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unbackfilled void space in the annulus and possibly the well. The permit did not contain information <br />showing that annulus around the well screen was packed with pea gravel or sealed so I suspect that <br />the fines from the backfilled cuttings may be silting the well in. The application does not have any <br />design plans for the wells other than depth, diameter and formation monitored. No information is <br />given as to whether the screened interval is gravel packed. Gravel packing helps to filter the fines and <br />keeps the wells from silting in. <br />The well has never had its total depth measured so it is not known if this well has a silting problem. <br />One way to check siltation of a well, is to measure the depth of the well to see how much of the <br />original design depth remains. I am recommending that all well depths be checked annually and this <br />is to be reported in the AI-IR. I have included this as a concern at the end of the AHR review. <br />Replacement of Well AO-2 <br />Alluvial well AO-2 was reported to have gone dry and the mine has committed to replacing this well <br />prior to the April 1993 sampling. The AHR did not give an explanation as to why the well went dry. <br />I reviewed past AHRs and found that the well had broken off in 1984. This possibly lead to it being <br />filled with sediment. A well broken off at ground level could easily fill with surface runoff and <br />sediment. Table 62a of the permit application shows that this well was drilled to 14 feet. Monitoring <br />of this well, encountered mud at 6 feet indicating that the mud was 8 feet thick in the well. This well <br />was never measured for total depth as part of routine monitoring and the AHIt. The AHR made the <br />conclusion that the well had gone dry. In the past, other wells have been broken by cattle and should <br />be suspect of having a good portion of the screened interval silted in. Wells that are in areas <br />accessible by cattle should be protected from breakage. <br />Also, I am concerned that the problems with this well were not recognized earlier and corrected. <br />The problem with this well appeared to have persisted for 8 years before being corrected. The <br />information from the routine monitoring should be used to locate wells that require repair or <br />rehabilitation. The following comments ,noted in the field note, should be an indication that the well <br />might have a problem. <br />AO-1 Broken off?/26/82 <br />AL-2 Broken off 7/26/82 <br />79-53 Lost -plugged <br />AH-2 Broken off 3/24/84 <br />79-43 10/26/83 Lost destroyed <br />79-26 plugged up for sampling <br />AP-2 Pipe broke at ground level picked up dead mouse 10/24/92 <br />Interpretation of Sampling Results and Graphical Representation <br />The Statistical representations of water quality data given in tables 1,2 and 3 of the 1992 AI-IR do <br />not adequately show changes in water quality. The tables should be supplemented with graphs. <br />Graphed water quality parameters would make changes apparent over time. The tables in the AHR <br />are indistinct, they represent the composite average, maximum and minimum analysis of all the coal <br />aquifer monitoring wells for 1992. Any change that may occur to a single well is diluted in the <br />average of the other wells. Graphing the data would facilitate the detection and interpretation of <br />