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~ ~ iii iiiiiiiiiiiu iii ` ~ Leonard Rice Consulting Wafer Engineers, Inc. Leonartl R,ce (303) 455-95139 / 2695 Alcott Street /Denver, Coloratlo 80211 Lesi~e H 6otnam Roor. rt E Brogtlen January 11, 1960 Mr. John Gates Energy Fuels Corporation Box G Steamboat Springs, Colorado 80477 Dear John, ;;'J J,`,,~, ... ,. ~ ~ j ~" I,UIU. ~ ' At your request we have designed an improved inlet to the existing 48 inch corrugated metal pipe (cmp) culvert under Haul Road E. Enclosed please find a drawing titled Haul Road E, 48" Culvert and Slope-Tapered Inlet, Plan and Pro- file. Also enclosed are back-up calculations. We have based our design on a procedure reported in Hydraulic Design of Improved Inlets for Culverts, Hydraulic Engineering Circular t3o. 13 of the U.S. Department of Tran- sportation, Federal Highway Administration. Several years ago I attended a seminar on the design of improved inlets sponsored jointly by the Federal Highway Administration and the Colorado Department of Highways According to Del Roupp of the Colorado Department of High- ways, there are currently 30 to 50 improved inlets of this type in use in Colorado. Most are constructed of concrete, and only two or three are cmp installations. We have talked to Thompson Pipe & Steel of Denver, about fabrication of this in~et, and they do not foresee any problems in constructing the unit. The unit will probably be fabricated in two pieces which can be bolted or welded in the field. Our design has been guided by the current Office of Surface Mining criteria which states that design flow should pass through the culvert withouf~ ponding above the top of pipe entrance. This translates into a Headwater to Diameter (HL4/D) ratio of 1.0 or less. ~9e have also used the design discharge of 200 cubic feet per second (cfs) you provided us. This improved inlet design, by virtue of its sloped and tapered entrance, enables the existing 48" cmp to perform Hytlrology Water R~gMs Env~ronmenlal Analysis Urban Drainage