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Stockton Meat Plant - Case Closure Page 11 <br /> March, 1996 <br /> because of poor water quality in the area The influence of the Delta with <br /> high total dissolved solids and methane gas from organic degradation have <br /> impaired the water quality in the area Thus, Cal Water has elected to <br /> discontinue use of these water wells <br /> Based on the existing data and considering the poor water quality within the <br /> general area, it does not appear that the ground water quality at the site and its <br /> beneficial uses have been impacted by the low concentrations of petroleum <br /> hydrocarbons detected in ground water on-site <br /> REMEDIATION ACTIVITIES AND EFFECTIVENESS <br /> Soil remediation consisted of removal of petroleum affected soil, to the extent <br />' possible, on the Safeway property Soils removed were stockpiled, <br /> bioremediated on-site, and disposed on-site (Attachment C). Deeper <br /> excavations just beyond the concrete tie-down slab were reported with non- <br /> detectable to trace concentrations (TP-26 @ 23 feet 4 ppm TPH) Final <br /> confirmation soil samples as the excavation proceeded in a southerly and <br /> westerly direction towards Navy Dr were reported with trace (TP-18 ® 21 feet <br /> 210 ppm TPH) to low concentrations (TP-22 0 22 feet 1,100 ppm) of <br /> hydrocarbons remaining in site specific areas at depths deeper than 20 feet <br /> Substantially all hydrocarbon affected soils from the reported release at the <br /> tank site appear to have been removed by the project, to the extent allowed <br /> without interfering with the integrity of Navy Drive <br /> Groundwater has been remediated at the site by pumping during tank <br /> removal activities Further ground water remediation is not required because <br /> of the low concentrations of hydrocarbons as diesel and the absence of volatile <br />' hydrocarbons in ground water The residual hydrocarbons in ground water <br /> do not appear to have impacted the beneficial uses of the ground water in the <br /> vicinity of the site <br />' The remediation work of tank removal and hydrocarbon soil excavation was <br /> effective in eliminating a diesel source. However, the residual hydrocarbons <br />' in the deeper soil strata (below 20 feet) cannot be effectively remove because <br /> of the constraints of Navy Dr Additionally, the trace to low diesel <br />' concentrations reported at the site do not appear to be impacting water <br /> quality The off-site well, MW-6, appears to be monitoring other diesel <br /> release sources This well is primarily cross-gradient from the tank site The <br />' diesel reported in MW-6 appears to be influenced by not only rising ground <br /> water elevations (comparison of Figures 3 and 4, between November 1994 and <br /> March 1995, but also by the wastewater mains located in Navy Dr In the <br />' majority of sampling events, coliform bacteria have been detected and <br /> reported above drinking water standards The source of coliform bacteria is <br /> wastewater Could seepage and leaks from the wastewater mains in Navy Dr <br />