2007-08-29_REVISION - M1980047 (2)

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Colony Shale OII Pmjacl, Coloratlo rJLRB Perron M-BC 047 Rev Auy 2a, 2007 2006 Aryaclod Area Status Summary and Repuesl fa Radurtion m Altectetl Acreaya 4.3 2 7 Plant Access Road (ISP Areas 19A, 196, 19C and 15D) ISP Area 19 .s the largest area assoc+ated with the access roads It ~s composed n( four sub-areas encompassing a total of 137 acres, of which 22 acres are the permanent roadway surace that climbs 1,500 vertical feet in a d+stance of 4 7 miles fram Iho lower valley noar the reclaimed Tosco Retort Site (Area 5A) to the plant Site (Area 18). The remairong 115 acres are benched vertical cuts in rock and generally steep fiu slopes slightly flatter than repose angle. The road s required for access to Middle Fork Dam and the upper portions of the sde, and except for routine maintenance blading its surface has been In its permanent post-mirong land use form snce construction was campieted +n 1983, All road cut and fill areas in Area 19 are also In their final post-mining topography as of complebon of construction. Tne cuts are all +n bedrock and are either near vertical benched cuts rn the Parachute Creek manstone or are laid tack benched rock cuts in the less competent overly+ng Uinta sandstones and siltstones. Like the road surface, these cuts were in their final form as o} completion of the road constructon S+grnficant effort was Invested in seetl+ng the flatter cut slopes m rock, using state-el-the-art techniques for steep slope revegetation descnbed In Section 2 of this submittal. These included some ~nnovadve techniques such as incorpnrabng hay mulch into polypropylene netting and unrolling the assembled mulch blanket down the hillside, wdh staples then applied ny workers on spell+ng lines. One area was aeriolly seeded using a heLCOpter. In spite of these efforts, the exposed materials In many areas had insuffiaent fines to support dense vegetation, which also means they are not likely to produce s+gndlcant amounts of sediment A similar but smaller scale issue is descnbed previously in context of revegetation of cut slopes on ilia Dam Access Road in Section 4.3.2.3 ,and close-up photographs of a few typical revegetated cut slopes on that road are presented as Figures 28 and 29. However, the height of the slopes receiving this treatment on the Dam Access Road was typ+cally under 25 feet, whereas the height of the cut slopes on the Plant Access Road was often over 100 feel. Wdh regard to fill slopes, the reclamation plan envisioned slope angles that could range from mild slopes (flatter than 2:1) that mlgnt be capable of supporting a topsoil veneer and vegetative cover. to near reposa anyle talus fills Inert wouVd not be amenable to vegetation (p. E-46) As it turned nut, none of the roadway fill slopes were flat enough to support a topsoil cover. but the large fill slopes were ;aid back at approximately 1.75 1 (sub-areas 19A and 198), and these areas did contain enough i+nes to support a vigorous plant cover These were seeded either t,•y hydroseeding or by broadcast seeding techniques as descrihed in the reclamation plan amendments included in Appendix D-1 from the 1982 Interim Site Plan amendment (see Appendix B1 These slopes were also provided wdh a mulch cover to assert in germ+nabon and rooting of the plants. either via a tackified hydromulch or a netted hay mulch. The ma)ority of the fill slopes therefore fell into nedher the mild revegetated topsoil slope category nor steep non-vegetated talus slopes category, but were in fact the " ,less steep slopes that may be broadcast seeded" as described in the original approved reclamation plan (Exhibd E p. E-9, E46). Tne vocations of ilia Plant Access Road, sub-areas 19A through 19D. are presented nn Exhibit F-3. and post mirong topography +s as shown on Exhibit F-4 lJmits of the areas that will remain actwe affected acreage after approval of this plan are depicted on Exhibd F-11 Current r..onniuons at representabve locations a'•onq the road are depicted on Figures 38 through 4c