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<br />OC1512 <br /> <br />has occurred within the project area in recent times. There is <br /> <br />nothing to indicate active disturbance that could be intensified by <br /> <br />the presence of the dam or reservoir. <br /> <br />Subsurface water at the dams1tAl. <br /> <br />2. Ground water: <br /> <br />prior to construction of the dam waS confined to the unconsolidated <br /> <br />material in the Purgatoire valley, where it is held up by the Pierre <br /> <br />shale. There is an indeterminate small amount of ground water moving <br /> <br />through some layered rocks from the south side of the valley into the <br /> <br />river, emerging a few feet above stream level. Ground water moving <br /> <br />through the unconsolidated material of the valley will be stopped <br /> <br />temporarily by the dam, but this same material will be rejfarr,ed <br /> <br /> <br />immediately downstream by normal flow through the outlet works and <br /> <br />the river downstream will be virtually unaffected by the presence <br /> <br />of the dam or the reservoir. <br /> <br />3. Coal mines: Coal has been mined on both the north <br /> <br />and south sides of the valley from the Vermejo formation. The <br /> <br />largest mines in the area are the Piedmont and Sopris Numbers I <br /> <br />and 2. These mines are south of the reservoir area and pose no <br /> <br />problems to the reservoir. Other mines in the gen(_~ area are above <br /> <br />maximum pool level, outside the reservoir area, or of such small <br /> <br />extent that they pose no problems, geologic or otherwise. Reported <br /> <br />quantities of aulfur in the coal are very small, varying between <br /> <br />.6 and .7 of one percent. All of the portals of the mines within <br /> <br />the project area were sealed prior to commencement of embankment <br /> <br />construction. <br /> <br />IV-Il <br /> <br />. <br /> <br />. <br /> <br />. <br />