Scraping Narrative.26.10.2022

CSECOASTAL SCIENCE & ENGINEERING
PO BOX 8056 COLUMBIA SC 29202 •TEL [phone] • FAX [phone] • www.coastalscience.com
26 October 2022
Heather Coats
Beach & Inlet Management Project Coordinator
Division of Coastal Management
North Carolina Department of Environmental Quality
RE: post4an dune modifications at Buxton village [CSE 2403-M]
Dear Ms. Coats:
On 4 October impacts from Hurricane Ion were observed at Buxton village in Dare County, North Carolina.
These impacts consisted of a small breach in the foredune, which was just constructed over the past
summer as part of the Beach Renourishment to Protect NC Highway 12 at Buxton.
The breach occurred near the seaward end of Ocean Drive Avenue in Buxton village and consists of a —30
linear foot (If) gap in the foredune with less than 6 ft of vertical sand loss across a "20 ft width (Fig 1).
Based on these dimensions, CSE estimates 100 cubic yards (cy) of beach -quality sand could be used to
restore the dune crest elevation to the design -specified +13 ft NAVD from CAMA permit 151-21.
Fortunately, as much or more sand was blown landward of the dune crest in a few locations during the
passage of Hurricane Ian. So, we believe there is enough material to fill the gap in the immediate vicinity
of the proposed fill area.
F
y
Fig 1. The dune breach at Buxton village was
isolated to an area representing less than 100 cubic
yards (cy) of sand. Overwashed sand deposited
landward of the dune crest (foreground of lower
image) will be used to fill the resulting gap. 7-1
Photograph taken 4 October 2022 by D Hallac.

CSECOASTAL SCIENCE & ENGINEERING
PO BOX 8056 COLUMBIA SC 29202 •TEL [phone] • FAX [phone] • www.cocstclscience.com
At this location, the post -construction dune crest elevation (surveyed 19 August 2022) is +8 ft NAVD. The
dune crest here is lower than the design -specified +13 ft NAVD because of the presence of a private beach
access walkover, which prevented the contractor from sculpting fill. There are two other locations at the
end of Cottage Avenue with similar elevations lower than the remainder of the dune template due to the
presence of beach access walkovers.
On behalf of Dare County, CSE is proposing to scrape sand from the landward side and overwashed
portions of the dune to fill these three gaps along Buxton Village (Fig 2). The lower elevations allow wind
and waves to push sand landward of the dune crest, where it no longer provides storm protection. If the
dune crest elevation is brought up to the 13-ft design specification, it will decrease the likelihood of
overwash and dune breaches during the coming winter storm season.
A survey crew is collecting an elevation model at Buxton Village today, which will be forwarded to DCM
as soon as possible (probably within the next two business days). However, we can construct a basic
profile of the proposed cut -and -fill plans using CSE Station 1895+00 at the end of Ocean Drive (see Figs 2
and 3). In this profile, the blue and red curves represent pre- and post -project conditions respectively. The
black curve is an approximation for the post -/an conditions at H1, H2, and H3 in Figure 2, while the grey
curve is the proposed cut -and -fill plan.
Fig 2. Overwashed sand deposits immediately landward of the constructed dune ('1­11', '1­12', 'H3') will be used to increase
dune crest elevations in the three low spots ('F1', 'F2', 'F3'). Photograph taken 19 October by P Barrineau.

CSECOASTAL SCIENCE & ENGINEERING
PO BOX 8056 COLUMBIA SC 292C2 •TEL [phone] • FAX [phone] • www.coastalscience.com
14
Buxton Station 1895+00 (Ocean Drive)
Post -Jan condition
—6/16/2022
—8/21 /2022
----------------- ,-------------------,------ ---- ---------y------------------ ,--- --
—Post Ian
I
Proposed Modification
50 70 90 110 130 150 170 190
Distance from Baseline (ft)
Fig 3. Using post -project conditions at Station 1895+00 and observations from a site visit last week as a proxy for post -/on
elevations, CSE estimates ^3 cubic yards per linear foot (cy/ft) of shoreline could be harvested in the locations labeled H1,
H2, and H3 in Figure 2. Applied over the alongshore length of these three areas, this represents >300 cy of beach -quality
sand along the landward face of the dune at Buxton village in the vicinity of Ocean Drive and Cottage Avenue. This volume
is sufficient to fill the dune breach and two nearby low spots in the dune crest.
The work plan consists of scraping sand along the landward dune face at locations H1, H2, and H3 down
to an elevation of 7 ft to match the design berm elevation on the seaward side of the dune. The sand
would be pushed up onto the crest of the dune in the three low spots (F1, F2, and F3) and graded using
light machinery to bring the elevation of the crest in those locations to the designed dune elevation of
+13 ft NAVD. As Figure 2 indicates, the scraped material will be transported a few dozen feet alongshore
in either direction to fill the gaps at locations F1, F2, and F3. H1 will be used to fill F1 and F2, while H2 and
H3 will be used to fill F3.
Upon completion, the entire village of Buxton will be protected by a dune with crest elevation at or near
+13 ft NAVD. This will help reduce the risk of storm -driven overwash or blowouts forming, and improve
the long-term sustainability of the nourishment project at Buxton by helping to retain more sand within
the active beach sand budget.

CSECOASTAL SCIENCE & ENGINEERING
PO BOX 8056 COLUMBIA SC 292C2 •TEL [phone] • FAX [phone] • www.coastalscience.com
The attached drawings consist of a site map depicting the proposed work area (Sheet 01), and a work plan
(Sheet 02) indicating which harvest areas ('H' series) will be used to fill gaps ('F' series). We are happy to
share our elevation model with DCM as soon as possible, if you feel that would help facilitate approval of
this scraping plan.
Please let us know if you have any questions or concerns about the proposed work, and thank you again
for your coordination on this matter. We look forward to hearing from you soon.
Sincerely,
Coosi:d Science • Engineering (CSE)
Patrick Barrineau PhD PG (NC 2761)