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Ms Lon Duncan April 12,2001 . Page 4 of 6 3.0 RESULTS OF INVESTIGATION 3.1 Subsurface Conditions Soil encountered beneath the site consisted primarily of clay and silt from the ground surface to a depth of between 24 and 26 feet bgs, and well graded sand from approximately 24126 feet bgs to between 29 and 32 feet bgs, the maximum depth explored during well installation Boring SB3, which was drilled through the former tank pit, contained silty sand from approximately 32 feet bgs to approximately 36 feet bgs, the maximum depth explored at the site Strong to moderate petroleum odor and soil discoloration were noted in boring MW3 from approximately 5 feet bgs to boring termination FID readings from the samples ranged from 2,000 parts per million (ppm) at a depth of 12 feet bgs to 600 ppm at a depth of 32 feet bgs An oily sheen was also evident in the saturated zone No hydrocarbon odors or soil discoloration were noted in borings MWl, MW2, or MW4 All recorded FID readings as well as noted odors or soil discoloration are included on the boring/well logs included in Attachment A Groundwater was first encountered at depths ranging from approximately 23 5 to 25 5 feet bgs during the drilling of borings NMI through MM4 Groundwater in the wells subsequently stabilized at depths ranging from approximately 21 9 to 22 6 feet bgs To determine groundwater elevation, the depth to groundwater was measured in each well and subtracted from the surveyed wellhead elevation Groundwater beneath the site on December 19, 2000 flowed northeasterly at a gradient of 0 003 ft/ft, or approximately 16 feet per mile Groundwater elevations are summarized in Table 4 A potentiometric surface map generated using the December 19, 2000 well monitoring data is depicted on Figure 5 Groundwater monitoring field data and development/purge logs are included in Attachment B 3.2 Soil Analytical Results Based upon previous analytical results, which indicate that soil contamination outside of the source area is limited to the capillary fringe zone (approximately 20 feet bgs), only the soil samples collected from the capillary fringe in bonngs MW 1, MM2, and MM4 were submitted for laboratory analyses No samples were submitted from boring MM3 due to its close proximity with boring SB3 No detectable concentrations of TPHg, TPHd, TPH oil and grease, VOCs, or oxygenated gasoline additives were detected in any analyzed sample The concentrations of total lead ranged from 8 6 to 10 ppm, which is consistent with background levels Soil analytical results are summarized in Table 2 Laboratory reports and chain of custody documentation are included in Attachment C 3.3 Groundwater Analytical Results No petroleum hydrocarbon constituents or lead were detected in groundwater samples collected from wells MMI, MW2, or MM4 However, each of the samples from these wells contained chloroform ranging from 5 8 to 10 parts per billion (ppb) and tetrachloroethene (PCE) ranging from 18 to 23 ppb In addition, well MMI contained cis-l,2-dichloroethene at 2 9 ppb and G 1Data1GROUNDZEIGABBA \rgmTis\WELLRPT doe