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• _1P_ The Division reviewed the application with respect to the aforementioned facts. For those mining facilities already constructed on alluvial valley floors, the Division is ensuring that those areas will be restored after mining in accordance with Rule 4.24. However, all new mining operations proposed by Snowmass Coal Company were reviewed under the full context of alluvial valley floor regulations. For the purposes of this section, the mine and loadout will be discussed separately. , A. Mine The operator conducted a reconnaissance level study of the mine area to determine those areas that might qualify as alluvial valley floors. The study area 1s indicated on Map D-5-1 and discussed in Volume I, Section 5.2 of the application. The study area includes the potential 20. year life-of-mine area, in addition to the permitted 5-year mine plan area. Also, areas adjacent to the life-of-mine were considered for distances to excess of three miles. The total area considered for this mine investiyation was in excess of 75 square miles. Black and white and color aerial photos were used for the study. In addition, areas were field checked for accuracy. The study identified areal of unconsolidated streamlaid deposits along the North, Middle, and Souttr Thompson Greeks and their tributaries. Surveys and field checks of these deposits revealed that the alluvium is relatively thin, intermittent, and restricted to ttre immediate stream channels. No identifiable soils were mapped wltfiln alluvial areas, the alluvium 15 primarily boulders and cobbles with minor stretches of sand, gravel, silt and clay. There are two criteria used by the Division to identify alluvial valley floors. They are: 1) Sufficient unconsolidated streamlaid deposits holding streams, and 2) Sufficient water to support agricultural activities. Hydrologic data available for North Thompson Creek indicates an annual runoff of 16.2 cfs or 0.6 cfs per square mile. Eighty percent of this runoff occurs during the snowmelt season of April through June. low flows during late summer average less than one cubic foot per second. Although water fs limited within the Thompson Creek drainage, the Division feels that sufficient water is available to support limited agricultural activity. ThereFore, the Thompson Creek drainage satisfies one of the crlterla for alluvial valley floors. Tho second end f1nd1 alluvial valley floor crlterla that needs to be considered is that of unconsolidated streamlaid deposits.