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1' <br /> • bioremediated It is also an oxygenate We hausubmitted a work plan to help define <br />' whether the MtBE is coming from the onsite tanks <br /> Dissolved oxygen levels were recorded this quarter The levels were measured with a <br />' calibrated YSI model 51 B meter by placing the sensor 5 feet below the surface of the <br /> water table after the bailing of the wells The measured levels are shown on Table 3A and <br /> Figure 5 The readings of dissolved oxygen are between 0 4 at well BM-1 and 8 2 at well <br />' BM-10 Figure 5 indicates that natural attenuation is taking place generally below the 3 5 <br /> mg/L level This is in the area of the old tanks The levels appear to be stabilizing across <br /> the site <br /> As requested in the EHD letter dated January 10, 2000, a plot of the wells and the old and <br /> new piping runs of the dispenser Imes is shown in Figure 7 <br />' VAPOR EXTRACTION SYSTEM <br /> The site has been under remediation since July 1997 A total of 43,441 pounds of <br />' gasoline has been removed since the beginning of this project <br /> The vapor extraction system (VES) was shut down since April 13, 2000 because of a <br />' problem with the sparging system We attempted to restart the VES system and found <br /> that the air sparging was not working After considerable study we found that the pipe that <br /> transports the air from the sparging compressor to the well has a leak At this time we are <br /> assessing the way we will correct this problem We expect the system will be operating <br /> this quarter <br /> The air sparging works as shown by the decrease in contamination in well BM-1 and BM-5 <br /> last quarter We feel it is beneficial to operate the system even if there is some mounding <br /> locally around the sparging well and pushing the contamination toward well BM-8 This <br /> contamination will be treated through natural attenuation as it moves eastward from this <br /> well <br /> Conclusions <br /> We will continue to monitor this site The next monitoring event will take place in July <br /> 2000 <br /> Attached is a Hazardous Waste Manifest indicating the prurged water was removed <br /> I <br />