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WASTE DISCHARGE REQUIREMENTS FOR -5- KEARNEY-KPF CLOSURE OF SURFACE IMPOUNDMENTS SAN JOAQUIN COUNTY 26. Heavy metals have generally been detected in the groundwater in concentra- tions that are less than the primary or secondary drinking water standards. However, barium, lead and mercury have been detected in ground water in concentrations greater than their respective PMCL with all three consti- tuents exceeding this limit in monitor Well B-1. Iron and manganese have also been detected in concentrations which exceed their respective Secondary Maximum Contaminant Level (SMCL) in several wells at the facility. However, previous analytical results have been based on unfiltered samples. Refer to Table 1. 27. Many of the wells in the upper water bearing zone exceed the SMCL for electrical conductivity (EC) and total dissolved solids (TDS) . In addition, ground water from monitor wells in the Pond 1 area have exceeded the SMCL for chloride. Monitor wells B-4 and DMW-1 have exceeded the PMCL for nitrate. Refer to Table 1. 28. Background concentrations of VOCs, heavy metals and standard minerals for ground water have not been determined for the facility due to the fluctuating flow direction caused by pumping from surrounding supply wells. SOIL INVESTIGATION 29. Several soil investigations have been conducted in the areas of the ponds. Sludge, soil and deep boring soil samples have been collected and analyzed for VOCs, heavy metals, cyanide, standard minerals and pH. Background soil samples have been collected from across the site and have been analyzed for VOCs, heavy metals, cyanide and pH. 30. No VOCs or cyanide were detected in background soil samples. The maximum background concentration for each heavy metal constituent has been identified and the statistical background concentration has been established. 31. Heavy metals in the soil and sludge which exceed the maximum background concentration, the statistical background concentration, or both, are: barium, cadmium, copper, cyanide, iron, lead, mercury, molybdenum, silver and zinc. 32. Heavy metals in the soil and sludge samples which exceed their respective Total Threshold Limit Concentration (TTLC) are zinc in the Pond 1 area and copper and silver in the Pond 2N area. Zinc, copper and silver have been reported at concentrations as high as 14,000, 7800 and 700 milligrams per kilogram (mg/kg) , respectively. Their respective TTLC are 5000, 2500 and 500 mg/kg. Hazardous concentrations of heavy metals have not been detected in soil or sludge samples from Pond 2S.