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Structure to minimize potential erosion at [he outlet. Construction and operation of the sedimentation ponds effectively confines increases in the suspended solids load of surface water to the permit area. ]n addition, • controlled discharge from the sedimentation ponds can be utilized to approximate pre-mining flow conditions in the receiving drainage. The sediment control structures were designed to accommodate runoff from the total area of watershed, which was partially disturbed by the mining operation. Localized, temporary diversion structures, including cutoff ditches and berms, were utilized in active mining areas to direct surface runoff around disturbed areas where this was feasible and practicable. No additional temporary structures were planned at the Eckman Park operation; however, these might be considered as a corrective measure if excessive sediment loads in runoff are encountered in the future. Any localized surface diversion measures implemented will be maintained until normal drainage patterns are reestablished on the regraded surface. Typically, CYCC installed contour ditches to minimize erosion of backfilled, graded, topsoiled and seeded slopes. A contour ditch minimizes erosion by shortening slope length on a hillside. These ditches are removed prior to final bond release, unless specifically approved for retention by the Division. The Division approved leaving the two contour ditches located above Pond H as permanent features (TR 99-39). These two contour ditches are shown on Map 9A, Sheet 3. All haulage and access roads were designed and constructed [o promote proper drainage and minimize erosion. Road design considerations that relate to drainage control included construction of lateral bar ditches, proper sizing and placing of culverts, practical limits on road grades, selection and placement of road base and surfacing material, and provisions for regular road maintenance. The drainage and erosion control measures for road construction practices at the Eckman Park operation limited the contributions of dissolved and suspended solids to the surface water system. • Water which accumulated in active pits was collected in pit ends and pumped [o the surface sediment control system. In addition to preventing potential impacts to groundwater quality, periodic pumping of accumulated pit water allowed settlement of suspended solids in the sedimentation control structures and returned pi[ drainage to the surface water system. • TR -3 iooo APR 2 ~ TR 00-39 780-144-9 04/17/00