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i SECOR International Incorporated I MEMORANDUM ' To: File N0026-001-01 From: CKMaslanka RE: Major Mart Site- Leach Area Soil Volume Date: November 18, 1994 Laboratory analyses of soil samples collected in the leach area of the Major Mart site, showed that the senuvolatile organics 2-methylnaphthalene and naphthalene were detected at levels of ' 4 4 and 2 5 mg/kg, respectively, at a depth of 26 feet below ground surface (bgs) These materials were not detected in samples collected at a depth of 31 feet bgs Soil boring 3 (SB-3) t is affected, SB-4 is not affected During the installation of monitoring well MW-4 by WESTON, it was reported that the well was drilled through the center of the area Therefore, for our worst case calculation, we have assumed that MW-4 is the center of the radius and the farther (and ' clean) soil boring, SB-4, delmeates the exterior point of impacts Therefore, in order to prepare the mass balance determination of the soil impacts in the former pit leach area, the following dimensions have been utilized ' Volume of impacted soils (assuming the volume of a cylinder is impacted) depth - maximum 31', minimum 26' ' affected radius - maximum 15' Area 4=2=4 x 3 1416 x 15' = 188 5 ft2 Volume Area x depth= 188 5 x 31 = 5843 ft3 = 216 yd Thus is a "worst case" estimate in that it assumes that soils are impacted unless otherwise proven ' clean If we are more optimistic about the extent of the impacts, and utilize the depth of 3 P and a ' conical volume of impacted soils (more likely), the estimated volume is content of cone = area of base/3 x height 188 5/3 ft2 x 31' = 1947 8 ft3 = 72 1 yd3 1 Utilizing this conical volume, and as shown on the attached table, the residual chemical mass (naphthalene and 2-methylnaphthalene) in the former septic leach area is calculated to be 0 1615 gallons (0 62 kilograms) N0026/LEACHAPE WPI) SECOR / SACRAMENTO