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March 16, 1988 P.6 Roberts Oil Company Page 3 the higher PID values. The analytical results indicated that due to the high number of alkanes and lack of octanes, that the hydrocarbon in the soil is diesel. J.H. Kleinfelder & Associates' concluded that hydrocarbon contamination in the underlying soil profile was limited to the area beneath the above ground storage tank yard, and between the transfer block and loading area. Kleinfelder postulated that the loading area is a possible source of the hydrocarbon contamination. The soil profile encountered during the drilling and sampling operations conducted by J.H. Kleinfelder & Associates consisted of silty sand from ground surface to a depth of approximately 10 feet, sand grading to a silt from 10 to approximately 30 feet below ground surface, and a clayey silt from approximately 30 to 36.5 feet below ground surface (total depth explored). J.H. Kleinfelder & Associates also installed three ground water quality monitoring wells west of the above ground storage tank farm, within the southwest portion of the site's fenced enclosure, and east of the underground storage tank farm. Ground water was first encountered at a depth of approximately 38 feet below ground surface in each of the three monitoring well boreholes. The monitoring well borehole logs prepared indicate that the aquifer system encountered is probably unconfined. Following Installation, each well was was initially sampled with a clear plastic bailer to visually inspect for the presence of floating product or sheen. Floating product was not encountered in the wells installed. However, approximatley 4 inches of product was encountered in MW -1, a pre-existing well, located at the southeast corner of the transfer block. Each of the wells installed by Kleinfelder were developed and purged prior to ground water quality sampling. Well MW -1 was purged prior to collecting a ground water quality sample. Samples were collected by bailer and submitted for laboratory analyses of aromatic hydrocarbons and total extractable hydrocarbons. The laboratory analytical results indicated that gasoline related constituents (benzene, toluene, and xylene), and total hydrocarbons, were detected in the ground water quality sample collected from MW -1. However, the same constituents and compounds were not detected, at their respective analytical detection limits, in ground water quality samples collected from the three wells installed. J.H. Kleinfelder & Associates' concluded that the prevailing hydraulic gradient is probably from northwest to southeast beneath the site,