2015-02-12_REVISION - C1981014 - Laserfiche WebLink

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George V. Patterson, Energy Fuels Coal, Inc. Page 3 February 12, 2015 1) Groundwater It was established during the original permitting of the Southfield mine that groundwater resources at the site could be categorized as either: • Alluvial /colluvial terrace deposits • Laterally discontinuous perched aquifers • Flooded mine workings • Trinidad Sandstone regional aquifer On page 2.05.640 of the Permit Application Package (PAP), in the PHC section, the possible hydrologic connection of these potential groundwater resources with the mine workings is discussed. It is stated that low permeability strata in the intervals between the mine workings and the Rex Carbon coal seam above, and the Trinidad Sandstone below, provide effective hydrologic barriers (see figure 1). As part of the TR43 review, the Division analyzed geologic data from the drill logs in Exhibit 8 of the PAP and constructed detailed cross sections which corroborate these statements; there are 300 -400 feet of interbedded low - permeability units consisting of mudstones, siltstones and shales located both above and below the Southfield Mine workings At the main mine site, groundwater in the alluvium /colluvium and in the Trinidad Sandstone may therefore be discounted from any further discussion, (the water monitoring plan was approved on the basis that these resources would not be affected by mining). The PHC specifies that only shallow alluvial / colluvial groundwater has the potential to be affected at the loadout. Since there are no groundwater monitoring locations at the loadout it will not discussed further in this section. Three formations remain under discussion: The Poison Canyon, the Raton and the Vermejo. In the PHC section the prediction is made that groundwater impacts will be confined to "the interval disturbed by mining extending up to and including abandoned mine workings in the Vento Seam within the mine area ". Referring to figure 1, this interval is entirely within the Vermejo formation, which is described elsewhere in the PAP as: approximately 900 feet thick. Lithology of the Vermejo formation is highly variable with significant cross - bedding and inter - bedding, and lithotypes varying from well cemented sandstones to fine grained indurated siltstones. While many of the sandstones and coal seams within the Vermejo formation are capable of storing and transmitting groundwater, the lenticular nature and significant cross - bedding and inter - bedding which characterize this formation effectively limit lateral continuity and consequent groundwater transmission capabilities." (Page 2.04.7 -2) This description of the subsurface is consistent with the information gleaned from the Division's analysis of drill logs (Exhibit 8 of the PAP). It is to be expected that multiple zones of perched groundwater may exist within the interval expected to be affected by mining, (as well as in the Poison Canyon and Raton formations, and the strata of the Vermejo formation above the Vento seam). To the best of our knowledge, no attempt has been made to systematically locate, map or characterize these perched zones; certainly such information does not exist with the Southfield mine PAP. Although