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175 <br /> 08 March 2023 Page 3 <br /> Eden View Subdivision EA <br /> DEQ Project No.23-0163 <br /> last for years. <br /> 10. a)The culvert must be designed to allow for aquatic life and fish passage. Generally,the culvert <br /> or pipe invert should be buried at least 1 foot below the natural streambed(measured from the <br /> natural thalweg depth). If multiple barrels are required,barrels other than the base flow barrel(s) <br /> should be placed on or near stream bankfull or floodplain bench elevation(similar to Lyonsfield <br /> design). These should be reconnected to floodplain benches as appropriate. This may be <br /> accomplished by utilizing sills on the upstream and downstream ends to restrict or divert flow to <br /> the base flow barrel(s). Silled barrels should be filled with sediment so as not to entrap wildlife or <br /> support mosquito breeding conditions. Sufficient water depth should be provided in the base flow <br /> barrel(s) during low flows to accommodate fish movement. If culverts are longer than 40-50 <br /> linear feet, alternating or notched baffles should be installed in a manner that mimics existing <br /> stream pattern. This should enhance aquatic life passage: 1)by depositing sediments in the barrel, <br /> 2)by maintaining channel depth and flow regimes, and 3)by providing resting places for fish and <br /> other aquatic organisms. In essence,base flow barrel(s) should provide a continuum of water <br /> depth and channel width without substantial modifications of velocity. <br /> b) If multiple pipes or cells are used, at least one pipe or box should be designed to remain dry <br /> during normal flows to allow for wildlife passage. <br /> c) Culverts or pipes should be situated along the existing channel alignment whenever possible to <br /> avoid channel realignment.Widening the stream channel must be avoided. Stream channel <br /> widening at the inlet or outlet end of structures typically decreases water velocity causing <br /> sediment deposition that requires increased maintenance and disrupts aquatic life passage. <br /> d) Riprap should not be placed in the active thalweg channel or placed in the streambed in a <br /> manner that precludes aquatic life passage. Bioengineering boulders or structures should be <br /> professionally designed, sized, and installed. <br /> The NCWRC encourages the applicant to consider additional measures to protect wildlife species in <br /> developing landscapes. More detailed information on each of these measures and supporting literature <br /> can be found in NCWRC's Guidance Memorandum to Address and Mitigate Secondary and Cumulative <br /> Impacts to Aquatic and Terrestrial Wildlife Resources and Water Quality(August 2002; <br /> http://www.ncwildlife.org/Portals/O/Conserving/documents/2002 GuidanceMemorandumforSecondaryan <br /> dCumulativelmpacts.pdf). <br /> At this time,the information provided is not sufficient for our staff to make definitive recommendations <br /> or conclusions concerning this project. Please contact me at(336)269-0074 or <br /> olivia.munzerkncwildlife.org if there are any questions about these comments or for free technical <br /> guidance. <br />