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Figure 5A represents the hydrocarbon groundwater plume in the A zone and shows an <br /> elongated plume extending west of MW2 out to "Geoprobe" hole P9 were degradation <br /> has left only minor TPHg(470 ug/L), Toluene (0 65 ug/L) and tert-Butanol (11 ug/L), the <br /> degradation byproduct of MTBE The newly installed temporary piezometers PZ1A and <br /> PZ2A contained the highest concentration of hydrocarbons with 140,000 ug/L and <br /> 62,000 ug/L TPHg respectively <br /> Figure 5B represents the hydrocarbon groundwater plume in the B zone and shows a <br /> similar elongated plume extending west from MW2 out to "Geoprobe" hole P9 where <br /> degradation has left only minor amounts of Toluene (0 81 ug/L), Xylenes (0 83 ug(L) <br /> and MTBE (1 6 ug/L) Again the highest concentrations are associated with the newly <br /> installed temporary piezometers PZ1B and PZ2B with 40,000 ug/L and 16,000 ug/L <br /> TPHg respectively <br /> Figure 6 illustrates the subsurface lithology and the extent of the A and B zones <br /> groundwater plumes within the A and B zones AIso shown in cross section is the extent <br /> of the excavation as of February 10, 2003 <br /> Figure 7 illustrates the site conditions on February 10, 2003 and shows the security <br /> fencing installed around the excavation area and the extent of the excavation on this date <br /> R EC'OMM ENDA TRONS <br /> 1) Continue to over-excavate former UST - piping and dispenser areas to approximately <br /> 24 feet bgs <br /> 2) Excavate area containing wells PZ1B, PZ2B and RIB to 30 foot depth Backfill <br /> excavation with pea gravel, road base and resurface with asphalt <br /> 3) Submit a report of findings/results <br /> TIME FRAME <br /> February 25, 2003 Commence with over-excavation of area containing wells RIB, <br /> PZ 1 B and PZ2B to approximately the 30 foot depth Develop this area as an excavation <br /> dewatering trench Proceed with over-excavating of contaminated soils Backfill <br /> excavation with clean pea gravel to within 7 feet of surface, compact backfill remainder <br /> of the excavation with clean road base to surface subgrade Resurface with 4 inch thick <br /> hot asphalt <br /> LIMITATIONS <br /> The discussion presented in this report is based on the following <br /> 1 The observations and data collected by field personnel <br /> 2 The results of laboratory analyses performed by a state certified analytical laboratory <br /> 7 QM 1 ST 2003 <br />