20130144 Ver 2_Handouts_20130809

NC Hwy -12 Protection Project
Figure: 1 - Proposed Beach Fill Design (3 -Year Life)
August 9, 2013

A. Technical Description: The beach fill will protect two areas of the road (Hwy 12) from
erosion damage for three years (See Figure 1). There will be some residual protection after
three years. The beach fill template for the southern area will be for a berm only design. The
beach fill template for the northern area will include a dune. The road in the southern area will
have back beach protection provided by bags placed by NCDOT. The north area will have a
dune to replace the dune lost due to overwash. The length of the two areas to be protected is
relatively short and the close proximity requires one continuous fill to protect both sites. The
main body of the fill will start and stop where road is approximately 300 ft from the exiting
shoreline. The main body will be 8,000 ft. There will be two design berm widths (construction
widths will be greater). The northern 2,000 ft will have a 100 ft wide berm and the southern
6,000 ft will have a 120 ft berm. There will be a mild transition between the two widths. There
will be a 2,000 ft transition on each end of the fill. Using the assumptions of a 24 ft depth of
closure, a 20% overfill ratio, and a 15% transport loss rate, gives a required dredge volume of
1,700,000 cubic yards.
B. Proposed Cross Sections: Shown below are typical cross - sections for the two
sand fill areas designed to protect the S -Curve area of NC Hwy -12. Remember that
these typical sections were prepared without beach profile data,
B.1: 100 Foot Berm Area (Northern 2,000 Ft)(Figure: 2)
20
18
16
14
12
z
X14
0
a
w g
6
4
2
0
Dune and Berm Profile
4 50 100 150 200 250 304 350 400 450
Cross Shore ©istanCe Ft
2 August 9, 2013

B.2: 120 Foot Berm Area (Northern 6,000 Ft)(Figure: 3)
20
18
16
14
12
z
10
W 8
6
4
2
Berra Seaward of DOT's Bags
a 50.... 100 150 208 250 300 350 460 450
Cross Shore Di Stance Ft
3 August 9, 2013

Proposed NC Hwy 12 N
Project Extent With W E
Potential Borrow Areas S
0 0.5 1 2
Miles
4
Lis Army Corps
of EngilneersD
Wilmington District
August 9, 2013

NC Highway
Potential Borrow
N
W E
Vibracore Locations S
MINE
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NC Highway
Potential Borrow
Elevation
Vibracore Locations
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NC Highway
Refined Borrow
Elevation
Vibracore Locations
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Highway
Refined Borrow
Elevation
Vibracore Locations
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Highway
Refined Borrow
Elevation
Vibracore Locations
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Highway
Elevation
Engineers,D
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NC Highway
Refined Borrow
Elevation
Vibracore Locations
Transects
am=*
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Highway
Refined Borrow Area A
Elevation
Vibracore Locations
Tra n sects
0.4 0.6
Miles
r
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Highway
Refined Borrow
Elevation
Vibracore Locations
Transects
0.4 0.6
Miles
r
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Highway
Elevation
Transects
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