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d` -MN f depth at this site. On August 8, 1991, four additional vapor extraction/air injection wells were installed to the 40 foot depth ^. around P3 to inhance the vapor recovey in that area. Conformation j soil samples were obtained at the 30 foot depth at that time, this depth exhibited the greatest degree of contamination in previous i borings at the site. Laboratory results of these samples indicated that this area had been vacated of contamination with only a minor amount of xylene being indicated at P3A (0.17 ppm), see Table 1 and Figures 3A and 4E. Ground water has also been effected by the vapor extraction at this site, Figures 6A and 6B represent the ground water gradient as measured on August 5 and September 15, 1991. The thin contour lines are the actual ground water gradient produced by vacuum extraction and show a high ridge being formed at MW1 and MWS. The dark lines are the contours of the potentiometric head, which shows the reverse as expected by creating a vacuum at these wells, a basin being formed around MWl and MWS. The actual ground water flow would follow the potentiometric pattern, or travel to areas of lower pressure. Table 2 shows how the ground water sampling has indicated ground water remediation Uy the vapor extraction at this site. MW1 sampling prior to vacuum extac' ion on November 21, 1990 had total petroleum hydrocarbons as gasline (TPH-g) of 2 parts per million (ppm) and benzene at 5.2 ppm.. The September 15, 1951 sampling shows both the TPH-g and Benzene to be below detection limits. Monitor well MW5 had TPr.-g at 31 ppm and benzene at 5.4 ppm on November 21, 1990. The September 15, 1991 sampling shows reduction of TPH-g to 0.4 ppm and benzene to 0.0098 PPM. DESTRUCTION OF VAPOR EXTRACTION WELLS P1, P3-SWARM AND EX. As stated above, vapor hydrocarbon production from P1, P3-Swarm and EX is very minor and it is felt that all recoverable hydrocarbons have been removed from the site to the 40 foot depth, thus completeing the remediation of sail for this site. Western Geo-Engineers along with Hogate Drilling will destroy these Wells (P1, P3-swarm, EX) at this time and also monitor well MW1, so the surface of the lot can be brought up to grade and resurfaced to the specifications of the land owner, who wishes to lease out this property, it has set vacant during this initial vacuum extraction phase. Monitor well MW1 will interfere with the future plans �,f the lot. The wells will be destroyed, by drilling them out with 10" augers to remove all well materials. Once the wells are drilled out neat cement with 6% bentonite will be trimied to surface to seal the wells and prevent these areas becoming potential conduits for vertical migration. --------- CONFIRMATION SAMPLE BORING ------ ---- - ----- --- ------ ---- - To verify that vacuum extraction has removed the recoverable gasoline range hydrocarbons from the vadose zone (25-40 foot page 3