FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

.Y , 27 September 2007 AGE-NC Project No. 99-0682 Page 2 of 6 wells MW- lA, MW-3 , MW-4 and MW-5 screened from 20 feet to 40 feet bsg) with air-tight well caps fitted to each observation well. A sample port was tapped into the PVC near the extraction well head and a portable OVA equipped with a PID was used to measure influent organic vapor concentrations. The organic vapor concentrations, the induced vacuum potential at the observation points (measured utilizing a Magnehelic vacuum gauges), and the extracted soil gas flow rate were measured at 0.25/0. 5-hour for the first hour of the pilot study, and then later at 1 -hour intervals for 1 the remainder of the pilot test. The pilot test data are summarized in Table 1 . 2. 1 . 1 . Lower Vadose SVE Pilot Test Sampling and Analysis A total of six soil vapor samples were collected during the pilot test. Vapor samples were collected at 2-hour intervals beginning at 0900 hr from the sample port at the extraction well VW- 1 to measure hydrocarbon concentrations in the extracted soil vapor; one sample was collected at 1700 hr from an effluent port at the end of the pilot test. The samples were collected into Tedlar bags, transported in a container under chain of custody to CTEL, and analyzed within 72 hours for the following constituents: • Total Petroleum Hydrocarbons as gasoline (TPH-g) in accordance with EPA Method 8015M; and • Benzene, toluene, ethyl-benzene and total xylene (BTEX) and Methyl-tertiary butyl ether - l (MTBE) by EPA Method 8260B. I 2. 1 .2 . Analytical Results of Soil Vapor Samples - Lower Vadose JTPH-g was detected in the influent vapor samples collected from lower vadose vapor well VW- I at concentrations ranging from 69,000 micrograms liter (µg/1; 0900 hr) to 90,000 µg/1 (1700 hr) . j Toluene, ethylbenzene and total xylenes were detected in the vapor samples at concentrations as high as 2,300 µg/1 toluene, 1 ,800 µg/1 ethylbenzene and 5,800 µg/1 total xylenes in the vapor sample collected at 1700 hr. MTBE and benzene were not detected at or above the laboratory detection limits in all the samples analyzed. Constituents of concern were not detected in the effluent vapor sample collected at 1658 hr on 17 July 2007. Analytical results of soil vapor samples are summarized in Table 2 . The laboratory report (CTEL Project No. CT214-0707135), QA/QC report, and chain of custody forms are included in Appendix B; the confirmation number for GeoTracker submittal of laboratory electronic deliverable format (EDF) is 9040231049 . Advanced GeoEnvironcnental, Inc. i 1