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Diversion design is addressed in Sections 2.4.1 and 2.4.4 of the application. Channel <br />reconstruction is discussed in Section 3.5 of the application. Applicable maps and tables are <br />referenced in the cited text sections. <br />The following specific approval is required by Rule 4. <br />1. Rock riprap lining is proposed for use to control erosion in certain reclaimed <br />ephemeral stream channels. This measure is proposed to be approved by the Division, since the <br />riprap lining is necessary to control erosion, and the lined channels will be stable and will require <br />infrequent maintenance (4.05.4(2)(a)). <br />C. Sedimentation Ponds <br />There is one sedimentation pond at the mine, located between the portal bench area <br />and the office facilities area, on the south side of the haul road. The pond treats runoff from the <br />portal bench disturbed area, the upper segment of the haul road surface and cut slopes, and a small <br />supply storage area. The pond is somewhat oversized (storage volume adequate to contain the <br />sediment and runoff from multiple 10 year, 24 hour precipitation events below the level of the gated <br />8" primary discharge pipe). In addition to the primary discharge pipe, the pond has an open channel <br />emergency spillway designed for the 25 -year, 24-hour precipitation event. The sedimentation pond <br />is discussed in Section 2.4.4 of the text, and designs are depicted on Figure 2.2-3. <br />The sediment pond was filled in with sediment by a 100 year magnitude storm event <br />in August 2001 that had buried and overwhelmed one of the primary upland diversion culverts. In <br />association with excavation of sediment, the inside slopes of the sediment pond were reduced to <br />approximately 2H:1 V. The re -constructed pond was properly certified by a professional engineer <br />(see "Impoundment Yearly Inspection" of March 29, 2002). The pond embankment failed in 2004, <br />apparently as result of leakage from the buried primary discharge pipe. The embankment was <br />reconstructed and the primary discharge pipe was replaced. Embankment reconstruction was <br />properly certified (see "Sediment Pond Certification" of December 14, 2004). <br />D. Surface and Ground Water Monitoring <br />GROUND WATER <br />Information provided by the applicant with respect to ground water in the permit area <br />can be found in 4.2.2 through 4.2.4 of Volume I of the permit application. The monitoring plan is <br />described in Section 4.2.4, and monitoring parameters are specified in Table 4.2-15. <br />As discussed in the Probable Hydrologic Consequences (PHC) section of this <br />document, no significant effects to bedrock or alluvial ground water systems are anticipated for this <br />operation. The applicant will conduct monitoring of ground water in a manner approved by the <br />Division to verify the projections of the PHC. The ground water monitoring plan is as follows <br />(4.05.13(1)): <br />1. Quarterly monitoring of alluvial wells GW -1 and GW -9 for static <br />water level, pH, temperature, and specific conductance. <br />2. Water quality sampling of mine water discharges as required by <br />CDPS permit. <br />