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BROWN AND CALDWELL <br /> CONSULTING ENGINEERS <br /> V <br /> April 25, 1989 <br /> Mr. Gordon Lee Boggs <br /> Underground Tank Program Coordinator <br /> California Regional Water Quality <br /> Control Board, Central Valley Region <br /> 3443 Routier Road <br /> _ Sacramento, California 95827-3098 _ _ - 017321.446/1 <br /> Subject: Work Plan for ARCO Station 434, 50.1 Kettleman Lane, Lodi <br /> Dear Mr. Boggs: <br /> We are responding, on behalf of ARCO Products Company (ARCO) to your March 27,. <br /> 1989, letter regarding Brown and Caldwell's work plan for ARCO Station 434 in Lodi. <br /> ARCO and Brown and Caldwell had hoped to address your comments in a meeting with <br /> the California Regional Water Quality Control Board, .Central Valley Region (Regional <br /> Board) and 'the San Joaquin Local Health District (County). Since Brown and Caldwell. <br /> was unable to arrange a meeting in a timely manner with both the Regional Board and the <br /> County, ARCO has requested us to respond in writing. ARCO believes a meeting with the <br /> Regional Board and County would still be useful. If all.parties can meet and come. to an <br /> agreement regarding the work pian, the work can proceed_ <br /> Soil Characterization s't'ork <br /> 1. The Regional Board requested an additio ai borehole west of the pump islands. <br /> The Regional Board is concerned that the hydrocarbons identified at 50 feet <br /> below ground surface in borehole .B-2 (Sample B-2-I) indicate a northwest lateral r <br /> migration of hydrocarbons in the soil in this area. <br /> In April 1987, depth to groundwater.was approximately 49 - feet below ground <br /> surface. Borehole B-2 was drilled in July 1987, at which time depth to <br /> groundwater was approximately 53 feet below ground surface. Brown and <br /> Caldwell believes the source of the hydrocarbons' identified in Sample B-2-1 was <br /> the hydrocarbons in the groundwater. Hydrocarbons would have been adsorbed <br /> onto the soil as groundwater levels dropped through this depth interval. Also, <br /> based on the hydrocarbon concentrations in the groundwater in well W-3, <br /> capillary fringe action may have been partly responsible for the hydrocarbon. soil <br /> readings. A borehole northwest of borehole B-2 is not necessary for soij- <br /> characterization purposes. <br /> 723 S STREET SACRAMENTO.CALIFORNIA 95814-7092•(916)444,0123 <br />