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• information submitted to the Division on December 23, 1994. Sediment yield is more sensitive to CN than particle size and thus, the reason for a much higher sediment yield. d. SCC added the .017 cfs in as baseflow. SCC came to the same conclusion as CDMG, it did not make any difference. 39. SCC reran the pond design using the same two watersheds that the Division used. The CN that the Division used for Pond l0 for spoil was 85, while that used for Pond 11 was 94. SCC used a CN of 85 for the design based on justification as noted above. 40. The SEDCAD+ output for Pond 11 has calculated the peak discharge to be 21.33 cfs going into the pond. The peak discharge coming out of the pond has been reduced to 2.74 cfs. The principal spillway for Pond 11 is a 12-inch diameter trickle tube. The culvert crossing the road mentioned will be ` verified by SCC personnel in the field to determine its size I and proximity to the spillway for Pond 11. Based on the above facts, SCC does not feel that outflows from Pond 11 will affect the performance of the road culvert. 41. A geotechnical evaluation was not conducted specifically for the Pond 011 embankment area. Ground reconnaissance of the embankment area did not show any signs of site specific problems. The completion log from monitoring Well YGAL16 gave an indication of the subsurface conditions as well as depth to ground water (6970 msl). Additional investigation was not warranted at this time. 42. The statements made by Northwest Colorado Consultants were, by their own admission, recommendations. Some of these recommendations have been instituted and others are and will be considered. The design and construction plans have been revised to incorporate these recommendations. A blanket and toe drain is the preferred alternative to lining the pond. In fact, in this situation, the drainage system will actually perform better than lining the pond. If the pond were lined, seepage could still flow beneath the system. The drainage system will allow the flow to be safely released at the toe of the embankment without the hydrostatic pressure buildup that might happen without the blanket drain. 43a. SCC revised the culvert designs using the 1.7 inch precipitation value. In doing so, the curve numbers were also reviewed. Justification for the weighted curve numbers is now included for Road A. This information is in Tab 13, Attachment 13-8. It should be pointed out that the headwater to diameter ratios are all within acceptable limits. Culvert's YA-6, due to the large drainage area, have been conservatively sized to safely pass the flow as a result of • the 25-yr, 24-hr storm. 9