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Minor Revision Request No. 16 Southfield Mine South Fan Installation approximately 4H:1 V and the bench highwall does not exceed 15 feet in height so there is little potential for adverse stability impacts on the fan installation. An expanded discussion of site geology is presented in Sections 2.04.5 and 2.04.6 of the EFCI permit application document (Volume 1) HYDROLOGY AND CLIMATOLOGY (2.04.7 AND 2.04.8) The Southfield Mine is located in a semi-arid region with average annual precipitation of approximately 15 inches. With the exception of diversion of Newlin Creek above the Southfield permit area, neither ground nor surface water resources are extensively utilized in the immediate area. The area to be effected by the proposed fan installation lies within the Mineral Creek surface drainage basin. Similar to other small area drainages, Mineral Creek is an ephemeral stream which normally flows only in response to spring snowmelt or major thunderstorm events. The proposed fan site is near the upper end of a small tributary to Mineral Creek. Given the limited annual rainfall and relatively high porosity of surficial outwash materials, it is unlikely that any significant runoff from the site would ever reach Mineral Creek. Several lithologic units which occur within the Southfield permit area have the ability to store and/or transmit groundwater. With the exception of the Trinidad sandstone, which is approximately 300 to 500 feet below the surface in this area, all of these units have limited lateral continuity and highly variable permeability due to extensive interbedding. There are no significant surface or groundwater resources in the immediate area, groundwater utilization is limited to mine use and stock-watering and beneficial downstream surface water use is limited by low flow volumes and c: xoik p~ ie ,emo1 B.BBO 12/23/BI fpm 5