SITE INFORMATION AND CORRESPONDENCE_2001-CURRENT

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Montgomery Wards/ Unocal Station #5098 - 6 - 12 April 2012 5400/ 5606 Pacific Avenue Stockton, San Joaquin County Public Participation Public participation was conducted from 4 May 2011 to 8 June 2011 with no adverse comments. Summary and Recommendations Chevron has complied with all of the requirements in CAO R5-00-707 and Regional Board staff letters. Concentrations of petroleum hydrocarbons in groundwater decreased significantly between 1993 and 2010. The petroleum hydrocarbons plume will reach WQGs in 2038. Residual soil, soil vapor, and groundwater contamination poses minimal risk to sensitive receptors, human health, or other beneficial uses of groundwater in the area. Based on the depth of residual contamination in soil making further remediation neither practical nor cost effective, lack of threats from vapor intrusion, declining groundwater concentrations, compliance with the tasks of Regional Board directives, and a well defined vertical and lateral extent of pollution, no further action is warranted for the Site. Staff recommends closure of this Site. The required public participation comment period was conducted with no adverse comments. The remaining monitoring wells (MW-1 through MW-7, MW-8D, MW-9R, MW-10, MW-10A, MW-11 through MW-14, MW-14A, MW-15R, MW-16 through MWA8, MWA8D, MW- 19S, MW-19D, MW-21S, MW-21D, MW-22S, MW-22D, MW-23S, MW-23D, MW-24S, MW-24D, MW-25S, MW-25D, and MW-27 through MW-30), remediation wells (VEW- 9A/B through VEW-13A/B , VEW-16, VEW-19, VEW-22, and SP-1A/B, SP-2 through SP-6, SP-7A/B, SP-8, AS-14 through AS-21, and AS-26) and soil vapor wells (SV-1 through SV-3) were properly abandoned on 1 February 2012. The RP and the San Joaquin County Environmental Health Department concur with case closure. Attachments: Figure 1: Site Location Figure 2: Site Plan with monitoring well locations Figure 3: Site Plan As-Built ((Wards SVE/AS) Figure 4: Site Plan As-Built (both sites)