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Coal A1e16ane Druimuge Projat- Pane6 16-24 Wert E!k Mine • Page 3-G <br />characteristic understory vegetation or distinct vegetation changes. Based on these site-specific <br />surveys, riparian areas typically extend along part or the entire bottoms of perennial and intermittent <br />drainages, varying in width from 25 to 100 feet and, in some cases, including small ponds and small <br />isolated wetland areas. Many of the smaller ephemeral drainages may have no flow for several <br />consecutive years and contain limited or no riparian areas. <br />Appendix B displays Special Stipulations that apply to riparian areas (Section 15, Item (b)(2)). The <br />stipulation states that "A 1/8 mile buffer zone (660 feet) will be protected on either side of riparian <br />zones (or a buffer zone may be established in accordance with the surface management agency <br />guidelines). No surface disturbances, except surface subsidence, will be permitted within these buffer <br />zones, unless no practical alternatives exist." For this project, the USFS has replaced the 1,320 foot <br />buffer zone with the buffer zone that is prescribed in the Forest Service Watershed Conservation <br />Practices Handbook (FSH 2509.25), the Water Influence Zone (WIZ). The WIZ includes the <br />geomorphic floodplain, riparian ecosystem and inner gorge. Its minimum horizontal width (from top <br />of each bank) is the greater of 100 feet or the mean height of nature dominant late-seral vegetation. <br />It includes adjacent unstable and highly erodible soils (Reid and Ziemer 1994). WIZ areas aze shown <br />on Map M1, Project Area Activities With Surface Stipulations <br />3.1.2 Environmental Consequences <br />3.1.2.1 Effects Common to Alternatives 2, 3, 4, and 5 <br />Soil removal, stockpiling, and replacement, along with consequent compaction and erosion would <br />change soil characteristics in affected areas. Although disturbed areas can be reclaimed and <br />rehabihtated, the soil productivity will be changed. <br />The potential for impacts on subsurface geology from the proposed activities is considered to be <br />negligible. The drilling activity itself and proposed methane drainage measures would not affect <br />geologic conditions or materials. <br />The Conditions of Approval listed in Section 2.4 of this document include many measures designed <br />to minimize soil disturbance. Despite these practices, erosion, soil loss, and sediment transport from <br />newly disturbed areas would still affect neazby drainages. Depending on proximity to streams and the <br />amount of sediment carried by mnoff, surface water quality (turbidity and suspended solids) could be <br />temporarily impacted. <br />No bedrock aquifers are expected to be intercepted during the proposed drilling operations, however, <br />shallow colluvial or perched ground water could be encountered. Those drill pads located near <br />drainage bottoms would be most likely to encounter ground water. Drilling operations would use <br />circulation media including air, water; and biodegradable polymer foams. Gels, surfactants; and <br />bentonite-based dolling muds would also be used to stabilize boreholes, if necessary. Other <br />materials, including crushed peanut shells, cottonseed hulls, and cedar fibers could also be added to <br />the circulation medium to help seal the walls of the hole to maintain circulation and minimi>e loss of <br />drilling fluids to the formation. These materials would normally maintain pressures in the boreholes <br />adequate to prevent substantial ground water inflows to the boreholes if water is encountered. <br />If substantial quantities of water were encountered in any borehole, high-density additives would be <br />introduced with the circulation media to contain the water flows, and casing would be extended and <br />cemented in place to case off the flow source. Casing of the IvmWs would prevent deterioration of <br />the borehole, and cementing the casing in the borehole would prevent flow of either gas or water in <br />the annulus between the casing and borehole and prevent contamination of ground water of mixing <br />between ground water sources. It is anticipated that these standard drilling and completion measures <br />would be effective in preventing or controlling any project-related effects to ground water quantity or (- <br />quality. L <br />IV.CP/AIwu~GdG/EAIO.yr Jl~/nS%i UjFj <br />i/1/OLb <br />Environmental A.rrerrment <br />