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Sites NPDES2, NPDES3 and SSG1 on the same day were 7.56, 8.31 and 7.57, respectively. The pH <br />value downstream at Site YSG5 on the same day was 8.35 so the exceeded value appears to be an <br />outlier. <br />The total recoverable (TR) iron standard of 1. 0 mg/ 1 was exceeded a total of twenty times (out of 46 <br />samples) at Grassy Creek Sites SSG1 (Grassy Creek upstream of PSCM outfalls), SSG2 and YSG5 <br />(both are Grassy Creek sites downstream of PSCM outfall NPDES2). High TR iron values are <br />normally associated with high total suspended solids. No excursions of this standard occurred at <br />PSCM NPDES2. Only one excursion of the iron TR standard occurred out of 62 samples collected at <br />PSCM Outfall NPDES3 during 2011 through 2015. <br />No sites exceeded the ammonia standard in the past five years. <br />The drinking water standard for mercury is 2 ug/1. The aquatic life standard for mercury is 0.01 ug/ 1 <br />which is set to protect the average human consumer of fish. PSCM's lab uses a method with a <br />detection limit of 0.2 ug/l. None of the stream samples collected in the past five years were above the <br />drinking water standard. During a previous NPDES permit renewal, the CDPHE performed a <br />reasonable potential analysis on Outfalls 002 (NPDES2) and 004 (NPDES4), and determined that <br />there was no reasonable potential for these outfalls to exceed the mercury limit; therefore, mercury <br />monitoring is no longer required at these outfalls. <br />Spoil Springs 1 and 2 flow into the NPDES 004 Pond, and Spoil Springs 10 and l0A flow into the <br />NPDES 002 Pond. Water quality data collected at Spoil Springs 1, 2, 10 and l0A were compared to <br />the agricultural standards. Four of the CWQCC surface water agricultural use standards were <br />exceeded. The manganese standard, 0.2 mg/l, was exceeded at Spoil Springs 2, 10 and 10A. <br />However, as indicated in the recently revised CWQCC Regulation 31, the standard of 0.2 mg/ 1 <br />applies to plants grown in acidic (< 6. 0 pH) soils. In alkaline soils, as are found in the PSCM region, <br />a more appropriate EPA (1976) standard would be 10 mg/ 1. The maximum dissolved (D) manganese <br />values for Spoil Springs 2, and 10 were less than 1.0 mg/l. <br />Permit Requirements of the Colorado Discharge Permit Systems (CDPS) <br />PSCM currently maintains three outfalls affected by the areas being requested for this Phase III bond <br />release: Ponds 002 (NPDES2), Spoil Spring 1(SSSPGI / NPDES6), and Spoil Spring 2 <br />SSSPG2/ NPDES5) which are monitored under the CPDS Permit No. CO -0048275. Prior to the <br />CDPS permit renewal, effective January 1, 2016, NPDES5 and NPDES6 fed pond 004 (previously <br />NPDES4). Data provided for this Bond Release Application reflect NPDES4 and not NPDES5 or <br />NPDES6. Sample data has been reported quarterly in discharge monitoring reports (DMRs) filed with <br />the CDPHE and the CDRMS. These DMRs indicate that no exceedances of permit limits (with the <br />exception of selenium noted above) have occurred in the past five years. The total recoverable iron <br />standard of 1.0 mg /1 was exceeded during January 2014 with a value of 1. 55 mg /1 at NPDES4. <br />NPDES4 has exceeded this standard only once since monitoring for total recoverable iron was <br />initiated in 1987. The subsequent February sample had a total recoverable iron value of 0.11 mg /1. <br />C-2009-087 Page 11 of 14 <br />