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<br /> monitoring wells and two of the soil borings were completed as vapor extraction wells The soil
<br /> boring, groundwater monitoring well, and vapor extraction well locations are shown on Figure 2
<br /> On July 3, 1997, the monitoring wells were developed and sampled for petroleum hydrocarbons
<br /> along with the adjacent property owner's well (CW) The samples from wells MW1, MW2, and
<br /> MW3 contained concentrations of total petroleum hydrocarbons as gasoline (TPHg) and benzene
<br /> ranging from 3,200 parts per billion (ppb) to 130,000 ppb and 920 to 11,000 ppb, respectively
<br /> Field activities and analytical results were detailed in Smith Technology's Summary Report
<br /> dated September 17, 1997
<br /> On March 24 and 25, 1998, ATC personnel supervised advancement of seven soil borings,
<br /> ASB1, MW4, MW5, MW6, MW7, SBS, and SB9, at the site to depths ranging from
<br /> approximately 26 5 to 62 feet bgs at the project site to 1) evaluate the horizontal and vertical
<br /> extent of petroleum hydrocarbon impacted soil and groundwater, 2) determine and define soil
<br /> stratigraphy, and 3) install groundwater monitoring wells (MW4, MW5, MW6, and MW7)
<br /> within the uppermost aquifer Groundwater samples collected from wells MW5, MW6, and
<br /> MW7 contained elevated concentrations of TPHg and benzene Field activities and analytical
<br /> results were detailed in ATC's Summary Report of Subsurface Investigation, dated August 14,
<br /> 1998
<br /> • In March 1999, ATC personnel supervised the advancement of three soil borings, S139A, SB 10,
<br /> and SB 11 Borings SB 10 and SB 11 were advanced to 46 feet bgs using hollow stem auger
<br /> techniques and boring S139A was advanced to 65 feet bgs using continuous core methods ATC
<br /> is currently preparing a summary report detailing the field activities
<br /> SAMPLING ACTIVITIES
<br /> On March 16, 1999, ATC Associates personnel collected groundwater samples from monitoring
<br /> wells MW1 through MW7 and CW The locations of the monitoring wells are shown on Figure
<br /> 2 Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity,
<br /> and temperature were measured in the monitoring wells and recorded A minimum of three well
<br /> casing volumes was purged from each well prior to sampling The wells were allowed to recover
<br /> and samples were collected from each well using dedicated disposable bailers
<br /> The groundwater samples collected from each well were submitted to State-certified Sequoia
<br /> Analytical (ELAP Cert No 1210) for chemical analysis of TPHg, benzene, toluene,
<br /> ethylbenzene, and xylenes (BTEX) utilizing EPA methods 8015/8020 Groundwater well purge
<br /> and sample logs are contained in Attachment 1
<br /> ANALYTICAL RESULTS
<br /> TPHg and BTEX were detected above laboratory method detection limits in the samples
<br /> collected from wells MW1, MW2, MW3, MW5, MW6, and MW7 The samples collected from
<br /> w 1625961quart1y\1gr-1999 doc 2
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