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California lVional Water Quality Cont Board <br /> A-104% <br /> Central Valley Region a <br /> Karl E. Longley,Sc D, PE, Chair <br /> Linda S.Adams Arnold <br /> Secretaryfor Fresno Branch Office Schwarzenegger <br /> .Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection (559)445-5116•Fax(559)445-5910 <br /> hitp://www.waterboards.ca.gov/centralvalley <br /> C V ,DD`�� <br /> 26 March 2007 <br /> k!AR 2 s 207 <br /> Er+l'JIiUNNIE1 4t HEALTH; <br /> PER@A!TI`-�:Q`f!Prf- <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> Room K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF ENVIRONMENTAL RISK EVALUATION— MOUNTAIN HOUSE <br /> DEVELOPMENT SITE #9, BYRON ROAD, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced report, dated 16 January 2007 for the <br /> Chevron Old Valley Pipeline (OVP)/Tidewater Associated Oil Company (TAOC) project site, <br /> northwest of Tracy, CA. The OVP and TAOC lines transported only heated crude oil from <br /> Kern County oil fields to refineries in the Richmond area until the late 1960's. In the early <br /> 1940's, the OVP reportedly transported Bunker C fuel oil from the Richmond refineries to <br /> railroad hubs in Tracy. The lines were abandoned in the 1970's. <br /> The site is located within an approximately 300-foot long section of the former pipeline right-of- <br /> way adjacent to Byron Road near Mountain House Creek, extending generally northwest - <br /> southeast. The report was prepared for Chevron by Science Applications International <br /> Corporation (SAIC). Additionally, we reviewed a 24 January 2005 soil and groundwater <br /> investigation report completed for Chevron by SAIC. The SAIC characterization addressed <br /> site conditions as a follow-up to investigations previously conducted by Geomatrix and Condor <br /> Earth Technologies in 2001 to 2002. <br /> Soil <br /> According to the 2005 report, concentrations of TPH as crude oil (TPHc) in soil were detected <br /> in 18 of the 30 borings and generally reported at 2 to 36 feet with highest concentrations <br /> occurring between 9 and 36 feet. TPHc ranged from 5.0 mg/kg at 21-feet in boring MH1-21 , to <br /> 29,000 mg/kg at 14 feet in boring MH1-10. Several samples from 5 to 12-feet reported greater <br /> than 1,000 mg/kg TPHc in ten borings. Crude oil in soil was reported at depths ranging from <br /> 10 to 30 feet; affected soil up to 12-feet in thickness or greater was observed in nine borings. <br /> Benzene was not detected; toluene concentrations (0.05 to 0.8 mg/kg), ethylbenzene (0.006 to <br /> 1 .7 mg/kg), and total xylenes (0.03 to 13 mg/kg) were reported in three, eight and ten borings, <br /> respectively. The highest concentrations coincide with samples having elevated TPHc. <br /> California Environmental Protection Agency <br /> day Recycled Paper <br />