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Suspended Solids Demonstration <br /> In addition to the pond effluent sample data submitted by SPL,the operator submitted sediment level data <br /> (pond capacity)in the Annual Reclamation Report(ARR), submittal (Illustration I, labeled Table 13-3 in <br /> SPL's 2019 ARR), for the ponds receiving run off from the proposed release area. The data show, as per <br /> the illustration below and monthly DRMS inspections that the ponds possess ample water capacity and <br /> that sediment levels in the ponds have stabilized since revegetation activities began in 2006. None of the <br /> ponds have required cleaning since Pond 10 was dredged in 2002 and Pond 11 in 2003. <br /> TABLE 13.3 SENECA SEDIMENT PONDS-WATER CAPACITY TRENDS <br /> Requ'rej TrCumn Decision <br /> d ID Capacity'(11 t Remaining Water Capacity2(ac- Reference <br /> 6, <br /> 'I <br /> YEAR 1 2008 2009 1 2010 2011 2012 2013 2014 2015 <br /> Y-010* 3.08 7.6 7.6 7.8 8 8 7.7 9.2 9.2 TR-37 <br /> Y-011 0.99 3.6 3.6 3.6 3.6 3.6 3.7 3.6 3.6 TR-37 <br /> Y-011A 0.633 NA NA NA NA NA NA NA NA TR-37 <br /> Y-012* 0.767 0.7 0.7 L I 0.83 1.2 1.3 1.3 1.3 TR-37 <br /> Y-012A 6.3 6.3 6.1 5.6 5 4.6 4.4 4.4 <br /> Y-013 1.325 4.5 4.4 4.5 4.4 4.3 4.5 4.5 4.5 TR-37 <br /> Y-014 1.6 10.5 7.5 7.6 7.5 7.5 7.5 7 7 TR-37 <br /> (*) Required every Syrs-next survey 2020 <br /> (1) Based on SEDCAD results for a 10yr/24hr storm event. <br /> (2) Remaining capacity below principal spillway or orfce. <br /> (3) TK 37,page 13-4A.1 A9(stock pond) <br /> Illustration 1: Pond Capacity from SPL's 2019 ARR <br /> The operator submitted pond discharge sample data for all of the ponds receiving discharge from the <br /> proposed release area, as well as receiving stream sample data for the Grassy Creek(YSGF5,YSG5), and <br /> Sage Creek(YSSF3 and YSS2) stream points in Attachment G of this application. Pre mine and post <br /> mine TSS (total suspended solids), are compared in Table 5 of Attachment G. <br /> Analytical results from monitoring points upstream and downstream of the 5 NPDES outfalls comprise <br /> Tables 6 through 10 of Attachment G. The pond outfall data indicate that total suspended solids(TSS) <br /> contributions do not exceed the limits set forth by the Colorado Department of Public Health and <br /> Environment. Monitoring data of the upstream and downstream receiving stream sites indicate that TSS <br /> is reduced from the upstream site at the downstream site, and TSS at outfalls 12, 13 and 14 are below pre <br /> mine average. Further comparison of pre mine and post mine NPDES TSS concentrations are available in <br /> revised the pages of the SL8 application dated 24 November 2020. This updated information was <br /> requested as part of DRMS's adequacy questions of August 2020. <br /> The sediment ponds receiving runoff from the proposed release area comprise Ponds 12, 12A, 13, and 14 <br /> and the operator demonstrated that the quantity and quality of impounded water is appropriate for their <br /> intended use. <br /> Permit Number C1994 082 Page 13 of 15 <br />