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3.4 Groundwater Monitoring for Petroleum Hydrocarbons On September 19, 1994, monitoring procedures were performed at the site Prior to sampling, the groundwater depths were measured in each well After depth measurements were collected, each well containing sufficient water was purged and sampled 3.4.1 Monitoring Well Purge Procedures A Solinst water level meter was used to measure the groundwater depth in each monitonng well (Table 3) Monitoring wells MW-1 through MW-5 were dry An attempt was then made to purge each well containing water of a minimum of three well volumes All wells had sufficient water for purging except MW-6 and MW-8, only one gallon could be removed from these two wells All wells except EW-1 were purged using PVC bailers Well EW-1 was purged using a 2" submersible pump Temperature, pH and conductivity of the purge water %sere measured at approximately 1-gallon intervals (5-gallon intervals for EW-1) using a ICM water analyzer Monitoring well stabilization data and field sheets are included in Appendix D The water was placed in labelled DOT-approved drums and stored on-site 3 4.2 Groundwater Sampling Water samples were collected from each well using clean, disposable plastic bailers The samples were collected in 40-m1 EPA vials, 1-liter amber bottles and plastic bottles Samples were transported in a chilled container to McCambell Analytical in Pacheco (MAI) The samples were analyzed for total petroleum hydrocarbons (TPH as gasoline), volatile aromatics (BTE&X), volatile halocarbons, lead (Pb) and ethylene dibromide (EDB) in accordance with EPA methods 8015m, 602, 601, 7420 (239 2) and 601, respectixely 4 0 FINDINGS 4.1 Monitoring for Biological Activity The full-scale inoculation of the site was initiated on August 16, 1994 Soil vapor monitoring was initiated on August 29, 1994 Indications that bioremediation is actn'e (and presumably working) at the site would be elevated concentrations of carbon dioxide and depressed concentrations of oxygen The highest concentrations of carbon dioxide and lowest concentrations of oxygen have been been measured in VW-4, VW-5 and MW-4 (see Table 2) We would expect to measure the greatest biological activity in the area of the highest concentrations of hydrocarbons, VW-4, VW-5 and MW-4 are located near the most heavily contaminated portions of the site Overall, the soil vapor monitoring results look encouraging a.obS"r,W,W s<— r.. 4 or.n<y R.wnA"n 33 cr_wa�S