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well. If this technique does not work then another hole will have to be drilled and the well constructed in the new boring. The Spring, 1991 sample from well 001-83-106 showed anomalously high calcium and magnesium and low sodium compared with samples from previous yeazs; however, the Fall, 1491 sample analysis values for these constituents were back within the normal range of previous years as were the 1992 and 1993 samples. \J i~ The water quality data for the Twentymile Sandstone wells 006-82-48A and 006-BRDH-7 aze summarized on Table 7. The data does not indicate any trends that appeaz related to the underground mining. The conductivity values for the Twentymile Sandstone monitoring wells aze plotted on Figure 14. They do not indicate any long term trend. The wells have a field conductivity ranging from 400 to 1430 umhos/cm. This is within the range expected for the unaffected aquifer, with the possible exception of the fall 1992 reading for well 06-82-48A which has been replaced. in the center of the basin, and the lack of proximitt1y t~ any r urge s~ ~~,ly ~ I W ~a~ r5 I-YS I ~[11~.~ i Q I Alluvium a ®p(p-87-1 ~ dole-~ ~ _ The water quality data for the Wadge Overburden aquifer wells is summarized on Tables 8 to 13. A plot of dissolved solids is presented on Figure 15. The plot does not indicate any trends that appear related to the underground mining. The unaffected Wadge Overburden groundwater is generally sodium-bicarbonate type as indicated by previous water samples from wells 006-87-1 and 006-88-2 prior to dewatering by mining activities. We11006-82-74C, and to a lesser extent we11009-79-4, aze probably affected by spoil water from the surface mining activities as they-are both located downgradient of reclaimed surface mined areas. This influence is reflected in higher total dissolved solids values and a trend to acalcium-magnesium sulfate water type. Well FBR-1la shows elevated TDS levels but this appears to be more a function of this well's location Sediments in the Foidel Creek valley upstream and downstream of the portal azea are monitored. Also, the sediments in the Fish Creek valley within Twentymile Park are monitored. Four wells completed in the Foidel Creek alluvium are monitored. Five wells completed in the Fish Creek alluvium are monitored. The Fish Creek alluvial well date associated with the undermining of Fish Creek are presented in Appendix B. One additional monitoring well has been installed in the Trout Creek alluvium, and the monitoring results for this site (08-AT-1) will be reported in the 1944 AHR. -4- 6110/94 1:23 pm 7 I