2017-03-23_PERMIT FILE - C1981019A

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RULE 2 PERMITS then a hogback formed by the uplift of the Iles formation is present. Proceeding north, the open area of the Axial Basin is then encountered. All drainages in the Collom Mine Expansion area form on the southern portion of the Collom syncline/Danforth Hills. These drainages all flow northward toward and cross the Iles formation and then flow into the Axial Basin. The drainages tend to be narrow, confined drainages until the drainages exit to the Axial Basin. A VF Specific Study-Collom Mine Area In 2005, Tetra Tech, doing business as Maxim Technologies, conducted a preliminary field investigation and technical evaluation of the Collom permit expansion area located in the Collom syncline area to determine the presence of alluvial valley floors. The drainages examined include Collom Gulch, Little Collom Gulch, and Jubb Creek (including the West Fork of Jubb Creek). The investigation was conducted in accordance with Section 2.06.8 of the Regulations of the Colorado Mined Land Reclamation Board for Coal Mining and OSMRE Technical Guideline. The results of the investigation concluded that no alluvial valley floors exist in the areas to be mined. The findings were submitted to CDRMS on September 23, 2005 in a letter, a copy of which is included in Volume 18, Exhibit 7, Item 24. These findings are also discussed further in appropriate sections below. The mined area is located within Little Collom Gulch, and the Collom Pit and temporary spoil pil will occupy much of the Little Collom Gulch valley bottom during the mining operation. Portions of the Collom Pit will lie within the adjacent watersheds of Collom Gulch and the West Fork of Jubb Creek, but will not encroach on the valley bottoms (Map 23B). Groundwater in the general area occurs in valley fill material associated with the stream valleys and in the permeable and semi -permeable bedrock strata (CDM, 1985a). As discussed in Section 2.04.7, the existence of groundwater in the permit expansion area is limited to perched systems that primarily discharge small amounts of water in the canyon walls near the mine on a seasonal basis, and in some of the unconsolidated valley fill. Little Collom Gulch is ephemeral, and did not produce any measurable flow during the baseline hydrologic monitoring efforts described in Section 2.04.7. Very little groundwater is found in the current active mine; and, based on existing geological and hydrological evidence, the area to be mined provides no or only minor amounts of recharge to local surface water features. Geomorphic Characteristics Tetra Tech's 2005 investigation included mapping unconsolidated valley deposits in the Collom permit expansion area, using published and unpublished geologic maps and ground reconnaissance. The results are shown in Figure 1 of Exhibit 7, Item 24. Much of the mapped valley deposits contained substantial proportions of colluvium and/or sheetwash materials. The source material for the valley fills was primarily erosion and deposition of loess, leading to a loamy soil texture which supports more lush vegetation than adjacent uplands, even absent sub -irrigation. In addition, valley bottoms within the permit expansion area were very narrow and historically uncultivated. Most floodplains in the area are generally extremely narrow (less than 20 feet), have been severely down -cut, and/or contain too much topographic relief in the form of slopes to be considered capable of being irrigated. Due to downcutting, flooding does not extend beyond the limits of the incised channel. Collom — Rule 2, Page 128 Revision Date: 1/6/17 Revision No.: TR -109