WORK PLANS - Laserfiche WebLink

Home Browse Search

20 October 2008 AGE-NC Project No. 99-0592 Page 2 of 3 3.0. TWENTY FOUR-HOUR SOIL VAPOR EXTRACTION PILOT TEST An initial 24-hour SVE pilot test will be performed at the site, conducted from wells MW-1 and MW-8 (screens exposed from 44 to 70 feet bsg). This test will utilize a minimum 21/2-horsepower, regenerative vacuum blower; the vacuum blower will be rated at a maximum 100 cubic feet per minute(CFM). The inlet of the vacuum blower will be directly routed to the vapor well heads and connected with a well head coupling and to the SVE unit by 2-inch diameter PVC piping.The outlet of the vacuum blower will be directly routed through four 200-pound,vapor-phase granular activated carbon(GAC) adsorption canisters located adjacent the vacuum blower. Air-tight, two-inch diameter PVC well caps, fitted with attached Magnehelic (Dwyer) vacuum gauges, will be attached to observation wells (MW-2 through -7) and the induced vacuum will be measured(i.e. inches of water) at these monitoring points. The induced vacuum will be monitored in 30-minute intervals during the pilot test and recorded in inches of water. Additionally, the vapor stream from the extraction wells will be monitored for the presence of organic vapor using an organic vapor meter(OVM)equipped with a photoionization detector(PID). The vacuum applied at the SVE well should cause hydrocarbons in the vadose zone to volatilize and flow into the operated vapor well or monitoring well,and through the regenerative vacuum blower. From the vacuum blower,the extracted hydrocarbon vapor will be processed and adsorbed through the carbon canisters as part of the treatment process.Hydrocarbon concentrations in the SVE effluent stream will be measured at hourly intervals utilizing an OVM. During the 24-hour SVE pilot test,the vapor flow rate for the individual wells will be monitored at the inlet of the vacuum blower using a Dwyer DS-200 flow sensor(inches of water); the flow rate will be converted to CFM using a manufacturer(Dwyer)-supplied conversion chart. Additionally, a Blue-White F452 flow rotometer will be used to measure influent and effluent SVE flow rates from the GAC system. Flow rates will be measured in 30 minute intervals and documented in CFM and inches of water of differential pressure.Each well will be monitored for depth to ground water prior and during the SVE pilot study. Influent vapor samples(air flow samples)will be collected at start-up,and at regular intervals from the inlet of the extraction well,to measure concentrations of extracted hydrocarbon vapor.An SVE effluent sample will be collected at the start and termination of the twenty four-hour test. The samples will be collected in Tedlar bags using an air-vacuum pump. Following sample collection, the samples will be placed in a covered container and transported under chain of custody to a California Department of Public Health (CDPH)-certified analytical laboratory for analysis. Each sample will be analyzed within 72 hours for TPH-g and Volatile organic compounds(VOCs)[BTEX and fuel additives] in accordance with EPA Methods 8015M and 8260B. Advanced GcoEnvironmcntal,Inc. t