Laserfiche WebLink
®AWAM_ <br /> -� "mW ®nim► <br /> Working to Restore Nature <br /> r <br /> Vapor Extraction Well Construction <br /> Vapor extraction wells were constructed of thread jointed, 4-inch-diameter schedule PVC <br /> casing. No chemical cements, glues, or solvents were used in well construction. The <br /> screened portion of the wells consisted of factory-perforated casing with 0.020-inch-wide <br /> slots. No. 3 sand was placed in the annular space opposite the screen to approximately 1 <br /> foot above the top of the slotted casing. A 2-foot bentonite plug was placed above the sand <br /> pack, and a cement-bentonite slurry was used to fill the remaining annulus to the surface. <br /> A traffic-rated cast-aluminum utility box with a PVC apron was placed over each wellhead <br /> and set in concrete flush with the surrounding concrete pad. This box has a watertight seal <br /> to protect against surface water infiltration and is opened with a special wrench. The design <br /> of the box discourages vandalism and reduces the possibility of accidental disturbance of the <br /> well. <br /> Monitoring Well Construction <br /> The monitoring well was constructed in the boring with thread jointed, 2-inch-inner- <br /> diameter, Schedule 40 PVC casing. No chemical cements, glues, or solvents were used in <br /> well construction. The screened portion of the well consisted of factory-perforated casing <br /> with 0.020-inch-wide slots. The well screen extends from the total depth of the well to <br /> approximately 5 to 10 feet above the groundwater surface. This screened interval allows <br /> sampling at. the air-water interface during seasonal fluctuations of the groundwater level. <br /> The annular space in the well was packed with number 3 sand to approximately 1 to 2 feet <br /> above the slotted interval. A 3-foot thick bentonite plug was added above the sand pack to <br /> prevent the cement from entering the well pack. The remaining annulus was backfilled to <br /> grade with a bentonite cement slurry. <br /> The well was protected with a traffic-rated, cast-aluminum utility box equipped with a PVC <br /> skirt. The box has a watertight seal to protect against surface-water infiltration and must <br /> be opened with a special wrench. The design of this box discourages vandalism and reduces <br /> the possibility of accidental disturbance of the well. <br /> Well Development <br /> We waited a minimum of 24 hours after well installation before developing the groundwater <br /> monitoring well to allow the grout to seal. Before developing the monitoring well, a water <br /> sample was collected for subjective analysis from near the water surface in the well with a <br /> Teflon bailer cleaned with a laboratory-grade detergent and deionized water. Floating <br /> product was not encountered. The well was developed with a surge block and pump. Well <br /> development continued until the discharge water was clear of silt and sand. Clay-size <br /> 1213ccar/3OW4-8 <br />