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0 <br />Mill <br />Creek -- - - ----- --- <br />Ass«ciat,es <br />January 23, 1995 <br />1. JqA�A'e-e-- <br />9 Jr JAN 2S -"I <br />"I�'r Water Resource and Environmental Consulting <br />12 <br />Dave Jenkins <br />Central Valley Regional Water Quality Control Board <br />3443 Routier Road <br />Sacramento, CA 95827-3098 <br />RE: Workplan for Additional Site Characterization <br />Roberts Petroleum. Services/Woolsey Oil Co., Lodi, CA <br />Dear Mr. Jenkins, <br />As requested by your office I am writing to present a workplan for <br />performing additional site characterization for the above <br />referenced property. <br />We have previously informed your office that recent data obtained <br />from the site indicates that very likely all, or at least a <br />significant portion, of the contamination did result from leakage <br />from underground tanks. Attached is an analysis of a free phase <br />product sample from well MW -8. This sample analysis indicates the <br />product is a mixture of gasoline and kerosene. While gasoline has <br />been stored in the above ground tanks, kerosene at the site was <br />only stored underground. This discovery led to additional review <br />of the file data concerning the removal of the underground tanks. <br />Although the discrete tank excavation and line trench bottom soil <br />samples were below action levels at the time the tanks were <br />removed, a set of analyses for the soils removed during the tank <br />pull (attached) show BTEX and TPH gas present at significant <br />levels. Based upon these data it appears that releases have <br />occurred from the existing or former underground tanks at the site <br />and that this problem should be regulated as an underground tank <br />case. We seek your concurrence in this regard and intend to submit <br />a claim pursuant to S.B. 2004. Without regard to the source of the <br />contamination we have prepared a plan for completing site <br />characterization in anticipation of remedial action. <br />Groundwater was not encountered in wells MW -1, MW -3, MW -4, MW -5, <br />and MW -6 during monitoring activities performed during December <br />1994, and January 1995. Groundwater was encountered in monitoring <br />wells MW -2, and MW -7 through MW -9 during these events. Preliminary <br />data indicates the groundwater gradient was to the southeast, <br />consistent with previous groundwater gradients oberved at the site. <br />We propose drilling three additional soil borings (B-10 through B- <br />12) using a rotary air equipped drilling rig to a depth of <br />approximately 15 feet below first encountered groundwater <br />(estimated at 55 +/- feet) and installing three 2 -inch diameter <br />monitoring wells (MW -10 through MW -12) in the borings at the <br />fort Office Box 130 0 Milford, Ca. 96121 9 Ph. 916-253 2155 0 Fax 916-253-2294 <br />