2020-02-07_REVISION - M1977211 (15)

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UKCONTINENTAL MATERIALS CORPORATION Exhibit G-1. Furthermore, both armored ditches presented in Exhibits G-2a and G-2b have bottom widths varying from 10 to 20 feet which is also not delineated on Exhibit G-1. Given the potential critical nature of these stormwater ditches,the DRMS deems it necessary to evaluate the hydraulic performance of these ditches. Please provide the following: a. Freeboard clarification: Page G-6, last paragraph states the minimum freeboard is 0.5 feet.The same paragraph references Figure G-2 (which should be Figures G-2a and 2b). Figures G-2a and 2b indicate all channels will have one foot of freeboard. Please clarify the intended design freeboard [for steep channels, 1 ft is preferable]. Response: The channel depths have been revised to maintain a minimum freeboard of one-foot. b.Table G-3: Several channels appear to have varying longitudinal slopes(e.g.,the ditch conveying flows from the design point of WS8 to the Design point of WS9 appears to have four different gradients, and WS3 appears flatter at the top/west end and at the bottom near it's outlet). Please provide design calculation summaries for both the minimum and maximum gradients for each of the channel and culvert summaries(see Comment No. 33.d.iv below). Response: The channel design summaries are in Table G-3.The table lists a variety of channel slopes and specifies the minimum riprap armoring and channel size to safely convey the peak flow from the 100-yr, 24-hr storm event. c. Channel Transition Design:The hydraulic performance at the intersection of the WS-3 Cross Channel and south flowing terrace channel is of concern to the DRMS. Higher flows and velocity in the cross channel may cause interference/backwater/reverse flow conditions in the terrace channel at these junctions, leading to overtopping and/or potential for significant erosion and significant water infiltration. Please provide design details for these critical junctions. Response: The intersection of the cross-channel from WS-3, flow from WS-4, and flow from the terrace occurs on native ground that is outside the slide area.This is the location of the existing culvert, and the combined channels will be flat across the culvert area, which will prevent backwater in the cross- channel or terrace. It also allows the three flows to combine and dissipate energy before flowing down the riprap armored channel. d. Exhibit G-1 with the following: i. Larger scale in order to delineate the locations and reaches(i.e., ditches listed in Table G-3)of the three different ditch types and a means to specify the bottom design width of the two armored ditch types, Response: Exhibit G-1 has been provided at a larger scale. Pikeview Quarry Amendment 4, Response to Adequacy February 7, 2020 8