Laserfiche WebLink
Mr. Rob Zuber <br />August 3, 2015 <br />Page 9 <br />Response: Page D-2 is an "intentionally left blank page" that was apparently not provided <br />during the initial submittal. Because the two subsequent map pockets holding Figures D 1 and <br />D2 are assigned page numbers, we are providing page D-2 within this submittal. <br />ITEM 32. In Figures DI and D2, the construction notes state that the cut and fill of the <br />sediment pond access roads will have Ih: Iv slopes. However, Rule 4.03.2(3)(e)(viii) states: <br />"Embankment slopes shall not be steeper than 1.5h: Iv, except that if the embankment material is <br />a minimum of 85 percent rock slopes shall not be steeper than 1.35h:1 v if it has been <br />demonstrated to the Division that embankment stability will result. " Please revise the access <br />road embankment .slope to meet the minimum criteria of this rule. <br />Response: Exh. 7-23, Figures D1 and D2 are being resubmitted with the construction note <br />modified as requested. <br />Exhibit 7-23, Part G <br />ITEM 33. Grass filter inputs in SEDCAD for roughness (0.0121) and spacing (0.67') do not <br />match the introductory text. Please address this apparent error. <br />Response: The previous submittal contained outdated models. The models that were included <br />were from the initial scoping models for which SEDCAD's default values of Manning's <br />roughness and grass spacing were used as input. As explained in the text, these values were <br />intended to be conservatively revised, downward in the case of the roughness coefficient to <br />0.001, and upward for the spacing, to 3". The correct models with the more pessimistic <br />roughness and spacing are resubmitted herewith. Note that with the more conservative input <br />values, the 70 -foot long test case will have a 24 -hr weighted settleable solids of 0.01 ml/l, <br />slightly higher than the value of 0.00 in the less conservative model previously submitted, but <br />still well below the 0.5 ml/l standard. The value has also been changed to 0.01 in the text to <br />track with the more pessimistic model, but the conclusion, namely that the existing grass filter <br />will consume the settleable solids in the first 70 feet or less of travel through the native grass, <br />remains unchanged. <br />ITEM 34. Please explain the selected stiffness factor of 20 N -sq m. It may be an order of <br />magnitude high. <br />Response: The SEDCAD User's manual suggests a stiffness factor of 2 N/m` on page 86, but <br />the drop down tables in the actual program suggest a value of 20 N/m2 for "native grass mixture, <br />good stand, unmowed". Since the grass filter areas being evaluated are native undisturbed <br />vegetation, we believe the stiffer value is more appropriate, and therefore have not revised it. It <br />was not a typographical error or table entry error. <br />