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TETRATECH RMC Page 6 Mr. Berhan Keffelew July 27, 2004 B) A visual inspection will be conducted after a major precipitation event that is equal to the 50 year, 24 hour event, using the same procedure as listed in section "A'. The operator will do this. C) If a visual inspection detects signs of a potential slope failure, qualif ed personnel will be contacted to evaluate and recommend remediation work to stabilize the area. The above recommendations were as the result of the two engineering stability analyses completed for the site, by the Applegate Group Inc. and by Tetra Tech RMC, included in the application. The operator will do this. All other Exhibits were adequate. In addition to our adequacy comments, Commerce City Engineering staff is still evaluating your applications and have indicated that they will send comments via fax as soon as possible. Once we receive it, it will be forwarded to you. If you have comments or concerns, please contact me at (303) 866-4072. We received the comments from Commerce City. I called Kathryn Lansink about her letter and she said that isn't anything that we need to respond to as part of this application. She said that their concerns will be addressed with the Adams County application. She also said that she wanted to reiterate that the timing of Phase lA is critical from their perspective because of the impact of Phase lA on existing residential land uses and wildlife in the area. The operator will keep this in mind when preparing the Adams County application. We also received the comments from Bryan Kohlenberg with the Urban Drainage and Flood Control District (UDFCD). Following are his comments and our responses: According to the "Technical Review Guidelines for Gravel Mining Activities Within or Adjacent to 100-Year Floodplains" (Guidelines), the north boundary of the mining pit qualifies as a Type A Lateral Berm. When a Type A lateral berm is left in its unprotected natural state, the Guidelines call for a minimum allowable top width of 250 feet. When properly protected according to Section 2.5.3 of the Guidelines, the minimum allowable top width can be reduced to only 100 feet. The applicant needs to show the limits of the adjoining mine to the north and confrm that the Guideline's conditions for a Type A lateral berm are being met. We have revised the Mining Plan Map to allow for the 250 foot setback along the northern property line as UDFCD requested. This limit is denoted as the mining limit without further approval of UDFCD. The maximum mining limit to the north remains unchanged.