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Varra Companies, Inc. <br />Office of Special Projects <br />8120 Gage Street Frederick. Colorado 80516 Telephone (970) 353-8310 Fax(970)353-4047 <br />Refer to Items A-1 to A-4, below; which identify the `additional comments' <br />received under separate cover as part of this section of the adequacy review; <br />and corresponding to items 1-4 in Kate Pickford's comments from her 14 <br />January 2011 memorandum. <br />10. The Applicant has stated their stormwater discharge permit allows them <br />to discharge into the seep ditch at an average rate of 7.2± MGD. If water is <br />discharged into a ditch that is unlined, it may be prone to erosion. The Applicant <br />should provide the Division with specifications as to how much water the ditch <br />can carry without experiencing erosion. <br />Whether utilizing one or more pumps, operating in one or more tracts, the <br />combined discharge of waters into the seep segment will not exceed 7.2± MGD <br />of water. As shown in the included Channel Report and Chart, prepared by Brad <br />Jones, P.E.; total discharge in the drainage is minimal, having a total depth of <br />0.7± feet, traveling over a 0.5± percent gradient at 1.57± ft/sec. Where Q for <br />the total capacity of the channel is measured at 835.18 cfs., Q for the discharge <br />at 15.09 cfs. comprises apx. 1.8± percent of the capacity of the channel. <br />Additionally, the physical condition of the channel does not exhibit any signs of <br />streambed or bank erosion from potentially larger capacities of flows that it is <br />capable of holding. Generally, the values determined from the typical cross- <br />section of the seep, are considered well below thresholds which could combine <br />the necessary detachment and transportation needed for erosive effects. <br />Regardless, a concrete dissipater will be utilized at the point where settled <br />waters meet the seep, to better deflect entering waters from eroding the seep at <br />the point of entry. <br />11. Much of the site is located within the floodplain of the Cache La Poudre <br />River. Whenever mining will occur within 400 feet of the river channel, a flood <br />analysis and flood control plan must be submitted. The flood analysis should <br />quantify the velocity and volume of flows expected on site from a 100-year <br />event, as well as the elevation of the 100-year base flood event and its relation <br />Varra Companies, Inc. correspondence of 23 February 2011 to the Colorado Office of Mined Land Reclamation 6 <br />(OMLR) in reply to OMLR correspondence of 4 October 2010 - Western Sugar Reclamation Land <br />Development Project - M-2010-049.