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• • a~ <br />/~~ ~~ <br />40. There appeazs to be a drainage and possibly a culvert crossing under Routt County Road <br />27 near the outlet of Pond 11, If there is a culvert there, has SCC considered whether <br />outIlows from the pond would affect the performance of that culvert? <br />41. There does not appear to have been a geotechnical investigation conducted on the <br />proposed location of Pond 11. Please provide information as to why this was not <br />wnsJdered, or provide the Division with the conclusions of any study that may have been <br />done. <br />42. Attachment 13-5, Geotechnical Investigation, encompasses recommendations of <br />engineering geologists consulted for an investigation mto feasibility of proposed haul <br />roads and Pond 10. Among those recommendations and conclusions were: <br />a. Observations indicate shallow groundwater, deep bedrock, and potentially <br />unacceptable seepage rates. <br />b. A clay liner may have to be used in sediment ponds due to seepage. <br />c. The Pond 10 embarilmlent should incorporate geotextile fabric. <br />d. Pond embankments should be placed in 8" lifts. <br />It appears that none of these rewmmendations were considered in the proposed <br />construction plan for Pond 10. Please explain. <br />43. The Division reviewed culvert designs presented in Attachment 13-8, and has the <br />following comments: <br />a. The Division was unable to verify inputs for the Road A culverts, and so cannot <br />concur with the results. SCC used an apparently weighted average curve number <br />for all culvert drainage areas. We do not have soils information for the entire <br />watersheds, and SCC did not provide detailed calculations of the curve numbers, <br />so we are unable to evaluate them. Please provide the information used to arrive <br />at the curve numbers. <br />b. Culverts for Road B appear to be adequate with three exceptions. Given the <br />discrepancies in SCCs and DMG's modelling efforts for the Pond 10 watershed, <br />culvert specifications for Y134, YBS, and YB6 are not in agreement. The sizing <br />of these culverts may have to be adjusted pending outcome of the comments <br />pertaining to Pond 10, above. <br />44. On Exhibit 13-2, Surface Water Confrol Plan, Sheet 1 of 2; there appear to be two <br />drainages located between culverts YA3 and YA4. How does SCC propose to duect <br />runoff from these drainages through or away from the road fill? <br />45. Exhibit 13-10.3 shows an intersection of Road A with a "dirt road " The dirt road appears <br />to be covered by roughly 10' of fill when the proposed Road A is constructed. Is this <br />road currently used? If so, how will SCC keep access open? Has SCC consulted with <br />the owner of this road? If an intersection is necessary, SCC should include this in the <br />narrative and/or maps. <br />46. Exhibit 13-10.6, the last segment of Road A does not coincide with Exhibit 13-11.1, the <br />first segment of Road B. The cuts and fills shown will not connect properlx. Please <br />revise whichever segment is in error, or explain how these segments will adlom. <br />47. The road proposed from the 1999 pit down to Pond 11 will be constructed through an <br />area of landshde/mudflow deposits, some of which appear to be relatively young. What <br />M. Altavilla and G. Wendt 9 January J3, 1995 <br />