REP42433

• Permit No: C1981008
• IBM Index Class Name: Report
• Doc Date: 12/11/2001
• Doc Name: APPROVED HYDROLOGICAL MONITORING PLAN 1996 PN C-81-008 APPENDIX A
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

chemistry. Production of acid may occur in very local settings and is probably most prevalent iii
the coal which will be mined. Calculations indicate that neutralization of they acid will occur
rapidly with mixing of water, or with movement of acidic water into calcite-bearing rocks. Also,
the analysis conducted indicates that chemical changes are not likely to occur. _
Effects of mining on the local geomorphologk Impacts from mining on the local
geomorphology will be long term, but appear to be of minimal significance. The reestablished
reach of the drainage which will be mined will result in a shorter, slightly steeper stream channel.
The potential for increased sediment loads in the drainage (once pond 007 is removed) should
be offset by the stable banksides and the relatively small change in overall gradient. The
increased runoff and consequent erosion potential on disturbed basins in the mining area due to
the temporary loss of topsoil stricture should be of minimal significance. Contour ripping,
mulching and revegetation have been demonstrated to minimize soil erosion and will be used tc
mitigate the increased runoff potential until the topsoil structure is developed.
Effects of sediment ponds on channel characteristics and downstream users. Potential
impacts of sediment pond 007 on downstream users will involve possible reductions in flow due
to impounded water. The water augmentation plan discusses the available ~roater which will be
used should impacts be identified. WFC currently has rights to a sufficient quantity of water to
supply all users associated with the mining activities, plus an additional quantity of water that can
be used to mitigate any impact io downstream users.
Effects of sediment pond discharge on surtace water quality, The effects of sediment pond
diversions on surface water quality will be negligible because the structure has been designed to
minimize imp<rcts to the hydrologic balance. The diversion involves such minor areas of
disturbance that chemical and sediment changes in the flows will be unmeasurable.
Effects of runoff from reclaimed areas on the quality of streamflow. Due to the relatively
small area of disturbance in the New Horizon 2 mining area, any reductions in runoff will have .
only a minimal impact on streamflow quantity, as flow in Calamity Draw is dominated by irrigatior
return flow. Decreased sediment loads predicated by SEDCAD+ indicate that reclamation effort;.
conducted in the mining area will ensure that additional contributions of suspended sediment in
runoff from reclaimed areas will not occur. Effects of runoff from reclaimed areas on the quality
of streamflow. Based on past operating history at the Nucla Mine, no significant trend toward
higher concen4rations of the selected parameters have been detected. In addition, the pond
discharge will be monitored in accordance with NPDES discharge limitations and any potential
impact will be identified. Therefore, runoff from the reclaimed area should have no significant
impact over time on the quality of receiving stream water quality. As a result, post mining land
uses which currently occur in the area should not be affected due to the mine plan which has
been approved.
Summary. The discussion presented herein of the probable hydrologic consequences of the
revised mine plan approved by WFC identifies the potential effects of mining. Table 2.05.6(3)-1
summarizes the discussion by listing the probable hydrologic consequences and the results of
the analysis of each. As can be seen, all of the probable impacts have been determined to be of
a short term nature, of minimal significance, or a plan has been presented to mitigate those
determined to have some significance. As a result, mining and post mining affects to current
land uses should be negligible.