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Ms. Lori Duncan March 31, 2008 Page 3 of 7 evaluation of soil and groundwater contamination. Borings SB9, SB10, and SB11 were advanced to approximately 50 feet below grade surface (bgs). The first water-bearing zone encountered during drilling was well graded sand from approximately 29-30 feet bgs in upgradient boring SB9, from approximatel 2y 5-27 feet bgs in downgradien onng SB10, and from approximately 25-30 feet bgs in cross-gradient boring SB11. Groundwater was initially encountered at depths corresponding to these upper sand units, but eventually rose within the well bore. Deeper sandy zones were encountered in boring SB9 from approximately 40-43 bgs, and in boring SB10 from approximately 48-51 feet bgs. No deeper sandy zone was encountered in cross-gradient boring SB 11. The lithology in the saturated zone at the source (SB3/MW3) was previously logged as clayey silt from approximately 19-28 feet bgs, well graded sand from approximately 28-33 feet bgs, and clayey sand from approximately 33-36 feet bgs, the maximum depth explore necT r-t 'e former UST. No petroleum hydrocarbons or VOCs were detected in soil samples collected during drilling. Discrete groundwater samples collected from the upper sand zone in borings SB9 (upgradient of UST) and SB10 (downgradient) contained PCE at 5.5 ppb and 7.9 ppb, respectively. No PCE was detected in the shallow water sample collected from boring SB 11 (cross-gradient). PCE was detected in a discrete water sample collected from the deeper sandy zone in boring SB10, at 25 ppb. No deeper water samples could be collected from borings SB9 or SB 11 because the deeper formations in these borings did not yield sufficient water to the sampler. The locations of the former UST, soil borings, and monitoring wells are shown in Figure 2. Soil analytical data are summarized in Table 2 and "grab" groundwater analytical results are summarized in Table 3. Historical depth to water data and analytical data for groundwater samples collected from the monitoring wells are summarized in Table 4. Free Product Removal Between July 2001 and April 2003 free product was removed manually from well MW3 by bailing during site visits. Between April 2003 and April 2005 free product was removed by the use of a passive oil skimmer. On April 20, 2005, Ground Zero installed a Mini Maxi automated belt skimmer into well MW3. The skimmer was designed to automatically extract the product/water mixture from well MW3 and transfer the mixture to a product/water separator. The product/water separator isolates the product from the water and transfers each to their respective drums for storage. The belt skimmer operated on an automatic timer to remove product during the day. The skimmer was shut down on May 12, 2006. No product was recovered during the first and second quarters of 2006 and none was measured in the well. The skimmer is not currently in operation. Since regular monitoring of MW3 began in July 2001, approximately 90 gallons of product/water G:\GROUNDZE\GABBARD\workpims\wp_0308.doc