REP01431 - Laserfiche WebLink

Home Browse Search

• • • 2.0 Hydro(agic Data lmrrpreranan and except for conductivity. After neazly four years of lowering levels of conductivity in well SG-1, east of the lower refuse pile, WY 1994 conductivity measurements increased sharply, with the maximum reading exceeding the range of baseline measurements. A comparable increase was not observed with the TDS data. This steel- cased well has exhibited measureable concentrations of [oral iron. This is attributable to both the well casing and the high concentration of sediment which is entrained while sampling this relatively dry hole (see comments in Appendix H). 2.3.2 Barren Member There were no significant changes in water level in Barren member wells during WY 1994. Shallow wells include SW-1 through SW-6 and B-32. Wells SW-1 through SW-6 were dry or had so little water as to not permit sampling and, except for SW-1, have been so since they were drilled. Well B-32 has collapsed at a depth of approximately sixty feet, five feet above the bottom of the well. Monitoring continues, as there may still be hydraulic integrity of the well, allowing measurement of the piezometric surface at the site. Even so, there is insufficient water in the well to obtain water quality samples. In general, water levels in B-32, SOM-13, and SOM-80 have not shown a seasonal fluctuation. Water levels did drop nearly fifty feet in Well SOM-13-H, a deeper well, during 1980 to 1981 and has stabilized except for a twenty foot rise and fall during WY 1993. Wells SOM-13-H and SOM-80-H also demonstrated a rise and fall in water levels during WY 1993, and have since returned to long term levels. Manganese concentrations in SOM-13-H ranged from 0.16 to 0.46 mg/I during WY 1994, exceeding baseline ranges of 0.0 to R1.210/10.V03/OS/93(8:04am) Arreument for the Permit and Adjarna Arrat 0.17 mgll (May and August samplings). Although the F seam was mined near this location, no specific explanation of the higher manganese concentrations has been developed. All other sampling parameters for wells SOM-13-H and SOM-80-H were within baseline ranges. Except for the portal azeas, no significant inflow of water has been seen in "F" Seam mined areas. If mining activities were a cause of the historic dewatering, apparently a hydraulic equilibrium is being reached. Although well information does not preclude establishment of a hydraulic connection via cracks in subsided overburden, no variance in spring flows have been recorded. At this time, the hypothesis that current mining has had little affect on shallow groundwaters within the Barren Member appeazs to be substantiated. 2.3.3 "F" Seam In WY 1994, a 20-foot water level drop was observed during the last of three measurements (October) at SOM-2-H. This well is located approximately 2,000 feet south of any mining activities. This water level drop in a well with historically stable water levels is presently unexplained. SOM-16-H, also an F-Seam completed monitoring well at similar distance from mining activities, did not show this peculiar water level decline. Continued monitoring of SOM-2-H should provide additional information on which to develop a conclusion regazding this observed decline. Levels of manganese in both well SOM-2-H and SOM-16-H rose over baseline maxi- mums of 0.05 mg/1 and 0.04 mg/1, respec- tively, during WY 1994. SOM-2-H exhibit- ed amaximum manganese concentration of 0.27 mg/1 while SOM-16-H exhibited a maximum concentra[ion of 1.05 mg/1. Both readings were associated with high concen- trations of TSS and reflect the sampling methodology rather than any impacts from 20 Revlse~ lo/ouvn