Laserfiche WebLink
Christy Woodward <br />September 17, 2008 <br />Page 10 <br />within the mine stopes generally below the groundwater table, so that the wells will be free- <br />flowing. Boreholes will be installed using a ring drill or jack leg drill at a maximum drill <br />length of 100 feet and a diameter of approximately 3 inches. Monitoring wells will be <br />constructed of 1 inch schedule 80 PVC casing and a threaded stainless steel packer. The collar <br />of the borehole will be sealed around the PVC casing with insulation foam and silicone <br />sealant. A standard bentonite or cement annular seal used in vertical wells above the screened <br />interval is not necessary in this application because the packer will isolate the sample interval <br />of the wells. <br />The stainless steel packer will be set at the top of the desired open interval. The open interval <br />will provide for groundwater sampling within a discrete interval of the borehole. In order to <br />facilitate use of a peristaltic pump in the event that the well is -not free flowing, an additional 1 <br />inch diameter PVC pipe will be attached to the bottom of the. packer and will extend down to <br />within 1 foot from the bottom of the borehole. The bottom 5 feet of PVC casing will consist of <br />slotted PVC screen and a bottom end plug. Permanent 1/4 inch polyethylene tubing (for <br />peristaltic pump operation) will be installed inside the entire length of PVC casing down to <br />middle of the bottom 5-foot screen section. In order to install the 1/4 inch peristaltic pump <br />tubing, the tubing must be threaded through all sections of PVC pipe prior to well <br />installation. <br />Once the appropriate length of open interval pipe is attached to the bottom of the packer, <br />additional 5-foot sections of PVC riser pipe will be attached to the top of the packer until the <br />entire well apparatus has reached the desired depth. Once the packer, casing, and tubing are <br />set to the desired depth, the packer will be inflated using the nylon packer inflation tubing <br />and nitrogen pressure regulator. After inflation of the packer, the well casing will be sealed <br />using a female threaded well cap with 1/4 inch barbed inlet/outlet fittings and stop/check <br />valve. Foam insulation and silicon joint sealant will then be applied around the PVC casing at <br />the collar of the boring hole. <br />For wells, that are drilled to a length of 100 feet, the open interval will be set at 80 to 100 feet. <br />For the smaller length monitoring wells, approximately 50 feet and 25 feet, the open intervals <br />will be set at approximately 35 to 50 feet and 15 to 25 feet, respectively. Note that for all wells, <br />the screened PVC length will only be 5 feet. After completion of well installation, well <br />locations will be surveyed. <br />The naming system for monitoring wells will be as follows: MW01 <br />MW = Monitoring well abbreviation <br />01 = Well number