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out4gkot no nks lnc Page 3 <br /> ULU—Pilot Test <br /> Project No. 425.2 <br /> June 14,2005 <br /> 2.1 Proposed Ozone Sparging (OS)Pilot Testing <br /> GTI proposes to install two ozone-sparging wells at the locations shown in Figure 2. The two <br /> sparging wells will be constructed as described in the Plan dated March 21, 2005 and shown <br /> in Figure 4. These two ozone sparging wells (OS-1 & OS-2) will be located in the highly <br /> contaminated area, Zone A, slightly north of the former underground storage tanks I and 2 <br /> (core of contamination). <br /> One observation (OW-1) well will be installed approximately down gradient(Figure 5) of the <br /> sparging wells (Figure 2). The observation well will be 23 feet deep and screened from 21 to <br /> 23 feet bgs (Zone A). MW-2 will also be used as an observation well during this pilot-testing <br /> phase. Site limitations preclude placing an observation well directly down gradient of the <br /> two OS wells without being in the east bound lane of Durham Ferry Road. <br /> Figure 3 shows the TPH-g contamination plume contours. Following is the procedure to <br /> operate the sparging system: <br /> o Prior to commencement of sparging, background groundwater samples will be <br /> collected from the two observation wells and analyzed for the following: <br /> ➢ Temperature,pH,EC,DO&ORP (field measurements) <br /> ➢ TBA, TBF, acetone <br /> ➢ TPH-g,BTEX and MTBE <br /> ➢ Hexavalent Chromium and Iron(total&ferrous) <br /> o The ozone sparging wells will be operated continuously for 7 days under the <br /> supervision of GTI professionals. <br /> o The water samples will be collected from each observation well for analysis as <br /> described below: <br /> ➢ Temperature,pH,EC,DO & ORP (field measurements)—every 4 hours <br /> ➢ TBA,TBF, acetone—daily <br /> ➢ TPH-g,BTEX and MTBE—daily <br /> ➢ Hexavalent Chromium and Iron— 1 a, 3rd,& 7a'day <br /> o A portable ozone sparging system will be used with the above ground ozone carriage <br /> pipes/hoses. <br /> o The equipment area will be secured with a temporary fence. <br /> o Depth to water (DTW) measurements will be taken in all "Zone A" monitoring wells <br /> and observation wells prior to sparging activities, on the 161, P, & 7a' days and <br /> immediately after sparging operations cease. <br /> o 'DTW measurements will also be taken in the observation wells twice daily to find any <br /> mounding due to ozone sparging. <br />