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Record of Decision for the Boston Harbor Inner Harbor Maintenance Dredging Project
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: August 9, 2006 (Volume 71, Number 153)]
[Notices]
[Page 45539-45541]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09au06-70]
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DEPARTMENT OF DEFENSE
Department of the Army; Corps of Engineers
Record of Decision for the Boston Harbor Inner Harbor Maintenance
Dredging Project
AGENCY: Department of the Army, U.S. Army Corps of Engineers, DOD.
ACTION: Notice.
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SUMMARY: The U.S. Army Corps of Engineers, New England District
announces its decision to maintenance dredge the following Federal
navigation channels in Boston Harbor, Massachusetts: the Main Ship
Channel upstream of Spectacle Island to the Inner Confluence, the upper
Reserved Channel, the approach to the Navy Dry Dock, a portion of the
Mystic River, and a portion of the Chelsea River (previously
permitted). Maintenance dredging of the navigation channels landward of
Spectacle Island is needed to remove shoals and restore the Federal
navigation channels to their authorized depths. Dredged material
suitable for unconfined open water disposal will be disposed at the
Massachusetts Bay Disposal Site; material not suitable for unconfined
open water disposal will be disposed in confined aquatic disposal (CAD)
cell(s) located within the navigation channels. Major navigation
channel improvements (deepening) were made in 1999 through 2001 in the
Reserved Channel, the Mystic River, Inner Confluence, and the Chelsea
River. A Final Environmental Impact Statement (EIS) prepared in June
1995 for this previous navigation improvement project (Boston Harbor
Navigation Improvement Project--BHNIP) identified selected use of CAD
cells in the Mystic River, Inner Confluence, and Chelsea River for
disposal. A Supplemental Draft and Final EIS was prepared for this
maintenance dredging project and built on the lessons learned from the
previous improvement project. A new CAD cell for the proposed
maintenance project will be constructed in the Mystic River (previously
permitted) and in the Main Ship Channel just below the Inner Confluence.
FOR FURTHER INFORMATION CONTACT: Mr. Michael Keegan, (978) 318-8087.
SUPPLEMENTARY INFORMATION: The U.S. Army Corps of Engineers is
authorized by the various River and Harbor Acts and Water Resources
Development Acts to conduct maintenance dredging of the Federal
navigation channels and anchorage areas in Boston Harbor.
Alternatives Considered: The National Environmental Policy Act
(NEPA) requires a discussion of alternatives to the project, including
the No Action Alternative. Since a Supplemental EIS was prepared, the
preferred alternative is evaluated in the context of the alternatives
addressed in the EIS for the navigation improvement project, including
alternatives to full maintenance dredging, dredging methods, and
disposal options.
Dredging--The Boston Harbor terminal operators, and shipping
interests were contacted to identify the type and size of vessels
currently using the navigation channels and if they were experiencing
any delay or impacts associated with the navigation project. The
results of the survey were used to determine if maintenance of all or
just a portion of the currently authorized navigation channels in the
proposed project is required. Based on the results of the survey, it
was determined that shoaling in the Charles River channel does not affect
any of the current operations in that channel and will not be dredged.
Dredging Methods--Various types of dredging methods were considered
for this project including a hydraulic dredge, a hopper dredge, and a
[[Page 45540]]
mechanical dredge. The type of dredge proposed for a project is
dependent upon the type of material to be dredged and the disposal site
selected. Due to the fine nature of the materials to be dredged from
Boston Harbor, and the aquatic sites selected for disposal, it was
determined that a mechanical dredge would best suit the needs of the
project. To minimize turbidity impacts from dredging, an enclosed
``environmental'' bucket will be used during silt dredging. In
addition, no overflow from the scows will be allowed to further reduce
the effects of turbidity on water quality.
Disposal Alternatives--Over 370 disposal sites were identified and
evaluated during preparation of the EIS for the previous navigation
improvement project (BHNIP). The screening process selected in-channel
CAD cells for disposal of the material unsuitable for unconfined open
water disposal and the Massachusetts Bay Disposal Site (MBDS) for
disposal of the suitable material. In addition, seven sites were
identified in the BHNIP Final EIS as potential disposal sites for
future maintenance dredged material. The sites included the MBDS,
Subaqueous B and E, Meisburger 2 and 7, Boston Lightship, and Spectacle
Island CAD.
The Subaqueous B and E sites, the Meisburger sites and the
Spectacle Island CAD are all located in previously undisturbed areas.
The Boston Lightship is a historic disposal site and would need to go
through a lengthy site selection process before disposal could be
considered. This site also recovering from previous disposal events.
The MBDS is an EPA-designated ocean disposal site that is currently in
use. Sites that have not been previously disturbed are not as desirable
for disposal of dredged material. Therefore, the MBDS was selected as
the preferred site for the suitable material and the in-channel CAD
cells selected for material unsuitable for unconfined open water disposal.
No Action Alternative--Under a No Action Alternative, the Federal
navigation channels in Boston Harbor would not be dredged. Failure to
dredge Boston Harbor will further restrict and delay commercial deep
draft vessels. Shoaling has reduced depths in the channel as much as
five feet in some sections of the project area. Without maintenance
dredging to restore authorized depths in the inner portion of the Main
Ship Channel, shippers will experience even longer tidal delays and be
restricted to operating within narrower time periods of higher tidal
stages. This results in a significant and negative impact to the
region, and raises significant operational, safety, economic, and
environmental concerns. With the increase in costs and reduction in
vessel movement opportunities, it is likely that shippers will by-pass
the port and will unload their products at other ports and ship the
products back to the region via trucks. This could impact limited
roadway capacity, resulting in increased air emissions, traffic, and
deterioration of highways and bridges. Although the No Action
Alternative is the environmentally preferred alternative, it does not
meet the project objectives, and is not considered a viable
alternative. Therefore the preferred alternative is dredging the above
described navigation channels to their authorized depth using a
mechanical dredge with disposal at the MBDS and in-channel CAD cells.
Environmental Impacts: Potential environmental impacts associated
with dredging and disposal includes water quality impacts from
turbidity plumes, potential release contaminants during dredging and
disposal activities, and impacts to biological resources. In
particular, concerns about biological resources centered on potential
blockage of anadromous fish transiting to spawning grounds, sediment
deposition from suspended solids on winter flounder eggs, and direct
impacts to lobsters.
Extensive environmental monitoring was conducted during
construction of the BHNIP as a requirement of the Water Quality
Certification (WQC). Environmental monitoring required as part of the
WQC included: (1) Silt plume tracking during dredging of and after
disposal into CAD cells, (2) water quality testing after disposal into
the CAD cells, (3) biological testing, (4) dissolved oxygen (DO)
testing within and outside the CAD cells, and (5) fisheries monitoring.
The results of the monitoring showed no water quality violations or
significant impacts to biological resources.
Additional investigations (i.e., outside the scope of the WQC) were
performed during construction to address concerns raised by the
Technical Advisory Committee (TAC) to address potential impacts from
changes in operations suggested by the dredging contractor. The TAC met
periodically to review monitoring results and discuss recommended
amendments to the WQC. These additional investigations included water
quality monitoring of disposal at low tide, plume monitoring of the
contractor's enclosed bucket, monitoring turbidity caused by vessel
passage over an uncapped and capped CAD cell, bathymetric measurements,
and lobster monitoring. Monitoring results showed no water quality
violations or significant environmental impacts from construction of
the project. One-year surveys and five-year surveys of the CAD cells
constructed in the Inner Confluence, Mystic River, and Chelsea River
for the BHNIP have also been completed, as required by the BHNIP WQC.
The results of the monitoring show that the CAD cells are performing as
expected. Experience gained from placing a sand cap on the CAD cells
will be incorporated into this project.
Mitigation: As a result of the extensive monitoring conducted for
the BHNIP, and the lack of any water quality violations or significant
impacts, only confirmatory water quality monitoring during initial
disposal operations is recommended for this project. It is recommended
that total suspended solids and turbidity monitoring be performed
during the initial disposal events at both the Mystic River CAD cell
and at the Main Ship Channel CAD cell.
To reduce potential impacts to resources in the project area, based
on lessons learned, the following mitigation measures will be implemented:
? An enclosed ``environmental'' bucket will be used for silt
dredging. To reduce the effects of turbidity on water quality, no
overflow from the scows will be allowed.
? Disposal into the CAD cells will occur only around periods
of slack tide: three hours at low tide and high tide (one hour before
and two hours after slack tide).
? A three-foot sand cap will be placed in the CAD cells when
the silt has consolidated enough to support a cap. The cap material
will be released from a moving as opposed to a stationary platform. No
spudding over the cap or mechanical disturbance of the cap will be allowed.
? To reduce the impact to biological resources from
blasting, all blasting will be conducted using inserted delays of a
fraction of a second per hole. Rock or similar material will be placed
into the top of the borehold to deaden the shock wave reaching the
water column. A fisheries and mammal observer, and fish detecting sonar
system, will be used to avoid blasting when mammals are present in the
area or when significant schools of fish are observed.
? A fisheries observer, sonar detection, and use of a fish
startle system from February 15 to June 15 will be required for the
Mystic River and Main Ship Channel CAD disposal activities to avoid
disposal during the time of anadromous fish migration.
? To reduce potential impacts to egg-bearing lobsters that
are less mobile in
[[Page 45541]]
the colder months, no dredging or blasting will occur seaward of the
Third Harbor Tunnel between December 1 and March 31.
? A marine mammal observer will be on board the scows
transiting to the MBDS from February 1 to May 31 to avoid potential
ship strikes with marine mammals, and in particular the North Atlantic
Right Whale.
? Rock removed from the Presidents Road Anchorage area will
be placed within a new area of the MBDS to increase habitat diversity.
? The dredge contractor will provide advance notice to the
lobstermen on anticipated significant dredge movements.
? The dredge contractor will maintain a short tow while
inside Boston Harbor to minimize disruption of lobster pots.
Based on incorporation of the above mitigation measures, the
experience gained during construction of the BHNIP, and lack of any
water quality violations or other significant effects from the BHNIP,
no significant impacts to the environment are expected from the Boston
Harbor Inner Harbor Maintenance Dredging Project. All practicable means
to avoid or minimize adverse environmental effects have been
incorporated into the recommended plan. The public interest will best
be served by implementing maintenance dredging as identified and
described in the Supplemental Environmental Impact Report.
Dated: August 1, 2006.
Curtis L. Thalken,
Colonel, Corps of Engineers, New England District.
[FR Doc. 06-6792 Filed 8-8-06; 8:45 am]
BILLING CODE 3710-24-M