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-2- No additional surface disturbance will occur as a result of this revision. Therefore, the only impacts that would occur would be limited to effects of subsidence on the South Starkville Gulch stream channel. The channel traverses the site in a westerly direction. Complete extraction of panels will cause changes in the profile of the streambed, but should not significantly affect flow. A small nick point in the stream channel may occur just inside the western permit boundary where the natural and subsided stream channels meet. This nick point may be the subject of increased erosion during rainfall events that lead to_ f_1ow in_the_ephemeral drainage.~The stream channel will be surveyed and \ monitored during full extraction to determine if any significant profile l change or excessive erosion at the nick point occurs. Also, as a result of subsidence, there is a possibility of surface water entering the ground along fractures. It is unlikely that any significant amount of surface water will enter the yround through fractures due to the limited time and amount of water flowing in the channel. The grade of the channel is steep and rapid flows occur during storm events which would not allow much seepage into fractures to occur. The nature of the immediate roof and other strata above the coal would not lend itself to the formation of cracks at the surface, or allow any cracks to remain unsealed. This would further impede surface water infiltration through subsidence-related fractures and cracks. As a result of the extended area of mining, there is a potential for an increase in the quantity of water entering the mine workings than previously expected. Fbwever, because of the low flow rates evident from springs, seeps and wells in the area, coupled with the fact that past mine workinys showed little water inflow, it is unlikely that a large enough inflow will occur to cause significant effects on water quantity downgradient. b. Cumulative Impacts Assessment The additional activities described in this permit revision will not change the cumulative impacts assessment that is found in the Findings of Compliance for the permit application. - c. Surface and Ground Water Monitoring The applicant has proposed a revised plan for monitoring surface water which may be potentially impacted by the operation. The ground water monitoring plan will remain as originally proposed and stipulated in the permit application and stipulations No. 6 and 7 of the Findings of Compliance. The current plan provides adequate monitoring coverage of potential impacts. The revised surface water monitoring plan includes the installation and use of a crest stage recorder in South Starkville Gulch at the point where the stream channel intersects the western permit boundary. Grab samples will also be taken at this point for water quality analysis during surface flow events. + `` y ~ a a a f • J~ ~• f u~a ~tb.fY "~ /1' .~` '.' . I et ~ A Y. ~ J.