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California sional Water Quality Con* Board <br /> Central Valley Region <br /> Karl E. Longley,ScD,P.E., Chair <br /> Linda S.Adams Arnold <br /> Secretary for 1685 E Street,Fresno,California 93706 E <br /> UD <br /> GovernorSchwarzenegger <br /> Environmental (559)445-5116•Fax(559)445-5910Protection http://www.waterboards,ca.gov/centralvalley nE ETV <br /> FR <br /> JUN v 0 2009 <br /> 26 June 2009 ENVIROMMENT HEALTH <br /> PERMIMSER`11OES <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> Rm 3432 <br /> San Ramon, CA 94583 <br /> REVIEW — 2009 ANNUAL GROUNDWATER SAMPLING AND MONITORING REPORT, US <br /> CAN-WELTY ROAD PROPERTY, VERNALIS, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted the Annual 2009 <br /> Groundwater Monitoring and Sampling Report (Report) dated 3 April 2009, for the US Can- <br /> Welty Road site (Site) in Vernalis. The Report was prepared for Chevron by Science <br /> Applications International Corporation (SAIC) and submitted to Central Valley Regional Water <br /> Quality Control Board (Central Valley Water Board) staff for review. <br /> SAIC's Report provides a summary of analytical results for the annual 2009 groundwater <br /> sampling and monitoring conducted at the former Old Valley Pipeline Site. Sampling and <br /> monitoring has continued at the Site since 1999. The 2009 annual sampling event was <br /> conducted 11 February 2009. <br /> According to SAIC's report: <br /> • Onsite monitoring wells MW-1 and 2 contain petroleum sheen and are not sampled. <br /> Approximately 0.51 gallons of crude oil/water has been removed from these two wells <br /> since 1999. Currently, oleophilic (absorbent) socks are used to collect crude <br /> oil/petroleum hydrocarbons from these wells. Socks are inspected and replaced as <br /> needed. <br /> • Total petroleum hydrocarbon as diesel (TPHd) of 3,000 micrograms per liter (pg/L) was <br /> detected in MW-3 and the results are consistent with data since 1998. Three <br /> polynuclear aromatic hydrocarbons (PAHs) exceeding Environmental Screening Levels <br /> were detected. <br /> • Depth to water, between 35 and 37 feet below ground surface with an easterly gradient, <br /> is consistent with prior information. <br /> SAIC recommended discontinuing use of oleophilic socks and that MW 1, 2, and 3 be properly <br /> destroyed in accordance with appropriate San Joaquin County well abandonment guidelines. <br /> California Environmental Protection Agency <br /> Za Recycled Paper <br />