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a .r+-^+ R a'�'� -,C � .1'M kr 1'7's- i'if' •• �yc y � y@„ n +�.A� � �. �j':S� �i�BA�.Y R � . L Mr. Chuck Cannel July 30. 1991 Nee 13 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 cone 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 jet assisted surge block and bailing. This process significantly increased the prDduction of each of the wells that were redeveloped thus reducing the time needed to purge three well volumes for sampling. Analytical restets of groundwater samples and water-Ievel elevation are summarized in Table 3, along with previous results. The complete laboratory repos for the February 1991 sampling is presented in Exhibit C. Figure 2 shows BETTY 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-I did not contain detectable concentrations of BETX and TPH. The benz - concentration increased in well E-5, and decreased in wells E-8, E-10,E-11,E-12,and BHD-1. W Ethylbenzene,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 nondeteetable in well PR- 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 graurtdwater extraction system went into full operation on June 5, 1991. The results of the testing of the discharge water are reported in monthly status reports. Changes in constituent concentrations in the monitoring wells as a result of extracting groundwater will be presented in future quarterly reports. Brown and Caldrica