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r <br /> PUBLIC ItEALTH SERVICES OPOU1 y <br /> �o <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health Officer �- <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 F, p I <br /> U01 <br /> FRANK COEHLO <br /> COELHO&BACCHETTI INC. <br /> 7474 W ELEVENTH STREET SEP 16 1999 <br /> TRACY CA 95376 <br /> RE: C& B EQUIPMENT SITE CODE: 1564 <br /> 7474 W ELEVENTH STREET <br /> TRACY CA <br /> San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) has reviewed the <br /> Amended Groundwater Monitoring Report Spring Quarter 1998 prepared by Geological Technics Inc. <br /> (GT)received August 5, 1999 and provides the following comments and directives. <br /> Considering the close proximity of the on-site drinking water well to the documented mass of petroleum <br /> hydrocarbon contamination in soil and groundwater and lack of site specific hydrogeologic data PHS/EHD <br /> does not concur with your consultant's recommendations for site closure at this time. <br /> On May 15, 1998 PHS/EHD provided the responsible party and their consultant (GT) with a copy of the <br /> Central Valley Regional Water Quality Control Board (CVRWQCB) Appendix B Tri-Regional <br /> Recommendations Checklist of Required Data for Closure of Underground Storage Tank Sites. In <br /> accordance with this checklist a well/receptor survey and risk assessment are required prior to site closure. <br /> The intent of the well/receptor survey includes evaluating the condition and vulnerability of water wells <br /> and the probability of the contaminant plume encountering preferential conduits that could spread the <br /> contamination particularly in the vertical direction ultimately affecting drinking water quality on-site and <br /> regionally. The well/receptor survey is intended to assess risk to water supplies by petroleum hydrocarbon <br /> releases and further understand groundwater flow dynamics past and present. The survey is to include a <br /> detailed search of all wells in the vicinity (2000-foot radius). Typical well/receptor surveys include <br /> performing a record review at the Department of Water Resources (DWR), the local regulatory agency <br /> (PHS/EHD), local water purveyors, and a visual inspection of the area. <br /> Groundwater is present at this site at a depth less than ten feet below grade surface. An on-site private <br /> domestic well is located within 40 feet of the former tank pit. According to the City of Tracy (Armando <br /> Salaiz,telephone interview by PHS/EHD)no municipal water supply is available on Eleventh Street east of <br /> MacAurthur Road. Within a 100-foot radius from the domestic well boreholes and monitor wells have <br /> been installed. Field screening and laboratory analytical data confirm the presence of fuel hydrocarbons in <br /> the subsurface within 100 feet of this domestic well. The consultant (GT) has estimated a petroleum <br /> hydrocarbon contaminant mass of 3,146 pounds resides in the subsurface (from 4 to 45 feet below grade) <br /> within a 50-foot radius of the on-site domestic well. The domestic well total depth is estimated at 93 feet <br /> below grade surface. No borehole log or well completion report describing the vulnerability of this well <br /> has been submitted to PHS/EHD for review. PHS/EHD is concerned that with time and continued <br /> pumping this private well maybe contaminated by the documented hydrocarbon mass. <br /> 1 <br /> A Division of San Joaquin County Health Care Services <br />