1992-08-05_GENERAL DOCUMENTS - C1980005

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Flow at NPDES 004 (Cow) over the past five years has been lower than previously measured. This is largely due to relatively lower snow melt runoff and the reduced diameter of the discharge culvert modified in 1987 (36 to 6 inches) . Flow at NPDES 008 (Replaced SW-S2-9 on Bond) has increased slightly since flow first passed through its spillway in early 1988. The particular flow increase in 1991 may be due to greater precipitation during this year. Peabody's predictions in the permit regarding flow at 004 have been substantiated. The permit should, however be updated to include a discussion of flow at NPDES 008 rather that SW-S2-9 which is currently concluded as part of the 1986 revision. Historically, in terms of water quality, trace metals (Cu, Pb, Zn, Cd, Cr, and Fe) , sulfate and TDS pose the greatest threat to Fish Creek water quality. These parameters have at least infrequently exceedanced water quality standards set by the Colorado Department of Health for Segment 13 of the Yampa River, Trout Creek and its tributaries (including Fish Creek) , during the permit term at one or more of the surface water monitoring sites (usually NPDES 004 and 008) . Also of concern in the Fish Creek drainage are nitrate levels for similar reasons. only four parameters commonly exceeded CDOH standards prior to 1986; Mn, 504, total Fe and NO3. According to the 186 revision these constituents had not shown any tendency toward increasing concentration levels or frequency. And, should increases occur, they were predicted to be too insignificant for laboratory detection. Total Cd, Cr, Cu, Pb, Mn, and Zn and dissolved Fe levels infrequently exceeded CDOH standards prior to 1986, were not considered to be injurious to the quality of surface water exiting the Seneca II mine, and were not showing any trend toward increasing frequency of occurrence. Peabody did however expect SO4 levels to continue to rise markedly along with total dissolved solids (TDS) concentrations. Thus far Peabody's assertion that sulfate and TDS have a direct relationship has proven to be true. TDS levels were not expected to exceed 607 mg/1 at 27-A; a 74 mg/1 increase from 533 mg/1 at 1002 (Sites SW-S2-11, 13 were not constructed until 1987) during June or July, the highest TDS level months historically. Moreover, Peabody predicted that increases in TDS concentrations would not preclude Fish Creek water from being used for irrigation and thus expected no noticeable effect on plant growth, health or yield. We should note that Peabody used the salt tolerances for the aforementioned hay crops published in Donahue, Miller and Shickluna, 1977 on page 7-252 of volume four to justify such a prediction. Section VII B.c. (7-242) , "Probable Surface Water Impacts due to Mining" should be updated to include predictions based on and about data at the newly constructed Bond Creek, Cow Camp Creek and Fish Creek sites (SW-S2-10, 11, 12, 13) . AVF POTENTIAL IMPACTS: ACTUAL AHR DATA (1287-19911 Four factors seem to preclude mining activities from impacting Fish Creek water quality and thus prevent damage to the Fish Creek