SITE INFORMATION AND CORRESPONDENCE

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� �ZAY, 1�, �9y ' � �9�. ��iC� B56EI PdO, 93� i6 METHODOLOGY ORC Injection Approximately 28 ORC infection points will be advanced within the site boundaries at the locatioas shown on Figure 4 using a truck-mounted Geoprobe System. Twenty five ORC injection points will be used for remediating the w1urated zone and three ORC injection points will be used for remediating the TPH impacts in both the witurated and unsaturated zones. The ORC in the saturated zone injection I points will be injected using a high pressure, horizontal injector tool from the total depth of each borehole(i.e., a depth of about 20 feet)to a depth of about 10 to 12 feet bgs. The remaining portion of the borehole(i.e.,from l Offeet bgs to the surface)will be backfilled with neat cement. The three injection points designed to treat both above and below the water table,will have ORC injected from the jtotal depth of tate borehole,to the ground surface. Regenesisg estimates that the ORC dose requirements will be about 6 pounds of ORC per foot for the saturated zone injections and about 25 pounds of ORC per foot in the vadose zone:. As a result of the winter reinfalt, there should be sufficient soil pore water in the vadose zone to satisfy this chemical reaction of the ORC and thereby facilitate the release of oxygen and the biodegradation of. TPH and BTEX. An irrigittion system may be installed at a later date if the monitoring data suggests that additional water is needed:for degrading the hydrocarbons in the vadose zone. The irrigation system would include an extraction well(EX-1)and six to eight sprinkler heads. Because electricity is not immediately available atthe site,the groundwater extraction system would be powered by a solar panel. In addition, if groundwate7 samples from wells MW-Z,MVV-5,MW-6 and MW-7 indicate that the site is deficient in nutrients(i.e.,nitrates and phosphates),a standard lawn-type fertilizer(or equivalent)may be spread onto the surface prior to irrigating the area,or mixed in with the irrigation water. Figure 4 is a three-dimensional sketch showing the conceptual layout of the remedy. Soil Sampling Soil samples wiil be collected from selected boreholes and analyzed for total petroleum hydrocarbons as gasoline (TPH-G)and BTEX compounds by EPA method 50301601518020,total extractable petroleum hydrocarbons as kerosene. diesel and motor oil (TPH-K,TPH-D, and TPH-MO) by EPA method 351016015M, redox poten,ial,and BOD and COD. The soil samples will be collected from a depths of about 7 and 15 feet Detai is regarding soil sampl ing procedures arc presented in Appendix A. Additional borings may bi; advanced and sampled adjacent to one or two injection points to document the horizontal distance the ORC penetrated into the surrounding soils using the high pressure,horizontal injector tool. 402 331-98 63 4-2