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CLOSURE 22, 03-25-93 i letter of February 25, 1993, which resulted in this futher investigative report: 1) The soil samples obtained in 1988 from the south and southeast ends of the former tank pit area indicate this area has not been impacted by petroleum hydrocarbons. Therefore, only the areas to the north- northeast and to the northwest of the former tank pit need further investigati,:;n, to verify that these areas have not been impacted by petroleum hydrocarbons. A soil boring in each of these locations would be sufficient for this verification purpose. The laboratory results of the soil sample obtained from the drillingof monitor well MW4, north-northeast of the tank pit, at the 10.5 foot depth (just above top of ground water) were below the detection limits for gasoline range hydrocarbons and BTEX. The laboratory results of the soil sample obtained from the drilling of soil sample boring SBI , west-northwest of tank pit, at the 11 foot depth (just above top of ground water) were also below the detection limits for gasoline range hydrocarbons and BTEX, see Figure 3, Table 3 and Appendix A - Laboratory report. 2) A monitoring well in the identified downgradient direction, to the northeast of the former tank pit area at this site, is needed to verify the quality of the ground water in this area. This monitoring well, constructed in the north-northeast soil boring would be sufficient to monitor this area of concern. The ground water samples obtained for verification analysis will, in addition to total petroleum hydrocarbons, benzene, -toleune, ethylbenzene and xylene, be o.nalyzed for soluble lead. This test will be sufficient to verify that the ground water quality has not been degraded by lead. MW4 was constructed in the north-northeast soil boring utilizing i 8 hollow stem augers to drill and sample the boring, and 21' F480 SCH . 40 PVC threaded casing with five feet of 0.02 inch slot to construct the well, see Appendix B for boring and construction logs and Appendix D - Addendum Work Plan. This monitoring well was installed on March 11, 1993. The well was developed on March 15, 1993, by :swabbing and surging the slotted interval and then j pumping the ground water from the well until water came clear, after approximately 10 gallons. An additional 17 gallons of ground water was then removed to insure proper development, see - ----Appendix 'C - Field Notes_ Sampling of this well--a?ong-with-.._the---------------------------_-- - --- -- three--prwiausly-existiing wells.: occurred on March 18, 1993 . (72 hours after development of Mw4) : All walls tested below detection: limits for: Total Petroleum Hydrocarbons as gasoline, BTEX : and- Lead, see Table .2 and Appendix A - Laboratory Reports and Appendix.C Field Notes. page 2