Laserfiche WebLink
Water discharge from each dam utilizes corrugated metal risers and steel <br />• discharge pipes. Each riser is designed to be completely watertight with the <br />exception of the surface aperture and dewatering device. <br />Pond dewatering is accomplished by means of two non-clogging skimming <br />devices -- one placed below the crest of the riser and above the trapped sedi- <br />ment, and the other placed just above the sediment storage area. A detailed <br />illustration of the dewatering device is presented in Map 13 and Map 14. <br />The sediment pond discharge pipes were constructed in competent foundation <br />material and extend below each dam, across riprap, to a point where discharge <br />water impacts to natural drainage would be minimized. <br />Sediment will be removed from ponds at such times as the sediment material <br />is equal to the sediment storage design capacity. A permanent mark located in <br />• the sediment storage impoundment area has been placed to make a visual inspec- <br /> tion when sediment removal will be necessary. Removed sediment will be exca- <br />vated from the ponds when sediment can be excavated. To enhance drying <br />sediment, the material will be excavated from the sediment pond and placed in <br />furrows in the area above the pond until the material is suitable for disposal. <br />Since the material is predominantly eroded topsoil, the material will be used as <br />topsoil for reclaimed backfill repair maintenance or disposed in the designated <br />sediment disposal area adjacent to Culvert No. 1 (Map 8). <br />In addition, a sedimentation pond was constructed to control runoff from <br />disturbed areas adjacent to the backfilled area. The pond is located on the <br />explosive storage area (Map 9), at the request of the landowner. Flow calcula- <br />tions for the structure are presented in Appendix 2.05.3-9 and are summarized as <br />• follows: <br />- 191 - (Rev. 5/86) <br />