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WASTE DISCHARGE REQUIREMENTS FOR -4- KEARNEY-KPF CLOSURE OF SURFACE IMPOUNDMENTS SAN JOAQUIN COUNTY 19. Sediments from ground surface to a depth of approximately 180 feet below ground surface (bgs) consist of unconsolidated, discontinuous, interbedded, lenses of sand, clay, sandy clay, silty clay, sandy silt and silty sand and gravel . The sand and gravel in this zone are poorly sorted, fine to coarse grained and subrounded to angular. Sediments from approximately 180 to 220 feet bgs are coarser and include gravel , silty gravel , and sandy silt. The sand and gravel in this zone are poorly sorted. Below about 220 feet bgs there is a blue clay which can contain silt to fine gravel . 20. Depth to water is about 60 feet below ground surface for the upper water bearing zones. However, ground water levels have dropped over 25 feet in three years. The dewatering of the upper water bearing zones has been attributed to off-site pumping which has resulted from current drought conditions. 21. The ground water flow direction fluctuates easterly to westerly. Changes in ground water flow direction are attributed to off-site pumping by surrounding supply wells. This pumping causes similar diurnal variations in the ground water levels in wells installed above 180 feet bgs and in wells installed between 180 to 220 feet bgs, indicating hydraulic connection between the zones. Hydraulic conductivity has been calculated to be 0.7 to 1.7 feet per day (ft/d) in the upper water bearing zones. GROUND WATER QUALITY 22. The beneficial uses of the ground water are domestic, municipal , agricultural and industrial supply. 23. Several ground water investigations have previously been conducted at the site. Phase I of the Ground Water Assessment Plan has been implemented. 24. The quality of the ground water is generally the calcium bicarbonate type, except for monitor well B-1 which has chloride as the major anion. Seasonal changes in ground water quality have not been determined to occur. 25. VOCs have been detected in the ground water from all wells at the facility. The VOCs of concern are the purgeable halocarbons 1 ,1-dichloroethane (DCA), 1,1-dichloroethylene (DCE) , and tetrachloroethene (PCE) , 1 ,1 ,1- trichloroethane (TCA) and trichloroethylene (TCE) . All of these constituents have been detected in ground water at concentrations which exceed their respective Primary Maximum Contaminant Level (PMCL) , except for 1 ,1-DCA which does not have and established PMCL. The maximum concentration of VOCs detected in the ground water has been approximately 5000 micrograms per liter (µg/1) from wells in the area of Pond 2N. Refer to Table 1 .