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QUARTERLY GROUNDWATER MONITORING REPORT • FOURTH QUARTER, 2000 ' Herman & Helen's Marina 15135 Eight Mile Road Stockton, CA ' January 12,2001 ' 1. INTRODUCTION On December 13, 2000, Condor Earth Technologies, Inc (Condor) conducted quarterly groundwater and surface ' water monitoring at Herman & Helen's Marina located at 15135 Eight Mile Road in Stockton, California (Figures 1 and 2, Appendix A) The work described in this report was conducted in accordance with sampling procedures included in the Work Plan - Monitor Well Installation and the Work Plan Addendum, prepared by ' Condor and dated May 30, 1997, and July 9, 1998, respectively The work pian was conditionally approved by Mr Ronald Rowe of the San Joaquin County Public Health Services/Environmental Health Department (PHS/EIID) in correspondence dated July 8, 1997 The work plan addendum was approved by Mr Rowe in ' correspondence dated July 27, 1998 The fourth quarter, 2000, monitoring described in this report is the thirteenth quarterly groundwater monitoring event and the tenth surface water sampling event to be conducted at the site This report was prepared at the request of Mr Andrew Smith of Herman & Helen's Marina ' The groundwater and surface water samples collected during the fourth quarter, 2000 monitoring event were laboratory analyzed for benzene, toluene, ethyl benzene and total xylenes (BTEX), total petroleum hydrocarbons quantified as gasoline (TPH-G), and selected gasoline oxygenates/additives This report includes site F1 background intonnation, a summary of the current monitoring event (including a description of the sampling and laboratory analytical results), and a summary with conclusions ' 2. SITE BACKGROUND On October 30, 1991, Warren E Games Excavating, Inc , of Rio Vista, California, excavated and removed three ' underground storage tanks (USTs) from the site (Figure 2, Appendix A) The USTs (TK 1, TK2, and TK3) contained gasoline and diesel fuel A small hole was found on the lower fill end of TK3 (diesel tank) Petroleum " staining and odors were noted in the soil beneath the former locations of the USTs Six soil samples were ' collected by Condor from the UST excavation at depths of 9 to 12 feet below the ground surface Laboratory analyses indicated elevated concentrations of TPII-G, BTEX, and total extractable petroleum hydrocarbons quantified as diesel (TEPI1) in the soil samples ' On August 22, 1995, three hydropunch borings were drilled at the site Gasoline odors were noted to each borehole Laboratory analyses indicated the presence of TPH-G and BTEX in the soil and groundwater samples ' analyzed from each borehole Based on the results of the August 1995, investigation, Condor recommended additional investigation be conducted to evaluate the extent of the hydrocarbon plume On August 29, 1996, five Geoprobe boreholes were installed at the site The results of the laboratory analyses indicated that elevated concentrations of TPII-G, BTEX, and methyl tertiary butyl ether (MTBE) were present in soil and groundwater samples collected from the northern portion of the site and that further investigation was necessary to evaluate the extent of soil and groundwater contamination Based on the results of the Geoprobe investigation, Condor recommended that monitor wells be installed at the site to investigate and monitor the lateral extent of the gasoline and diesel contamination plume in the groundwater On September 10, 1997, Condor installed four monitor wells at the site The Report - Additional 4VOW—It" t1 coiuooa