Although a 10,000-linear-foot central area on the Southern Shores oceanfront experienced both an increase in sand volume and a “positive shoreline change” between December 2017 and May 2019, the Town’s coastal engineering consultant recommends in a new report that the so-called “Main Placement Area” undergo beach nourishment.
APTIM Coastal Planning & Engineering of North Carolina also recommends beach nourishment, aka “fill,” for a 5,000-linear-foot area south of the Main Placement Area, which it calls the “Transition Area” and where it reports a minor loss in sand volume and beach width (shoreline change) during the same time period.
A third analyzed “portion” of Southern Shores’ 3.7-mile shoreline, which is north of the Main Placement Area and starts around Fifth Avenue, also gained sand volume and underwent a positive change in width, APTIM reports, and is not a target for nourishment.
APTIM Program Manager Kenneth Willson submitted the new data to the Town Sept. 10 in a draft 2019 Beach Assessment Report. (You may access the draft report here: https://www.southernshores-nc.gov/wp-content/uploads/minutes-agendas-newsletters/Meeting-Packet_2019-09-17.pdf)
Mr. Willson will present the results of his firm’s latest beach survey to the Town Council today at its special planning session, which starts at 5:30 p.m. in the Pitts Center. The Town Council may decide to choose from among the “design options” that Mr. Willson recommends for a Town beach nourishment plan, which would occur in summer 2022, with financial planning starting next year.
Earlier this year, the Town Council and Southern Shores property owners considered APTIM’s 2018 Vulnerability Assessment and Beach Management Plan, which the company filed with the Town last December.
The cost estimates for three beach-fill plan “options” submitted by APTIM in its 2018 assessment report ranged from $9 million to $13.5 million. The projected costs of the two options that Mr. Willson now recommends are $14,026,800 and $16,749,900—substantial increases in costs that property owners already found daunting.
(See The Beacon, 2/28/19 for background on the 2018 assessment report and a writeup on the Town Council’s Feb. 26 special planning meeting. The Beacon subsequently reported on a public hearing on beach nourishment held by the Town Council April 2.)
The controversial subject of beach nourishment tops this evening’s overly ambitious Town Council meeting agenda. Also on the agenda are the following important town-planning matters, ranked in an order determined by Mayor Tom Bennett:
*Future capital rehabilitation/replacement of Town buildings
*Capital apparatus/equipment needs of The Southern Shores Volunteer Fire Dept.
*Town land-use plan update
*Town-wide walking path system
*Seasonal cut-through traffic
The Beacon believes these concerns are upside-down in terms of importance to Southern Shores property owners, with seasonal cut-through traffic and stormwater runoff being bread-and-butter concerns that deserve airing before discussion about Town buildings, an update of the Land-Use Plan, and a town-wide walking path system.
A town-wide sidewalk system has never been discussed by the Town Council before, nor has it been a subject of public comments by property owners at Council meetings.
Returning to beach nourishment . . .
The shoreline that APTIM calls the Main Placement Area extends from near Third Avenue south to about 450 feet south of where Chicahauk Trail intersects with Ocean Boulevard. Although this area experienced a gain in sand volume, APTIM does not consider the gain to be sufficient.
An area that APTIM refers to as the “taper” extends about 500 feet north of Third Avenue. Above the taper is the northern portion of the Southern Shores shoreline, which starts just north of Fourth Avenue and ends at the Southern Shores-Duck border. This area is not included in any beach-nourishment plan option.
The Transition Area of the Town’s shoreline extends from the southern border of the Main Placement Area to the town’s border with Kitty Hawk. According to APTIM’s 2019 update, this area averaged a sand-volume decrease of about 27 cubic yards per linear foot between December 2017 and May 2019.
The Southern Shores shoreline, according to APTIM’s 2018 assessment report, is highly variable, in terms of the height and width of the primary dune, the distance that residential structures are set back from the vegetation line, and the rates of sand-volume change. Again, in its 2019 report, as it did in its earlier assessment, APTIM describes the shoreline as “relatively stable.”
As explained in the 2018 report, APTIM used special technology and design storm scenarios to arrive at target sand-volume densities in cubic yards per linear foot (cy/lf) that it says must be maintained along the Southern Shores oceanfront in order to sustain it.
The engineering technology it used is known as a “Storm-Induced Beach Change Model” (SBEACH). The results that APTIM obtained with its model, according to its 2018 assessment report, “informed the development [of the beach-nourishment plan options] with regards to what sections of the Town may be vulnerable to impacts from the design storm, and what amount of additional [sand] volume would be required to reduce that vulnerability.”
In other words, APTIM based its 2018 assessment report recommendations of sand volume density on theoretical storm scenarios. The coastal-engineering firm also conducted a physical assessment of the Southern Shores beach in February 2018.
BEACH-NOURISHMENT PLAN OPTIONS
In its 2018 assessment report, APTIM recommended the following beach nourishment-options for “managing” the Southern Shores shoreline:
2017 DESIGN OPTION ONE, projected to cost $11,593,000, targeted a volume-density goal of 846 cy/lf. The average density measured along the Main Placement Area in APTIM’s December 2017 survey was reportedly 801 cy/lf. Therefore, Option One posited a recommended “fill density” of 45 cy/lf. At this density, the Main Placement Area would require 450,000 cubic yards of sand.
Option One also included fill for the taper and Transition Area. The average volume density measured along the Transition Area in December 2017 was 818 cy/lf. Altogether, the total volume of sand projected for this option nearly two years ago was 665,650 cubic yards.
2017 DESIGN OPTION TWO, projected to cost $9,010,400, also targeted a volume density of 845 cy/lf, but recommended adding only 30 cy/lf to the Main Placement and Transition areas. The total sand volume for Option Two was 492,300 cubic yards.
2017 DESIGN OPTION THREE, projected to cost $13,557,000, targeted a volume density of 858 cy/lf. This option’s total design volume for the taper, Main Placement, and Transitions areas of the shoreline was 803,050 cubic yards.
APTIM has updated design volumes, based on changes that have occurred to the oceanfront since the December 2017 survey. In doing so, it notes, significantly:
“The measured rate of erosion that occurred along the portion of the Town where beach fill is being recommended [the 15,000-linear-foot Main Placement and Transition areas] averaged 3 cy/lf/yr. This volume was used to determine the amount of advanced fill to include in the beach fill options, resulting in an increase of 225,000 cy for each option.”
It now presents the recommended options as follows:
2019 DESIGN OPTION ONE: The total design volume decreased by 60,000 cubic yards, from 600,000 cy to 540,000 cy. “However,” the 2019 report states, “with the significant increase in the advanced fill, the total volume required for Option One increased by 162,750 cy or 24 percent.”
2019 DESIGN OPTION TWO: “Given the erosional trend measured along the southern 5,000 feet of the beach, Design Option Two is essentially the same as Design Option One,” the report states.
2019 DESIGN OPTION THREE: The total design volume remained the same at 720,000 cy. “However,” the 2019 report states, “with the significant increase in the advanced fill, the total volume required for Option Three increased by 222,750 cy or 28 percent.”
With the increase in volume that APTIM recommends, the cost for Option One has increased by 21 percent to $14,026,800; the cost for Option Three has increased by 24 percent to $16,749,900.
APTIM concludes its 2019 report by recommending that the Town:
1) Determine which option to pursue;
2) Continue coordination with Dare County and neighboring communities;
3) Initiate financial planning, which will require professional financial advice;
4) Initiate permitting and design of the beach bill, projected to start in February 2020;
5) Continue monitoring the Southern Shores beaches
Projected construction would occur in summer 2022, when the Towns of Duck, Kitty Hawk, and Kill Devil Hills are doing five-year maintenance (renourishment) of their beach-fill projects. A collaborative effort would save on expense, APTIM points out.
The “biggest cost” in any beach-fill project, Mr. Willson told the Town Council in February, is sand, especially if its source is distant.
Doug and Andrew Carter, the father-son team who own DEC Associates in Charlotte, explained the various complicated methods available for beach-nourishment funding to the Town Council at its Feb. 26 special planning meeting.
Popular among these methods are special obligation bonds, which permit a town to set up “municipal service districts” and to levy different tax rates within the MSDs, Andrew Carter explained, so that, for example, people who own oceanfront property would pay more than other property owners do for the sand fill/replenishment.
Once a beach town embarks upon a nourishment plan, said Mr. Carter, whose firm specializes in N.C. shoreline protection financial planning, it commits to “long-term planning” for future periodic maintenance and beach operating costs.
He echoed Mr. Willson’s earlier assertion at the February meeting that beach nourishment is “an exercise in adaptive management. . . . It is never seen as a one-time event.”
The question for the Southern Shores Town Council and its constituents is whether APTIM’s data compel Southern Shores to make the “forever” commitment to beach nourishment now. The Beacon believes both the data and the commitment deserve further thoughtful study.
Ann G. Sjoerdsma, 9/17/19