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r Mr Harlan Knoll rAugust 9, 2001 �j Page 4 of 7 rthe well development process, temperature, pH, and electrical conductivity were measured and allowed to stabilize prior to collecting groundwater samples Groundwater purged from the wells was placed into DOT approved drums and labeled in accordance with 49 CFR part 172 and 40 rCFR part 262 Purged groundwater/ansate is currently stored on site pending disposal r Groundwater samples were collected from each well after physical parameters had stabilized and the water in the well had recovered to at least 80% of pre-development levels Samples were placed in an ice chest at a temperature of 4° Centigrade and submitted to Argon Laboratory under r chain of custody protocol The samples were analyzed for the presence of TPHg and TPHd by EPA method 8015K BTEX by EPA method 8020, and oxygenated gasoline additives, EDB, and 1,2-DCA by EPA method 8260 Field development/purge logs are included in Attachment B r3.0 RESULTS OF INVESTIGATION r3.1 Subsurface Conditions Fill material was encountered in boring MW 1 to a depth of approximately 14 feet bgs Soil r encountered in the borings located outside the limits of the excavation was classified as clay, silt, and sand Soil in borings MW2 and MW4 are primarily sands below approximately 8-12 feet bgs (to approximately 24 feet bgs, the maximum depth explored), and native soil in borings MW 1 and MW3 rare primarily clays and silts Soil boring logs are included in Attachment A Groundwater was initially encountered at depths ranging from approximately 8 to 11 feet bgs ' during drilling The depth to groundwater on May 21, 2001 ranged from 7 70 feet bgs in well MW4 to 8 96 feet bgs in well MW 1, and flowed in a southwesterly direction with a gradient of approximately 0 003 ft/ft Groundwater elevations are summarized in Table 1 A potentiometric ' surface map generated using the May 21, 2001 data is depicted on Figure 4 Groundwater monitoring, field data and well development/purge logs are included in Attachment B I3.2 Soil Analytical Results No TPHd, BTEX, 1,2-DCA, or EDB were detected in any soil samples collected from borings ' MWl-MW4 TPHg was detected at 7 1 parts per million (ppm) in the sample collected from MW3 at 5 feet bgs and MTBE was detected at 0 016 ppm in the sample collected from MW3 at 15 feet bgs 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 ' MTBE was the only constituent of concern detected in any site well MTBE was detected in wells MW1, MW3, and MW4 at concentrations of 58 parts per billion (ppb), 320 ppb, and 96 ppb, respectively MTBE was not detected in well MW2 Groundwater analytical results are . summarized in Table 3 Laboratory reports and chain of custody documentation are included in ' Attachment B ' G Oata1GROUNDZE43arnyard-Manser\Reports\WELLRPT doe