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i ff�,,j KLEINFELDEr 1 I On Plate 3, analytical :eults inr_luuing volatile aromatics are referenced to sampling locations. ttenzene levels in the two soil samples with the highest TPH levels were 11.2 milligrams per kilogrr= (mg/kg) and 5.6 mg/kg. Low levels of benzene (.045-.129 mg/kg) were detected in three additional soil samples. Toluene, atnylbenzene, and xylenes were also detected in soil samples as shown on Plate 3. 4.2 SITE GEOLOGY Soils consisr_s of interbedded silts and some silty sands to an approximate depth of 16-13 feet. A clay 'layer of 4-5 foot thickness was observed in four of the five borings. The borings are all Iithologi.cally similar. Somewhat symmetrical distribution of hy3rocarbons from any point source is therefore probable. Hydrocarbons from a near surface s»rce would be expected to migrate nearly vertically downward in the areas of high horizontally when reachir; ar¢as of lower permeability then spread permeability such as the observed clay layer. � I extent of migration has not been fully determined. The The horizontal g _ highest levels of hydrocarbons detected during this preliminary investigatica were in borings on either side of the pump islands. High PID readings were not found above the 15---foot depth. It is probable that doth B-3 and B--5 are some distance horizontally from the source or sources of the hydrocarbons. 4.3 DISCUSSION Moderatelevels of petroleum hydrocarbons and benzene were detected in native soil at this service station in the vicinity of the pump islands at the 20-foot level. There is evidence (PTD readings and observations) that -" the petroleum hydrocarbons have migrated deepei than 20 feet, possibly into ground water. Ground water quality has not been assessed to date. . i f 85-88-219 - f MI URS; 111pow