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Chapin Brothers, Inc. - 4 - 5 January 2011, <br /> 1766 Monte Diablo Ave., S.-,;kton <br /> San Joaquin County <br /> Public Participation <br /> Public participation was conducted from 16 September 2010 to 18 October 2010 with no <br /> comments received by this agency. <br /> Summary and Recommendations <br /> The Chapin Brothers has complied with all of the requirements in Regional Board staff letters. <br /> Concentrations of petroleum hydrocarbons in groundwater decreased significantly between <br /> 1990 and 2010. The stable petroleum hydrocarbons plume is estimated reached water quality <br /> goals (WQGs) within 25 years. Additional soil or groundwater remediation are not cost <br /> effective or necessary, as residual soil and groundwater contamination poses minimal risk to <br /> sensitive receptors, human health, or other beneficial uses of groundwater in the area. Site <br /> use (commercial as an auto repair shop) is not expected to change in the foreseeable future. <br /> Based on the minimal residual contamination in groundwater, lack of threats from vapor <br /> intrusion or residual soil contamination, a stable plume with declining groundwater <br /> concentrations, compliance with the tasks of Regional Board directives, no plans to use <br /> groundwater in the next 100 years, and a well defined vertical and lateral extent of pollution, <br /> no further action is warranted for the Site. Staff recommends closure of this Site. The required <br /> public participation comment period was conducted with no adverse comments. The <br /> monitoring and remediation wells were properly abandoned on 10 December 2010. The RP <br /> and San Joaquin County Environmental Health Department concur with closure. <br /> Attachments: Figure 1: Site Location <br /> Figure 2: Site Plan with borings, grab groundwater sample locations, and wells <br />