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Section 780.21 (b) Continued. <br />• water that has infiltrated through the spoils leaches through to <br />the toe of the most recent spoils ridge and collects in the current <br />pit. In order to remove the coal, this water must, of course, be <br />pumped out. TSS is not a problem with this water, since the pit <br />acts as a detention facility, but the TDS concentration is increased <br />primarily due to leaching and partially due to evaporation during <br />detention. Another potential salt-loading problem exists with <br />respect to excess spoil stockpiles. If water is allowed to saturate <br />the spoil and if enough water is allowed to pass through the spoil, <br />dissolution of solids can occur. Eventually, these dissolved <br />solids can enter either the surface or ground water systems unless <br />specific protection measures are taken. A final potential problem <br />with some mining operations is leaching of or drainage from toxic, <br />acid- or alkalinity-producing materials. This problem can be <br />dismissed at the outset with respect to the coal mining and recla- <br />mation operation covered by this permit application on the grounds <br />. that exhaustive analysis of overburden and topsoil from the mine <br />plan area along with gravel to be used for haul road surfacing, has <br />demonstrated that no toxic, acid- or alkalinity-producing materials <br />exist within the proposed permit area. This analysis was based on <br />the determinaton of concentrations of twenty-seven chemical para- <br />meters from a total of 190 overburden samples, analysis of 112 <br />topsoil samples, and analysis of one sample of gravel to be used <br />for haul road surfacing. A detailed discussion of the chemical <br />characteristics of overburden samples is set forth in Section <br />779.14 (b)(1)(iv); a detailed discussion on the chemical charac- <br />teristics of topsoil is presented in Section 779.21. The chemical <br />characteristics of the gravel are set forth in Table 99, Chemical <br />Analysis of Gravel. <br />Based on analysis of water quality data collected for several years <br /> by the applicant and by several government and private agencies, <br /> the only possible surface water quality problems are with TSS and, <br />• to a very small degree, TDS. Slightly alkaline waters have prevented <br />780-146 <br />