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j.n <br />2. Regarding the treatment system infrastructure: <br />a. The final disposition of the pipes transporting the iron- <br />rich water across the creek and their protection from the <br />elements and vandalism need to be further discussed with <br />the OMLR, as the Office feels at this time that the pipe <br />integrity could be compromised if left as is. <br />b. Regarding the corrugated half pipe leading to the long <br />pond, it may be necessary to include a means of <br />containing any spillage due to blockage or unexpected <br />high flows. OMLR encourages the operator to discuss this <br />issue with them before final approval can be made. <br />3. The landowners and county commissioners should be notified of <br />the proposed land use change by the operator as soon as <br />possible as is stated in the permit, page 4-99. <br />4. Regarding the pond and ditch designs on submitted revised <br />pages P-9-5 through P-9-8, three areas of concern were noted <br />and are detailed below. <br />a. Both the long pond capacity to withstand a 25 yr-24 hr <br />event and the present spillway capacity for same were <br />modeled on Sedcad. Using both field observations together <br />with the Sedcad results a model was developed that <br />simulated a 25 yr-24 hr event. Sedcad calculations <br />are attached for your review. <br />The model divided the area above the long pond into two <br />subwatersheds; an upper and lower, using slope as a dividing <br />factor. The upper subwatershed included the steeper sloped <br />areas directly below the road, while the lower subwatershed <br />included the flatter slopes from the base of the steep slopes <br />to the edge of the pond. Vegetative cover was estimated on <br />both the upper and lower subwatersheds to be 80 and 76 <br />respectively. Based on the model's results, the long pond <br />would experience an increase of .10 acre feet of water and 1 <br />ton of sediment under current conditions. Assuming that the <br />water level was at the level of the secondary spillway, the <br />water would enter and leave the pond with a peak discharge <br />rate of 1.37 cfs, which is above the carrying capacity of the <br />four inch secondary outlet. <br />b. From the drawing submitted, it is not clear what the <br />capacity of the pond is above the level of the standing <br />treatment pool or, where T1 and T2's spillways are <br />located from the bottom of the pond. This issue needs to <br />be clarified, and documentation as to the spillways exact <br />location needs to be submitted. <br />