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HomeMy WebLinkAboutAvon Narrative(30Jul2021) Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 1 AVON VILLAGE BEACH NOURISHMENT COUNTY OF DARE, NORTH CAROLINA NARRATIVE DESCRIPTION OF PROJECT Dare County (NC), as the Applicant, is proposing a beach renourishment project, which calls for up to 1 million cubic yards (cy) of beach-quality sand to be pumped onto the 2.5-mile (13,200 linear feet) beach via offshore dredging scheduled to start the summer of 2022. The anticipated average fill density (volume of nourishment per linear foot of beach) is ~7 5 cubic yards per linear foot (cy/lf) of shoreline. The purpose of the project is to restore sand losses due to chronic erosion and to improve storm protection along the vulnerable section of the project area. The Applicant and its authorized Engineer (Coastal Science & Engineering) had the official pre- application meetings on 4 March 2021 with federal and state agencies in addition to other individual meetings with resource agencies. The sign-in sheet is included herein as Attachment 1. Initial guidance regarding preparation of environmental documents required by state and federal resource agencies before, during, or after construction was received from the meeting. The Applicant also requested Section 7 consultation under the Endangered Species Act at the earliest time, along with instructions regarding endangered species monitoring requirements during construction, and environmental sampling (if necessary) before and after construction The Applicant submitted the DWR Pre-Filing Meeting Request Form on 14 June 2021 per the Clean Water Act Section 401 Certification Rule (Attachment 2).  The project proponent hereby certifies that all information contained herein is true, accurate, and complete to the best of my knowledge and belief.  The project proponent hereby requests that the certifying authority review and take action on this CWA 401 certification request within the applicable reasonable period of time. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 2 Introduction Dare County encompasses ~89 miles of ocean shoreline from the Town of Duck to Hatteras Inlet. The northern 30 miles (on Bodie Island) includes (from north to south) the towns of Duck, Southern Shores, Kitty Hawk, Kill Devil Hills, and Nags Head. There is a 5-mile undeveloped portion of Cape Hatteras National Seashore (Seashore) at the southern end of Bodie Island. The southern ~53 miles on Hatteras Island encompass the National Seashore and the communities of Rodanthe, Salvo, Avon (the proposed project site), Buxton, Frisco, and Hatteras (Figure 1). Approximately 16 miles are developed and 38 miles are undeveloped along the oceanfront. In total, 50 percent of Dare County’s ocean shoreline is developed, and 50 percent is undeveloped and held in permanent trust by the Cape Hatteras National Seashore. The narrative for the proposed Avon beach nourishment project accompanies application forms and drawings (sheets 01–13) and includes the following sections: Project Background .......................................................................................................... 3 Historical and Recent Erosion Rates .................................................................................. 4 Beach Condition Survey in July 2020, Volumetric Analysis, and Project Formulation ............ 4 Alternatives ..................................................................................................................... 6 Project Description .......................................................................................................... 7 Sediment Quality and Compatibility .................................................................................. 8 (1) Beach Sampling .................................................................................................................. 8 (2) Offshore Borrow Area Sediment Quality and Compatibility Analysis ............................ 8 Cultural Resources Study in the Borrow Area ..................................................................... 9 Dune Management Plan .................................................................................................. 10 Methods of Construction ................................................................................................ 11 Supplementary Reports .................................................................................................. 12 References Cited ............................................................................................................ 13 Figures .......................................................................................................................... 14 Attachment 1 (Scoping Meeting Sign-Up Sheet) ................................................................ 24 Attachment 2 (DWR Request Form for 401 Certificate) ...................................................... 25 Attachment 3 (15A NCAC 07H.0312 - Effective 1 April 2021) ............................................... 27 Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 3 Dare County, as the Applicant, proposes to place up to 1 million cubic yards (cy) of beach-quality sand along a 13,200-foot (2.5-mile) length of the Cape Hatteras National Seashore in front of the developed shoreline at Village of Avon (Figure 2). The average fill density is ~75 cubic yards per foot (cy/ft). Nourishment sand will be excavated from a ~250 acre offshore borrow area located ~2–3 miles offshore of Avon within state waters. Confirmed by reconnaissance vibracores and the final twelve 10-ft long vibracores in the proposed borrow area, the Applicant proposes an excavation depth of 10 feet in Borrow Area 1 (~150 acres) and 6 feet in Borrow Area 2 (~100 acres). The proposed borrow area contains approximately 3.4 million cubic yards of beach- quality sand if the proposed excavation depths are permitted. Project Background The Village of Avon is one of seven historic villages on Hatteras Island situated adjacent to (and within) the Cape Hatteras National Seashore (CAHA) between Salvo and Buxton around mile marker 36. It is an unincorporated community under the jurisdiction of Dare County with a 2010 population of 776 permanent residents. South of the Tri-Villages of Rodanthe, Waves, and Salvo, past a ~11.5-mile stretch of the undeveloped Cape Hatteras National Seashore, Avon is considered the largest and busiest of the Hatteras Island towns. There are another ~20,000 feet (~3.8 miles) of the CAHA between the south boundary of Avon and Buxton, the next village along the barrier island (see Figure 1). Avon is bordered to the east by the Atlantic Ocean and to the west by Pamlico Sound , with a total land area of ~2.4 square miles, as shown in the location map. Avon’s primary industry is tourism, with hundreds of homes, dozens of motels, and campgrounds available for short-term rentals. There are also facilities on the ocean and sound side to accommodate the recreational fishing community, surfers, and boaters. NC Highway 12 is the main artery for public and emergency vehicle access to the Avon, Hatteras Village communities, and National Seashore facilities. Avon Ocean Pier is located close to the center of the village a nd provides a coastal landmark on maps. The section of shoreline north of the pier has generally been relatively stable over the past 50 years (NCDENR 2012). In contrast, the ~1.5 miles south of the Avon Pier have experienced accelerated erosion in recent years (Figure 3). The dunes along this highly eroding section of the beach have been washed away, and ocean waves have frequently washed over and flooded NC Highway 12 during inclement weather events (Figure 4). This occurs not only in named storms but also in common nor’easters and other winter storms. The County reported that “the overwash [on NC Hwy 12] has impeded, and at times prevented, first responders from responding to emergencies; our sanitation workers from picking up trash; the citizens of Avon from performing normal daily tasks, such as attending doctor appointments, buying groceries, attending community events, and the list goes on. In addition to the safety issues, there has been flood damage to homes and businesses, and it has negatively affected our tourism economy.” (Source: Dare County’s More Beach to Love at: Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 4 https://www.darenc.com/government/avon-beach-nourishment/avon-faq). In response to the emergent need for beach restoration in Avon Village, Dare County completed a feasibility study to assess erosion and formulate solutions along the Village of Avon in November 2020 (CSE 2020). This feasibility report evaluates the beach in detail upcoast and downcoast of the critically eroded area to place the area in context and establish linkages with the sand sharing system alongshore. It also provides several levels of beach restoration plans for different project longevities. Historical and Recent Erosion Rates The NC Division of Coastal Management (NCDCM) reports official erosion rates (“setback factors”) for Avon in 2020 ranging from 2.0 feet per year (ft/yr) north of Avon Pier to 6.0 ft/yr along a ~4,000 ft section of beach south of the pier. Erosion reduces to 3.0 ft/yr at the south limit of the Village. In the feasibility report, CSE analyzed historical shorelines for fourteen different dates (1852 to 2020) and determined that the critically eroded section south of Avon Pier has experienced erosion as high as 16–20 ft/yr over the past 20 years (CSE 2020). Because state erosion rates average over 60+ years, the official rate is lower but has been increasing with each update along south Avon. The cause of accelerated erosion is unclear, but one factor is rhythmic alongshore sand waves spaced ~3000 ft apart that slowly migrate downcoast , producing systematic variations in beach width. The trough (narrow dry beach area) of one such rhythmic sand wave has persisted south of Avon Pier in recent years. Beach Condition Survey in July 2020, Volumetric Analysis, and Project Formulation CSE established a baseline and measured profiles every 500 ft along the shoreline from the dune line to deep water (>30 ft below sea level) along the entire 18,000-ft (~3.4-mile) Avon Village in July 2020. An additional 5,000 ft of upcoast and downcoast shoreline into the Cape Hatteras National Seashore, managed by the National Park Service (NPS), was also surveyed. It is believed that the July 2020 data set is the first comprehensive data set for the beach condition of this area, and it provided the basis for the proposed nourishment formulation along with the historical erosion analysis. The calculation limits extend from the dune crest to the offshore depth of closure* at –24 ft NAVD, representing where nearly all sand exchange across the beach occurs. Volume analyses were used to determine the sand deficit south of the Avon Pier relativ e to healthy sections of beach north of the Pier that contains a high protective dune and wide dry -sand beach. [*Depth of Closure is the approximate limit of measurable bottom change over particular time scales , and it is where waves and currents have no measurable impact on bottom elevations. The calculation limits from the dune to the depth of closure will be used by FEMA to determine sand volume losses after a declared Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 5 disaster under Category G – Public Assistance (FEMA 2020). Based upon historical profiles analysis in the adjacent Buxton project area (USACE-USDOI-NPS 2015), the closure depth for the Avon project area should be around −24 ft NAVD.] Figure 5 illustrates the Digital Terrain Models (DTM) of the study area by color-coded, smooth- contour maps. Light colors indicate the dune-beach zone and longshore bar; deep blue represents water depths >30 ft. The bathymetry DTMs show re latively smooth, continuous morphology of a longshore bar represented by a yellow-green color band (inside the 20-ft depth contour) along the northern half of Avon. The longshore bar diminishes to the south , and an inshore bar develops in shallower water. Figure 6 shows unit volumes station by station using the July 2020 survey. The five reaches delineated for the study area are marked in the figure, and the horizontal lines (in red) show the average unit volume of each reach. The present results indicate that Reach 4 has the lowest unit volume of 748 cy/ft, which is 128 cy/ft less than Reach 3, 133 cy/ft less than Reach 5, 44 1 cy/ft less than Reach 1, and 472 cy/ft less than Reach 2. These profile volume differences along Avon provide a basis for CSE’s proposed nourishment volume determinations. We used the results to determi ne the profile deficit with respect to an ideal or target beach condition (CSE 2020). All of the original Reaches 3 and 4, and part s of the original Reaches 2 and 5, are included in the proposed project. Hereafter and in the project map/permit application drawings, the original Reach 3 and a few hundred feet of Reach 2 are referred to as Reach 3 (9,200 ft north of Avon Pier), and the original Reach 4 and ~1,000 feet of Reach 5 are now referred to as Reach 4 (4,000 ft south of Avon Pier). The long-term, historic erosion rates adopted for the project area is 140,000 cy per year. It would take approximately 1 million cubic yards of sand to restore the 13,200 -ft project area for five years under normal weather conditions. This is the total nourishment volume proposed herein. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 6 Alternatives Three alternatives have been evaluated for the proposed beach nourishment:  Alternative 1 – No-Action  Alternative 2 – Nourishment with Offshore Sand Source and Winter Construction  Alternative 3 – Nourishment with Offshore Sand Source and Summer Construction Additional alternatives and other sand sources (material dredged from Avon Harbor and inland deposits from nearby sand stockpiles) were initially considered during the feasibility study but were dismissed for environmental, geological, technical, or economic reasons (CSE 2020). Construction during the summer months is necessary in this setting because of high wave conditions for the remainder of the year, as shown by other nourishment projects completed (or being planned) in Dare County as listed in Table 1. The full scope of work proposed under Alternative 3 would best protect NC 12 and NPS facilities at Cape Hatteras. It would increase the area of sea turtle and shorebird nesting habitat, and it would also reduce the frequency of future remedial or emergency measures. The short-term biological impacts to benthic organisms under Alternative 3 may be greater than Alternative 2. However, Alternative 2 would require work in the winter months, placing Contractor personnel at much greater risk due to unsafe conditions offshore. Therefore, Alternative 3 is the Applicant’s preferred alternative. Location Volume (Million CY) Construction Period Main Sponsor Nags Head 4.6 May-Oct 2011 County Rodanthe 1.7 Jul-Sep 2014 NCDOT Duck, Kitty Hawk, Kill Devil Hills, and Southern Shores 3.8 May-Oct 2017 County Buxton & Seashore 2.6 Jun 2017-Feb 2018 County Nags Head 4.0 May-Aug 2019 County & FEMA Duck, Kitty Hawk, Kill Devil Hills, and Southern Shores 1–2 Summer 2022 County & FEMA Nags Head 0.567 Summer 2022 FEMA Buxton & Seashore 1.2 Summer 2022 County & FEMA Avon 1.0 Summer 2022 County TABLE 1. Beach nourishment projects using offshore borrow areas completed or planned in Dare County. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 7 Project Description Based on the feasibility study (CSE 2020) and available funds, Dare County has elected to nourish the critically eroded section of beach and its immediate upcoast. The proposed project area, marked as Reaches 3 and 4 in Figures 7 and 8, is 13,200 ft (2.5 miles) out of the 18,000 ft (~3.8 miles) oceanfront of the Avon Village. The maximum nourishment volume will be 1 million cubic yards. It will involve excavating beach-quality sand from an offshore borrow area via hydraulic and/or hopper dredge (see Figure 2). Borrow sediment will be pumped to the beach and spread by land - based equipment (eg – bulldozers) in the beach zone between the toe of dune/mid -dry sand beach and the low watermark. The elevation of the nourishment berm will be set at or below the normal dry-beach level (approximately +7 feet NAVD) so that it is naturally overtopped by waves during minor storms. The nourishment profile will be designed to adjust rapidly to changing wave conditions with an expected gradual shift of sand into deeper water as the profile equilibrates. Backshore areas are expected to be enhanced gradually after construction by natural dune building processes. The average maximum fill density (volume of nourishment per linear foot of beach) will be ~75 cy/ft. This is equivalent to an average beach width increase after natural profile adjustment of ~40 ft in Reach 3 and 90 ft in Reach 4. During construction for a 2.5-mile-long project, the anticipated maximum impact area is ~100 acres. The maximum project is expected to create ~15 acres of new dry-beach habitat. This expanded dry-beach area will eventually produce ~3.5 acres of new dune habitat via natural processes after the equipment is removed from the beach. The maximum scale is expected to provide approximately five years of erosion relief, dune growth, and NC 12 protection under normal conditions. The final project volume will be determined according to the state and federal permits, the County’s construction fund, and the responsible bid. Fill densities will vary from 43 cy/ft in Reach 3 (north of the Avon Pier) to 90 cy/ft in Reach 4 (south of the Avon Pier) to best achieve the Applicant’s purpose and goals of the proposed nourishment project. Figure 9 includes the fill design of two representative stations, and the details of the design are illustrated in Permit Drawing Sheets 03–10. The elevation of the dry-sand berm is set to be at +7 ft NAVD, and the initial dunes will be constructed along Reach 4 from stations 1590+00 to 1682+00. The dune crest is set to be at +13 ft NAVD, the typical dune width is 20 ft, and the dune seaward slope is 1 on 3 (vertical versus horizontal). The width of the constructed dry-sand berm (before normal profile adjustment) in front of the toe of the initial dunes varies from 100–200 ft. The initial dune will tie into the existing profile but will not encroach on existing vegetation or house foundations under any circumstances. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 8 Final fill templates for each section of the beach will be determined close to the time of construction (according to standard practice) based on beach conditions. These will be submitted to the permitting agencies for approval prior to the commencement of nourishment. However, the total project volume and the impact area will not exceed the maximum values proposed herein. Sediment Quality and Compatibility (1) Beach Sampling CSE established five stations in 2020 along the proposed project area while conducting the feasibility study (CSE 2020). Sediment samples were collected at 14 positions across each station in March 2021. The location of the five alongshore stations are shown in Figure 10, and the 14 positions across each station are illustrated in F igure 11. The mean grain size of beach sand at the Avon project area was 0.289 millimeters (mm) with 4 percent of shell, 1.7 percent granules (2 to 4 mm), and 0.1 percent of gravel (4 to 76 mm) as of March 2021. Samples collected below –8 ft NAVD were finer than those collected from the upper port ions of the profile. Samples collected within the trough (next to MLW in Figure 11) were significantly coarser. The mean grain size of samples collected above mean low water (MLW) is 0.323 mm with 4 percent shell material and 1.8 percent gravel (>2 mm) by weight. Not including the trough, beach samples contained ~2–3 percent shell material, 1.7 percent granules (2 to 4 mm), and almost no gravel by weight . (2) Offshore Borrow Area Sediment Quality and Compatibility Analysis The proposed offshore borrow area encompasses ~250 acres and is located within NC state waters. Fifteen (15) 3-inch borings were obtained in April 2021, and each core has a uniform depth of 10 ft below the existing substrate. Twelve out of the 15 cores are located in the proposed borro w area, yielding an average core density of one core per ~20 acres. The core locations are marked in Figures 2 and 12, and on Permit Drawing Sheets 11–12. The borings were split, logged, subsampled, and analyzed for grain-size distribution and comparison with the existing beach sand, then pro - rated according to the length of each sample interval. This allows the calculation of boring statistics to a specified “composite” depth, which is useful for t he operational considerations of dredge vessels. After calculating the composite values to 6 ft, 8 ft, and 10 ft depths, seven borings were found to have beach-quality sand to a depth up to 10 ft in Borrow Area 1, and five borings were found to have beach-quality sand to a depth up to 6 ft in Borrow Area 2. The mean grain size of the seven borings in Borrow Area 1, composited to a 10 -ft depth, is 0.308 mm with 16.4 percent shell material, 2.6 percent granules (2 to 4 mm), and 0.2 percent gravel (4 to 76 mm) by weight. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 9 The mean grain size of the five borings in Borrow Area 2, composited to a 6 -ft depth, is 0.331 mm with 16.8 percent shell material, 5.1 percent granules, and 0.7 percent gravel by weight. Overfill factor provides a measure of how a particular sand source will perform as beach nourishment. Low overfill factors are generally preferred, with the ideal being equal to 1.0. The overfill factor of Borrow Area 1 (10-ft cut depth) is 1.0, and 1.1 for Borrow Area 2 (6 -ft cut depth), indicating a good match between the material in the borrow areas and the native beach. The boring density in both Borrow Area 1 and Borrow Area 2 is approximately 1 core per 20 acres. Based on these descriptive statistics, the proposed borrow area contains compatible sand (Figure 13) and meets the requirements of the updated North Carolina Technical Standards for Beach Fill Projects (15A NCAC 07H .0312 effective April 1, 2021 –Attachment A) and National Park Service Sediment Management Framework (NPS 2021a and 2021b). The proposed 250-acre borrow area would provide up to 3.4 million cubic yards of beach-quality sand if excavation is permitted to a depth of 10 ft in Borrow Area 1 and 6 ft in Borrow Area 2. More details of the geotechnical data and analysis are included in Appendix A – Littoral Processes of the Environmental Assessment. Large sediment sampling was conducted in March 2021 as required by North Carolina sediment standards for the proposed beach nourishment (15A NCAC 07H.0312 Effective 1 April 2021). The fieldwork, data analysis, photo processing, and the report were performed under Grant Contract No. CW20490 between the North Carolina Department of Environmental Quality and the County of Dare. Large clasts are defined as sediments greater than or equal to one inch (25.4 millimeters) in diameter, and shell material greater than or equal to three inches (76 millimeters) in diameter. Survey results show that 26 clasts were observed along the five transects in the Avon project area in March 2021. Each transect averaged 5.2 shell fragments greater than three inches in diameter . More details and the full conclusions are included in Appendix C – Large Sediment Sampling Report of the Environmental Assessment. Cultural Resources Study in the Borrow Area The coastal waters off the Outer Banks of North Carolina have one of the highest documented concentrations of shipwrecks in the western Atlantic. Hundreds of vessels have been reported lost off the Outer Banks and especially off Cape Hatteras. Weather, c urrents, natural magnetic anomalies, and shoals make navigation along the Outer Banks and off Cape Hatteras more hazardous than in most East Coast areas. Although the proposed action area lies within this area, no shipwreck remains have been documented on the adjacent beach or in the offshore vicinity (USACE-USDOI-NPS 2015). Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 10 A submerged cultural resource remote-sensing survey of the proposed borrow area was conducted by Tidewater Atlantic Research (TAR) of Washington, North Carolina. Field work was completed by 24 July 2021, and the results and findings are included in Appendix G - Cultural Resources Survey of the Environmental Assessment. Work performed by TAR consisted of a background literature survey, historical research, and cartographical investigation. Field investigations identified three magnetic anomalies inside the proposed borrow area, and three within the 200-ft perimeter of the borrow area. All six anomalies represent very small ferrous objects. None appear to represent a potentially significant submerged cultural resource and therefore, no avoidance was recommended. Analysis of the acoustic data identified no evidence of sonar targets in the borrow area or its immediate vicinity. Consequently, no potentially significant submerged cultural resources will be impacted by dredging in the proposed borrow area or its adjacent 200-ft buffer. Dune Management Plan Dare County proposes to integrate a dune management plan into the pro posed nourishment project. The purpose of the plan is to improve storm protection along the vulnerable section of the project area, accelerate dune growth, and provide guidance for possible sand relocation activities in the event of future sand encroachment to existing structures . The dune management plan proposed as part of the nourishment plan and present permit application includes the following actions at two major stages: (1) During Construction – Initial dunes are proposed to be built along Reach 4 – south of the Avon Pier. The typical elevation at the top of the dune will be +13 ft NAVD, and the typical width of the dune crest will be 20 ft. The typical seaward slope will be at 1 on 3 (vertical versus horizontal). The constructed berm width in front of the dune varies from 100–200 ft, providing sufficient dry-sand beach to minimize scarping at the toe of the dune following project completion. The protective dune will tie into the existing profile but in no circumstance encroach on existing vegetation or house foundations. (2) Following Construction – Sand fencing will be installed on the newly constructed dune crest as close to the stable vegetation line as practical. Vegetation will be planted along the entire project area (ie – Reaches 3 and 4) following nourishment. General instructions are illustrated on Permit Drawing Sheet 13, and the exact locations of sand fencing and vegetation will be determined based on conditions after the proposed renourishment. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 11 Methods of Construction The proposed beach renourishment will be placed by ocean-going trailing suction hopper dredge(s) or cutterhead pipeline dredge(s) between the seaward crest of the existing dry beach and the outer bar. Only the profile above high water is controllable in nourishment construction. Intertidal and underwater portions of the profile will be subject to natural adjustment by waves. The fill will be placed no higher than +7 ft NAVD (the average natural elevation of the berm). Work will progress in sections within the borrow area and along the beach. Fill placement along the beach will typically progress at an average rate of 300 ft per day. Construction activities will involve the movement of heavy equipment and pipe along ~4,000 -ft sections over a period of 1–2 weeks. Once a section is complete, piping and heavy equipment will be shifted to a new section , and the process will be repeated. As soon as practicable, sections will be graded and dressed to final slopes. Beach residents along the project area will experience construction -related disruption for only seven days or less, other than at equipment staging areas. Land-based equipment will be brought to the site over public roads and will enter the beach at designated beach access areas. Any alteration of dune vegetation/topography necessary for equipment access will be authorized prior to undertaking any work and be repaired to pre-project conditions. Daily equipment staging will be on the constructed beach seaward of the dune line. Existing dunes and vegetation on the beach will be avoided and preserved. The Contractor will provide proper storage and disposal of oils, chemicals, hydraulic fluids, etc. necessary for operation according to state and federal regulations. Construction Schedule — The proposed project will require summer dredging because of safety issues, particularly the lack of a nearby safe harbor for ocean dredges. Construction duration is expected to be a maximum of ~3 months if work is permitted between 1 May and 15 September. CSE evaluated potential cost savings during the feasibility study should an Avon nourishment project using offshore deposits be combined with similar work at Buxton (CSE 2020). Some sharing of mobilization costs would potentially offer savings of $2 –3 million for the proposed project. Permit applications for the Buxton renourishment project were submitted to the state and federal agencies at the same time as the Avon project, targeting construction in summer 2022. Therefore, the preferred schedule for the proposed Avon nourishment is summer 2022. The summer construction proposed herein is consistent with all prior nourishment projects in Dare County since 2011 (see Table 1). It also follows the Applicant’s goal of maintaining the project with renourishment at approximate five-year intervals between projects. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 12 Supplementary Reports The following reports are prepared in support of the permit application: Appendix A) Geotechnical Data Analysis — Contains geotechnical data on the proposed borrow areas and the beach before the proposed renourishment. Detailed results of beach sampling and borrow-area coring are presented, including the large sediment sampling results. The Technical Standards for Beach Fill (15A NCAC 07H.0312 Ef fective 1 April 2021) were followed. Appendix B) Monitoring and Mitigation Plan — This plan is based on similar special conditions prescribed for beach nourishment during the summer months in North Carolina at Nags Head, Rodanthe, and Buxton. It describes the anticipated monitoring and protect ion measures for the proposed nourishment action. Sampling stations and data analysis methodology for the ecological survey required by NPS is included. Appendix C) Large Sediment Sampling — Contains large sediment survey stations, photos, and data analysis of the large sediment sampling required by NCDEQ under Technical Standards for Beach Fill (15A NCAC 07H.0312 Effective 1 April 2021). Appendix D) Littoral Processes — Provides detailed discussion and additional data analyses of erosion, wave climate, and littoral processes in the proposed Avon project area and the predicted performance of the proposed renourishment project. Appendix E) Biological Assessment — Analyzes the potential effects of the proposed nourishment on federally listed threatened, endangered, candidate animal species (wildlife, invertebrates, and fish) or plant species, and designated or proposed critical habitats pursuant to Section 7 of the Endangered Species Act of 1973 (as amended). Appendix F) Essential Fish Habitat Assessment (EFH) — Evaluates the impact of the proposed nourishment to essential fish habitat or habitat areas of particular concern for those species managed by the South Atlantic Fisheries Management Council and Mid-Atlantic Fisheries Management Council. Appendix G) Cultural Resources Survey — Provides the methodology and results of a submerged cultural resource, remote-sensing survey of the proposed borrow area and identi fies any magnetic anomalies in those areas. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 13 References Cited CSE. 2020. Phase 1 Feasibility Report – Shoreline Erosion Assessment and Alternatives for the Avon Beach Restoration. Report for County of Dare, NC; CSE, Columbia, SC, 103 pp plus appendices. FEMA. 2020. Public Assistance Program and Policy Guide V4.0. Federal Emergency Management Agency, Washington, DC, pp 221 + 14 appendices. NCDNR/NCDENR. 2012. North Carolina 2011 long-term average annual oceanfront erosion rate update study methods report. NC Department of Environment and Natural Resources, Division of Coastal Management, Raleigh, 125 pp. NPS. 2021a. Cape Hatteras National Seashore Sediment Management Framework – Final Environmental Impact Statement. National Park Service, Fort Collins, CO, 50 pp + appendices. NPS. 2021b. Joint Record of Decision Sediment Management Framework – Cape Hatteras National Seashore. National Park Service, Fort Collins, CO, 13 pp + appendices. USACE-USDOI-NPS. 2015. Environmental assessment — beach restoration to protect NC Highway 12 at Buxton, Dare County, North Carolina. US Army Corps of Engineers, US Department of Interior, National Park Service, NPS 603/129663, Volume I (204 pp) and Volume II (Appendixes A to G). Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 14 FIGURES FIGURE 1. Location of Buxton and Cape Hatteras National Seashore, Dare County, North Carolina. FIGURE 1. Location of Avon and Cape Hatteras National Seashore, Dare County, North Carolina. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 15 FIGURE 2. Proposed beach nourishment at Avon showing the project limits and offshore borrow area. Core locations are marked on the figure. All cores have a uniform length of 10 ft. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 16 FIGURE 3. Aerial photo taken on 15 July 2020 showing the highly eroded section of Avon (Reach 4). The ground photo was taken by Daniel Pullen on 20 September during Hurricane Teddy. NC Highway 12 was closed for 5 consecutive days due to overwash caused by ocean swell generated by Teddy. FIGURE 4. Ground photo taken by Daniel Pullen in front of Supermarket Food Lion. It shows the frequent flooding and un-accessible road condition of NC Highway 12 at Avon. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 17 FIGURE 5. Color-coded topography and bathymetry Digital Terrain Models (DTM) from the July 2020 beach condition survey for the Avon study area. Note: the proposed nourishment project area is from stations 1550+00 to 1682+00, mainly along Reaches 3 and 4. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 18 FIGURE 6. Unit volumes by station from the foredune to the approximate depth of closure at –24 ft NAVD along the Avon study area using the July 2020 survey. Note: the proposed nourishment project area is from stations 1550+00 to 1682+00, mainly Reaches 3 and 4. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 19 FIGURE 7. Aerial photo taken on 15 July 2020 showing the proposed project area, particularly Reach 3 – north of the Avon Pier. FIGURE 8. Aerial photo taken on 15 July 2020 showing the proposed project area, particularly Reach 4 – south of the Avon Pier. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 20 FIGURE 9. Representative fill templates at station 1560+00 for Reach 3 and 1610+00 for Reach 4. Beach profiles represent the beach condition in July 2020. An initial dune is proposed to be constructed along portions of Reach 4. The dune crest is set to be at +13 ft NAVD and the seaward slope is 1 on 3. The typical dune crest width is 20 ft, and the constructed dry-sand berm in front of the dune is approximately 164 ft at station 1610+00 (~2,000 ft south of Avon Pier). Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 21 FIGURE 10. Location of the five sediment sample transects (14 samples per transect) along the Avon project area. Samples were collected in March 2021. FIGURE 11. Sample positions for “beach” grab samples along the Avon project area following North Carolina sediment sampling criteria rules. The Avon littoral profile exhibits a narrow berm (dry-sand beach) and deep trough separating the outer bar from the beach. Elevations and depths (y-axis) are relative to approximate Mean Sea Level. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 22 FIGURE 12. Mean grain size, percent shell, and percent gravel for core composite samples to 10 ft in the proposed offshore Borrow Area 1 and 6 ft in the proposed Borrow Area 2 based on borings obtained in April 2021. Each boring has a uniform length of 10 ft. Composite results of the twelve vibracores are listed in table on the upper right. Coastal Science & Engineering Permit Application — Narrative Avon Village Beach Nourishment Dare County, North Carolina 23 FIGURE 13. GSDs for Avon native beach samples (n=70) compared with offshore samples in the proposed borrow area (composite). [UPPER] Borrow Area 1 where 10 ft excavation depth is proposed. [LOWER] Borrow Area 2 where 6 ft excavation depth is proposed. In both borrow areas, sediments are expected to be coarser than the native beach initially. Over time, the grain size of the post-nourishment beach is expected to move closer to the historical grain size distribution around Avon.