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<br />• • III IIIIIIIIIIIII III <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmenl of Natural Resources ~ I <br />I } I J Sherman 51.. Room .I 5 <br /> <br />Denver, Colorado 8U?O} ~~ <br />Phone 130}1 866-)567 R~~1 <br /> <br />FAY (303183?-8106 E 11/~~ <br /> DEPARTMENT (>: <br /> JUN Og NATURAL <br /> 199I RESOURCE'? <br />DATE : A r i 1 1, 19 9 7 <br />P division or <br />Mmnrdl~ s ueol Ror Romer <br />Governor <br /> <br />T0: Gary Curtiss o <br />9Y lames 5. Loc hhead <br />E.ecmire olreclor <br />,S ~ <br />FROM: A11en Sorenson //'iL hn chael B. Lang <br />orvisioo o~rec br <br />RE: Storm Water Management Plan, Deer Creek Quarry, Permit <br />No. M-79-214-HR <br />I have reviewed the most recent revisions to the Deer Creek Quarry <br />storm water management plan. These revisions are in the form of a <br />memo and attachments from Mike Applegate dated March 27, 1997. In <br />order for the Division to accept the plan, the following issues <br />need to be addressed: <br />1. There is no mention in the plan of culvert outlet protection. <br />Structurally lined aprons or other acceptable energy dissipating <br />devices must be placed at the outlet of all pipes. The operator <br />must provide details on proposed outlet protection. <br />2. There is what appears to be a typographical error in item #2 <br />of Mike Applegate's memo. I believe the reference in item #2 <br />should be to Basin B1 rather than to Basin D. <br />3. At those locations where flows are routed over rock cliffs, <br />the impact zones need to be cleaned to bedrock or adequately sized <br />and armored splash pools installed. <br />4. The plans submitted call for installation of trickle tubes in <br />all the ponds, with the trickle tube inlets located at the base of <br />each reservoir. This design would result in rapid emptying of the <br />ponds, and removal of suspended solids would be virtually non- <br />existent. The operator must provide principal spillway designs <br />that will maximize the settling of suspended solids. I would <br />recommend either a riser and barrel type principal spillway, or a <br />steeply sloped trickle tube with the inlet located high in the <br />impoundment, but at least one foot below the crest of the emergency <br />spillway. This recommendation need not apply to Pond UB1 where a <br />concrete culvert is already in place. <br />5. The revised plans indicate that a "swale" will be installed on <br />the access road near the entrance to the quarry. This structure is <br />actually a diversion dike to be built up on the road in order to <br />