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State Reg. <br />Co-Mg-504 type. This is typical of runoff from the Williams Fork For- • <br />motion (lorns, 1965). The following discussion presents information on <br />quantity and quality for (I) the Seneca II Mine effluent and (2) Little <br />Grossy and Grassy Creek. <br /> <br />I. Seneca II Mine Effluent <br />a. ~uantitY. At the Seneca II Mine, continuous information on flow from <br />NPDES Discharge Points 002 and 003 has been recorded since 1975. This <br />information is presented in Tables 7-21 through 7-24 and in Appendix 7-3, <br />Tables 7-3-I through 7-3-6. However, it should be noted that NPDES <br />discharge points have been shifted. Before October 1979, the entire <br />drainage of Grassy Creek wos routed through the sediment pond due <br />north of the shop and the discharge point from the pond was labelled <br />001. This pond also received runoff from a fly ash disposal site. In the <br />fall of 1979, Grassy Creek was diverted around the impoundment but fly <br />ash disposal site runoff was still received by the pond. The discharge <br />point was relabelled 003. In October of 1980, this pond was eliminated • <br />and a new pond was designed and constructed. This new pond is <br />NPDES 003. The fly ash disposal site runoff was diverted away from the <br />pond and treated by its disposer. The new pond now receives runoff from <br />the shop area and reclaimed land For more details; see "Protection of <br />the Hydrologic Balance". <br />Flow is currently being monitored by a V-notch weir at 003, a H-flume at <br />002, and by crest stage gages at SW-52-I and SW-S2-2 upstream and <br />downstream from mining respectively on Little Grassy Creek. SW-52-3 <br />is above the upper impoundment and SW-S2-4 and SW-52-5 are located on <br />streams which enter the mining permit area. Continuous recorders have <br />been placed on the flumes and weir, and crest stage gages are checked <br />once a month for flow. The location of these points is given in <br />Exhibit 7-2. <br />Data from gaging stations upstream and downstream from mining is • <br />given in Tables 7-25 through 7-27A. Discharge information from the <br />mine is also well maintained and is presented in Tables 7-21 through 7- <br />7-64 <br />Revised 5/27/81 <br />