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404 WEST FREMONT STREET <br /> -(A No.No. 1628.09 <br /> August 31, 2001 <br /> Page 10 <br /> be used to remove petroleum hydrocarbons and VOCs before discharge into the atmosphere. The <br /> filters will consist of two 55-gallon drums filled with 400 pounds of 4 x 6 mesh coal based <br /> : .� activated granular carbon pellets. The carbon filters will be equipped with two-inch diameter <br /> '= influent and effluent piping, sampling ports, temperature gauges,pressure gauges and a 6-foot <br /> :., high exhaust stack. The filters will also be equipped with diffuser manifolds designed for <br /> =+ uniform vapor flow and maximum exposure to the carbon bed. <br /> Vapor Extraction Wells <br /> Existing vapor extraction wells VEW 1 through VEW3 will be used to extract residual VOCs from <br /> the subsurface soil. Two additional vapor extraction wells will be installed in the vicinity of <br /> monitoring wells MW4 and MW5 as part of the remediation process. <br /> Two soil borings will be drilled to depths of 12 feet below surface grade using a truck-mounted <br /> drill rig equipped with hollow-stem augers. The borings will be converted into vapor extraction <br /> wells at the locations shown on Plate 3 to be used as a part of the remediation process for extracting <br /> subsurface soil contaminated with petroleum hydrocarbons beneath the site. <br /> The vapor extraction wells will be constructed using two two-inch diameter, flush jointed, <br /> - Schedule 40 PVC casing; 0A2-inch slotted casing will be used for the screened interval. The <br /> screened interval will extend from approximately 7 feet bsg to 12 feet bsg. Number 3 Monterey <br /> sand will be placed as a filter pack in the well annulus. The filter pack will extend from the bottom <br /> of the screened interval to approximately two feet above the top of the screened interval. A <br /> minimum two-foot thick bentonite seal will be placed in the well annulus above the filter pack. A <br /> F. <br /> grout seal consisting of Portland cement and bentonite slurry will be placed into the well annulus <br /> above the bentonite seal. Each well will be completed with a locking well cap and a flush- <br /> mounted,traffic-rated well cover(Plate 5). All drilling equipment will be steam cleaned as <br /> `. described above. All soil cuttings generated during drilling will be placed on a stockpile and stored <br /> on site. <br /> The vapor extraction wells will be connected to underground piping and stubbed-up and manifold <br /> J and connected to the vapor extraction unit inside the treatment enclosure. The soil vapor extraction <br /> 11tfr39,A�na i(l4pl$ <br /> ndrd�ajw. cj.A�;SQ iATF. �1YC, <br />