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ovrsrnrE nRrna~e ~aarncrior~/oo~wr ~ <br />• Purpose: Areas in which surface runoff is concentrated and routed over <br />outslopes have been identified as problematic in terms of <br />creating erosional features whidi are unacceptable order the <br />performance sta,rla,rls of the CNIIRD. Zb address these areas, <br />OOVCC installs dowrdrains as appropriate to el~m~*+~te and or <br />mitigate the development or potential development of these <br />erosional features. Zhe purpose of this specification is to <br />standardize the usage and wnstnu-tion of downdrains. <br />Usa4e: Dowrcirains will be used at, but are not limited to use at, the <br />following: <br />1.) Areas where surface runoffs from roads are concentrated <br />and discharged over outslopes and cannot, due to <br />topographic constraints, be rerouted. <br />2.) Areas where waste waters from facilities maintenance arcs <br />cleaning operations are concentrated and discharged wer <br />outslopes and cannot, due to topographic constraints, be <br />rerouted. <br />Construction: Dorm drains will be constructed as follows: <br />1.) Downdrains will be constructed from flexible EL1S plastic <br />• pipe or other such suitable material. <br />2.) Dowrdrains will be secured in place by excavating <br /> material below the pipe to ensure that the bottom of the <br /> pipe is installed below grade. <br />3.) Dowrdrains will be further secured by anchoring the pipe <br /> with roof bolts or fence posts driven into the grand <br /> immediately adjacent to and on either side of the pipe. <br />4.) Dowrdrains will be wnstructed and inspected after <br /> construction under the direction of an individual <br /> trained to assess the stability of the installation. <br />5.) Dowrdrains will be constructed and maintained to ensure <br /> that excessive erosion does not develop at the outlets. <br />6.) Dowrdrains utilized on or in conjunction with roads will <br />be sized at 16 inch diameter; dowrdrains used in <br />conjunction with mine facilities will be sized as <br />appropriate to convey the anticipated flows. <br />IrLSOec.-tions: 1.) Dowrdrains will be inspected on at least a quarterly <br />basis to ensure stability. <br />• 2.) Dowrdrains will we replaced or repaired as necessary. <br />ME2 92-81 Added 05/22/92 <br />