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Chaptei 4- Best Mana ement Practices.for Erosion.and-Sedlnfent COntroh Maximum velocities The maximum allowable velocity in the emergency spillway channel will depend upon the type of lining used . For vegetated linings, allowable velocities are listed in Table 5 .35a .. (STORMWATER CONVEYANCE CHANNEL - Section 5 . 35 - ES SMP 1 .35), For non-erodible linings , such as concrete or asphalt paving and riprap , design velocities may be increased . However, the emergency spillway channel shall return the flow to the natural r channel at a non-eroding velocity . See Appendix 1 .26A for design details . Stabilization of the Embankment and Basin r The embankment of the sediment basin shall be temporarily seeded within 15 days after ifs completion as per TEMPORARY SEEDING - Section 6.65 (ES BMP 1 .65) . if excavation is r required in the basin , side slopes should not be steeper than 2: 1 . Cleanout r Sediment shall be removed from the basin when the capacity is reduced to 55 cubic yards per acre (104 3/ha) of drainage area. This elevation should be clearly marked; preferably r sin shall .state the methods for disposing of on the riser. Plans for the sediment. ba sediment removed from the basin . Possible alternatives are the use of the material in fill areas on-site or removal to an approved off-site dump . Finaremoval r. Sediment basin plans shall show the final disposition of the sediment basin after the upstream drainage area is stabilized . The plans shall specify methods for the removal of excess water lying over the sediment, stabilization of the basin site, and the disposal of any excess material. Sediment shall not be flushed into the stream or drainageway. Safe VE Sediment basins are attractive to children and can be very dangerous . Therefore , they should be fenced or otherwise made inaccessible to persons or animals unless this is ,. deemed unnecessary due to the remoteness of the site or other circumstances . Strategically placed signs around the impoundment reading "DANGER-QUICKSAND" should also be installed. In any case , local ordinances and regulations regarding health r and safety must be adhered to . Construction Specifications r Site Pry an Areas under the embankment and any structural works shall be cleared , grubbed , and stripped of topsoil to remove trees , vegetation , roots , or other objectionable material. In order to facilitate cleanout and restoration , the pool area (measured at the top of the +� principal spillway) will be cleared of all brush and trees . 4-89