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Mr. Michael Collins September 3. 1993 + Page 2 A total of 13 soil samples have been collected for laboratory analysis from the excavation: four samples from the bottom of theit and nine samples from the sidewalls. All samples P P p were collected under the supervision of the San Joaquin County Environmental Health r Department. Samples were collected between July 19 and July 27, 1993. Sidewall samples ! have been collected along the north and east walls and from the northwest. northeast, and ' southeast comers of the excavation. Bottom samples have been collected along the northern, northeastern, and southeastern edges of the pit. Samples have not been collected from the k r southwestern region of the excavation. All samples have been collected at varying depths and have been analyzed for TPH as gasoline (TPH-G), TPH as diesel (TPH-D), TPH as motor oil (TPH-MQ), and benzene, ethylbenzene, toluene, and total xylene isomers (BETX). Sample locations are shown on Figure 1. In addition, three soil samples were collected from the stockpiled soil to determine if the material exhibits the characteristics of a hazardous waste. as defined under the Code of California Regulation. Title 22. Subsections 66261.21 through 6626.24. The three stockpile i samples were collected from areas which visually appeared to be saturated with petroleum hydrocarbon constituents and submitted to an analytical laboratory for determination of ignitability, corrosivity, reactivity, and toxicity, following the methods listed in the above-referenced sections. i R 4 Summary of Analytical Results The following section summarizes the results of laboratory analyses of soil samples collected from the excavation and stockpiled soil. For discussion purposes, the excavation has been M divided into five areas: southwest quarter, southeast quarter, northeast corner, northwest corner, and northern wall. Analytical results of the excavation soil samples are summarized in Table L. Results of the three stockpile soil samples are summarized in Tables 2 and 3. Southwest Quarter. Current excavation activities are limited because of the presence of the vehicle access ramp in this area. Analytical samples have not been collected from this area and the extent to which soil has been affected by hydrocarbon constituents is not known at this time. SoutheastQ samples,Five soil les E-17, S-18, SE-20 BSE-28, and BSE-44, were collected from the southeastern quarter of the excavation at depths ranging from 17 feet to 44 feet bsg. Although analytical results of samples E-17, S-18, SE-20, and BSE-28 did not identify TPH-affected soil at their respective locations, visual inspection of the surrounding I material indicated that further excavation was warranted. Laboratory results of soil sample BSE-44 and visual inspection of the surrounding material indicate that TPH-affected soil is not present below this depth. i Use or disclosure of data contained on this sheet is subject to the restriction specified at rhe beginning of this dgrrown and Caldwell LOriSU:;drS;S 7603COEZRFSP7603.02.L-1