SITE INFORMATION AND CORRESPONDENCE FILE 1

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-�CLEARWATER G R O U P, I N C. were less than 1.5% in all wells within the contaminant plume (VW-1 through 3, MW-2), and 10.5 % in MW-7, which is located outside of the contaminated area. These results indicate that the combustion process will be hindered during initial stages of the planned SVE test, resulting in the application of a less than ideal vacuum to the tested wells. The vacuum is limited due to the need to bleed fresh air into the system during the test through a pre-combustion bleed valve. A diagram of the Ceecon IC engine is attached. The location of the subject air inlet valve is shown. Analysis As we discussed yesterday, the results of the pre-testing have yielded the following information: • The shallow subsurface does not yield groundwater readily under bailing conditions. It is anticipated that the well would exhibit the same characteristics during the pump test. • The recovery well was only marginally developed during installation. While it is recognized that the formation will only yield low flows, it is also recognized that the test well should be as well developed as possible, thereby allowing the collection of the best data set possible during the aquifer/vadose zone testing. • Even with the limited information currently available, it is fairly certain that groundwater extraction alone will not sufficiently remove the contaminants from the subsurface. Experience with similar sites, however, suggests that vacuum assisted groundwater extraction is a potentially feasible remedial approach, and as such should be evaluated during the pilot testing process. As we discussed yesterday, this approach involves the application of vacuum to a groundwater extraction well, which a) increases the rate of sediment dewatering, b) exposes the vadose zone in the vicinity of the pumping well to the well screen and facilitates air flow, and c) generally incre=ases the rate of site remediation. A figure showing a generalized cross section of a dual phase well is attached. • While vacuum extraction may be feasible, it alone will not facilitate total site cleanup. Air sparging (also due to be tested) may assist in the removal of hydrocarbons from the water-saturated zone and for that reason is incorporated into the pilot testing program. Based on information generated to date, however, it appears as if some form of dual-phase extraction and treatment will be necessary, and Clearwater recommends the inclusion of the associated testing in the pilot program.