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MAY 09 195 04:01PM CLERRWATER GROUP r•dl4 <br /> CLEARWATER <br /> S I� 2 0 lJ J1, F N C. <br /> Recon ended Modifications <br /> Well Developrt;ent <br /> In order to ensure that the extraction testing planned for the site obtains the most <br /> representative data, Clearwater recommends that the newly installed recovery well <br /> be re-developed. This redevelopment shall be accomplished using a development <br /> rig. Activities will include swabbing, air jetting and bailing as appropriate until <br /> such time that it is determined that the well is as developed. as possible. <br /> Development fluids will be containerized irk a poly tank or in 55 gallon drums, and <br /> removed %ith fluids generated during the formal testa <br /> Aquifer/Vadose Zone—T& tin <br /> Given the observed.lack of recovery well recharge during the preliminary test, a <br /> conventional groundwater extraction test (as proposed in the approved workplan) <br /> will not be possible. It is also apparent that the ultimate remediil approach will <br /> likely not include simple groundwater recovery from wells. As such, an alternate <br /> means of aquifer performance testing is recommended. <br /> Experience with similar projects suggests that the consideration of a dual phase soil <br /> vapor/groundwater extraction system as a long term remedial rneasute may be <br /> appropriate for this site. In order to evaluate this possibility, Clearwater <br /> recommends that the pilot testing approach planned for this site be slightly <br /> modified. These modifications include the completion of a dual phase pilot test <br /> using the existing recovery well and (possibly) an additional morii-toring well. The <br /> test will be executed by performing a modified version of the proposed groundwaker <br /> extraction test and the proposed vapor,extraction test. <br /> A low flow pneumatic pump shall be situated near the bottom of the recovery well. <br /> The pump will remove standing water, as well as any water that entered the well <br /> during the test. The well head will be configured to enable a connection to the <br /> Ceecon internal combustion GQ engine that will be used for test vacuum <br /> generation. The dual phase test will then be completed. Methods to be employed <br /> during the combined test will be similar to those associated with tests completed <br /> individually.(as described in the previously submitted workplan). <br /> .The.low measured oxygen levels will initially compromise the effectiveness of the <br /> IC engine (hinder combustion and applied vacuum). The oxygen levels will, <br /> however, increase within 'a fairly short period as ambient atmospheric air is <br /> transferred to •the subsurface, enabling efficient engine performance- and the <br /> application 'of .the appropriate vacuum to the wellhead. It is therefore <br /> recommended that the combined application be allowed to operate for five days. <br /> The sparge test will be completed on the fifth day, with the dual phase system in <br /> operation_ <br />