Add Info for CAMA application

Oak Island 2019/2020 Renourishment Project
Additional Information for CAMA Major Permit Application
For the Town to maintain adequate cash flow, the renourishment of the entire oceanfront is being
completed in separate projects to ensure manageable budgets. The 2019/2020 Renourishment Project is
the first of three planned over the next three years (2019, 2020 and 2021).
As a result of recent hurricane activity, there is effectively no protective dune throughout most of the
oceanfront. Therefore, the first two planned renourishment projects will focus on building a dune to
withstand a 25-year return period storm event across the island. The design also includes a support pad
with a 1V:20H slope that will move MHW seaward on average 80 ft; see Table 1 and Figure 1. This is to
meet the Town's immediate need to provide protection to vulnerable infrastructure from increasingly
active hurricane seasons. The third project, planned for winter 2021, will focus on repairing what dune
volume is lost in the interim as well as provide additional storm protection in the form of a recreational
berm in front of the dune across the island.

Table 1- Summary of volume per cubic yard planned for dune and pad
Station
MHW
Advancement
Total
Unit Fill
Dune
Unit Fill
(above 7'
NAVD)
Pad Unit
Fill
(Below 7'
NAVD)
Pad
Percentage of
Total Fill
Dune
Percentage
of Total Fill
300+00
1 0.0
1 7.4
1 7.1
1 0.2
1 3.3%
1 96.7%
310+00
64.6
28.6
8.4
20.2
70.7%
29.3%
320+00
66.7
36.1
8.7
27.4
75.9%
24.1%
330+00
97.4
55.7
10.6
45.1
81.0%
19.0%
340+00
85.2
52.9
10.8
42.1
79.6%
20.4%
350+00
80.8
37.7
8.8
28.9
76.6%
23.4%
360+00
98.6
44.7
11.1
33.6
75.3%
24.7%
370+00
111.9
56.9
12.1
44.8
78.8%
21.2%
380+00
142.1
65.2
11.8
53.5
82.0%
18.0%
390+00
106.5
51.9
12.0
39.9
76.9%
23.1%
400+00
62.2
25.6
7.8
17.8
69.4%
30.6%
410+00
91.8
40.9
9.1
31.8
77.7%
22.3%
420+00
64.2
21.1
5.4
15.7
74.4%
25.6%
430+00
99.7
38.4
8.6
29.9
77.7%
22.3%
440+00
76.7
36.0
10.5
25.5
70.8%
29.2%
450+00
67.0
31.3
9.4
21.9
69.9%
30.1%
460+00
71.3
32.4
9.0
23.4
72.3%
27.7%
470+00
82.6
37.3
9.3
28.0
75.1%
24.9%
480+00
53.3
24.7
6.5
18.1
73.6%
26.4%
490+00
47.7
20.9
4.1
16.7
80.2 %
19.8
500+00
75.9
31.4
7.7
23.6
75.3%
24.7%
Average
82.3
38.5
9.1
29.4
75.7%
24.3%
Min
47.7
20.9
4.1
15.7
69.4%
18.0%
Max
142.1
65.2
12.1
53.5
82.0%
30.6%

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Figure 1— Representative profile depicting construction template of dune and pad
An analysis was also performed to compare the amount of 'recreational' beach, which was defined as the
width from elevation +7 ft NAVD88 to MHW (+1.8 ft NAVD88)), to determine how the construction of the
proposed renourishment template would affect the amount of recreational beach available. The widths
of recreational beach were determined for the 2016 profiles (pre -Hurricane Matthew), pre -construction
profiles (June 2019 survey), the proposed construction template profiles, and representative SBEACH 2-
yr return period storm equilibrated profiles of the construction template, see Table 2.
One important caveat to mention in this analysis is that the 2019 pre -construction profile represents the
beach in a state of erosion, as many profiles are currently without a dune. Therefore, these profiles will
have more recreational beach available since the beach face is on a shallower slope and the +7 ft NAVD88
contour has been pushed landward due to dune erosion. When comparing the width of recreational beach
available in the 2019 pre -construction profiles to the SBEACH equilibrated profiles the majority of the
profiles show a reduction in the recreational beach width.
A more representative comparison would be the recreational beach width that was present in 2016 when
a dune existed with the SBEACH equilibrated profiles. This 2016 survey was taken before Hurricane
Matthew at a time when a dune was present along a majority of the profiles. When comparing 2016

profiles to the SBEACH equilibration profiles the majority of profiles show maintaining or increasing the
recreational beach width.
Plots are provided to show how the construction template compares with the historical profiles. It is
important to note that the construction template is designed for a 25-year return period storm level of
protection, this did not exist across much of the island in 2014 (date of earliest survey). The construction
template in many cases will restore what was there in 2016 (before Matthew), however in many cases it
will add to what was there before Matthew. This is the intent of the design so that the Town will be in a
better position to recover from future storm events. Please also recall that the Town's plans involve the
construction of a dune repair/recreational berm project in the future that should greatly enhance the
recreational beach. Even if this project were to never materialize, we could expect that the same behavior
that has happened recently would occur, and the recreational beach would be fed by the dune during
larger storm events.
Table 2 — Recreational Beach Width Values
Recreational Beach Width from +7' NAVD88 to MHW
Station
Pre -Matthew 2016
Pre -Construction
June 2019
Construction
Template
SBEACH 2-yr Storm
Construction Equilibration
300+00
67
93
63
310+00
51
82
104
320+00
59
86
104
330+00
59
77
104
66
340+00
53
78
104
350+00
56
67
104
360+00
47
66
104
370+00
48
71
104
53
380+00
53
171
104
390+00
62
70
104
400+00
74
81
104
410+00
59
74
104
67
420+00
79
66
104
430+00
98
49
104
440+00
90
86
104
450+00
90
86
104
61
460+00
71
85
104
470+00
58
75
104
480+00
71
80
104
66
490+00
64
81
104
500+00
77
72
104
Average
66
81
102
63
Minimum
47
49
63
53

Recreational Beach Width from +7' NAVD88 to MHW
Pre -Construction
Construction
SBEACH 2-yr Storm
Station
Pre -Matthew 2016
June 2019
Template
Construction Equilibration
Maximum
98
171
104
67