Laserfiche WebLink
10 June 1999 <br /> AGE-NC Protect No 97-0290 <br /> Page 7 of 26 <br /> I The extracted air stream was monitored for the presence of organic vapor using an organic vapor <br /> analyzer(OVA)equipped with a photo-ionization detector(PID Thermo Environmental 580A, 10 0 <br /> eV, calibrated to isobutylene) The air flow was monitored using a Dwyer DS-300 flow sensor The <br /> flow rate was determined from the measured differential pressure and the piping diameter using a <br /> nomograph (Appendix A) Field measurements were recorded at regular intervals throughout the <br /> pilot test and are summarized in Tables 8 and 9 <br /> I <br /> 43 COLLECTION AND ANALYSIS OF SOIL GAS SAMPLES <br /> I Four soilsam as les were collected at two-hour intervals from the inlet of the extraction well <br /> g p <br /> I (VW1B) to measure concentrations of extracted hydrocarbon vapor One additional soil gas sample <br /> was collected after 30 minutes of extraction from VW1A The samples were collected in Tedlar bags <br /> using a hand air pump <br /> IFollowing sample collection,the samples were labeled, placed in a cooled container and transported <br /> under chain-of-custody to McCampbell Analytical Inc (MAI) in Pacheco, California Each sample <br /> • I vas analyzed within 72 hours for TPH-g and BTE&X with methyl tertiary butyl ether (MTBE) in <br /> accordance with EPA Methods 8015m and 8020, respectively <br /> 44 RESULTS OF VAPOR EXTRACTION PILOT TEST <br /> The extraction flow rate from VW I B was approximately 55 to 60 standard cubic feet per minute <br /> (scfm) with an induced vacuum ranging from approximately 30 to 40 inches of water Extraction <br /> flow from VW1A was approximately 17 scfm with an induced vacuum ranging between 50 inches <br /> of water to approximately 6 inches of mercury (82 inches of water) Hydrocarbon concentrations in <br /> the well effluent stream were measured at regular intervals PID field measurements ranged from as <br /> high as 5094 parts per million(ppm)near the beginning of the test to 887 ppm during the second half <br /> of the test The lower hydrocarbon concentrations may be due to water vapor in the extracted vapor <br /> stream effecting the OVA Field measurements are summarized in Table 8 <br /> Induced vacuum measurements were recorded at wells M W I, MW2, VW 1 A, V W 1 C and six -vapor <br /> monitoring points (installed with SW I and SW2) utilizing magnehelic gauges The greatest vacuum <br /> Imeasurements were observed at SW213 and MW2, each located approximately 10 feet from VW1 <br /> High vacuum potentials were also measured at SW 1 B, located 20 feet from V W 1 and at V W I C, <br /> I which was screened 4 feet below V W 1 B Induced vacuum was also observed at MW I, SW2A and <br /> VW 1 A Induced vacuum was not detected at S W 1 A, S W 1 C and S W2C Measured induced vacuum <br /> potentials (negative pressure) for the SVE pilot test are plotted on Figure 7C <br /> Adraeced GcoEn%ironmental,Inc <br /> I <br />