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.. R Y w.m-,. 3PUTP+Ye. / — e•�'ss J.'.J. _ <br /> MRS.sr <br /> n <br />'�J e <br /> FIELD MEMODS <br /> Vapor-Extraction Well installation <br /> A schematic diagram of a vapor-extraction well is shown on Plate P-3. The wells will be <br /> constructed of thread-jointed, 4-inch-diameter schedule polyvinyl chloride (PVC) casing. <br /> No chemical cements, glues, or solvents will be used in well construction. The screened <br /> portion of the wn!!r %v;!! c^nsist of factory-perforated casing with 0.020-inch-wide slots. <br /> The interval between 10 and 25 feet below grade will be screened using slotted casings. <br /> No. 3 sand will be placed in the annular space opposite the screen to approximately 1 <br /> fool above the top of the slotted casing. A 2-foot bentonite plug will be placed above <br /> the sand pack, and a cement-bentonite slurry will be used to fill the remaining annulus to <br /> the surface. <br /> A traffic-rated cast-aluminum utility box with a PVC apron will be placed over each <br /> wellhead and set in concrete flush with the surrounding concrete pad. The box has a <br /> watertight seal to protect against surface water infiltration and is opened with a special <br /> wrench. The design of the bQx discourages vandalism and reduces the possibility of <br /> accidental disturbance of the well. <br /> Vapor-1 xtraLIon Test <br /> The vapor-extr"ction test has two objectives: (1) to collect operational data to evaluate <br /> the efficiency and practicality of vapor extraction as a soil remediation alternative and <br /> (2) to select the most appropriate off-gas treatment alternative, if the operational data <br /> suggest that vapor extraction is recommended. Applied GeoSystems will perform the <br /> vapor-extraction test in accordance with San Joaquin County Air Quality District <br /> guidelines. <br /> A portable vapor-extraction system will be transported to the site and operated as <br /> required to obtain vapor samples and vacuum pressure and flow rate information. <br /> Vapor samples will be collected into sample bags at the inlet and outlet of the vapor- <br /> extraction test system and submitted to a State-certified laboratory for analysis of TPHg <br /> and BTEX. Chain-of-Custody protocol will be followed throughout field and laboratory <br /> procedures. <br /> Applied GeOSYWOMS <br />