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Comment Response Page 5 CDRMS additionally stated disagreement with the land use designation of `Yorest with heavy ground litter'; which was assigned to disturbed areas with a curve number of 91. The intent here was fo make a distinction between the upper portion of the watershed, where overland flow conditions will occur. Colowyo agrees that the land use designation should not be "forested" and has changed it to `nearly bare and untitled, and alluvial valley fans" where appropriate. The SEDCAD modeling has been revised and is attached. 51. Rule 4.05.9(7) requires that one foot of freeboard be maintained while the emergency spillway is flowing at design depth. The SEDCAD design output does no[ show compliance with this Rule. Please ensure that [he pond design demonstrates adequate freeboard will be maintained as required. Response: CDRMS noted the requirement of one full foot (minimum) of freeboard for the emergency spillway. The previous design had 0.5- to 0.8-foot freeboards. The dam crests (in the redesign for the second revision of the mine plan) have been set at a minimum of one-foot above the water surface elevation in the emergency spillway during the 50% of PMP discharge. Section 28 Pond 52. The introductory text indicates that a practice factor of 1.0 was always used. However, the 10- year storm even[ SEDCAD run indicates a value of .4 was used for SWS #1. Please correct and rerun the 10-year, 24-hour storm event with a practice factor of 1.0. Response: CDRMS noted that a practice factor of 0.4 was used for the 10-year storm event SEDCAD run for Section 28 pond instead of the intended 1.0 value. This was an inadvertent error and has been corrected. 53. Additionally, the SEDCAD analysis indicates that [he pond discharge will not meet [he required effluent limitation of 0.5 ml/I for a storm event equal to or less than the 10-year storm. The Division cannot approve a pond design that fails to demonstrate compliance with applicable effluent limits. Response: CDRMS noted that the pond discharge for Section 28 pond did not meet the required effluent limitations of 0.5 ml/1 for a storm event equal to or less than the 10-year storm. The mine plan has been revised, including incorporation of additional sediment controls, such that the pond meets applicable effluent limits. 54. Rule 4.05.9(7) requires that one foot of freeboard be maintained while the emergency spillway is flowing at design depth. Please ensure that the pond design demonstrates adequate freeboard will be maintained as required. Response: See response to Comment No. 51 above. Section 21 Pond 55. The SEDCAD analysis indicates that the pond discharge will not meet the required effluent limitation of 0.5 mUl for a storm event equal to or less than [he 10-year storm. The Division cannot approve a pond design that fails to demonstrate compliance with applicable effluent limits. Response: See response to Comment No. 53 above West Tavlor Pond