2011-03-18_PERMIT FILE - C1981044A (4)

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In the event that mining-induced surface subsidence impacts the Trapper Mining facilities or the EC facilities, they will be maintained or repaired as deemed necessary by EC. The specific responsibilities for mitigation for mining- induces subsidence impacts on the reclaimed land are detailed in an agreement between EC and Trapper Mining, Inc. Private Residences (Houses) There are three-(3) private residences located within the permit area. The three-(3) residences are located outside the planned mining area. They are also located outside the area of subsidence influence. Therefore, these structures are protected from any subsidence-induced damage due to their locations. However, should subsidence impact these private residences, EC will repair or replace the structures as deemed necessary. OiI Pipeline A high-pressure, oil pipeline owned by AMOCO Pipeline Company traverses the mine complex from the southwest to the northeast, approximately paralleling County Road 107. In the event that disruption of oil flow in the pipeline occurs due to subsidence, EC will inspect the pipeline for evidence of rupture. If ruptured, the pipe will be repaired as soon as possible. If ruptured, the pipe will be repaired as soon as possible. EC will also visually inspect the pipeline segment being actively subsided on a daily basis. In order to provide the maximum degree of environmental protection in the event of a pipeline rupture, EC is proposing to install the following: An upland clean-water diversion which will route upslope watershed runoff around the area which has been left open for undermining; a livestock water tank, which will be less than 2 acre-feet in size, and which will have an embankment height of less than 5 feet to the invert of the spillway (this tank will be constructed in conformance with the State Engineer's criteria); and two temporary diversions which will convey any oil escaping the pipeline during a rupture to the livestock tank. EC is also providing information on contingency diversions, which might be constructed in the event of an emergency. The 2-year 24-hour sizing event is being utilized for all items other than the livestock pond spillway, which is sized for the 25-year 24-hour event. The livestock pond contributing area used for the sizing is reflective of the post-undemilning phase, where the upland diversion will no longer be present. Once the undermining is complete and the upland diversion removed, the livestock tank will be retained and should provide a good water source for this upper area of the property. The demonstration materials for the livestock pond to be permanently retained will be provided by EC, prior to the time final reclamation is initialed if the pond is to be retained as planned. During the period when the pipeline is exposed, two temporary diversions will be inscribed to convey any oil from the pipeline into the livestock pond, An additional diversion may be inscribed, as shown on the location map to divert any oil to another existing pond, in the event subsidence effects preclude the maintenance of the required grade on the temporary diversions. Due to the subsidence effects, EC wishes to point out that the temporary diversions may need to be re-cut a number of times, progressing upslope as mining passes in order to maintain the ditch gradient. Backgrading and reseeding of interim ditch segments will be conducted concurrently with installation of new ditch segments. It is anticipated that the topsoil (associated with the pipeline segment in question) will be windrowed to the upslope side of the pipeline corridor by Amoco, and will be left in a stable configuration during the interim period in which undermining occurs. Upon completion of undermining to Amoco's satisfaction, an Amoco contractor will complete the installation of the pipeline segment, and this same Amoco contractor will reclaim, stabilize, and revegetate [he site. EC wishes to reiterate that the final stabilization and reclamation of the Amoco pipeline corridor will be the responsibility of Amoco, as it would be during any routine pipeline repair project. It is anticipated [hat subsoil excavated will also be placed to the uphill side of [he trench, in order to maintain an area for the temporary access road along the lower side. This access would be a temporary two-track within the Amoco right-of-way preparation area, and would be reclaimed by Amoco upon completion of the pipeline burial. During the undermining process, the pipeline will remain exposed in the open trench, until such time that subsidence in the area immediately adjacent to Permit Revision 04-34 2.05-64 Revised 7/2/04