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Field Investigation. SSI - Phase Two INITIAL MONITORING WELL ADDITIONAL WELL DEVELOPMENT AND DEVELOPMENT, PURGING AND SECOND PURGE AND SAMPLE OF WELL SAMPLING May-7 On May 3, 1999, HLA developed the well As described in detail in the Results Section according to the following procedures The below,the analytical data on the groundwater groundwater levels and total well depth were sample collected from well MW-7 on May 5, 1999 measured to the nearest 0 01 foot with an showed detectable, but very reduced, electronic water-level meter These measurements concentrations of TPHg and BTEX relative to the were used to calculate the casing volume results on the Hydropunch sample collected at Following these initial activities,the well was depth of 31 to 34 feet bgs from boring HP-2 ' developed by using a 2-inch submersible Grunfos These results indicated that the Hydropunch data pump to purge the well of standing water in the did not represent ambient groundwater well casing and borehole During purging field concentrations of formational waters, but were due measurements of temperature, pH, and to cross-contamination Based on this first conductivity were recorded on HLA Ground- sampling of MW-7, HLA returned to the Site on Water Sampling Forms(Appendix E) June 8, 1999 to perform a more aggressive Development continued until purging parameters development of well MW-7 Development was stabilized to within 10 percent of previous performed using a surge block by starting at the measurements Approximately 55 gallons of well bottom and surging the well in 2-foot water was purged from the well and was placed in increments for approximately 2 minutes in each 2- labeled DOT-approved 55 gallon drums and left foot interval Upon completion,the well was onsite for subsequent disposal pumped from the bottom until the water cleared up This process was then repeated a second time On May 5, 1999,HLA purged and sampled Following the second surge and pump cycle,the monitoring well MW-7 according to the well was purged by hand bailing with clean bailer procedures listed described above Following until minimum purge volumes and parameter ' purging and groundwater recovery to near-static stabilization was achieved The well was then levels(>90%), groundwater samples were sampled according the procedures described collected in a clean stainless-steel bailer and above decanted into laboratory-cleaned 40-milliliter(ml) sample containers and immediately sealed with FINAL PURGE AND SAMPLE EVENT OF teflon-lined lids Care was taken to eliminate ALL MONITORING WELLS headspace in sample containers by inverting the 40-m1 sample containers to check for bubbles In accordance with HLA's Work Plan Addendum, The stainless-steel bailer was steam-cleaned or (HLA 1998a), all wells were to be resampled in washed in Alconox or Liquinox soap and triple- one final round after a minimum of 30 days ' rinsed in deionized water The samples were following the sampling of well MW-7 On July labeled and immediately placed in iced storage 19, 1999,the final quarterly monitoring round was and chain-of-custody forms were initiated by the performed Depth to water was measured at 1 sampler The samples were transported under approximately 8 to 9 feet bgs The purge and chain-of-custody protocol to a state-certified sample procedures were performed and the analytical laboratory The samples were analyzed samples were analyzed in accordance with the ' in accordance with the analytical program protocol and analytical program described above described above Copies of the chain-of-custody In addition, the samples were also analyzed for the forms and the analytical reports are included in five fuel oxygenates and 1,2-DCA to satisfy Appendix D RWQCB closure requirements • ' LL300001387371WPM737N19 Harding Lawson Associates 9s