2002-05-16_REVISION - M1977342 (2)

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Sorenson, Allen From: Bower, Erich [ebower~phelpsdodge.com] Sent: Thursday, May 16, 2002 10:45 AM To: Erica Crosby (E-mail); Allen Sorenson (E-mail) Cc: Beierle, Anne; Lucero, Tony Subject: Henderson Bond Recalculation Information Erica, Here is more of the information you requested during our meeting several weeks ago. More detailed maps of the Henderson Mill tailing area and maps identifying the total disturbed acreage around the mill facility are being developed. A current map of all of our topsoil stockpile locations and volumes is also being developed. These maps will be sent to you as soon as they are finalized. As usual, please call any of us with any questions that you have. [Anne (303) 569-3221 x. 1397, Tony x. 1287, Erich x. 2214] Mill Site Tailing Line The tailing line is comprised of 36-inch reinforced concrete pipe (RCP). The pipe strength varies from 50 feet of head (- 22 psi) at the start to 100 feet of head (- 43 psi) at the north end of 1-Dam. The tailing line length is as follows: 8,200 feet -From cut out (Main Mill) to start of 1-Dam 7,600 feet -Across 1-Dam 2,500 feet - Spur to and across 3-Dam Power Lines The only power lines that are owned by Henderson are: The line to East Branch Pumphouse The line to Ute Park Pumphouse The line to Williams Fork Pumphouse The short splits off of the Ute Park line to the Pond Shop and the Gravel Pit East Branch Reservoir Sediment The following sediment estimate comes from information provided to Henderson by divers that were sent into East Branch last year to investigate the reservoir outlet works. They said the sediment at the bottom of the reservoir near the dam was approximately 6 inches of a fine silt. No noticeable sediment has been noted at the inlet end of the reservoir. Henderson feels a safe assumption would be 6 inches of sediment over 1/2 the area of the reservoir. Once dewatered, this should be a conservative number. Henderson may want to talk with some reservoir managers in the future to investigate typical sediment loading in reservoirs and whether or not it would be necessary to remove. Surface Area (E. Branch) = 46.6 acres or 225,545 square yards. 1/2 Surface Area X 6 inches =(0.5)(225545)(0.1666667) = 18,796 cubic yards of sediment Mine Site 5-ICS-Dz// / ~j S~ l~ ~ `7 F f~vvu : Ke~ide.rsd,ti ~C7 ~. NG-Hte- I~QT i ~L~ ~~t~Q~t~t7/ -take-of`~'S .( o ~ /' ~ C 1 A.WC dL~ i o vL C CJ'~~ ~ 5~ i vH- t~-~ `e Disturbed Acreage Total disturbed land at the Henderson Mine site is 120.6 acres.