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. Parameter # of Sites / # of Excursions <br />Iron 3/5 <br />Nitrite 1/2 <br />Selenium 1{1 <br />None of the iron exceedences were from NPDES sites. They were from <br />stream sites and are probably due to suspended solids. Nitrites are <br />unstable in aerated water (Hem, 1989), and will oxidize to nitrates. <br />The one selenium value exceeded the chronic (30 day average) standard <br />but not the acute (one day max.) standard. <br />Ammonia values require extra calculations to determine exceedences. The <br />standard is 0.06 mg/1 un-ionized NH3, while the method detects both un- <br />ionized NH3 and ionized NH4. The following table calculates the actual <br />un-ionized NH3 concentration of the exceedences reported on Table 12. <br />Site Date <br />• NPDE516 4-3-02 <br />6-5-02 <br />" 9-3-03 <br />WSDS 4-8-02 <br />WSH7 " <br />WSHF1 " <br />A = exceedence <br />VH3+NH4,mg/1 pH Temp,C <br />2.79 7.95 4 <br />2.70 8.43 15 <br />3.14 8.40 15 <br />0.32 8.39 9 <br />0.82 8.22 7 <br />0.37 8.30 7 <br />8NH3 NH3 concentration, mg/1 <br />1. 2 0.033 <br />8. 0 0.216 A <br />8. 0 0.251 A <br />5. 6 0.016 <br />5. 6 0.096 <br />5. 6 0.021 <br />Only two samples exceeded the ammonia standard, the June and September <br />samples from NPDESI6. The ammonium nitrate blasting agent is most <br />likely the source. These values will subside after mining. <br />Sulfide values also require extra calculations. The standard is 0.002 <br />mgll un-ionized H25, while the method detects for un-ionized H2S and <br />ionized HS. The following table calculates the actual un-ionized H2S <br />concentration of the exceedences reported on Table 12. <br />21 <br />