-1998 - Laserfiche WebLink

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• CITY OF TRACY 3 30 August 1990 SLUDGE MANAGEMENT PLAN JULY 1990 lower aquifer has ground water containing too much dissolved solids to be used as drinking water or agricultural supply (TDS > 1400 mg/1) . The Report states that under natural conditions the seasonal high water table is between 2 to 4 feet below the surface. However, due to a regional shallow underdrain system which includes the entire 2000-acre farm, no shallow ground water was encountered in the test pits (from 8 to 10 feet below the surface) that were excavated during the winter when no irrigation was occurring. During irrigation season, ground water may rise beneath the site. The Report states that water quality in the upper aquifer varies extensively which in the San Joaquin Valley from impacts due to agricultural practices, irrigation water, incursions of Coastal Range and Delta water high in chloride, sulfate, and boron. In the Tracy area, the ground water is known to be high in concentrations of dissolved solids, chloride, sulfate, nitrate, and boron. Ground water samples were taken from three wells in the immediate vicinity of the sludge application site and three wells at the San Joaquin River Club, a housing development that lies along the San Joaquin river east of the site. Water quality data form all six wells is summarized in Table 3 of the Report. The wells were selected because they provided good geographic and hydrogeologic distribution around the study area. The sample results confirmed that the local ground water is high in dissolved solids as well as sulfates and chlorides. SOIL, WATER, AND CROP MANAGEMENT The plan states that under current K & L Farm (K & Q operation, all lands are graded for surface irrigation by ground water taken from a series of relatively deep (>800 feet) onsite wells and with surplus Western Stanislaus Irrigation District, when it is available. Since the farm relies primarily on ground water, especially during dry years, K & L collects all surface runoff and irrigation return flow from the 2000 acre farm and recycles the water back into the irrigation system. The K & L Farm includes an almond orchard on 300 acres in which no sludge will be applied. Therefore, only 1700 acres will ultimately be used for the sludge disposal . A typical crop rotation includes 5 years of alfalfa, followed by 7 years of row crops which include dry beans, sugar beets, etc. Unlike the almond orchard in which the sludge could not be mixed into the soil , the row crops allow for the sludge to be mixed into the soil . Hence, using the sludge as soil amendment/fertilizer is compatible with current farming operations. The plan states that primary tillage of row crops is performed during the fall which includes ripping to 20 inches (in alternate years) as well as disking to 8 inches and cultipacking. Seedbed preparation occurs in the spring which includes another disking as well as raising and shaping the beds. Primary tillage of alfalfa and wheat take place in the late summer and early fall . All crops are fertilized to meet expected nutrient requirements.