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• (Page 3) • <br />MINE ID # OR PROSPECTING ID # M-99-002 <br />INSPECTION DATE 10/20/99 INSPECTOR'S INITIALS ACS <br />The wells installed in the large diameter multiple completion holes are 2 inch PVC grouted <br />above and below the screened interval. High pH in the Uinta completion of well 29-4 may be <br />an indication that the cement grout has infiltrated the filter pack and well screen. The <br />usual causes of grout in the filter pack are: <br />• Cement emplaced directly on top of the filter pack without an adequate intervening layer <br />of bentonite and too close to the well screen. <br />• Consistency of cement mix too thin (too much water). <br />• Cement not allowed to cure prior to well development. <br />The result of cement in the filter pack/well screen may be persistent contamination of <br />samples where the analysis shows: <br />• High pH. <br />• High specific conductance. <br />• High alkalinity. <br />• High calcium, chloride, sodium, and sulfate. <br />Grout contamination may also result in lower dissolved metals in the analysis due to <br />precipitation caused by higher pH. The Operator should provide, with submittal of the first <br />data set, a comparison and analysis of wells where grout contamination is suspected with <br />results from other wells completed in the same stratigraphic horizon. From this comparison, <br />the utility of the potentially contaminated wells may be evaluated. <br />It was observed that water drawn from monitoring well 29-4 was degassing as it is brought to <br />the surface. The Operator reports that this effect is typical of most of the monitoring <br />wells at the site, with the exception of the alluvial wells. Certain monitoring wells have <br />bubbled over the top of the casing during sampling operations. Overtopping of the casing <br />could lead to cross contamination in the multiple completion wells. The DMG suggests that <br />the following procedures be followed: <br />• Fill sample bottles to the top leaving zero headspace prior to replacing the bottle cap. <br />• Drill a drain hole in the surface casing at the top of the cement such that water would <br />exit the surface casing onto the ground instead of overtopping and flowing into the <br />monitoring wells. A drain hole is a good idea for all the wells in case rain or snow get <br />in under the protective locking well caps. <br />The Operator was able to collect water quality samples from the dissolution surface during <br />the first sampling round at wells 29-2, 21-4, and 21-3. However, subsequent efforts to <br />collect samples from the dissolution surface have been unsuccessful due to mineral <br />precipitation in the small diameter sampling tubing. Chemical (weak acid) and mechanical <br />efforts to clear the tubing have been unsuccessful. During this inspection, 750-psi pressure <br />was applied to the dissolution surface tubing in well 29-4 without moving any water. These <br />problems with dissolution surface sampling were anticipated in the approved Groundwater and <br />Surface Water Monitoring Plan, which states: <br />Micro purging has been unsuccessful at the monitoring wells completed at <br />the dissolution surface because the high TDS concentration promotes mineral <br />precipitation within the bladder pumps. Dedicated down-hole conductivity <br />and temperature monitoring devices will be used to monitor the dissolution <br />surface. <br />