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18. Maintenance free stormwater facilities: DRMS experience suggests there is no such thing as a <br /> maintenance free stormwater control facility (ref. 5th paragraph, p. G-3). Please remove this statement <br /> from the narrative. <br /> Response: Exhibit G has been revised to remove this text. <br /> 19. Curve Numbers,Table G-2:Two of the three proposed curve numbers in Table G-2 require some <br /> explanation. Please provide rationale for the following: <br /> a.The 71 proposed for"Reclaimed stockpile and slope" presumably references"Meadow" in TR- <br /> 55,Table 2-2c, which is described as"continuous grass, protected from grazing and generally <br /> mowed for hay".As this is proposed wildlife habitat and will likely be grazed by bighorn sheep, it <br /> is likely more appropriate to use either 79—TR-55,Table 2-2c: "Pasture,grassland, or range", <br /> assuming Fair cover; or 81—TR-55,Table 2-2d: "Herbaceous—mixture of grass,weeds, etc.", <br /> assuming Fair cover. <br /> Response: TR-55 has a range of curve numbers for meadow and pasture/grassland that correspond to <br /> amount of grazing expected, and the grazing is associated with agricultural land not wildlife habitat.The <br /> impacts of light to heavy grazing by cattle or other agricultural units is very different than the impacts of <br /> grazing by wildlife. The reclaimed quarry will likely continue to be "grazed" by bighorn sheep; however, <br /> the impacts to vegetation density are expected to be negligible resulting in minimal impacts to the curve <br /> number.The existing vegetation is grazed by the bighorn sheep, and there are no noticeable impacts to <br /> the density of the grasses on the reclaimed slopes.The photograph below shows reclaimed grassed <br /> slopes above the quarry from August 2016. Increasing the grassed area will further reduce the impacts <br /> grazing has on the grasses. This is summarized in the table below. Considering the quarry will only have <br /> light or occasional grazing,Stantec and Castle recommend revising the curve number for grassland to <br /> 74.The hydrologic calculations, models,and channel sizing calculations have been revised to include the <br /> higher curve number. <br /> Curve Numbers for Grazing on Meadows and Grassland for C-Type Soils <br /> Hydrologic Condition Grazing Curve Number <br /> Meadow Protected from grazing 71 <br /> Grassland, Good Lightly or occasionally grazed 74 <br /> Grassland, Fair No heavily grazed 79 <br /> Grassland, Poor Heavily grazed 86 <br /> Pikeview Quarry Amendment 4, Response to Adequacy <br /> December 11,2019 <br />