ARCHIVED REPORTS XR0010978 - Laserfiche WebLink

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CLOSURE 22, 03-25-93 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 investigation, 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 drilling of monitor well- MW4, north-northeast of the tank pit, at the 11.5 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 SB1 west-northwest of tanx 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 .duality of the ground water in this area. This - .,,nitoring well, constructed in the north-northeast soil boring would be sufficient to monitor this area of concern. Theg round water samples obtained for verification analysis will, in addition to total petroleum hydrocarbons, benzene, •toleune, ethylben.zene and xylene, be analyzed 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-northeaeL soil boring utilizing 811 hollow stem augers to drill and sample the boring, and 2° 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 = 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 along with the three previously existing wells occurred on March 18, 1993 (72 hours after development of MW4) . All weds tested belcw Petr Hydrocarbons detection limits for Total. Petroleum y rocarbons as gasoline, =: BTEX and Lead, see Table 2 and Appendix A - Laboratory Reports ' and Appendix C - Field Notes. page 2