Local knowledge
What is the existing local body of knowledge from coastal
protection projects near the site? What types of designs
have been used over time in the area and in what ways
have they succeeded or failed?
Construction resources
What is the availability and cost of both natural and
man-made construction materials (soil and beach fill,
stone, timber, concrete, steel)? There is a unique set of
concrete construction components for shore protection
(Reef balls, Core-loc units, Coastal Haven WAD®
(Wave Attenuation Device), etc.) which can be used in
certain site conditions with design guidance. How long
will it take to obtain the materials for construction and
what are the transportation costs?
Often specialized construction equipment (dredges,
barges, tugs, workboats, divers) is necessary to complete
a coastal construction project. Is the equipment required
available locally and is there local infrastructure to get it
to the site? Are their local contractors with experience
with the equipment?
Increasingly coastal projects are completed with the
contribution of community volunteers, particularly with
landscaping and project monitoring. How can these
resources be efficiently combined with the commercial
contractors work?
Customer
Coastal engineering projects are initiated by a customer’s
desire to protect/enhance their coastal property. The customer can be an individual, business, nonprofit, or public
entity. The property may be residential, recreational, commercial, or coastal infrastructure (roads, bridges, marinas,
ports, railroads). The primary controls are the budget and
the proposed life of project and maintenance intervals.
What is the customer’s permissible level of damage due
to an extreme storm/seismic event? How is the project
being funded? If public funds are being used, can the economic return to the community from the contribution be
justified? The use, the life, the budget, and an acceptable
level of risk are balanced in the final design.
Regulation
Every design project is subject to both engineering codes
and permitting for zoning and environmental review.
Engineers must maintain knowledge of design and construction codes. Permitting is done at the local, regional,
and national levels and varies between jurisdictions. As
complex as it has become, obtaining permitting for a project has become a special area of legal and policy expertise
separate from the engineering. An engineer must continuously communicate and solicit input from all involved
parties to insure the coastal project is built to everyone’s
satisfaction.
Coastal engineering designs
Coastal engineering design solutions can vary from letting
nature take its course to any of the following man-made
alterations to the shoreline:
Beach fill or nourishment
Beach fill or nourishment is the restoration of a natural
beach with sand fill and reconstructed dunes to recreate a
historical beach profile. Dunes protect the backshore of
the coast in an extreme storm. Models exist to predict
two-dimensional coastal erosion due to extreme storm conditions (Kriebel and Dean, 1985). Correct estimates of
wave run-up and overtopping are necessary (Jones et al.,
2005). Beach fill must be selected that matches the color,
weight, median particle diameter, d 50 , and distribution at
the location.
Living shorelines
The concept of “living shorelines” involves the use of
native vegetation and low-lying structures to provide
shoreline stabilization while attempting to mimic the natural landscape and preserve the intertidal habitat at a site
location (Walker et al., 2011). In low-wave energy locations or within estuaries, shoreline marshes can be
constructed with toe stabilization provided by rock or timber sills with low crest elevations that provide water
exchange, habitat, and protection especially while the vegetation is regrowing. Openings in the sills are provided for
wildlife.
Groins
A groin is a low wall or sturdy timber barrier built out into
the sea from a beach to check erosion. They are
constructed perpendicular or at a slight angle to the shoreline, as shown in Figure 1a. Groins are intended to interrupt the longshore transport and deposit sand adjacent to
the structure; sometimes excessive deposition can occur
on the updrift and downdrift sides of the groin, so their
length and porosity need to be designed carefully.
Breakwaters
Breakwaters are structures designed to provide shelter
from the waves and/or manipulate the littoral transport
conditions to trap sand in their lee. Breakwaters transform
or reduce the height of waves in their lee. They can cause
wave setup or an increase in the water level due to the
waves trapped behind them. They can be composed of
concrete units or layers of rock with varying weights and
sizes. Breakwaters can extend at any angle to the shoreline
to create a sheltered area depending on wave conditions,
as shown in Figure 1b. Rock or concrete breakwaters are
constructed with front and back slopes. Rock breakwaters
can be composed of a single homogeneous layer of rock or
layers of graded rock. A layered breakwater has a central
core of finer stone to improve wave transmission. The central core is covered with a level cap and front and back
slopes composed of layers of larger heavier stones to
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101
What is the existing local body of knowledge from coastal
protection projects near the site? What types of designs
have been used over time in the area and in what ways
have they succeeded or failed?
Construction resources
What is the availability and cost of both natural and
man-made construction materials (soil and beach fill,
stone, timber, concrete, steel)? There is a unique set of
concrete construction components for shore protection
(Reef balls, Core-loc units, Coastal Haven WAD®
(Wave Attenuation Device), etc.) which can be used in
certain site conditions with design guidance. How long
will it take to obtain the materials for construction and
what are the transportation costs?
Often specialized construction equipment (dredges,
barges, tugs, workboats, divers) is necessary to complete
a coastal construction project. Is the equipment required
available locally and is there local infrastructure to get it
to the site? Are their local contractors with experience
with the equipment?
Increasingly coastal projects are completed with the
contribution of community volunteers, particularly with
landscaping and project monitoring. How can these
resources be efficiently combined with the commercial
contractors work?
Customer
Coastal engineering projects are initiated by a customer’s
desire to protect/enhance their coastal property. The customer can be an individual, business, nonprofit, or public
entity. The property may be residential, recreational, commercial, or coastal infrastructure (roads, bridges, marinas,
ports, railroads). The primary controls are the budget and
the proposed life of project and maintenance intervals.
What is the customer’s permissible level of damage due
to an extreme storm/seismic event? How is the project
being funded? If public funds are being used, can the economic return to the community from the contribution be
justified? The use, the life, the budget, and an acceptable
level of risk are balanced in the final design.
Regulation
Every design project is subject to both engineering codes
and permitting for zoning and environmental review.
Engineers must maintain knowledge of design and construction codes. Permitting is done at the local, regional,
and national levels and varies between jurisdictions. As
complex as it has become, obtaining permitting for a project has become a special area of legal and policy expertise
separate from the engineering. An engineer must continuously communicate and solicit input from all involved
parties to insure the coastal project is built to everyone’s
satisfaction.
Coastal engineering designs
Coastal engineering design solutions can vary from letting
nature take its course to any of the following man-made
alterations to the shoreline:
Beach fill or nourishment
Beach fill or nourishment is the restoration of a natural
beach with sand fill and reconstructed dunes to recreate a
historical beach profile. Dunes protect the backshore of
the coast in an extreme storm. Models exist to predict
two-dimensional coastal erosion due to extreme storm conditions (Kriebel and Dean, 1985). Correct estimates of
wave run-up and overtopping are necessary (Jones et al.,
2005). Beach fill must be selected that matches the color,
weight, median particle diameter, d 50 , and distribution at
the location.
Living shorelines
The concept of “living shorelines” involves the use of
native vegetation and low-lying structures to provide
shoreline stabilization while attempting to mimic the natural landscape and preserve the intertidal habitat at a site
location (Walker et al., 2011). In low-wave energy locations or within estuaries, shoreline marshes can be
constructed with toe stabilization provided by rock or timber sills with low crest elevations that provide water
exchange, habitat, and protection especially while the vegetation is regrowing. Openings in the sills are provided for
wildlife.
Groins
A groin is a low wall or sturdy timber barrier built out into
the sea from a beach to check erosion. They are
constructed perpendicular or at a slight angle to the shoreline, as shown in Figure 1a. Groins are intended to interrupt the longshore transport and deposit sand adjacent to
the structure; sometimes excessive deposition can occur
on the updrift and downdrift sides of the groin, so their
length and porosity need to be designed carefully.
Breakwaters
Breakwaters are structures designed to provide shelter
from the waves and/or manipulate the littoral transport
conditions to trap sand in their lee. Breakwaters transform
or reduce the height of waves in their lee. They can cause
wave setup or an increase in the water level due to the
waves trapped behind them. They can be composed of
concrete units or layers of rock with varying weights and
sizes. Breakwaters can extend at any angle to the shoreline
to create a sheltered area depending on wave conditions,
as shown in Figure 1b. Rock or concrete breakwaters are
constructed with front and back slopes. Rock breakwaters
can be composed of a single homogeneous layer of rock or
layers of graded rock. A layered breakwater has a central
core of finer stone to improve wave transmission. The central core is covered with a level cap and front and back
slopes composed of layers of larger heavier stones to
COASTAL ENGINEERING
101