WORK PLANS - Laserfiche WebLink

Home Browse Search

t • • October 1,2004 NOA Project Number: LE03-034 3.1 Well Design ' The anticipated monitoring well design is proposed next. The ground-water depth for the area has been reported to be between 107 to 127 feet. The actual depth to ground water may affect the proposed monitoring well design. Please see attached monitoring well design (Plate 2). Anticipated Monitoring Well Design for Ground Water Depth of 120 feet. Bore Hole Diameter= 6 %z inch (hollow stem auger) Anticipated Total Bore Hole Depth = 130 feet(no over drilling). Anticipated Solid Casing Below Ground Surface = 1 15feet;from a depth of 0 to 115 feet. Anticipated Solid Casing Above Ground Surface = 3 feet Anticipated Perforated Well Screen Interval= 15 feet;from a depth of 115 to 130 feet. Anticipated transition seal= 2 feet thick;from a depth of 111 to 113 feet. Filter Pack = 113 to 130 feet in depth (minimum 2 feet over well screen). Annular seal thickness= 2.1 inches The proposed drilling of the monitoring wells will be by a Mobile B53 truck mounted drill rig operated by Neil O.Anderson &Associates, Inc. of Lodi,CA. The rig is capable of drilling with either 6 '/z to 8 inch diameter hollow stem auger to a depth of 150 feet. Should a larger drill rig be required should auger refusal be encountered,the drilling will be subcontracted. Sampling of the soil will be either every 5 to 10 feet using a Shelby sampler through a wire line. Satisfactory conditions for well completion include locating a permeable strata at or below the ground water level. We anticipate this level to be about 120 feet plus or minus 10 feet. ' Schedule 40 PVC, 2-in diameter casing will be installed through the hollow stem auger. The outside diameter of the Schedule 40 casing is 2.35 inches. A 2 inch annular seal will be obtainable with the use of the 6 '/2 inch diameter auger flight. The filter pack will be placed through the hollow stem auger. The filter pack will be surged to induce settlement and checked to ensure proper filter pack dimensions. A sanitary seal will be ' pumped through a tremie pipe from above the transition seal to the ground surface. The sanitary seal will consist of neat cement grout with 5%bentonite. ' Should the depth of ground water be different than 120 feet, the well design will be adjusted so 10 feet of screen are below ground water and 5 feet are above ground water where permeable material exist. If no relatively permeable materials exist at the ground water surface, deeper drilling will ' proceed to locate suitable permeable strata. Based on well logs in the area,we expect relatively permeable sands to exist near the anticipated ground water depth of 120 feet. 5 '404