Laserfiche WebLink
periods of irrigation, Tuttle Draw is flowing at a higher rate while the River is running low, which is <br />the time of maximum impact of the flows. at this time, the increase in TDS of the River is from 620 <br />to 652 ppm, or an increase of 5.1%. It should be noted that Tuttle Draw flows are always higher <br />in TDS than the River, regardless of the spoil springs, therefore, the impact from the spoil springs <br />may be only 2 -3% increase in TDS. During March /April, the River is flowing fast and Tuttle Draw <br />is at low flow, therefore the increase in TDS for the River is only 2 ppm, or an increase of 0.4 %. <br />Also, these impacts are for the time when the spoil material is leaching salts at a maximum. As <br />described earlier, the TDS levels will drop as pyrite and salts are leached out of the spoil, lessening <br />the impact to the waters downstream even further. <br />Calamity Draw is not included in the above table since the spoil springs from both mine areas will <br />not enter this stream. This intermittent stream should not be affected in the long term by the mining <br />and reclamation operation. <br />Overall, the effects of the spoil springs are not significant to the waters downstream. <br />71 Effects of mining on the local geomorphology. Impacts from mining on the local <br />geomorphology will be long term, but appear to be of minimal significance. The reestablished <br />reach of the drainage running south into Pond 007 will result in a shorter, slightly steeper stream <br />channel. The potential for increased sediment loads in the drainage (once pond 007 is removed) <br />should be offset by the stable bank sides and the relatively small change in overall gradient. The <br />reclaimed land will be graded to enhance irrigation and restore similar drainage patterns to those <br />which existed on the area prior to mining. The increased runoff and consequent erosion potential <br />on disturbed basins in the mining area due to the temporary loss of topsoil structure should be of <br />minimal significance since all disturbed areas will be protected by a system of sediment ponds. <br />Contour ripping, mulching and revegetation have been demonstrated to minimize soil erosion and <br />will be used to mitigate the increased runoff potential until the topsoil structure is developed. <br />Irrigation will help this to occur rapidly. <br />8) Effects of sediment ponds on channel characteristics and downstream users. Potential <br />impacts of sediment pond 007 and the other future ponds on downstream users will involve <br />possible reductions in flow due to impounded water. The water augmentation plan discusses the <br />available water which will be used should impacts be identified. WFC currently has rights to a <br />sufficient quantity of water to supply all users associated with the mining activities, plus an <br />additional quantity of water that can be used to mitigate any impact to downstream users. <br />REVISED August 2010 2.05.6(3) -41 <br />