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S E C ® R � I •' Mr Michael lnfurna i July 16, 2004 II Page 2 { f I f ASSESSMENT ACTIVITIES AND FINDINGS 17 On September 2, 2003, SECOR supervised Cascade Drilling Incorporated (Cascade) of Sacramento, California, as they advanced two soil borings, USB-1 and USB-2, and installed ' one groundwater monitoring well, MW-67UA, at the locations shown on Figure 2 Soila borings USB-1 and USB-2 were advanced to 10-%2 feet below ground surface (bgs) h Groundwater monitoring well MW-67UA was advanced to a total depth of 16-1/2 feet bgs On December 11, 2003, SECOR supervised Cascade as they installed one additional h3 groundwater monitoring well, MW-68A, at the location shown on Figure 2 Groundwater ,k,I monitoring well MW-68A was advanced to a total depth of 41-'/2 feet bgs Each boring location was hand-cleared using an air-knife tool to a depth of approximately 8 feet bgs Groundwater and select soil samples were collected for each boring and submitted for oE1'"ia chemical analysis Field and laboratory procedures are included in Attachment 3 Assessment activity findings are summarized below 4 , SUBSURFACE CONDITIONS I Field observations and boring logs indicate that the top 5 feet of soil consisted primarily of JI • clayey silt with sand or silt with sand From approximately 5 to 10 ft bgs sandy silt, silty sand with clay, and clayey silt was encountered Beyond 10 feet bgs, the sands, silts, and µ clays were interspersed with lenses of clay ranging from 1 to 5 feet in thickness The color ` of clays logged within 1 to 10 ft bgs were generally grayish-brown or olive-brown, black, and r dark gray During boring activities groundwater was typically encountered around 7 to 9 ft ;+ bgs Boring logs are included in Attachment 4 14, SOIL ANALYTICAL DATA Selected soil samples were submitted to Lancaster Laboratories Incorporated (Lancaster) of Lancaster, Pennsylvania for chemical analysis With the exception of the UST soil samples, which were not analyzed for ethanol and methanol, soil samples were analyzed for the following constituents • total petroleum hydrocarbons as gasoline (TPHg) using CA LUFT Gasoline method, • total petroleum hydrocarbons as diesel (TPHd), methanol, and ethanol using modified EPA Method 8015B, • benzene, toluene, ethylbenzene, and total xylenes (BTEX), methyl tertiary butyl ether (MtBE), tertiary butyl alcohol (TBA), ethyl tertiary butyl ether (EtBE), di- ryR isopropyl ether (DIPE), tertiary amyl methyl ether (TAME), 1,2-dibromoethane (1,2- DBA), and 1,2-dichloroethane (1,2-DCA) by EPA Method 8260B, and i . • total lead by EPA Method 6010B I IChevron110016211REPORTS120041UST Site Assessment Report doe