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California Regional Water Quality Control Board <br /> g <br /> Central Valley Region Arnold <br /> Linda Adams Robert Schneider,Chair Schwarzenegger <br /> Secretary Governor <br /> Fresno Branch Office <br /> 1685 E Street,Fresno,California 93706 <br /> (559)445-5116•Fax(559)445-5910 <br /> http://www.waterboards.ca.gov/centralvalley &'A <br /> ENVIF�pNM � X006 <br /> 23 May 2006 PER-4 IT/,g�VCESI� <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 OFF-SITE INVESTIGATION REPORT, 990 BEECHNUT PROPERTY, TRACY, <br /> SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced document, dated 10 March 2006 for <br /> the Chevron Old Valley Pipeline (OVP) project site, prepared for Chevron Environmental <br /> Management Company (Chevron) by Geomatrix Consultants, Inc. (Geomatrix). The property <br /> occupies the western portion of the former TAOC Tracy Pump Station on Beechnut Avenue, <br /> west of Tracy Boulevard. <br /> The purpose of the investigation, in conjunction with previous investigations, was to complete <br /> borings and obtain groundwater samples to delineate the lateral extent of total petroleum <br /> hydrocarbon (TPH)-impacts downgradient (north-northwest) of the site. Regional Board staff <br /> approved the additional investigation on 3 June 2004 and as amended in June 2005. Access <br /> agreements with various propert owners caused numerous delays and ultimately the recent <br /> borings were placed within the 9 Street right-of-way (ROW). The report describes the <br /> installation of two temporary borings in August 2005 and collection of groundwater samples for <br /> laboratory analysis. <br /> Based on monitoring well data at Alden P�r� and the 15 feetformer TAOC and flows o theyacy Pump north-northwest. <br /> n ste, <br /> depth to groundwater generally occur <br /> During the investigation, two soil borings were advanced and grab groundwater samples <br /> obtained for analysis of total petroleum hydrocarbon as diesel (TPHd), polynuclear aromatic <br /> hydrocarbons (PAHs), total petroleum hydrocarbon as gasoline (TPHg), and benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) co990SB 01 omBoring <br /> letedOtoB 20 feet) wa(completed <br /> othe6140feet) <br /> feet was <br /> advanced 400 feet downgradient and (completed <br /> further downgradient. <br /> TPHg, BTEX, and PAHs were not detected above the laboratory reporting limit in the sample <br /> from 990SB-1; TPHd at a concentration of 180 pg/I was detected in this sample. According to <br /> California Environmental Protection Agency <br /> �a�Recycled Paper <br />