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1 <br /> <br /> <br /> <br /> <br /> <br />1 <br />Draft: March 31, 1999 Page 7 <br />monitoring well, designated 21-4, will be located inside the northeast boundary of the first-phase <br />mine panel which isdown-gradient of the assumed flow directions. Monitoring well 21-4 wil I have <br />four completion zones, as detailed in Section 1. This layoutprovides forup-gradient, down-gradient, <br />and cross-gradient groundwater monitoring, according to all published and site-specific data. <br />The multiple-completion monitoring wells will be constructed in large-diameter boreholes <br />to allow a grout mixture to flow freely and fully seal the borehole between the completion zones. <br />All well construction materials (sand, bentonite, and grout) will be placed from the bottom of the <br />borehole by the tremmie method. Each completion will be constructed of 2-inch-diameter, <br />Schedule 80, flush-threaded, O-ring sealed, solid PVC, and machine-slotted PVC well screen of <br />equal specifications. Atypical multiple-completion monitoring well is shown on Figure 3. <br />2.2.2 Existing Monitoring We/ls <br /> <br /> <br />LJ <br />1 <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br />I~ <br />Groundwater monitoring wells have been constructed at the Yankee Gulch Project site to <br />monitor the experimental test mine phase in preparation for monitoring of commercial operations. <br />These wells will be incorporated into the proposed groundwater monitoring plan. The existing wells <br />are all single completions. Of the ten existing wells, two aze completed at the Dissolution Surface, <br />two are completed in or near the B Groove, two are completed in or near the A Groove, and three <br />aze completed in the Uinta Formation. Monitoring of the water supply well 20-8 for water quality <br />provides monitoring of changing conditions resulting from operation of the test facility. <br />The existing Dissolution Surface monitoring wells include 29-2 and 20-1. Monitoring well <br />29-2 is an up-gradient well, and monitoring well 20-1 is adown-gradient well. <br />The existing B Groove monitoring wells include 20-4 and 20-9. Monitoring well 20-4 is a <br />cross-gradient well, and monitoring we1120-9 is adown-gradient well. <br />The existing A Groove monitoring wells include 29-3 and 19-2. Monitoring well 29-3 is in <br />the well field and will monitor cross-gradient or down-gradient trends, depending on the position <br />of the mine cavities. Monitoring well 19-2 is across-gradient well. <br />The existing Uinta Formation wells aze 20-5, 20-8, and 20-]0. Monitoring well 20-5 is a <br />down-gradient well, water we1120-8 is adown-gradient water quality and water supply well, and <br />monitoring we1120-10 is across-gradient well. . <br />Agapito Associates, Inc. <br />