WORK PLANS - Laserfiche WebLink

Home Browse Search

• well construction is included on the boring logs in Appendix A. Well elevations and horizontal locations were determined by professional survey. The professional surveyor's letter of transmittal of survey results is included as Appendix B. The top of PVC casing reference elevation for each well is included in the summary of well construction information (Table 1). Location and elevation information is also included on the boring logs for each well (Appendix A). The well locations shown in the site map(Figure 2)reflect the relative well positions as determined by professional survey. Wells were developed using a variable flow rate submersible pump. Development water was discharged to the ground near the well head such that it did not runoff into any surface water body. Wells MW-2 and MW-4 were developed immediately prior to the January 6th initial sampling as specified in the Workplan. These wells were pumped to dryness repeatedly until clear water was produced during pumping. Development and sampling of MW-1 and MW-3 could not be completed at the same time due to equipment and other problems as described below. Well MW-1 and MW-3 were developed using a pneumatic pump approximately 1 week prior to initial sampling of those wells on January 25,2005. Wells MW-1 and MW-3 were also repeatedly pumped to dryness until clear water was produced during pumping. The occurrence of a"flowing sand"complicated well construction and well development at MW-3. During placement of the sandpack,the augers had flooded with a black,organic-rich water to a depth of 70 feet below ground level. Some of the organic material was obviously incorporated into the sandpack during well construction. After placing the sandpack, a"slow reacting"bentonite was used at MW-3 in order to assure that the material reached the top of the sandpack before hydrating. When well development activities were initiated,it was discovered that an unusual amount of mud had settled in the base of the well pipe and the static water level in the well was at approximately 60 feet BGL. The mud was eventually removed to a depth of 118 feet BGL after using a downhole probe to loosen the mud and a pneumatic pump to remove muddy water. Earlier attempts to remove the mud by over-pumping with an electric pump were limited due to lack of significant water flowing into the well, and adding water also failed to produce significant results. 5