Laserfiche WebLink
California Regional Water Quality Control Board -� <br /> Central Valley Region ' <br /> 4 M� <br /> Katherine Hart, Chairw <br /> Linda S.Adams 1685 E Street, Fresno,California 93706 Arnold <br /> Secretary for (559)445-5116• Fax(559)445-5910 SchwarzenEgger <br /> Environmental <br /> Protection http://www.waterboards.ca.gov/centralvalley Governor <br /> To: Shelton R. Gray FROM: C. Dean Hubbard <br /> Senior Engineering Geologist Engineerin eologist <br /> DATE: 6 August 2010 SIGNATURE: <br /> SUBJECT: SOIL AND GROUNDWATER INVESTIGATION REPORT, MOUNTAIN HOUSE <br /> DEVELOPMENT SITE#6, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted the 25 February 2010 <br /> report entitled Soil and Groundwater Investigation Report (Report), Mountain House <br /> Development Site #6 (Site), Mountain House, San Joaquin County. The Report was prepared <br /> on behalf of Chevron by Science Applications International Corporation — Benham Companies, <br /> LLC (SAIC). I have reviewed the Report and related 2001 to 2010 project file reports and my <br /> comments are provided below. <br /> The Site, northwest of the intersection of West Byron Road and Wicklund Road, northwest of <br /> Tracy, is within an area predominated by agricultural fields and rural residences. The Site lies <br /> within the West Byron Road and Union Pacific Railroad (UPRR) right-of-way easements. The <br /> historical Old Valley Pipeline (OVP) is parallel to and west of West Byron Road and the former <br /> Tidewater Associated Oil Company (TAOC) pipeline easements, between the road and the <br /> railroad tracks. In addition, two refined petroleum products pipelines are reported to be within <br /> the utility corridor easements, but the alignment/locations are unknown. Several soil and <br /> groundwater investigations have been completed at the Site by SAIC and other Chevron <br /> consultants since 2001; copies of historical documents are contained in our files. <br /> Previously, based on findings provided in a July 2008 soil and groundwater investigation <br /> report, SAIC determined that crude oil affected soil and groundwater was not defined and <br /> additional characterization was needed. SAIC recommended additional borings to investigate <br /> the lateral and vertical extent of impacted soil and groundwater onsite and offsite to the east- <br /> northeast. A workplan was approved by Central Valley Regional Water Quality Control Board <br /> (Central Valley Water Board) staff in November 2009. SAIC proceeded to drill soil borings and <br /> obtain soil and groundwater samples for analysis. Previous fuel fingerprint evaluation <br /> determined that the crude oil present was consistent with degraded San Joaquin Valley crude <br /> oil from the historical Chevron pipelines. <br /> According to the findings, affected soil and groundwater were identified at two separate areas, <br /> designated as Areas 1 and 2. Area 2 was previously described as two separate impacted <br /> areas but based on the recent reports, were combined collectively into, and henceforth will be <br /> referred to as, Area 2. SAIC's February 2010 Report describes the approximate dimensions of <br /> crude oil affected soil within Area 1 as about 150 feet across. Area 2 consists of one <br /> elongated area of crude oil affected soil, parallel to and within the historical OVPITAOC <br /> pipelines' alignment, with an approximate dimension of 75 feet to 200 feet across and about <br /> California Environmental Protection Agency <br /> Recycled Paper <br />