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~ • III IIIIIIIIIIIII III <br />~~ ENGINEERING s. SURVEYING COMPANY <br />BOX 674 443 DODGE DELTA COLORADO 81416 303-874-7593 <br />#10.179 g~--~--~-•^~ ~- <br />May 16, 1980 <br />fr1AY 2l 1980 <br />Marion Dodson MiPa~" i ;,~ ~'"CI_AMATION <br />Reclamation Specialist Cole. Oc,pi ~.: na-..,.ia' ~~eeu!ces <br />Mined Land Reclamation <br />423 Centennial Bldg., 1313 Sherman Street <br />Denver, Colorado 80203 <br />Re: Sunflower Energy Corporation - Blue Ribbon Mine, <br />Somerset, Colorado. <br />In response to your letter of April 16, 1980, we submit <br />the enclosed two copies each of drawings and calculations <br />for the sediment control system, Blue Ribbon Mine. <br />Sizing calculations for the ponds and overflow structures <br />are included as copies of our original calculations. <br />Sources used for data are referenced. <br />Flow from the bench to the reservoir amounts to a max- <br />imum of 1.56 cfs at peak flow, slope of 0.39 feet per <br />foot (steep). A 10" pipe will carry in excess of 10 cfs <br />on this gradient. Use a Manning n of 0.013. The mine <br />has decided to abandon the ditch and install a 10-inch <br />culvert pipe as shown on the drawing. The ditch on the <br />outslope of the bench area will be incorporated into <br />this culvert. <br />The reservoir is no longer proposed for use as a sed- <br />iment pond. Two small ponds are proposed instead. <br />Pond 1 is located at the toe of the bench outslope in <br />the area as suggested by Hydrologist Gibson. Sizing <br />calculations and flow rates are enclosed. The dewater- <br />ing device is to be a 6-inch pipe with a removable cap <br />on the outside of the berm. Elevation of the 6-inch is <br />above the calculated sediment storage level. <br />We have enclosed plans and specifications for the sed- <br />iment control ponds, with the statements requested. <br />All of the comments in your letter of 4-16-80 have been <br />addressed herein, as far as they relate to hydrology, <br />with the exception of the sample of spring water. On <br />the date of this letter, we had not submitted the sample <br />to the lab for analysis. Would you please provide me <br />with the parameters required, and 2 will send you the <br />results of the analysis immediately. <br />