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Mohr-Fry Ranches <br /> 950 Industrial Drive, Stockton, California August 6, -1996 <br /> Site Closure Report page: 2 <br /> I were developed into monitoring wells A third boring, developed into a monitoring well <br /> g p g <br /> was located towards the south of the two former tank excavations The additional borings <br /> Iwere located around the former tank excavations to help in the lateral definition of the soil <br /> contamination <br /> On February 16, 1995, WHF, Inc completed a "Technical Data Review Report- Waste <br /> Acetone Tank Site" report regarding the removal of two (2) 8,000 gallon acetone tanks <br />' The excavation samples detected contamination at approximately 15 feet b g A work <br /> plan was submitted to San Joaquin County PHS/EHD, and was to be completed by April <br /> 15, 1995, to identify the lateral and vertical extent of contamination All proposed work <br />' regarding the acetone tanks was conducted by others <br /> On March 29, 1995, WHF, in conjunction with SEMCO, a Iicensed hazardous substances <br />' removal and remediation contractor, began the first of three (3) remedial excavations at <br /> the Mohr-Fry site WHF screened soil samples with a portable photo ionization detector <br /> (PID) and logged the lithology of the exposed walls using the Unified Soil Classification <br />' System All excavations were closed by April 6, 1995 Wall and floor samples were taken <br /> at various times throughout the project at the direction of Mr Steve Sasson or Mr Ron <br /> Rowe with San Joaquin County Public Health Services, Environmental Health Department <br /> (PHS/EHD) <br /> Excavation 1 was in the vicinity of three (3) former 6,000 gallon surface tanks MW-3 <br />' was left with a protective "island" of undisturbed soil The excavation measured 15 feet <br /> wide by 30 feet long by 10 feet deep, less the 5 by 9 foot area around MW-3 This was <br /> about 150 cubic yards Excavated soils were stockpiled in two 75 yard piles S-1-1 and <br /> S-1-2 One laboratory sample was taken for each 25 cubic yards (three per pile) and <br /> composited for each pile The excavation was backfilled with pea gravel to approximately <br />' four feet b g and compacted soil was placed to grade <br /> Excavation 2 was an ov-er-excavation of a former underground fuel tank removal The <br /> pea gravel backfill was removed from the area of the original excavation, screened with <br /> the PID and used to backfill Excavation 1 The original excavation was 15 feet wide by <br /> 30 feet long by 15 feet deep, or about 250 cu yd The over-excavation resulted in <br /> removing an area 20 feet wide, 40 feet long and 10 feet deep (-300 cu yd ) An <br /> additional bottom area of 11 feet by 30 feet was deepened to 15 feet (--61 cu yd ) below <br /> ground level Soil from this excavating was stockpiled as S-2-1, S-2-2 and S-2-3 The <br />' total pit volume (-361 cu yd ) minus the previous pea gravel backfill (-250 cu yd ) <br /> resulted in a net soil removal (to the stockpiles) of—111 cu yd , or ---37 cu yd per pile <br /> Two laboratory samples from each pile were composited to characterize each pile <br />' While screening the wall samples with the PID it was i cov red that the sand above the <br /> peat layer, and in most places the peat layer, had diesel and oil contamination from 11/2 to <br /> 4 feet b g After the former tank area was excavated, the sand and peat layer were <br /> I <br />