SITE INFORMATION AND CORRESPONDENCE

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interpreted to be aquifer water entering the casing. When the well recovered to about 80% of the initial water level, the sample was carefully collected with a clean bailer and poured into the appropriate laboratory prepared container with minimum cavitation. The water sample was labeled, logged onto a chain-of-custody form, and placed in a chilled ice chest. Upon completion of well sampling, the well was closed and locked. A copy of the well monitoring data is enclosed. Existing Deep Vapor Well Modification The existing vapor monitoring well (VW-1) is in our opinion poorly designed and has an excessively long screened interval. The well is positioned over the former tank location where some soil vapor recovery is possible, the excessive amount of screen is not appropriate for vapor extraction of the contamination known to be present in the upper 30 feet. This well was modified to allow for a more effective cleanup of the upper soil column where the previous chemical data shows the most apparent contamination. Modification of the well was accomplished by backfilling the lower 53 feet of the well with a thin cement grout slurry placed by tremie line, filling the well from the bottom to a level of 30 foot below ground surface. In this way, the lower well screen and sand pack was plugged so that extraction can be made in the interval from 10 feet to 30 feet. Subsurface Conditions Two exploratory borings were advanced, the deepest of which went 119.5 feet. These soil borings encountered interbedded sandy silts, silty sands and sand to depths of 95 feet. A clayey silt strata occurs from 95 to 105 feet. A sand underlies the clayey silt and is saturated between 1.05 and 118 feet, and flowed during drilling. A very moist sandy silt underlies the sand. Evidence of soil contamination was not observed in the deep boring, although traces soil vapors were observed in the shallow vapor well :boring. Groundwater was first observed at 105 feet and stabilized at 104.35 feet during drilling, indicating unconfined conditions. The underlying silt is interpreted to be a leaky aquitard based on this preliminary information. Chemical Analysis Seven soil samples and one groundwater sample were submitted for analysis. These samples were analyzed for the following: Total Petroleum Hydrocarbons as Gasoline (TPHG), Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) by EPA Methods 3510/8015, and 8020. Three of the soil samples were selected analyzed for Total Lead by EPA Method 6000. These samples were submitted to and analyzed by Priority Environmental Labs of Milpitas, CA, a state certified laboratory. Four samples were submitted to A & L Western Agricultural Laboratories of Modesto, CA, for aerobic microbiotic activity. The samples were run on an "normal" turnaround (ten working days). The results are enclosed on Table 1. Linden School District 3