2017-02-21_REVISION - C1981019 - Laserfiche WebLink

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Colowyo Page 2 2/21/17 • culverts along the associated access road between 170+00 and 180+00; • and the culvert located between 380+00 and 390+00. 6. When reviewing Map 25E, Sheet 3 of 4 — Collom Haul Road Profile and Road Template, it appears that the culverts do not match along the haul road profile and Map 25E, Sheet 2 of 4 — Collom Haul Road Drainage Design. According to Sheet 3, there are three culverts between 138+00 and 140+00. When comparing to Sheet 2, only two culverts are shown. Additionally, it appears Culvert 47 isn't shown on Sheet 3. Please provide and updated Map 25E, Sheet 2 and/or Map 25E or associated explanation regarding the culverts. 7. As per Rules 4.03.1(3)(d) and 4.03.2(3)(d), road cuts for haul and access roads shall not be steeper than 1.5h:1v in unconsolidated materials or 0.25h:ly in rock, except that steeper slopes may be specifically authorized by the Division if geotechnical analysis demonstrates that a minimum safety factor of 1.5 can be maintained or in geotechnical analysis demonstrates that a safety factor less than 1.5 will not result in significant environmental hard or harm to the public health and safety. Multiple proposed maps and figures have details regarding road cuts to being steeper than 1.5h:ly without associated geotechnical analysis or details of material that would meet the above mentioned Rules. For the following maps and figures, please provide additional details and/or demonstrations that would meet Rules 4.03.1(3)(d) and 4.03.2(3)(d): • Map 25E, Sheet 3 of 4 — Collom Haul Road Profile and Road Template • Exhibit 7-23, Figure D1— West Side Pond Access Road • Exhibit 7-23, Figure D2 — East Side Pond Access Road • Exhibit 7-23, Figure D3 — Facility Access Road Eastern Portion • Exhibit 7-23, Figure D4 — Facility Access Road Western Portion • Exhibit 7-23, Figure D5 — Jubb Creek Access Road 8. In Exhibit 7, Item 23, Part J — Sediment Control System for the Initial Facilities Disturbance Area, it is stated that "[a]ll undisturbed areas are modeled at a curve number of 57 ... based on Volume 25, Exhibit 7, Table 1 values." Reviewing Volume 25, Exhibit 7, Table 1 values, the curve number 57 is associated with cover type — Oak/Aspen. For the associated areas in Exhibit 7, Item 23, Part J, it appears to the Division sagebrush is the dominant cover type, when comparing to the approved Map 4C, Sheet 6 of 11. According to Volume 25, Exhibit 7, Table 1 values, sagebrush is associated with the curve numbers 47 or 63 depending on hydrologic condition and percent cover. Please provide the Division a reason for the use of curve number 57 in Exhibit 7, Item 23, Part J — Sediment Control System for the Initial Facilities Disturbance Area or a revised hydrologic model using a corrected curve number.