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1. Re: design specifications for bedding and filter material to be used for the various <br />barrier configurations shown on the previously submitted Exhibit CS-2. <br />Resno~rse: Three of the jour details on this Exhibit refer to barriers for [he upper <br />and lower ends of the Renewable Resource Area (RRA). As noted above, the <br />Renewable Resource Area has now been removed from the plan Therefore, further <br />it formation on details referring to this area should riot be necessary. <br />The fourth detail on Exhibit CS-2 is the River Bank Armoring Detail. Project <br />engineer High Country Engirreertrrg has reviewed this detail and your comments acrd <br />will supply additioru7l design specifications as reyriested. Based on the results of the <br />flood plain study, the location where the armoring will be required has now been <br />determined. The location of the armoring it based on the stream velocities expected <br />from the /00 year flaws mid the ability of the berms or banks to withsta~rd these <br />flaws. The sizing of the rip-rap material has already bee» determined, !hough a soils <br />.study will still be required to determine the underlying Etter .rpecificaliorts. This <br />it formation will be provided through a technical revision later this year. <br />2. Re: clarification on design and costs for a weir on the discharge end of the <br />Renewable Resource Area. <br />Response: With the removal of the Renewable Resource Area from the p/an, <br />additional information nn the weir should not be necessary. <br />3. Re: an evaluation of off-site impacts due to flooding during mining and <br />reclamation. <br />Response: As noted above, a complete flood plain s[rrdy has now been completed for <br />the entire .rite analyzing [he impacts dare to flooding. As noted in the study summary, <br />the Mamm Creek Gravel Pit "will have a net effect of raising Jhe water surface <br />elevations by 1.3 or less" and "the armoring of [he beans decreases the probability <br />of having the Colorado River captured by the gravel pits. " <br />4. Re: depth of mining in the Renewable Resource Area. <br />Response: With the removal of the Renewable Resource Area, this is rro longer <br />applicable. <br />5. Re: preparation of a Spill Containment and Countermeasures Plan. <br />Response: Please frrrd attached a detailed Spill Contaitrmenl and Courtermeasures <br />Plan that should address Dtvisiorr concerns regarding the handling offrrel and oil <br />materials. <br />6. Re: stormwater detention and drainage considerations. <br />Response: brclnded with this submittal package is a Stormwaler Mmragemen[ Plmr <br />(SWMP) mid a Drainage Study prepared in response to the concens noted above. <br />The SWMP was submitted to the Colorado Department of Health [amid-May, and <br />approved in early July. A copy of the permit, rmmber COG-500408, is attached <br />The Drainage Study indicates that the only upgradient runoff shat enters the site does <br />so in the Dry Creek Mining Area. Runoff discharging towards the site in the other <br />2 <br />