Laserfiche WebLink
California Regional Water Quality Control Board <br /> g',: c, <br /> Central Valley Region �„��o �` s/ <br /> WG.'!,B. <br /> Katherine Hart, Chair <br /> Edmund G. Brown Jr. <br /> Linda S. Adams 1685 E Street, Fresno,California 93706 Governor <br /> Acting Secretary for (559)445-5116-FAX(559)445-5910 <br /> Environmental Protection http://www.waterboards.ca.gov/centraIvaIley <br /> TO: Douglas K. Patteson � FROM: C. Dean Hubbard <br /> ' <br /> Supervising WRCE l Engineering Geologist <br /> P. <br /> SIGNATURE: <br /> Shelton R. Gray <br /> DATE: 6 January 2011 Senior Engineering Geologist <br /> SIGNATURE:Z-�� 6=--- <br /> SUBJECT: CONSIDERATION OF REQUEST FOR NO FURTHER ACTION REQUIRED <br /> DETERMINATION, BANTA ROAD-UPRR, TRACY-FRESNO RIGHT-OF-WAY, <br /> TRACY, SAN JOAQUIN COUNTY, CA <br /> Rationale: The extent of groundwater affected by crude oil has been delineated on the <br /> Chevron Environmental Management Company (Chevron) historical Old Valley Pipeline <br /> (OVP) and Tidewater Associated Oil Company (TAOC) crude oil pipelines Banta Road- <br /> UPRR property (Site). Findings provided in the Site investigation reports indicate the <br /> extent of total petroleum hydrocarbons as crude oil (TPHc) in soil is delineated generally <br /> beneath and within the South Banta Road easement right-of-way. Soil borings were drilled <br /> to depths of up to 32 feet below ground surface (bgs) and the vertical extent of TPHc <br /> affected soil was determined to be between depths of 11 and 19 feet bgs. <br /> Affected groundwater has been defined onsite by investigations conducted at the Site and <br /> does not appear to extend offsite. Depth to groundwater ranges from 15 to 24 feet bgs. <br /> There are no monitoring wells associated with the Site. <br /> Chevron's consultant, Science Applications International Corporation — Benham <br /> Companies, LLC (SAIC), indicated that based on their investigations, residual TPHc <br /> detected is limited in extent. SAIC conducted an evaluation of risk to human health based <br /> on conservative residential setting and ecological screening levels. Based on results, it <br /> was concluded that exposure to TPH chemicals of potential concern present do not exceed <br /> respective environmental screening levels. TPH levels reported, attributable to the former <br /> crude oil pipelines, do not pose a threat to future commercial/trench maintenance workers <br /> or to potential ecological receptors at the Site. <br /> SAIC's findings indicated that based on the laboratory analyses, the water quality values of <br /> underlying groundwater do not meet some minimum State and Federal drinking water <br /> quality or agricultural use standards. Given the project's location beneath/within the road <br /> easement, it is unlikely that the shallow groundwater would be considered a source of <br /> drinking water given the availability of alternative water supplies for the area. <br /> California Environmental Protection Agency <br /> 4aRecycled Paper <br />