WORK PLANS - Laserfiche WebLink

Home Browse Search

O1 July 2008 AGE-NC Project No. 97-0301 Page 7 of 8 After installing each well casing, a filter pack material consisting of coarse-grained aquarium gravel will be added over the screened interval to approximately two feet above the screened interval. A nominal two-foot bentonite seal (bentonite chips) will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite chips into the annulus and allowing them to settle on the filter pack. The bentonite chips will be hydrated using approximately five gallons of tap water and allowed to hydrate for a minimum of one-half hour prior to grouting. The remaining annular space will be filled to the ground surface with a cement grout. The grout mixture will consist of Type IM Portland neat cement and not more than 6 gallons of water per 94M pound sack of cement. The grout will be placed by pumping through tremmie pipe. 3 .5 . SOIL VAPOR EXTRACTION PILOT TEST Following SVE well installation, an &hour SVE pilot test will be performed at the site. The &hour SVE pilot test will be conducted from well VW- 1 (screened 10 to 30 feet). The 8-hour pilottests will be conducted at the site utilizing a minimum 2%2-horsepower, regenerative vacuum blower; the vacuum blower will be rated at a maximum 100 standard cubic feet per minute (scfin). The inlet of the vacuum blower will be directly routed to the VW-1 well head connected by 24nch diameter PVC piping. The outlet ofthe vacuum blower will be directly routed through four 400-pound, vapor-phase activated carbon adsorption canisters located adjacent the vacuum blower. Air-tight, 2-inch diameter PVC well caps fitted with attached Magnehelic (Dwyer) vacuum gauges will be attached to observation wells (MW-6, MW-7, VW-2 and VW-3) and the induced vacuum will be measured (i.el 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 extraction wells will be monitored for the presence of organic vapor using an organic vapor analyzer (OVA) equipped with a 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 8-hour SVE pilot test, the vapor flow rate extracted at VW- 1 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 standard cubic feet per minute (scfm) using a manufacture (Dwyer) supplied I Advanced GeoEnvironmental, Inc. it