2012-03-07_HYDROLOGY - C1981033 - Laserfiche WebLink

Home Browse Search

Sandra Brown March 7, 2012 Page 11 flows. With this level of mixing and dilution even in a worst case scenario at low flow the impact that the approximate 4 gpm seep would have on the water quality of the river would be undetectable. There are no metals that would be above the applicable stream standards or that would contribute any significant degree of degradation to the stream segment. Of some interest is the color of the water. The tea color is not the result of iron but likely the presence of humic acid. This has been shown to be caused by organics that are not specifically identifiable but, are not pollutants that are considered hazardous. The water is of relatively good quality. There appears to be no basis for treating this particular hillside seep with a treatment pond in perpetuity. My recommendations are that the existing sediment pond (Outfall 004) and the treatment pond (Outfall 001) be backfilled and reclaimed in accordance with the approved reclamation plan. The sediment pond has never discharged and the hillside seep can be discharged directly to the river with no adverse impact. We should recommend to the WQCD that they consider terminating the CDPS permits for these two outfalls in coordination with BCC and our Division. BCC has submitted a technical revision for removing the treatment pond and installing a 6" seepage pipe from the base of the seep to the North Fork of the Gunnison River. I recommend that the revision be reconsidered to incorporate a more geomorphic design into the plan for discharging the seep water to the river. This would include more of a channel design with some sinuosity and removal of the straight hard pipe. The cat tails function well to lower iron levels so incorporation of additional small wetland area with cat tails should be included. Riprap or other erosion control would be incorporated as needed. C: David Berry Denver File