PERMFILE64153 - Laserfiche WebLink

Home Browse Search

State Rea. • The analysis above shows that TDS levels at SW-S2-2 duri~ September are controlled by the relative contribution of NPDFS 003 dischan7es to Grassy Creek; when fIPDFS 003 flaw contributions to Grassy Creek are relatively high (when with the alluvial aquifer contribution) , high TDS concentrations can be expec.~ted at SW-S2-2. Zile contribution of NPDFS 003 to Grassy Creek arrmearS to be controlled by precipitation, since water year 1990 had the lowest annual precipitation total since precipitation monitoring began at the Seneca II Mine (see Table 7-90). Zhis relationship is verified by a review of flan data from other years with closer to normal precipitation totals, and these data show that NPDFS 003 dicrhames generally aooow~t for approximately 50 percent of the flora at SW-S2-2 during September. As can be seen by the information just presented, future TAS wnoentrations in Grassy Creek during September are dependent upon precipitation receives at the mine, as well as Zfl,S levels at NPDFS • 003 and the Grassy Creek alluvial aquifer. Water quality at DTPDFS 003 has beccene relatively stable in recent years after showing a marked increase in TDS concentrations when the truck was system came into use. Unless changes occur in the truck wash operations, TQS values at NPD£S should remain within the range seen in recent years at this site. TDS levels at Wells GW-S33-A and GW-S31-A2 show a slight increasing trend since 1986, probably in response to the reduced precipitation received in the area (when cca[g~ared to water year 1986 aryl earlier). Since it is difficult to aa:urately predict ZDS levels at NPDES 003 or the alluvial aquifer, arri impossible to predict future precipitation levels, it is also difficult to predict future maximum ZS)S concentrations in Grassy Creek as measured at SW-S2-2. PWCC estimates that Z'DS levels in Grassy Creek should remain similar to those seen in recent years at SW-S2-2, and the hic~est ZDS measurement seen thus far (3018 mg/1) should not be exceeded by more than 10 percent. R4CC would also like to stress that even if '~. le~rels ; n. massy Creplc sittailri increase by lA • percent to 3320 mg/1, Grassy Creek water would still be quite suitable for livestock use. 7-328 Revised 08/20/93