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West Elk Mrne Most springs in the lease block derive their water from perched aquifers in the colluvium and ~ Barren Member of the Mesaverde Formation. The fact that most springs dry out during the late summer indicates that the groundwater reservoirs supplying the springs are limited in extent. The dischazge rates of the springs respond closely to precipitation events, another indication that the rechazge azeas for the springs are very localized. There aze three different types of springs within the pemut azea: 1. Alluvial Springs -Subsurface water moving through the alluvium emerges as a spring, and dischazges into the drainage channel. 2. Coluuvial Springs - Colluvial groundwater moving downgtadient emerges from the colluvium as a spring. The source of the groundwater in the colluvium can be snowmelt infiltration, rainfall infiltration, dischazge from a surface channel or upgradient bedrock spring flows that infiltrate into the colluvium. 3. Bedrock Springs - Springs can be encountered where subsurface formations outcrop. Groundwater moves along the surface of the formation and eventually daylights. Historic Snring Monitoring Data Spring monitoring to establish baseline data and to assess the impacts of mining in the F Seam has been conducted by MCC for over 10 years. Monitoring of springs potentially subject to impact from B Seam mining has been conducted since 1992. The relevant data indicate that F and B Seam mining has had little, if any, impact on spring flows. Specific information on spring-related mining impacts for these seams can be found in the Annual Hydrology Reports from 1982 to the present. Plots of spring flow hydrogrnphs are contained in the Annual Hydrology Reports. Considerable variation from yeaz to year is also appazent along with the seasonal pattern. A comparison of operational data with pre-mining data reveals no discernable difference. Flow monitoring will be continued by MCC in order to assess trends over time. A visual comparison of the data presented in the Annual Hydrology Reports reveals a lack of correlation among spring flows. MCC has been building a representative database for springs in the permit and lease azeas, since 1978. Sufficient baseline data, in accordance with CDMG regulations have been established to enable future detemunations as to whether longwall mining could be affecting the springs. Conceptual Description of Subsidence Impacts to Springs The key to evaluating whether or not any given spring will be adversely affected by the E Seam mining in the permit area is to define its elevation relative to both the mine seam and the ground surface. Essentially, the higher the elevation of a spring (and spring source), the smaller the probability of adverse impact as a consequence of fractures that extend upwazd from the mine. However, for a spring to avoid impacts from subsidence, in addition to being above the mine fracture zone, the source of the spring needs to be faz enough below the ground surface to avoid surface fractures that may be the result of subsidence. This phenomenon is described by Liane 2.05-I63 Revised June 2003 PRIO