Environmental Engineering Reference
In-Depth Information
Box 7-3. Restoration Project Highlight: Ecosystem Restoration May Require a Multifaceted
Program Covering a Wide Range of Biological and Engineering Techniques and Activities
Location: Jamaica Bay Watershed Protection Plan, New York, New York, United States
Jamaica Bay is an eighteen-thousand-acre body of water adjacent to the communities of
Queens and south Brooklyn of New York City. During the past one hundred years, the bay has
undergone significant changes that have disrupted its natural ecosystems. The significant pop-
ulation increase of New York City has contributed to increased levels of pollutants and sewage
discharged into the bay. New York City, like numerous other cities on the US east coast, has a
combined sewer and stormwater system that frequently gets overwhelmed during intense storm
events, causing sewage to enter Jamaica Bay at a number of outlets. Another impact to the bay
has been from extensive dredging during the past century, resulting in a bay bottom that no
longer has the topography and substrate that can support extensive benthic organisms. As an
outcome of this dredging, the water currents and hydroperiod of the bay have been significant-
ly altered, causing erosive activity on numerous shores of the bay and its islands.
In 2005, the New York City Department of Environmental Protection initiated a multi-
faceted approach to solving the Jamaica Bay pollution and environmental degradation prob-
lem. After realizing that engineering solutions alone (not discussed here) were not going to
solve the problem, the study began exploring innovative environmental engineering and
ecological-based actions that could help reverse the pollution problem.
Of immediate concern within the bay has been eutrophication. One of the most preva-
lent problems is sea lettuce ( Ulva lactuca ) that dislodges from the bottom and creates large
floating mats over a significant area. These mats eventually sink to the bottom to smother
and kill the benthic organisms on the bay floor. To control this problem, the city successfully
tested their trash skimmers to collect these mats.
Sewerage is a problem that requires several approaches because it ends up in the bay and
causes eutrophication. Used in many locations outside of New York, the algal turf scrubber
system is essentially a chute with an algal-encrusted bottom that cleans the water as it passes
over the algae. Typically, the water traverses a channel 100 to 150 feet long, depending on the
amount of algae growing in the chute. The length is typically determined by the location of
the device and the native algae. Trials were designed to confirm the effectiveness of the sys-
tem and to fine-tune the physical structure for maximum effect. The cleaned water is then
discharged back into the bay.
A second method currently being evaluated is the use of a ribbed mussel bed. The mussel
beds function to filter the water coming into the bay. As a natural system, the mussel beds
can expand naturally and produce more individuals serving to filter the water. The mussel
beds can be located in different areas within the bay itself—at stream outlets and other
sources of pollution. Beds are located in areas not frequented by humans; the mussel is not
used as a food source by humans.
To enhance and restore various biological resources in the bay, efforts have been made to
establish oyster beds and eelgrass beds, and to stabilize or increase existing islands through
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