EM 1110-2-1100 (Part V)
31 Jul 2003
borrow areas, increased turbidity during dredging operations and wave climate alterations by sand volume
removal in borrow sites, etc.
These potentially negative impacts must first be identified. Detailed surveys and sampling
investigations are conducted to catalog the species and habitats in the project area under existing
conditions. Use should be made of previous studies and summary information. The U.S. Fish and
Wildlife Service (F&WS) prepares a planning aid report for large Corps projects that detail existing
fish and wildlife resources and their habitats. This report also identifies threatened and endangered
species and critical fish and wildlife habitats. The National Marine Fisheries Services (NMFS), state
and local resource agencies, and local universities may also provide valuable information.
The offshore, sand borrow site is the greatest environmental concern for beach nourishment projects.
New, benthic sampling and collection efforts are often needed to catalog existing species and habitat.
Of concern are species capable of rapid recolonization, commercially important species, or protected
species. These surveys provide data on abundance and diversity together with a complete list of all
species present. This knowledge can be critical in borrow site selection and hence overall cost of the
In most cases, an Environmental Assessment (EA) report is sufficient to demonstrate the minor
environmental impact of shore protection projects. Rarely is a full, Environmental Impact Statement
(EIS) needed which is time consuming and can be expensive. Corps project needs for an EIS are
discussed in Part V-8.
(b) Impact on natural sediment transport system. The negative, downdrift impact on the local and
regional sediment budget can be a key environmental constraint. These concerns are addressed in detail in
Part V-3 for armored (Part V-3-2) and shoreline stabilization (Part V-3-3) structures and in Part V-5 for jetties
at navigation inlets. A beach nourishment project has many positive, environmental impacts by bringing new
material to sand starved beaches and expanding the beach habitat. Studies in turtle nesting areas have proven
that renourished beaches increase the number of turtle nests (Broadwell 1991; Nelson et al. 1987).
(c) Mitigation. Procedures, or measures which avoid, minimize and/or compensate for negative impacts
are defined as mitigation. Threatened and endangered species such as the piping plover, least tern, sea turtles,
and whales required special consideration during the planning and construction stages of shore protection
projects. Avoidance of negative impacts is achieved by scheduling construction activities at times when the
species do not normally inhabit the project area. Piping plovers and least terns are most vulnerable during
the nesting/fledging period from early spring to late summer. Disturbances on the beach cause the nest to be
abandoned before the eggs hatch.
Avoidance for sea turtles and whales is not practical for the southern section of the Atlantic coast
because these species inhabit the area for most of the year. Minimization of negative impacts is
achieved in various ways including monitoring to document contact; using deflectors on the dragarms
and collection boxes on hopper dredges; and conducting turtle relocation projects. These techniques
are approved by the National Marine Fisheries Service.
Mitigation by compensation is employed when resource loss is unavoidable. The most common
example is new wetlands construction to compensate for the wetlands area lost due to project
construction. Some states require more new area constructed than lost and permit wetland banks that
are used to pay for planned, future wetlands loss. New and rebuilt dunes are replanted with grasses
to compensate for any plants lost during construction. Mitigation by compensation methods are
normally carried out and completed during project construction.
Shore Protection Projects