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Mr. Jeff Cosgray and Ken Yeo - 3 - 18 March 2010 <br /> Mountain House Site#4 • <br /> that an investigation was warranted. However, both the pipeline integrity tests and <br /> the reports of the relative percentages of product types transmitted via the BAPL and <br /> KPL covered a short time interval of the lifetime operation of the pipelines. <br /> Therefore, neither Chervron's nor KMEP's claims that their respective pipelines were <br /> not sources for the contamination found in MH4-6 cannot presently be verified. <br /> 2. The soil data presented on Tables 1 and 3 of Chevron's 2006 report'. show that <br /> petroleum hydrocarbon contamination in MH4-6 extends from one foot bgs to the <br /> water table. This indicates that the release may be attributable to a surface spill <br /> instead of the pipelines, which we believe are buried at about four feet bgs. <br /> 3. Both Chevron's and KMEP's findings that weathering typically removes shorter- <br /> length carbon chains as well as benzene and toluene compounds suggest that <br /> additional analysis may be needed to identify the petroleum hydrocarbons in soil and <br /> groundwater in the vicinity of MH4-6. As such, additional sampling and fingerprint <br /> analysis for company-specific, temporal fuel components such as tetraethyl lead, <br /> tetramethyl lead, and the lead scavengers ethylene dibromide and ethylene <br /> dichloride may be have to be applied to more accurately determine the company of <br /> origin. <br /> The above comments as well as the KMEP and Chevron Letters confirm Central Valley <br /> Water Board staff's previous conclusion that further investigation is warranted by both <br /> companies. However, because KMEP and Chevron were unable to cooperatively <br /> conduct the investigation as we previously requested, we will contact both companies to <br /> set up a meeting to scope the investigation. The purpose of the meeting will be to <br /> formulate an investigative strategy to delineate (1) the time and source(s) of the release <br /> and (2) vertical extent of the groundwater plume. Data obtained during this phase of the <br /> investigation will be applied to determine the extent of any further investigation and <br /> cleanup. <br /> If you have any questions regarding this letter, you may contact me at (916) 464-4811 <br /> or by email at betayjor@waterboards.ca.gov. <br /> BRIAN TAY ,, R, P.G. <br /> Engineering Geologist <br /> cc: Mr./Mike Infurna, San Joaquin County Environmental Health Department, <br /> Stockton <br /> Mr. Steve Osborn, Kinder Morgan Energy Partners, Rocklin <br /> Mr. Rand Reynolds, Chevron Pipeline Company, Pittsburg <br /> SAIL, 2006. Soil and Groundwater investigation report, Mountain House Development Sites 94 and#5, Mountain <br /> House California. May <br />