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<br /> <br />Comments on CWI's Proposed Refuse Site <br />February 3, 1983 <br />Drainage and Sediment Control <br />1. Is the construction of the West Ridye pile sedimentation pond <br />necessary? If there is additional available capacity in CWI's existing <br />ponds 3 and 4, it may be advantageous to route runoff from the pile to <br />the drainage that leads to these ponds, as opposed to constructing a new <br />pond. <br />2. The pond proposed below the West Ridge pile was desiyned to handle <br />runoff from a 5.17 acre area of the refuse site. However, from mine <br />drainage maps, it appears that additional runoff from the mine crushing <br />and screening level, as well as other mine levels, is discharged through <br />the waste area site (by way of culvert N). This extra runoff volume will <br />need to be accounted for in the pond volume designs, or else diverted <br />away from the site. <br />3. Drainage from the East Ridge pile will flow to CWI's existing ponds <br />3 and 4. This plan appears to be acceptable. However, the applicant <br />should verify that the existing ponds have extra available capacity to <br />handle any extra flow from the pile. Also, would it be possible to <br />install a collection ditch at the lowermost portion of the pile to route <br />flows directly into the drainage? This would be better than allowing the <br />funoff to disperse uncontrolled over the adjacent undisturbed areas. <br />4. Runoff from the East Ridge pile than collects in the east diversion <br />flows to the pond access road. Please indicate whether this road culvert <br />has been sized to handle the design flow. <br />5. CWI should submit a plan view of the proposed West Ridge pond at a <br />scale capable of showiny 1-2 foot contour intervals. This will be needed <br />to verify pond volwnes (Rule 4.05.6(4)). <br />b. The stage-area-storage capacity curves for the waste pile pond <br />should be submitted to verify pond volwnes and levels (Rule 4.05.6(4)). <br />7. A non-clogging automatic dewatering device needs to be located at <br />the 100% sediment storage level to dewater the pond after rainfall events <br />(Rule 4.05.6(3)). The existing pond has been built as an impoundment. <br />8. The design of the dewatering device should consider an adequate <br />detention time that will be needed to settle solids to meet effluent <br />limits. Detention time (or decant time) should be calculated and stated <br />(Rule 4.05.2(9)). <br />