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<br />F. SATO AND ASSOCIATES <br />CONSUL71h'G ENGINEERS <br />PROJECT MANAGERS & PIANRJERS <br />81240 <br />September 12, 1983 <br />~~ <br />5898 80. RAPP ST, <br />LITTLETON, COLORA00 80120 <br />(3031 797-1 200 <br />R~CEIi/~® <br />SEP 15 )gg3 <br />Colorado Mined Land Reclamation Division <br />1313 Sherman Street, Room 423 <br />Denver, Colorado 80203 <br />ATTN; Ms. Sue Mowry <br />Dear Sue, <br />MINEO LAND RECLAMATION DIVISION <br />Colo. Dept, of Na?oral Resources <br />This letter is to serve as a Request for Minor Revisions to <br />the Pryor Nline Permit, No. C-0310-81. <br />The revisions are: <br />( (1~Changinp, the control used on the principal spillway <br />outlet pipe for Sediment Pond A. The original <br />submittal involved a concrete vault and an 8-inch gate <br />valve. The revision would utilize a slide gate which <br />will be suitable for the head developed when the pond <br />is full. See attached drawing. <br />(2) liminating the culvert used as an emergency spillway <br />n Pond 'K' and replacing it with a Swale cut into the <br />road. The Swale would be 20 foot in width and 3 feet <br />below the existing road surface. See attached <br />drawing. The Swale would handle flow depths from both <br />the 25 year and 100 year storms as shown: <br />Recurrence Flow, Flow Depth, Velocity, <br />Interval, vrs cfs ft ft/sec <br />25 88 1.5 3.0 <br />i00 122 1.8 4.2 <br />from SOAP report <br />This change results in setting the emergency spillway <br />2.8 feet higher than originally proposed. Other than <br />increasing the volume of the pond, no other impacts <br />are anticipated. The depth of water in the pond will <br />be 10.5 feet above the invert of the principal <br />spillway during i00 year event. A11 calculations have <br />assumed that the principal spillway would he inoper- <br />ative during the 25 and 100-year flow events and that <br />/mall discharge would be through the emergency spillway. <br />• /3) _A variance from the reference area revegetation <br />success criteria methodology is requested for woody <br /> <br />