20211126 Ver 1_NC DMF_20210802

MEMORANDUM: TO: Garcy Ward, NCDWR FROM: James Harrison, NCDMF Fisheries Resource Specialist SUBJECT: Bridge No. 7 on US 64 over the Alligator River, Dare and Tyrrell Counties DATE: 30 July 2021 A North Carolina Division of Marine Fisheries (DMF) Fisheries Resource Specialist has reviewed the NC Division of Water Resources (NCDWR) permit application documents for proposed actions that may impact fish and fish habitats. The proposed work is located parallel to the existing US 64 bridge over the Alligator River, within Dare and Tyrrell Counties. The applicant is proposing to conduct geotechnical borings associated with the proposal for the new Alligator Bridge. This project involves approximately 222 Standard Penetration Test (SPT) borings. The applicant anticipates 149 bridge borings will be located within the Alligator River to the north of the existing bridge. These locations will be accessed using barge-mounted drilling equipment. Approximately 40 roadway and 3 bridge borings will be performed along the western bridge approach and 27 roadway and 3 bridge borings will be performed along the eastern bridge approach and will be accessed using ATV mounted drilling equipment. The bridge borings in the Alligator River will involve drilling rigs mounted to self-propelled floating barges or jack-up barge platforms. The floating platforms will be used closer to the shores of the river or in shallow water. These will be stabilized at the boring locations using aluminum or steel spuds placed into the river bottom to hold the barge in place during drilling. Additional spud casings can be added or removed depending on water depth, and will be extended above the working platform in order to allow the barge to move up or down with the water level. The jack-up barges will mechanically lower the spuds to the river bottom and will then be used to raise the platform completely out of the water in order to provide a stable working platform during drilling operations unaffected by changing water levels. Each boring will advance a 3-inch or 4-inch diameter steel outer casing from the platform to the mudline and into the subsurface by rotation or driving, creating minimal disturbance to the river bottom. The temporary casing will be advanced as needed to provide borehole stability. It is expected that disturbance from the borings will be limited to a 2-foot radius

around the boring site. The drilling and sampling of the borings will be completed within the steel casing using mud-rotary drilling methods. Drill fluids consisting of a water-bentonite slurry will be circulated from a mud tub on the platform through the drill tools and drilling bit and recirculated to the mud tub through the outer casing. Drilling cuttings will be captured and removed as necessary to facilitate drilling and sampling operations, and will be temporarily stored in metal drums on the platform until boring termination is achieved. Upon boring termination, stored drill cuttings will be shoveled back down the outer casing and into the subsurface prior to casing removal. Cuttings unable to be returned will be brought to shore and deposited on land outside of wetland areas. The barge drilling platforms will be launched and recovered from a nearby marina/boat ramp. It is expected that each boring will be advanced to a depth of approximately 150 feet and will take two days to complete. The applicant anticipates having up to three barge mounted drilling rigs in operation and estimates approximately 6 months to complete the borings. The Alligator River at the location of the proposed work is designated as Anadromous Fish Spawning Area (AFSA) – north of the existing bridge, the designation is under MFC jurisdiction; south of the bridge, the designation is under joint jurisdiction between the MFC and WRC. Waters designated as AFSA are areas where evidence of spawning of anadromous fish has been documented through direct observation of spawning, capture of running ripe females, or indication of eggs or early larvae. Many of the species that utilize these areas are recreationally, economically, and/or environmentally important species. In this area, these species include river herring and shad. The river provides appropriate water quality conditions that support these species during some of the most critical life history stages. As such, DMF would recommend that the permit include a moratorium of 15 February to 31 October in order to minimize potential impacts to this important habitat. DMF is amenable, though, to granting relief from this moratorium, pending adherence to the conditions below. First, the applicant should strive to complete the work during the environmental window, and request moratorium relief as necessary. Additionally, the applicant should organize their work plan in such a way that potential impacts that may result from moratorium relief will be minimized. The most biologically sensitive time for river herring and shad is approximately 15 February through early April, and the more critical habitat is closer to the middle of the river. In order to minimize impacts associated with moratorium relief, the applicant should organize their work plan in such a way that the work closer to the middle of the river is completed during the window (1November through 14 February). This would result in any work needing to be completed during the moratorium period being away from the critical habitat area. As noted above, DMF recommends that any permit issued include the 15 February to 31 October moratorium and that the applicant should strive to adhere to the moratorium to the fullest extent possible. Adherence to the moratorium is the primary means of avoiding impacts to these important species and their habitats. Agreement to adhere to the above minimization measures does not specifically guarantee that relief will be granted. However, should these measures be implemented and relief requested, DMF will take these

minimization measures into consideration when reviewing any request for relief, and weigh those into any decision made. Thank you for consideration of our comments. Please contact Jimmy Harrison at [phone] (office) or [phone] (mobile – preferred), or at [e-mail] with any further questions or concerns.