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Transit Mix Concrete Co. <br /> first phase. After the first phase, only those portions that change (i.e. Quarry area) for the <br /> subsequent phases are shown. <br /> The presented design summary of the ditches, culverts, and sediment basins are based on the <br /> worst-case drainage conditions from the various phases. Thus, the structures will be able to <br /> function for all other cases. <br /> For the reclaimed phase/configuration on Figure G-13, this represents the final configuration. <br /> Between the Phase VI and the final reclaimed state, the sediment basin and associated ditches <br /> will be left in place until the reclamation standards are met. Once that occurs, then the ditches <br /> and sediment basins will be removed and the area treated with temporary BMPs. <br /> a. Ditches <br /> The water management plan includes four types of channels: clean water diversion ditches, <br /> terrace ditches, road ditches, and down drain ditches. Clean water diversion ditches divert un- <br /> impacted runoff to existing stream channels. The terrace and down drain ditches have been <br /> designed to collect runoff from affected areas and convey it to sediment basins. Road ditches <br /> will collect the runoff from the access road and convey it to a series of sediment basins. Runoff <br /> from native areas between the clean water diversion ditches and the affected areas will collect <br /> in the down drain ditches and is included in the sediment-laden water volumes. <br /> i. Terrace Ditches <br /> Terrace ditches will intercept runoff from the affected areas, minimizing local erosion and <br /> assisting the shedding of water off the surface. The terrace ditches have been spaced to limit <br /> the excess fine stockpile slope lengths to approximately 200 feet. This slope length is typical <br /> for stockpiles in the mining industry and will help reduce the sediment volume that erodes from <br /> these areas. During the operational period, terraces are included on each of the benches at the <br /> toe of the slope. For reclamation purposes, terraces will be built into the slope as benches. The <br /> terrace ditches will be triangularly shaped with 3H:1 V and 1 OH:1 V side slopes. These ditches <br /> have gradients of approximately 1% to 2% and do not require armoring. Terrace ditches have <br /> been designed to convey runoff from the 100-year, 24-hour storm with a minimum of one-foot <br /> of freeboard. The typical terrace ditch depth is two feet. A typical cross-section for terrace <br /> ditches is shown in Figure G-14. <br /> ii. Ditch Designs <br /> The designs for clean water ditches, road ditches, and down drain ditches are based on <br /> calculated peak flow rates. Ditches have been included along the edges of the overburden and <br /> fines stockpile, where a ditch naturally forms or along roads, and at the boundary between native <br /> and affected areas. <br /> Hitch Rack Ranch Quarry Permit Application <br /> October 3, 2017 G-20 <br />