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I13 April 2005 AGE-NC Project No 01-0827 Page 2 of 7 2 1 OZONE SPARGE SYSTEM OPERATION The ozone-sparging (OS) system has operated continuously since 01 July 2003, the system was I monitored and serviced at regular intervals throughout the quarter In February,the compressor was replaced, due to system vandalism The OS system consists of an ozone generator, which produces ozone-rich air at 10 standard cubic feet per minute (scfm) and a pressure of 20 pounds per square inch This ozone-rich air is delivered to wells IAS-1 through TAS-3 via a subsurface network of a/a- inch polyethylene tubing ' Because the infected ozone will eventually break down to dissolved oxygen(DO), a DO meter was utilized at each monitoring well during the monitoring events to determine the effectiveness of ozone sparging DO and/or oxidation/reduction potential(ORP)in ground water wells adjacent to the IAS ' wells were measured on II February 2005 Dissolved oxygen concentrations have generally increased in ground water wells since remediation-system startup in July 2003,negative ORP values in the monitoring wells near ozone infection well IAS-1 suggest a reducing environment around the Iozone discharge points (Appendix B) ' 22 OZONE SPARGE WELL INSTALLATION ' In February 2005, one additional sparge point was installed and connected into the sparge network through a dedicated tubing connection On 07 February 2005, one soil boring was advanced for collection of soil samples and installation of one air-sparge diffusion well (OZI) I 2 2 1 Drilling and Sampling On 07 February 2005, a soil boring (OZ1) was advanced at the site A CME-95HT truck mounted drill rig was utilizing to advance 8 25-inch diameter hollow-stem augers to a depth of approximately ' 32 feet below surface grade (bsg) The drill rigs and three-man crew were supplied by Cascade Drilling Incorporated of Rancho Cordova, California Auger returns generated by drilling were containerized in properly labeled Department of Transportation (DOT)-approved model 17H ' 55-gallon drums and were stored on-site The waste soil was then stored on-site pending disposal Soil samples were collected from the air sparge well pilot boring ahead of the drill bit using a ' California modified split-spoon sampler loaded with three pre-cleaned 2-inch by 6-inch brass sleeves The samples were collected from the pilot boring at 5-foot intervals,beginning at 5 feet bsg, yet not sampled at 10 or 15 feet due to sand backfill and concrete in the base of the former ' excavation, using a 140-pound hammer to advance the sampler The number of blows required to advance the sampler over each 6-inch increment of the 18-inch sampling interval was recorded on IAdvanced GeoEnvzronmentai,Inc 1