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1 <br /> • <br /> TABLE 4. GROUNDWATER INORGANIC CHEMICAL DATA <br /> Sample Nitrate Sulfate Ferrous Alkalinity <br /> No Iron <br /> mg/l mg/l mg/1 as CaCO3 <br /> mg/1 <br /> MW-1 1 64 31 004 74 <br /> MW-2 153 27 003 68 <br /> MW-4 012 28 003 15 <br /> ND -Not Detected NR-Not Requested mg/kg - milligram per kAlogram <br /> ug/l - microgram per liter ug/kg - microgram per kilogram <br /> VOC 8010* - All constituents ND except for those shown in the table <br /> E - exponent Fuel Ox - Fuel oxygenates by 8260 <br /> Microbial - Microbial activity as heterotrophic plate count <br /> CFU/g - Colony forming units per gram <br /> Permeabil - Permeability - Soil permeability in centimeters per second <br /> Discussion of Results <br /> The contaminants are localized in the vicinity of MW-1 near the former tank location <br /> Monitoring well samples laboratory data indicate that only residual concentrations remain at MW- <br /> 1 and were not detected in new well MW-4 Contanunants were not detected at B-5 at 15-feet <br /> within the upper contact of the aquifer These data strongly suggest that residual hydrocarbon <br /> fuel contaminants are present in the former tank pit and are the source of residual degraded <br /> hydrocarbons detected in MW-1 In our opinion, the distribution of contamnants indicate that <br /> hydrocarbons have leaked in the vicinity of the former tank location This agrees with previously <br /> collected subsurface data <br /> A relatively slow groundwater movement is inferred from the groundwater measurement data <br /> and overall groundwater movement is northerly The soil permeability data indicate the sediment <br /> is of moderately low permeability (inferring a moderately low hydraulic conductivity) The <br /> absence of any contaminants at MW-4 indicates a lack of mobility and/or degradation of <br /> contaminants as they move in the aquifer This again agrees with the previous reconnaissance <br /> boring data in the street <br /> A preliminary estimate of indigenous microbiologic activity was collected at B-5 upgradient of <br /> monitoring well MW-2 and at downgradient well MW-4 This data showed that there was more <br /> microbial activity at B-5 than at MW-4, with slight decreases in pH, ferrous iron, nitrate and <br /> alkalinity In our opinion, this suggests that there has been some biodegradation of the <br /> contar unants in the plume The decrease in these parameters downgradient to MW-4 are <br /> interpreted as remnants of previous microbial activity, having used iron and nitrate as electron <br />