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Section 2.05.3 Page 2 December 2021 (RN-02)  <br />OPERATION PLAN <br /> <br />Introduction <br />This section describes the historical mining activities that were used at the New Horizon North <br />(NHN) Mine from 2013-2017. NHN is now in the final stages of reclamation. <br /> <br />2.05.3(1) Production Methods and Equipment <br />NHN employed surface coal mining with a truck-shovel fleet when it was operational. <br /> <br />2.05.3(2) Detailed Operation Description <br />The primary coal seam that was recovered was the Lower Dakota seam; however, the Upper <br />Dakota seam was also recovered if it was thick enough and of sufficient quality. Mining cuts <br />were generally east-west orientation and progress northward. <br /> <br />NHN excavation was performed by dozers, loaders, trucks, and a shovel. The sequence was to first <br />remove topsoil with dozers, a shovel, and loaders loading trucks which took the material to <br />designated stockpiles or to regraded area behind the pit for reclamation. Soft upper overburden <br />was removed by a shovel or loader and trucks and taken to a designated stockpile or to the pit for <br />backfilling. If the material was taken to the pit for backfilling, dozers regrade the spoil overburden <br />to approved post mining topography. The lower overburden was usually cast blasted where <br />approximately 25% of the overburden was casted into its final position in the backfill. The <br />remaining shot overburden was then either pushed with dozers into its final position in the backfill <br />or loaded with a shovel or loader and taken to a designated stockpile or placed behind the pit for <br />backfilling. The exposed coal was loaded either from the pit or stockpiles into over-the-road haul <br />trucks which took the coal to the nearby Nucla Station power plant operated by Tri-State <br />Generation and Transmission (Tri-State). A cross section of the typical pit is shown on Map 2.05.3- <br />1. <br /> <br />Mining occurred south of Meehan Draw, and a cut mining method was used to develop the pits. <br />The cuts varied in length and width according to conditions encountered. Cut lengths approached <br />2,200 feet and the cut widths varied from 100 to 120 feet. A bottom pit width of 120 feet was the <br />maximum that will be used. The exposed coal portion of the bottom of the pit was also generally <br />120 feet wide. Since this operation used the graded spoil as a base for the overburden truck traffic, <br />no ungraded spoils remained behind the pit. <br /> <br />Mining generally progressed south to north with the long axis of the pits generally east to west. <br />The overburden was placed or pushed into an adjacent or nearby mined out pit cut except for the <br />initial cut where topsoil and overburden was placed adjacent to the pit onto land designated as an <br />overburden stockpile. This stockpiles was located in southern portion of the permit area. This <br />topsoil and overburden used to reclaim the last cut, but was also used to backfill when the mine <br />ceased operation. During overburden removal operations, some selective handling of material may