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k" KLEINFELDER 4.6 SYSTEM SHUTDOWN AND DISSASSEMBLY Aller the pilot testing is complete, the system will be shutdown, the main electrical breaker switched off and the sparge and ventilation well valves secured. Where necessary, the supplier(s) of the equipment will complete the piping and electrical disconnection and the system will be removed within two weeks of shutdown. Kleinfelder will manage removal of fencing, piping, wiring, and related items which were installed. To the extent possible, the site will be restored to conditions present prior to the pilot test although abandonment of the pilot test well will occur later. 1 4.'7 OZONE BENCH SCALE TEST Though Kleinfelder will be field testing ozone sparging in the source area of the site, there is potential that this testing will not provide sufficient information to evaluate effectiveness or to design a full scale remediation system utilizing ozone to treat the DCA at the site. The ozone generator has a relatively low production(1 pound per day)relative to demand of TPH for ozone f in oxidation(3 pounds of ozone per one pound of TPH). Consequently, there is potential that f ozone from the sparge well will be rapidly consumed in the TPH-rich source area before reaching the monitoring wells. Considering the intended use of the ozone sparging is to remediate the leading edge of the relatively low concentration DCA plume, we will simulate this condition with a bench-scale test using groundwater from MW-DISC-11. This testing will provide more specific information on the effectiveness of ozone exclusively on DCA in groundwater containing a concentration of 1,2-DCA and the dissolved minerals indicative of the proposed target area of the technology. The test will involve first purging MW-DISC-11 and drawing a sample and sending it to the laboratory for analysis for DCA. Extracted groundwater will then be placed into two 5-gallon plastic vessels, one completely filled (Vessel#1) and one half-filled, sealed and placed at room temperature (Vessel#2). A ceramic-dome fine bubble diffuser(see Appendix B) will be placed in Vessel #1 and ozone delivered through the diffuser at a rate of 0.1 ppm of ozone at 2 scfm for four hours. Gaseous ozone in the vicinity will be continuously monitored and ORP in the vessel will be monitored hourly. Immediately after the four hour sparging is complete, Vessel #1 will be tested for dissolved ozone and Vessel #2 will then be f lled with half of the ozone-rich groundwater from Vessel #1. After one hour at room temperature, a laboratory sample will be collected from Vessel #1 and analyzed for EPA 8260 compounds. After the ozoned groundwater from Vessel#1 has been in contact with groundwater in Vessel #2 for at least 2 hours it will be tested for dissolved ozone and a laboratory sample will be collected and analyzed for EPA 8260 1 compounds. The intent of this testing program is to investigate the effectiveness of gas phase ozone and dissolved ozone in reducing DCA in groundwater characteristic of the target area. The testing in Vessel#1 will indicate the effectiveness of gaseous-phase ozone oxidation on DCA. The testing in Vessel 92 will indicate the effectiveness of dissolve ozone oxidation on DCA and indicate the { effectiveness of DCA remediation in the absence of direct air bubble contact. The information 12280/2002R476 Page 21 of 26 Copyright 2002 Kleinfelder,Inc. May 17,2002