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n <br />Supplementary <br />Henderson Mine <br />March 26, 1985 <br />Page 3 <br /> <br />Information - 1984 Annual Report <br />_~ <br />The spillway-pipeline would probably cross the dam on <br />the northwest end, proceed along the existing peri- <br />meter access road at the toe of the tail dam, and <br />outlet into the northwest end of the seep water <br />canal. <br />This pipeline-spillway affords a backup to the <br />already-existing decant and flood bypass pipelines <br />which underlay the tailing deposition area and drain <br />surface water from the basin. <br />5,000' feet of 36" reinforced concrete pipe at <br />$35/linear foot would cost a total of approximately <br />$175,000.00. Excavation and backfill for installa- <br />tion of the pipe would cost approximately 523,500.00, <br />bringing the total to approximately $200,000.00. <br />Question 5: Page 4, Area 9 references "Revegetation Peri. Road" <br />with a cost per acre of 5700.00. Page 2 of this <br />attachment referenced reclamation costs of $1,045.00 <br />per acre. Please specify why a lower amount is <br />required in this area. <br />Answer: The effective cost per acre for the treatment cf the <br />94 acres in Area 9 is $700/acre because portions of <br />the areas and roads included in this total acreage <br />have been treated, were only partially disturbed by <br />timber clearing for the canal ROW, or are recov~=ring <br />unaided due to invasion of adjacent plant and seed <br />material. <br />The costs were arrived at in the following manner: <br />(Thousands) <br />a) Reveg. tailing, 715 acres @ 54,068/acre $2,909 <br />b} Flood control 200 <br />c) Reveg. peri.road, 62 acres @ $1,095/acre 65 <br />d) Fert. peri.road, 32 acres @ 533/acre 1 <br />e) Perm. use, Canal/road, 40 acres 0 <br />f) Buffer , 1,597 acres 0 <br />53,175 <br />As you can see, the 94 acres of perimeter road <br />treatment is further broken down as shown it items c) <br />and d), This breakdown was not detailed in the <br />Annual Report. 566,000.00 to revegetate 94 acres is <br />an average of $700.D0 per acre. <br />