ARCHIVED REPORTS_XR0012222 - Laserfiche WebLink

Home Browse Search

' r M . Nuel Henderson ' Page 4 of S VAPOR EXTRACTION SYSTEM ACTIVITIES ' Vapor Extraction System Operation ' Several attempts were made to operate the vapor extraction system during the third quarter. However, for unknown reasons, the system shuts down after running for approximately 8 hours. Additional repairs are necessary before the system can be placed back in full time ' operation. The system was started on August 18, 2005 to collect an influent vapor sample and to collect ' vapor samples from wells VW2, VW3, VW5, and VW6. Vapor wells VW 1 and VW4 were not sampled as the screens are submerged. Vapor samples were submitted to state-certified Air Toxics Laboratories for the analysis of TPHg, BTEX and MTBE by EPA Method TO-3. The system was then shut down pending the laboratory results. Field notes are included in Attachment D. the concentration of TPHg in the influent sample, which is a composite of the flow from each of the vapor wells, including necessary dilution air was 830 micrograms per liter (ug/1). Analytical data for the influent sample are summarized in Table 4. TPHg concentrations in the individual vapor wells ranged from 240 ug/l in well VW3 to 7,300 ug/l in vapor well VW6. MTBE was detected at low concentrations in the vapor samples from ' wells VW3 and VW6. These are the furthest upgradient vapor wells. See the laboratory report, included. in Attachment E, for individual vapor well sample results. lie RECOMMENDATIONS ' Groundwater Monitoring and Sampling Reduce the sampling frequency for wells that are monitoring the plume of contamination originating from the onsite release. Given the massive quantity of historical groundwater data at this site, continued quarterly sampling is not warranted. We also recommend that sampling ' responsibility for the wells that are affected by the offsite release(s) be transferred to the appropriate responsible parties. As requested in your letter of August 31 we propose the groundwater sampling schedule described in Table 5 pending the possible transfer of sampling ' responsibility for several of the wells. Vapor Extraction System Operation The analytical data collected on August 18 indicate a fairly substantial rebound since the ' system was idled in 2002. An initial hydrocarbon extraction rate of at least 20 pounds per day could be anticipated if the system were in operation. By focusing on wells VW2, VW5 and VW6, this rate could quite likely be increased. Only by placing the system back in operation ' can it be determined how quickly vapor concentrations will decrease. We recommend placing the system back in operation as soon as repairs can be made. lie ' G:IGROUTNDZFIROF.K\QMR12@051-3gtn26p5.dnr, I I� I