2022-07-12_PERMIT FILE - C1981019A (4)

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RULE 2 PERMITS Collom – Rule 2, Page 32 Revision Date: 4/28/22 Revision No.: TR-154 Much of Little Collom Gulch is located within the Collom Pit and spoil piles. As a result, an upgradient monitoring station was not established. Sampling point LLCG is located immediately adjacent to valley fill well MLC-04-01 east and just above the confluence of Little Collom and Collom Gulches (Map 10B). Another monitoring well named MLC-04-20 was attempted to be drilled in Little Collom Gulch to monitor valley fill ground water in the upper portion of the gulch. The location selected was downstream of and within 500 feet of the northern end of the Collom Pit excess overburden pile. The location selected for the placement of the monitoring well was on a bench within the bottom of the valley that was considered to be underlain by valley fill material. The bench is 25 to 30 feet above the floor of the narrow incised channel of Little Collom in this area. The MLC-04-02 location was sited approximately 30 feet west of the valley bottom. During the drilling of the hole, weathered bedrock was encountered at approximately four feet below ground surface, with a mixture of colluvium and eolian material from ground surface to four feet below ground surface. Drilling was advanced to 20 feet to determine if any shallow ground water could be encountered. The drilled materials to 20 feet were dry. Examination of the bank wall above the floor of the Little Collom Gulch valley revealed weathered bedrock near the surface and less weathered bedrock encountered when digging further into the bank. The floor of the valley revealed predominantly colluvial and eolian material with some sheet wash material. Based on the activities at the MLC-04-02 location, further examination of the Little Collom Gulch valley was undertaken from this point downstream (northward) to near the site of MLC-04-01 (near the confluence with Collom Gulch). The valley bottom of the Little Collom Gulch is narrow for over 0.3 miles to where the valley starts to spread out, but the channel remains narrow and deeply incised. The surface material throughout the valley remains predominantly colluvial and eolian with some sheet wash deposition. The banks along the deeply incised channel do not show any significant falls due to undercutting of the banks. Only normal erosion seems to be occurring throughout the length of Little Collom before it enters Collom Gulch. Large trees and heavy rangeland vegetation occurs through the valley bottom. Where the valley flattens on each side of the incised channel of Little Collom Gulch (approximately 0.9 miles north from the MLC-04-02 site), a two track road has crossed the incised valley bottom of Little Collom Gulch. Examination of this location shows no evidence of near surface ground water and no “wetlands” type vegetation is apparent in this area. The crossing is approximately 30 to 40 feet deeper than the flat area of the valley on each side of the incised channel. Several impoundments in Little Collom Gulch show some water storage in the past. However, there is no evidence of recent surface water flow and/or storage due to the presence of rangeland vegetation in the incised channel bottom and the water storage areas. Another crossing near where Little Collom Gulch turns to the west to intersect with Collom Gulch, also shows no recent water flow or wet bottom in the incised channel bottom. This crossing is also approximately 30 to 40 feet deeper than the valley sides. In addition to these observations, monitoring of surface and ground water in the valleys of the Collom mining area has been undertaken for over a decade and no surface flow has ever been noted in Little Collom. Drilling and field surveys by Colowyo geologic contract personnel in the Collom mining area for over the past 20 years have not noted any water flow in Little Collom Gulch. The surface conditions of Little Collom Gulch north of the MLC-04-02 location and the shallow bedrock throughout the valley seems to preclude the presence of any significant valley fill north of the excess