ARCHIVED REPORTS_SOIL AND GROUNDWATER INVESTIGATION WORK PLAN

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�.d California Regional Water Quall�ty Control hoar Central Valley Region vw-; � Robert Schneider,Chair Arnold Linda S. Adams SehwarLenegger seev ewrujnr Fresno Branch Office Governer Environmental 1655 L Streci,Fresno Cmifornis 9371Hi — —.- Protecfron (559)445-5116•Fax(559)445-5910 �<: ' http:I/}v��ti�,ivtiterboarc�s.iti-go�kerrtr�lvhltr} 20 September 200£ SEP 2006 M. Scott Mansholt Chevron Environmental Management Company 6001 Bollinger Canyon Road, Room K2066 San Ramon, CA 94583-2324 ' REVIEW- SOIL AND GROUNDWATER INVESTIGATION REPORT — VERNALIS PUMP STATION, 35500 WELTY ROAM, VERNALIS, SAN JOAQUIN AND STAN1SLAt1S COUNTIES Regional Water Board staff have reviewed the referenced report, dated 29 August 2006 for ' the Chevron Old Valley Pipeline (OVP) project site, near Vernalis, CA. The report was prepared for Chevron by Science Applications international Corporation (SAIL). The site consists of two separate properties: Bellini (formerly Roberts) and Arcos. Bellini, the northern ' contains triangular portion, is undeveloped and generally vacant. Arcos, adjacent #o the south, a residence and office used as a storage facility for miscellaneous materials and equipment. The Vernalis sites are located in a rural and light-industrial area, generally surrounded by ' residences and agricultural land. ' The purpose of the investigation was to characterize the extent of impacted groundwater downgradient of the site, east of Highway 33 and upgradient (onsite) west of existing monitoring wells and historical borings. Monitoring wells were installed downgradient of the ' site and additional groundwater monitoring and sampling conducted. Additionally, a search of public records was conducted to obtain information on water supply wells within a 2,000-foot radius of the Vernalis sites. Shallow soil samples, collected at one and five feet for health risk assessment data and samples near the maximum depth at each boring (33 to 68 feet), were obtained and submitted ' for analysis. Two one-foot samples reported total petroleum hydrocarbons (TPH) as crude oil (TPHc) at 330 and 380 mg/kg; based on the analysis for the one-foot samples (,330 and 380 mg/kg) and five-foot soil samples (ND) results, the report su aother g unknownshallow rsources ults may be attributed to surface spills by former site operations unrelated to the pipeline that was buried several feet below ground. ' Low concentrations (0.001 to 0.0008 mg/kg) of polynuclear aromatic hydrocarbons (PAHs), at or slightly over their respective method detection limits, were present in the one-foot samples. The PAH concentrations were less than the U. S. EPA Preliminary Remediation Goals (PBGs) for those compounds. The other one-foot samples, the five-foot samples, and the remaining deeper samples were non detect (ND) for TPH compounds. California nvironmet 411 Protection A en.cy rr. _.