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Drainage Designs <br />10. Please provide revised Exhibits F, C-2B, & C-2C to include a drainage channel receiving upland <br />diversion flows neaz the northwest comer of the Processing Plant & Product Stockpile azea (PPPS) which <br />routes the runoff along the southern edge of the PPPS azea and connects with the runoff diversion channel <br />that flows along the northern edge of the PPPS azea. If the applicant has determined that a diversion <br />channel in this location is not necessary, please provide a rationale for deleting the diversion channel in <br />this location. <br />11. Please provide a representative cross section and percent slope for each reach of diversion channel to <br />be installed. The cross sections should include the following features: channel co~guration, side slopes, <br />bottom width, & depth. <br />12. Please provide supporting watershed information and/or hydraulic computations to verify the adequate <br />sizing of sediment pond structures, culverts, or drainage channels treating or conveying runoff waters from <br />the contributing watershed. <br />13. Please provide a representative plan view and cross sectional design for the porous rock check dams to <br />be installed at 50' intervals in the roadside ditches of the main access road. <br />The applicant will also need to provide a representative profile of the main access road showing the slope <br />of the access road and a series of at least two (2) rock check dams. <br />14. A statement on page 13 of the Response to Adequacy Review, "A pemranent sedimentation basin, <br />referenced as Sediment Pond C in the initial drawings and the DMG adequacy review letter, has been <br />removed from the reclamation plan" is inconsistent with the Revised Exhibit C-2C which shows the <br />permanent Sediment Pond C. Please address. <br />15. Revised Exhibit C-2B shows two sedimentation ponds labeled as sedimentation pond B. One of the <br />sedimentation ponds labeled "B" is labeled with a capacity of 220,000 cubic feet, and the other pond <br />labeled "B" does not show a design capacity. Please address. <br />16. On Revised Exhibit C-2B sedimentation pond C is labeled as permanent and appeazs from the <br />construction drawing to be smaller than sedimentation pond B, which is contradictory to the values for the <br />ponds shown in the table on the drawing. Please address. <br />17. The McDermid memorandum (page 2) indicates historic peak flows from the 100-yeaz event in each of <br />the basins aze 81 cfs (West Basin), 166 cfs (East Basin), and 55 cfs (South Basin). None of the revised <br />exhibits delineate these drainage basin boundaries. Also, please confirm the sedimentation ponds aze <br />capable of handling these storm event flows. Please address. <br />Drainage Design Inputs <br />18. The Mazch 15, 2005 Memo from Mike McDennid to Alex Schatz quantifies historic peak flows in cfs <br />from a 100-yeaz storm event from various drainage basins within the contributing watershed at the MMRR <br />Quany site. These volumes aze used in the sizing of all pemranent drainage features. The applicant will <br />need to clarify the period of time the historic peak flows apply to, ie: 24-hour storm, 6-hour storm, 2-hour <br />storm, etc. and provide a discussion for why this storm period was selected. Given the site location and its <br />capacity for frequent high intensity-short duration storm events, it is appropriate for the applicant to <br />provide an evaluation of the various storm periods and select the period which will generate the highest <br />peak flow and corresponding peak flow velocity. The applicant will also need to specify the peak flow <br />