Laserfiche WebLink
sufficient water for flood irrigation, the lack of flood irrigation, the small size of the <br />valley bottom and the narrow nature of the stream, and the lack of meaningful <br />production or cover differences between the creekside and upland vegetative <br />communities. <br /> <br />Therefore, in summary, the Division finds that all valley bottom areas along Foidel <br />Creek upstream of the County Road No. 33 crossing are not alluvial valley floors. <br /> <br /> Middle Creek <br /> <br />Prior to PR-03, no previous AVF determination had been made for areas above the <br />Foidel/Middle Creek confluence AVF on Middle Creek as these areas were not <br />proposed to be affected or impacted by the Foidel Creek mine operation. During the <br />PR-03 review process, the applicant submitted information to support its position that <br />areas along the Middle Creek valley floor in sections 12, 23, and 26 T5N R86W are <br />not alluvial valley floors. Twentymile Coal provided information which is contained <br />in the permit application as Exhibit 42a and consists of vegetation sampling data, <br />valley floor cross-sections, and a transect location maps. The applicant also refers to <br />the narrow and deeply incised nature of Middle Creek. <br /> <br />There is no indication of past or current flood irrigation of these areas along Middle <br />Creek, and the geomorphic characteristics of this area would not lend themselves to <br />the development of an irrigation system. Based on the lack of flood irrigation <br />potential, the narrow and incised nature of the valley bottom, and the lack of <br />meaningful differences between the creekside and upland vegetative communities, the <br />Division has determined that areas upstream of the Connel ditch lateral crossing of <br />Middle Creek, as shown on Map 15, are not alluvial valley floors. In this case, the <br />extent of farmable acreage would be 10 acres or less. The areas are not presently and <br />have not historically been farmed and evidence presented indicates that farming is not <br />typically practiced on similar parcels in the region. A previous negative determination <br />had already been made for those lands along Middle Creek downstream from the <br />County Road No. 33 in section 12 to the first irrigation ditch crossing (Connel ditch <br />lateral). <br /> <br /> Effects of Mining on Identified Alluvial Valley Floors <br /> <br />Due to elevated levels of salinity documented in current and future mine discharge <br />water, and to potential inhibitory effects of increased soil and alluvial ground water <br />salinity on flood irrigated and sub-irrigated crops, the potential for material damage <br />caused by salt loading was a concern which had to be evaluated for each AVF <br />identified above. <br /> <br />Material damage projections were calculated in both a sub-irrigation and a flood <br />irrigation case analysis, using data obtained during low-flow-of-record years. The <br />sub-irrigation scenario assumed that the stream would recharge the alluvial aquifer in <br />the spring during peak flows. The flood irrigation case utilized the period between <br />June 1 and August 31. Assumptions and equations used in projecting water quality <br /> <br /> <br />37 <br /> <br /> Foidel Creek MineOctober 8, 2013 <br /> <br />