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1.0 Introduction <br /> This report presents the results of the first half 2010 groundwater monitoring activities conducted at <br /> the Western Oil and Spreading,Inc. (WOS),Acampo Plant Site(site),located at 19356 N.Highway <br /> 99 in the city of Acampo,San Joaquin County,California (Figure 1). Based on the results of this and <br /> previous monitoring events,we believe that no future action is necessary at this site. Therefore,this <br /> report also includes a request for site closure. SHN Consulting Engineers&Geologists,Inc. (SHN) <br /> performed this work on behalf of WOS. <br /> L 2.0 Field Activities <br /> 2.1 Monitoring Well Sampling <br /> L SHN conducted groundwater monitoring at the site on January 19,2010. As part of the monitoring <br /> program,monitoring wells MW-1 through MW-7 were purged and then sampled (see Figure 2). <br /> Prior to purging,each monitoring well was measured for depth-to-water,and checked for the <br /> presence of Light Non-Aqueous Phase Liquid(LNAPL) (none was observed). Each well was then <br /> purged of three well casing volumes using a clean,disposable polyethylene bailer. Electrical <br /> Conductivity (EC),pH,and temperature were monitored periodically during purging activities <br /> using portable instrumentation. All wells were measured for Oxidation-Reduction Potential(ORP), <br /> Dissolved Oxygen(DO),and Dissolved Carbon Dioxide (DCO2). <br /> Following completion of well purging activities,a groundwater sample was collected from each <br /> well using a new disposable polyethylene bailer. The water samples were immediately placed in a <br /> cooler filled with ice and submitted to the laboratory for analyses under appropriate chain-of- <br /> custody. Appendix A presents field notes and groundwater-monitoring data sheets. <br /> 2.2 Laboratory Analysis <br /> Each groundwater sample was analyzed for Total Petroleum Hydrocarbons as Motor Oil (TPHMO) <br /> and as Diesel(TPHD),in general accordance with U.S. Environmental Protection Agency (EPA) <br /> Method No. 8015B. Samples with detectable concentrations of TPHMO and/or TPHD were <br /> subjected to a silica gel cleanup procedure and then re-analyzed. <br /> Groundwater analyses were performed by North Coast Laboratories,Ltd. (NCL),a state-certified <br /> analytical laboratory located in Arcata,California. <br /> 2.3 Equipment Decontamination Procedures <br /> All monitoring and sampling equipment was cleaned prior to being transported to the site. All <br /> smaller equipment was cleaned using the triple wash system. The equipment was initially washed <br /> in a water solution containing Liquinox®cleaner,followed by two distilled water rinses. <br /> L <br /> \\Eureka\projects\2007\007152-WOS\PUBS\rpt\201003241stHa1f2010GWMR&RFC.doc � <br /> 1 <br />