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k€ a Di Salvo Trucking-WP July 25,1945 1 : Page-2- 2.2 Over-excavation F On May 6, 1994, the east sidewall near the fo er location of TK4 was over-excavated eastward approximately 4.feet and the floor of the excavation was extended to a depth of approximately 15.5 feet. Excavated soil was visually inspected for petroleum staining and screened with a portable organic vapor analyzer (OV ). Two soil samples were collected from the east sidewall at approximately 15 feet bgs and one soil sample was collected from the floor at a depth of approximately 15.5 feet bgs. Laboratory analyses indicated 6.2 Mcg/kg toluene and 10 ,ug/kg xylene in the sample collected from the floo of the excavation. Laboratory analyses of the soil samples collected from the east sidewall indicated no evidence of hydrocarbon constituents analyzed for at or above the reported laboratory detection limits. No petroleum staining, odors or OVA readings were noted during the over-excavation. Based on the results of field observations and laboratory analyses, the lateral extent of soil contamination at the site F i had been evaluated. Groundwater was not encountered during the over-excavation. A complete description of the over-excavation is in Over excavation Soil Sampling Results, prepared by Condor, June 21, 1994. 2.3 Monitor Well Installation On June 2, 1995, Condor observed the installat on of 1 monitor well (MW1) located in Fthe estimated down gradient direction approximately 10 feet northwest of the former east end of TK4. The monitor well was constructed with tWO-ilLch I.D. Schedule 40, flush-threaded, 0.020 j machine-slotted PVC screen. The screen extended from a depth of approximately 10.5 feet to i 18.5 feet bgs. Blank PVC casing was installed from t e top of the well screen to approximately flush with the ground surface. The static water level nieasured from the top of the well casing Fprior to development and sampling was approximately 11.90 feet. Laboratory analyses of the groundwater sample collected from MW1 indicated a oncentration of 0.4 mg/l diesel. A complete description of the installation; development pd sampling of MW1 is in Monitor Well Installation Report, prepared by Condor, June 28, 1995 Ff` 2.4 Site Geology The native soil at the site from the ground surface to approximately 10.5 feet bgs consists of dark yellowish brown to light brown;° silty fine sand. From 10.5 feet to approximately 16 feet, fine- to course, generally medium grained sand is present and from 16 feet to approximately F; 18.5 feet silt is present. t� CONDOR