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Mr . Dave Karls 202/029000-080 May 12 , 1988 Page 2 PROBLEM DESCRIPTION Within the site , a natural gas drying unit is operated to dehydrate natural gas from the Lathrop gas field . During the dehydration process , water is extracted and released to the subsurface soils via a leach line approximately 2 feet below ground surface. The possibility exists that heavier hydrocarbons were also extracted during the process and possibly leached into the soils along with the water . The amount , depth, and lateral extent of hydrocarbon contamination beneath the site is unknown at this time . The leach line is presently not in use . PG&E presently wishes to construct a concrete pad above the old leach line. Prior to any construction, they wish to determine the vertical and lateral extent of any contamination present in the immediate vicinity of the old leach line . If soil contamination is encountered, excavation may be the preferred remedial action. The excavation would necessitate a delay of on- site construction. The following work steps are not intended to provide comprehensive site characterization, but rather to obtain data needed to determine if any on site construction should proceed. PROPOSED WORK STEPS Following receipt of permission to proceed, the following work steps would be performed: " Drill three soil borings to either water or 10 feet maximum depth in the area of the leach line (see Figure 2 for proposed boring locations) . A field geologist would supervise all drilling and maintain a continuous log of all materials encountered. " Collect soil samples with a split-spoon sampler at 5- foot intervals . " Analyze samples for characterization of petroleum hydrocarbons in the C4 to C22 range by EPA Methods 8020/8015 and 418 . 1 . " tend o soil boring to 20 feet and install//-a 2-inch d 'ameter P C monito Ing wellonsistnof X5-ieo 0 20--inch s otted,.-tve 1 screAn end ( feet'of blank s- casing (see PitonTicCre 3 , Typical Mitoring Well } Construction) .