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R&B Trucking Project No.01-37.1.1 March 27,1990 Page 6 During the drilling process,soil samples were collected every 3 feet using a 2 inch(O.D.) modified California split spoon sampling tool lined with brass sleeves. A PID was used to field screen the samples for hydrocarbons. A detailed boring log was kept for each well that listed sediment type and description. The wells all terminated at a depth of 25 feet below the surface. The bottoms of the wells were seated in a thick clay layer that was continuous throughout the site. The monitoring wells were constructed of 2 inch treaded joint,schedule 40 PVC pipe. The screened interval was constructed with factory perforated .040 inch slots. These perforations extended from total depth of 25 feet to a depth of 10 feet. A filter pack consisting of#3 sand was installed from total depth to 2 feet above the perforations (8 feet). An annular seal consisting of 59 pounds of bentonite pellets and a bentonite grout was installed above the sand filter pack (8 feet) to a depth of 3 feet. Above this seal in the annular space was filled with neat cement up to grade. The wells were secured with a locking cap and encased in a water tight well cover. As shown in Table 2,the analytical data for both rounds of ground water sampling indicate that no contamination was detected. As no contamination was detected, the corresponding bailer and travel blanks were not analyzed. 5.0 PRELIMINARY HEALTH RISK ASSESSMENT This property will soon be subdivided into urban housing. With this intended future use,The City of Tracy would like to know if the property is safe for domestic use. Given the historical use of the land,a trucking service company yard, there are only a few sources for potential environmental damage. One potential source is the under ground storage tanks(UST s)that store fuel for truck use. This report primarily deals with that issue. Another potential source is the used crankcase oil from the trucks. Often times truck maintenance personnel will improperly dispose of the waste oil to the ground surface. However,R&B Trucking disposed of their waste oil to a UST. When the fuel USTs were removed the waste oil tank was removed and tested to be clean(Table 1;Appendix B). A third potential source for environmental damage would be the steam cleaning of the trucks for maintenance. At the time of this study no steam cleaner was observed at the site and there was no visible evidence that one ever existed. In a conversation with Mr. Barenchi, he stated that R &B Trucking had never operated a steam cleaner. Therefore, GTI extrapolates from the lack of evidence that steam cleaning has not adversely affected the environmental health of the property. A fourth potential source of contamination to this property is the leakage or spillage from parked trucks in the yard. There is some evidence that small volume releases of this kind ocurred in the yard. However,in our opinion this has not adversely impacted