REV09711 - Laserfiche WebLink

Home Browse Search

portion of the channel shows no down-cutting or erosion and is vegetated similar to the reclaimed area. The Division believes that modifications to the 700 feet of channel below the culvert would not appreciably change the amount of sediment deposited in the outlet of the eight-foot culvert and furthermore, additional disturbance would increase the sediment load downstream as a result of mine activities. Close inspection of the silt deposited in the end of the culvert indicates mostly pebble size and smaller material with an occasional larger particle, indicating relatively slow flow velocities that are not capable of transporting large particles. Some sedimentation in the end of the culvert is expected and is likely transient, with sediment constantly moving downstream due to natural erosional processes. Unless the hydrologic conditions in the watershed above the mine are altered drastically by man or nature, there is no reason to believe that a threat to persons or property exist due to the small amount of sediment in the outlet end of this culvert. Given all these factors, the Division does not believe that modifications or maintenance to the channel below the eight-foot culvert, or the culvert itself, are warcanted. t 00-r r ditch ahnve refi~se highwall and chnp~Phninc 5,6,7 and Rl The 100-year ditch is the responsibility of the mine to maintain until final bond release. As we understand it, due to siltation from the undisturbed area above and possibly damage to the ditch berm, flow exited the ditch and flowed down the slope to the door of the shop building. This flow was contained within the mine disturbance and ultimately entered the sediment pond rather than the permanent diversion. However, as we discussed during the bond release field inspection, this ditch is the responsibility of EFCI to maintain. The portion where the breach occurced had been repaired prior to the bond release inspection. However, a few other areas where the channel is armored with gabion baskets will require further attention. The Division will ensure that this work is completed prior to final bond release. 13 taini wall¢ at short door and n, ren nTlant (Photos q Rc 101 Field inspection indicated that you had constructed the retaining wall at the shop door and nothing further is required. The other azea where a retaining wall is desired is at the east end of the prep plant concrete slab and structure. At this location, some sloughage from the hillside adjacent has resulted in soils on a small portion of the concrete slab. Structures at both of these locations are approved as permanent as requested by the landowner in letters included in Addendum E ofthe permit application. Specific to the retention ofthe concrete slabs at the prep plant is the attached letter to Mr. Randy Acre of EFCI dated March 16, 1994. The pertinent portion of the letter reads as follows; Dear Mr. Acre It is our desire that the existing structures listed below, located at the Raton Creek Mine, be retained for our use in conjunction with the anticipated future site activities. We understand that as surface owners, retention of these facilities will impose upon us both the responsibility of ownership, and all rights for use, maintenance and disposition of the facilities. We desire to retain the following facilities for anticipated future uses as noted.' Preparation Plant Pad (two levels) Intended to be used as storage area for hay and ranch equipment. Will probably build walls and roofs to protect stored materials. The letter is signed by owners Albert and Marilyn luppa and Nick Cimino. The Division notes the unambiguous statement of the intention of the surface owners to construct walls and roofs at the prep plant. Based on the approved reclamation plan, land-use, and the permit documents that include Addendum E, the Division will not require that EFCI construct a retaining wall at the east end of the prep plant concrete slab. Any wall or barriers constructed would be the option of EFC[.