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w'�f S c�U-e�•w-.!- �., .,.'� �.�� _� �� .*:tr'��yam' �.*.hc �� :'� <v^w 'j,"'`^' �' Nlr. Chuck Carmci July 30. 1991 Page 1'_ r shows the water-level elevations and flow direction calculated from the April 23, 1991 data. Figure 1 does not represent static conditions nor does it represent the cane of depression or capture zone of the extraction well during continuous pumping. In April 1991,many of the on-site wells were redeveloped by surging with a water iet assisted surge block and bailing. This process significantly increased the production of each of the wells that were redeveloped thus reducing the time needed to purge three well volumes for sampling. Analytical results of groundwater samples and water-level elevation are summari:ed in Table 3, along with previous results. The complete laboratory report for the February 1991 sampling is presented in Exhibit C. Figure 2 shows BEl'X and TPH concentrations for each well. Discussion The general groundwater flow direction has not changed at this site since the last groundwater monitoring(February 1991). Water-level elevations have increased from 0.47 to 1.87 feet in all of the 15 wells (average of 1.07 feet). Monitoring well PR-1 did not contain detectable concentrations of BE1^.d and TPH. The benzene concentration increased in well E-5, and decreased in wells E-8, E-10,E-11,E-12, and BHD-1. Fthylbenzene,toluene,and xylene concentrations decreased in all of the sampled wells. The TPH concentration increased by approximately 5 percent in well E-10. The TPH concentration has decreased by 35 to 45 percent in wells E-2, E-5,and BHD-1,by 70 to 75 percent in E-8 and E- 11,and by>90 percent in E-12. The TPH concentration has remained nondetectable in well PR- 1. Two weeks prior to the April 23, 1991 sampling event, the groundwater extraction system was in operation intermittently. During this time approximately 12,500 gallons were discharged to the sewer. The groundwater contours in Figure 1 most likely reflect the operation of the groundwater extraction system. The:grotmdwmer extraction system went into frill operation on June 5, 1991. The results of the ruing of the discharge water are reported in monthly status reports. Changes in constituent concentrations in the monitoring wells as a result of extracting groundvmrer will be presented in future quarterly reports. Brown and Caldwell u'NU