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HomeMy WebLinkAbout20170799 Ver 3_Plan Sheet Impact Maps (6)_20200403 Fig. 1. Existing conditions, Mist Lake Dam, Durham NC. Wetland delineation by Timmons Group; PJD approved 10/16/2017 by Ross Sullivan (attached). Mist Lake has no discrete surface water channel connection with the stream to the east (UT Goose Creek) and is a non-jurisdictional water feature. Fig. 2. Existing conditions, Mist Lake Dam, Durham NC. Toe of dam embankment, Jurisdictional wetlands, NC-DWR Neuse buffers, and Durham City-County stream buffers and wetland buffers. The existing dam has no functioning outlet structure; it overflows at multiple low points along the dam crest. Fig. 3. Proposed site plan, Limits of disturbance, and temporary (T) and permanent (P) impacts to Jurisdictional wetlands and Neuse River Buffers. Construction within the existing dam footprint indicated in the Pre-Development Plan above is not counted toward Neuse Buffer impacts. Fig. 4. Proposed site plan, Limits of disturbance, and impacts to Durham City-County 50 to 100-ft stream buffers (Falls/Jordan watersheds). Construction within the existing dam footprint indicated in the Pre-Development Plan above is not counted toward Durham F/J Buffer impacts. Fig. 5. Proposed site plan, Limits of disturbance, and impacts to Durham City-County 25-ft wetland buffers (Falls/Jordan watersheds). Construction within the existing dam footprint indicated in the Pre-Development Plan above is not counted toward wetland buffer impacts. The filled areas represent impacts to both Durham stream buffers and Durham wetland buffers, and were not subtracted from either impact measurement. The total of these three buffer overlap areas is 4370 sq.ft. Fig. 6A. Level spreader outlet plan and profile. Per the NC BMP Manual, the design storm for the Level Spreader is the 0.75 in/hr storm (about 3.1 cfs). Greater flow will discharge through the main barrel outlet onto the riprap dissipator (see next sheet). Fig. 6B. Riser outlet and riprap dissipator, for heavy rainfall events greater the 0.75 in/hr, per the NC BMP Manual.