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kn K L E I N F E L D E R 40 • Total Purgeable Petroleum Hydrocarbons as referenced to Gasoline (TPH-G) by EPA Method 8015/8021B The samples were analyzed on a standard laboratory turnaround schedule requiring approximately 10 working days For a summary of the results of the chemical analyses conducted, please refer to the attached Table 1 3.0 FINDINGS The groundwater flow direction was calculated to be towards the northeast with a gradient of approximately 0 0058 ft/ft (see Plate 3) during the July 3, 2002 sampling event Previous groundwater flow directions between October 1998 and July 2000 have historically been to the northeast however, in December 2000 and December 2001, groundwater flow direction was calculated to the east and east/southeast, respectively Groundwater gradients have ranged from 0004 to 0010 ft /ft Although no measurable product or sheen was noted, a petroleum-like odor was noted from purge water in monitoring well MW-1 No unusual odor was noted in monitoring wells MW-2 and MW-3 . TPH-G and BTEX constituents were detected in one or more groundwater samples collected from the three wells during the sampling event The analytical results are summarized on the attached Table 1 TPH-G was detected in groundwater from each of the three wells at concentrations ranging from 30 to 380 µg/l (parts per billion) BTEX constituents were detected primarily in MW-1 Benzene was detected at 134 µg/1 in MW-1 and at 70 µg/1 in MW-3 Ethylbenzene was detected only In MW-1 at 6 8 µg/l Toluene and total xylenes were not detected at or above laboratory reporting limits In the three-groundwater samples r The sampling event shows an overall decrease in petroleum constituent concentrations as compared to the previous December 2001 sampling event Based upon this data it appears that the overall petroleum constituents in the contaminant plume have decreased For a review of historical laboratory analyses conducted, refer to Table 1 Copies of the laboratory data sheets along with the laboratory reporting limits are presented In Attachment C Kletnfelder recommends that a copy of this report be submitted to the San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) for their review and comment if necessary i 20-4439-01 E04/ST02R397 Page 4 of 6 Copyright 2002,K1einfelder,Inc August 22,2002