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California R&ional Water Quality Cool Board s, v <br /> k NJ Central Valley Regiones <br /> Katherine Hart, Chair <br /> 1685 E Street, Fresno,California 93706 <br /> Linda S,Adams (559)445-5116 • FAX(559)445-5910 <br /> Acting Secretary for httpJlwww.waterboards ca.govlcentralvahey Edmund G. Brawn Jr. <br /> Environmental Protection Governor <br /> To: Doug Patteson �'� FROM: C. Dean Hubbard <br /> Supervising Engineer Engineering Geologist <br /> SIGNATURE: <br /> ,�p-Shelton-R. Gray <br /> DATE: 6 May 2011 , SenliprlEngineeripg;Geologist <br /> SIGNATURE: , <br /> . - -- <br /> SUBJECT: CONSIDERATION OF REQUEST FOR NO FURTHER ACTION REQUIRED <br /> DETERMINATION, MOUNTAIN HOUSE DEVELOPMENT SITE #3, WEST <br /> BYRON ROAD, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Rationale: Crude oil affected soil and groundwater has been delineated. Affected soil is <br /> confined to an area of approximately 150 by 300 feet, and defined vertically by samples <br /> containing no detectable concentrations of petroleum hydrocarbons from an approximate <br /> depth of 54 feet below ground surface (bgs). The area of affected groundwater is slightly <br /> larger, having dimensions of approximately 400 by 500 feet. The affected area of soil and <br /> groundwater is beneath the historical and active pipelines alignment, the West Byron Road <br /> right-of-way (ROW) easement, within the utility corridor and extending beneath an adjacent <br /> alfalfa field. Future site use is not anticipated to change. <br /> A human health screening evaluation (HHSE) completed in August 2008, considered an <br /> exposure by a construction worker and a residential risk scenario which is the most <br /> conservative estimate of risk associated with potential exposure to crude oil at the site. <br /> The approach is consistent with a land use scenario described in the California Department <br /> of Toxic Substances Control (DTSC) Preliminary Endangerment Assessment (PEA) <br /> Guidance Manual. <br /> Consistent with State Water Resources Control Board (SWRCB) Resolution No. 92-49, <br /> Section IIIA through C, Science Applications International Corporation (SAIC) evaluated <br /> alternative cleanup technologies and found that technologies other than natural attenuation <br /> would be ineffective, infeasible, and costly since the affected area is beneath West Byron <br /> Road, the active pipelines, and an agricultural field. <br /> Issues: in 2001, crude oil affected soil was discovered in the vicinity of historical Tidewater <br /> Associated Oil Company pipelines and the Old Valley Pipelines which cross the property. <br /> The pipelines were utilized by Chevron predecessors to transport crude oil from Kern <br /> County oil fields to refineries in the San Francisco Bay area. Soil impacts consisted <br /> primarily of total petroleum hydrocarbons as crude oil (TPHc) which may contain <br /> polynuclear aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and <br /> xylenes (BTEX). Soil and groundwater affected by crude oil have been delineated. <br /> California Environmental Protection Agency <br /> CiRecycled Paper <br />