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California Regional Water Quality Control Board <br /> Central Valley Region <br /> Karl E. Longley,ScD,PE,Chair <br /> Linda S.Adams Arnold <br /> Secretary-for Fresno Office 5ehwarzenegger <br /> Envirownenral 1685 E Street,Fresno-California 93705 Governor <br /> Prole'Ghon 0,59}445-5116•Fax(559)445-5910 <br /> http:Ihvwu-waterhoards-ca.gov!centralvaf Eey <br /> 28 July 2998 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 5111 Bollinger Canyon Road <br /> BR1Y3432 <br /> San Ramon, CA 94583 <br /> REVIEW - SOIL AND GROUNDWATER INVESTIGATION REPORT, VERNALIS OFFSITE, <br /> VERNALIS, SAN JOAQUIN AND STANISLAUS COUNTIES <br /> Regional Water Board staff has reviewed the referenced report, dated 25 June 2998 for the <br /> Old Valley Pipeline (OVP) project site, near Vernalis, CA. The report was prepared for <br /> Chevron Environmental Management Company (Chevron) by Science Applications <br /> International Corporation (SAIC). Additionally, we reviewed previous soil and groundwater <br /> investigation reports conducted for Chevron by SAIC and others from 1999 to 2907 that <br /> evaluated soil and groundwater conditions at the former Vernalis Pump Station property, <br /> including the Vernalis Offsite property. <br /> Vernalis Offsite is located east of the former Vernalis Pump Station site and development <br /> includes an orchard in a rural and light-industrial area. California Highway 33 and the Union <br /> Pacific Railroad (UPRR) are adjacent to the west side of the project. The former Tidewater <br /> Associated Oil Company (TAOC) Ohm Pump Station is adjacent to the south-southeast side <br /> of the project. <br /> Two monitoring wells and five borings were previously installed on the Vernalis Offsite property <br /> as part of the offsite groundwater evaluation downgradient. The vertical extent of affected <br /> groundwater was determined during earlier investigations. <br /> The purpose of the current investigation was to evaluate if affected soil was present at <br /> Vernalis Offsite and to delineate the lateral extent of impacted groundwater on the property, <br /> downgradient and east of the former pump station. Seven soil borings (SB-25 through 33) <br /> were advanced to collect soil and groundwater samples for analysis. Depth to groundwater <br /> was between 32 and 39 feet below ground surface (bgs). <br /> SAIC's report summarized and concluded the following: <br /> • Affected soil was not observed in cuttings from the borings completed to depths of 49 to <br /> 44 feet bgs. Analysis of the soil samples for total petroleum hydrocarbons as crude oil <br /> (TPHc), benzene, toluene, ethylbenzene, and xylenes (BTEX); and polynuclear <br /> aromatic hydrocarbons (PAHs) were non detect (ND) at respective detection limits with <br /> the exception of 4.2 milligrams per kilogram (mg/kg) TPHc for a sample collected at <br /> California Environmental Protection Agency <br /> ;:yRecycled Paper <br />