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constructing a sediment pond is not warranted. Sediment contributions from the small disturbed area can effectively be controlled using the stated Best Management Practices (BMP's), and therefore falls under a n SAE, consistent with • applicable provisions of Rule 4.05.2(3)(b). The will be no discharge or mixing of mine water with surface drainage from the site. Given the limited site azea, agravel-surfaced pad area, the drainage and sediment control measures, and the effectiveness of the BMP's in reducing peak settleable solids concentrations to 0.23 mUl (modeled results), TCC submits that an SAE is justified for this site. The estimated peak flow and nrrtoff from the site for the 10-year, 24-hour storm event is 1.52 cfs and 0.17 acre-feet, respectively. The peak settleable concentration in the runoff from the proposed Bleeder Shaft pad area is less than nattual settleable solids concentrations for runoff from undisturbed lands, given similar conditions. The upgradient diversion ditches will be triangular ditches designed to safely divert the peak flow from the 10-year, 24- how storm with a minimum of 1-foot of freeboard and located as shown on Figwe 1, Bleeder Shaft Pad SAE. The shaft pad will be constructed such that it slopes towazd the gravel filter. The check dam and grass fiker efficiency was modeled using the SEI)CADTM4 check dam and grass Slter utility. Exhibit 5 is submitted to demonstrate that application of diversion ditches, drainage collection ditches, wattles, Curlex blankets, and the sump, rock check dam, and grass filter can effectively control and treat nuroff from this azea. Thickener Under-]ow Pipelines and Borehole (TR07-60. MR07-221) -With the exceptions of the sutface casing for the Underflow Borehole and any intermediate access manhole(s), surface distwbance for the Thickener Underllow Pipelines and Borehole wID be temporary and surface activities will be. limited to pipeline'borehole installation activities. During construction, and for the minor surface structures, drainage and sediment control will be provided by Alternative Sediment Controls (ABC's) consisting of combined Best Management Practice (BMP) meastues. Construction-related surface disturbance will be limited to soil removal and windrowing from the pipeline trench alignment and borehole pad azea, excavation of the trench and temporary stockpiling of excavated material adjacent to the Vench, and excavation of temporary pits (within existing disturbance areas) for pipeline boring or jacking operations under the Foidel Creek culvert crossing and railroad spw. Following installation of appropriate ABC's for each portion of the project disturbance, available soil materials will be bladed from any new disturbance areas and temporarily • windrowed on the upgradient edge of the distwbance area. Much of the pipeline excavation and borehole pad disturbance will occw in areas that are, or have previously been, distwbed. For the remaining pipeline Vench aeeas, consideration of soil horizon segregation must be balanced with the objective of limiting overall surface disturbance. In the interest of m;n;.,,;zing overall surface disturbance, TCC proposes to not segregate and separately stockpile individual soil horizons for the pipeline Vench distwbance, and submits that this approach will not significantly alter soil suitability characteristics, since the differences between the soil horizons is not significant over the areas to be affected by trenching. For the borehole drill-pad, individual soil horizons will be segegated. Generally, to avoid contamination of the windrowed soil material, excavated material wilt be temporarily placed on the opposite side of the distwbance area. BMP's for the construction activities include: • Minimizing the area of surface disturbance • Installation of the Foidel Creek crossing as a bored/jacked pipeline under the existing Foidel Creek road crossing culverts (avoids new surface disturbance of the stream channel and floodplain) • Completion of construction activities during the dry summer period • Placement of staked straw wattles downgradient of all surface distwbance areas to intercept any surface runoff and trap associated suspended solids • Soil replacement and stabilization with temporary revegetation plantings immediately following completion of construction acgvities Where pipeline disturbance traverses steep slopes, additional staked straw wattles will be placed on contour to limit overland flow following revegetation seeding. Temporary drainage and sediment control measures will remain in-place until vegetation is sufficiently established to effectively control runoff, erosion, and sediment loss. Drainage and sediment control for the minor surface swetures (borehole surface casing and any manhole(s)) will also utilize BMP's • including the vegetative fiber provided by temporary vegetative stabilization, and berms and/or wattles; as appropriate. As a relatively small (0.6 acres) linear surface disturbance. the additional disturbance required to either construct or intercept and route runoff from the disturbed area to a sedimentation pond is not wan arned. The proposed BMP's have M R07-2? ] 2.05-84. ] 08/21 /07