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CaliforniAegional Water Quality Cor*l Board -. <br /> Central Valley Region =_ <br /> Karl E. Longley,ScD, PE,Chair <br /> �: <br /> Linda S.Adrtms <br /> secreraryfor Fresno Branch Office Arnold <br /> Environmental 1685 E Street,Fresno,California 93706 Schwarzenegger <br /> Protection (559)445-5116•Fax(559)445-5910 Governor <br /> littp;//www.waterboards.ca,govicentralva l ley <br /> 16 April 2008 ���I1�1U <br /> APR � 2 2CiO8 <br /> M, Scott Mansholt ENVIP0NMEl\i I' HEALT <br /> Chevron Environmental Management Company PERMIT/aERdI.,ES <br /> 6001 Bollinger Canyon Road <br /> Room K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW - SOIL AND GROUNDWATER INVESTIGATION REPORT, MOUNTAIN HOUSE <br /> SITE #3, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced report, dated 19 February 2008 <br /> submitted by Science Applications International Corporation (SAIC) on behalf of Chevron. <br /> The report provides information describing results of a soil and groundwater investigation to <br /> evaluate the lateral and vertical extent of total petroleum hydrocarbons (TPH) due to crude oil <br /> leaks from the historical Tidewater Associated Oil Company (TAOC) and Old Valley Pipeline <br /> (OVP) pipelines. <br /> Currently, the site and surrounding area is agricultural land under development to residential <br /> and/or commercial properties. Byron Road, the former TAOC and OVP easements are <br /> present at.the site with an existing active Bay Area Pipeline located near the former TAOC <br /> lines; the Union Pacific Railroad (UPRR) easement right-of-way is adjacent to the north- <br /> northeast side of the property. Rural residences are present south of the site. <br /> In addition to the referenced report, we reviewed other soil and groundwater investigative <br /> reports completed between 2001 and 2006 by SAIC and other consultants. A summary of the <br /> prior investigations and site conditions are provided in SAIC's 5 October 2005 soil and <br /> groundwater investigation report. <br /> Regional Water Board staff approved SAIC's workplan 23 October 2006, amended 26 January <br /> 2007; fieldwork was conducted in September and October 2007. The purpose of the recent <br /> investigation was to advance borings and collect samples for analysis to better define the <br /> extent of affected soil and groundwater due to historical crude oil leaks. Two nearby private <br /> domestic water supply wells were also sampled. <br /> During the investigation, three upgradient (southeast) and five downgradient (north-northeast) <br /> borings were advanced for delineation purposes; soil and groundwater samples were collected <br /> and submitted for analysis of the petroleum constituents of concern. <br /> C41ifornia Environmental Protection Agency <br /> Recycled Paper <br />