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very low vertical permeabilities. Given this vertical separation and <br />limited permeabilities, the Trinidad Sandstone is effectively isolated <br />from any potentia] groundwater effects which might result from the <br />Southfield mining operations. <br />Within the mine area, the colluvial/alluvial deposits are located well <br />above the interval to be mined in the stratigraphic sequence. These <br />deposits are exposed on the surface and are intersected by many small <br />ephemeral drainages. As a result, any water which may be stored in the <br />terrace deposits discharges to the surface water system along down- <br />gradient outcrops, and terrace deposits in the mine area do not represent <br />a significant or consistent source of groundwater. <br />Most of the loadout area is on an upper terrace of the Oak Creek flood- <br />plain. While some colluvial/alluvial gravels and cobbles exist over most <br />of the loadout area, finer alluvial materials are found only on lower <br />bench elevations, particularly in the western portion of the loadout area. <br />• These deposits are all essentially flat lying and discharge any <br />groundwater which they may contain along their exposed boundaries on the <br />northern side of the Oak Creek drainage. Amore detailed description of <br />colluvial/alluvial terrace deposits in the loadout area is presented in <br />Sections 2.06.8 and 4.24 and in Exhibit 24, Alluvial Valley Floor <br />Investigations. <br />Other stratigraphic units in both the mine and loadout areas, including <br />the Poison Canyon, Raton and Vermejo Formations, can function as poor to <br />fair quality aquifers. However, their value as aquifers is severely <br />limited by low horizontal and vertical transmissivity resulting from <br />extensive cross-bedding and interbedding of individual lithologic units. <br />Small perched water tables can and do develop within all of these units, <br />particularly near outcrop and subcrop recharge areas and in areas where <br />fracturing or favorable depositional characteristics result in increased <br />permeability. <br />• With the exception of abandoned mine workings, exploration drilling in the <br />mine area has not encountered any significant aquifers or other <br />groundwater resources within the noted formations. There has been <br />2.05.6-12 <br />