ARCHIVED REPORTS XR0004611 - Laserfiche WebLink

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(VYATC . A S S O C I A T E S I N C On February 18, 1999, a geologist from ATC Associates supervised the installation of three groundwater-monitoring wells from 39 to 41 feet bgs Soil borings MWI, MW2, and MW3 were completed as two-inch monitoring wells One soil sample from each boring was collected and after the groundwater monitoring wells were developed one groundwater sample was collected from each well Soil and groundwater samples contained detectable concentrations of petroleum hydrocarbons Results are summarized in ATC's Summary Report of Additional Subsurface Investigation, dated June 1, 1999 On September 12, 2001, and October 4 and 5, 2001, a geologist from ATC Associates supervised the advancement of six soil borings, SB7 through SB 12, to approximately 20 to 25 feet bgs and one CPT boring to approximately 45 feet bgs Analytical results of soil samples indicated no detectable presence of petroleum hydrocarbons or fuel oxygenates One groundwater sample was collected from each boring at the depth groundwater was first encountered Groundwater samples indicated no detectable presence of petroleum hydrocarbons or fuel oxygenates Results are summarized in ATC's Summary Report of Supplemental Subsurface Investigation, dated January 4, 2002 On July 16, 17, and 18, 2002 an aquifer test was conducted over a 48-hour period by extracting groundwater at a generally constant rate from well MWI The test was performed to determine the aquifer properties and the radius of influence for groundwater pumping The groundwater . extraction pilot test yielded a pumping rate of approximately 4 76 gpm and a ROI of up to 85 feet Results are summarized in ATC's Feasibility Study Report, dated December 12, 2002 SAMPLING ACTIVITIES On March 5, 2003, ATC personnel collected groundwater samples from monitoring wells MWI, MW2, and MW3 The locations of the monitoring wells are shown on Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the monitoring wells and recorded A minimum volume of three well casings was purged from each well prior to sampling The wells were allowed to recover and samples were collected from each well using disposable bailers The groundwater matrix samples collected from each well were submitted to State-certified Argon Laboratories (FLAP Cert No 2359) for chemical analysis of total petroleum hydrocarbons as gasoline (TPHg) utilizing EPA method 8015 modified, and benzene, toluene, ethylbenzene, xylenes (BTEX) and methyl tertiary butyl ether (MTBE) utilizing EPA method 8020 Groundwater well purge and sample logs are contained in Attachment 1 ANALYTICAL RESULTS The groundwater analytical results measured at monitoring well MWI showed detectable concentrations of TPHg and BTEX The measured concentration of TPHg at MWI was 1,300 • pg/L Benzene was detected at 9 0 pg/L, toluene was detected at 12 gg/L, ethylbenzene was detected at 8 2 pg/L, and xylenes were detected at 2 0 pg/L W Iwordpro1149811ReportsUQR-03 doc 2