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Ms. Connie Davis/Aggregate Industries - F Street Juty 2002 QMR/Closure Request <br />Project Number 1001018 P~1R~GON <br />September 20, 2002 <br />Page 4 <br />3. GROUNDWATER QUALITY RESULTS <br />Information collected during the July 2002 quarterly sampling events relative to groundwater <br />quality at the site is summarized below. That information includes temperature, electrical <br />conductance and pH measurements; dissolved oxygen (DO) measurements; and laboratory <br />results. <br />3.1 Quarterly Monitoring Field Data <br />Groundwater temperature, electrical conductance and pH measurements were performed on <br />July 29, 2002 during purging of the wells prior to collecting groundwater samples for <br />laboratory analyses. Measurements were recorded during the removal of water from the <br />wells. The wells were considered purged when temperature, electrical conductance and pH <br />measurements stabilized to within ten (10) percent for three (3) consecutive measurements <br />and a minimum of three (3) well volumes were removed from the well. Purge water was <br />discharged on site. <br />DO measurements were also performed on July 29, 2002. DO monitoring results are <br />summarized in Table 2 and on Figure 4 which are attached to this report. As seen from <br />Table 2 and Figure 4, DO concentrations ranging from approximately 0.8 to 1.4 milligrams <br />per liter (mg/L) were observed at the site during the July 2002 sampling event. <br />3.2 Quarterly Monitoring Laboratory Data <br />Groundwater samples were collected on July 29, 2002 by Paragon from wells MW-1 through <br />MW-5 and EW-1. The samples were placed in glass vials with Teflon septa and transported <br />under standard Paragon chain-of-custody procedures to Technology Laboratory, Inc. (TLI) <br />for BTEX and TEPH analyses. Laboratory results for groundwater samples collected from <br />the site between July 2001 and July 2002 are summarized in Table 2. The laboratory results <br />for the groundwater samples collected from wells MW-1 through MW-5 and EW-1 on July <br />29, 2002 are also summarized on Figure 4. A copy of the July 2002 TLI laboratory report is <br />also attached to this report. <br />As seen from Table 2 and Figure 4, BTEX concentrations were not observed above the <br />laboratory detection limits of 0.5 micrograms per liter (µg/L) in the groundwater samples <br />collected from wells MW-1 through MW-5 and EW-1 on July 29, 2002. TEPH <br />concentrations were not observed above the laboratory detection limit of 0.5 mg/L in the <br />groundwater samples collected from wells MW-1 through MW-5 and EW-1 on July 29, <br />2002. Concentrations of BTEX and TEPH observed in the groundwater samples collected <br />from wells MW-1 through MW-5 and EW-1 during July 2002 remained generally consistent <br />