On again, off again
dredging now under full steam.
EverythingWestport.com
Thursday,
November 27, 2008
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“Everything is weather and tide dependent,” Pyne Tripp reflected as he prepared the dump scow for
another long trip to the dumping grounds off Provincetown. “The tug should be under
way around 7 tonight. We need to steam out in a late head tide.” The Tripp
Marine crew missed a day yesterday because of high seas and Thanksgiving. “We
could have left late Wednesday,” Tripp said, “but that would have spoiled the
holiday for the crew.” Full dump scow pictured left.
At 3 to 7
knots depending on tide, twelve hours out and ten hours back to complete a
3-minute dump is a long day in anybody’s book. The 140 foot long, full dump
scow draws a little over 10 feet, making it a dangerous object to tow in tides
and high seas. Passage through the treacherous Westport channel entrance and
the Cape Cod Canal is a serious and dangerous endeavor, and requires the utmost
skill and attention of a tugboat captain.
A time-consuming and slow process.
It takes 2
˝ hours to fill up the 110+ cubic yard “pigpen” on the crane barge with dredged
materials, which is then off-loaded to the dump scow by a large clamshell
shovel; powerful work boats shuttle the crane barge back and forth. Because a
different shovel is used for the transfer, the uncoupling and re-coupling of
clamshells is more time.
Maneuvering
the crane barge into position can be tricky at best because the 38 foot vessel
is attempting to clear a 40 foot channel. The Westport River’s notorious tidal
currents don’t make the job any easier. Especially troublesome are high points
or rocks in the channel that could crush the barge’s hull as its draft is
lowered when filled with wet sand. White stakes previously placed in the
dredging area help guide the crane barge into position.
Hydraulically-controlled “spuds” (metal pilings to landlubbers!) on the crane
barge secure the barge in place. The spuds are raised to reposition the barge.
“We have to
be sure all rocks in the dredged area are cleared,” Tripp said. “This requires
the use of the smaller clawed shovel that will penetrate the harder sand and
capture rocks.”
24 hours of
potential dredging time is lost each time the dump scow makes its run to the
approved dumping grounds in Cape Cod Bay. Tripp Marine expects about 20 trips
that will potentially cost the dredging operation 20 lost work days. Thus the nighttime operation.
The dump
scow holds approximately 850 cubic yards of the dredged materials, mostly fine
sand, and takes between eight and nine loads from the “pigpen” to fill. The TMC
140 dump scow is a split-hull design, and opens up like the clamshell bucket
that fills it to empty its load. “The scow’s bottom hull unlocks and spreads to
about 10 feet at the bottom,” Tripp said. “It only takes a few minutes to
empty.”
But lengthy
is also a word that is used to describe the acquisition of funding and environmental
approval from the state and regulatory boards.
“Delays in
funding and permitting almost scuttled the project for 2008,” said Westport
harbormaster Richie Earle, The intervention by Town
Administrator Mike Coughlin and state Representative Mike Rodriques
finally secured the funding, but the project lost almost a full month. “We just
have to work day and night and hope for good weather,” Pyne
Tripp said. Federal guidelines call for all ocean and estuary dredging projects
to be completed between October 15 and January 15 to protect spawning fish;
state guidelines are slightly offset by 15 days. “As it is, Pyne
will have only 60 days or so to complete the $1.39 million project,” Earle
said.
The
commercial wharves were last dredged more than 25 years ago.
Nighttime dredging left to right: (1) Two work
boats position the crane dredge; (2) crew members prepare to attach the clawed clamshell
shovel; (3) the white stakes help mark the channel for dredging; and (4) crane
operator Pyne Tripp fills the “pigpen”.
Read the article and view photos of the Westport Harbor channel
dredging in 2007/2008.
The dredging of the town docks follows the substantial
clearing of the harbor channel last year by Southwind
Construction, who discovered the high rock ledge in the middle of the channel just
north of the Spindle Rock Yacht Club. “Divers went down and drilled between 20
and 25 holes, and then packed the holes with fast-drying hydraulic cement,”
Tripp said. “The very top of the ledge developed a few cracks, but the outcropping,
shaped like the back of a turtle, resisted the effort.
Divers had to revisit the obstruction and, with pneumatic drills, create holes
and use “feather wedges” (see diagram far left) to split and remove the rock
facing to a depth of 11 feet below the water line.” The pieces were hauled out
and trucked away by Tripp Marine.
Groundings and turbidity.
“The
problem at the town docks was periodic boat groundings and “turbidity”, prop
wash that was stirring up the sand and clouding the water with debris which
interferes with spawning fish,” harbormaster Earle said. “Deep draft boats will
now be able to come in on both tides. When you’re working on the ocean, 12 wasted
hours is time and money!”
Lt.
Governor Timothy P. Murray stated previously that this project “will help
support Westport’s commercial fishing industry, and in turn, promote economic
development in the port area.”
In the diagram to the left the proposed areas for
sediment removal are noted as cross-hatched patterns. “The mud dock is next to
and west of Lees Wharf,” explained Russ Hart, longtime Westport Point resident
and a former town official of too many positions to name here. “This area was a
problem for early whalers, and is a thorn in our side to this day.”
The entire
mud dock will be deepened to 6 feet. The town commercial wharves will be
dredged to 7 feet around the northeast inner corners and inside west side. The
area to the west of the Harbormaster shack and south of Leach’s Marina will be
deepened to 7 feet.
A sandbar
to the immediate southwest of the commercial docks will also be dredged to 7
feet.
The
trickiest dredging is the 40 foot wide channel behind the Paquachuck
Inn that extends north into a marshy channel. Eel grass in this area will be
replanted at the completion of the operation. The cost of this portion of the
dredging is being shared with the residents who abut this channel and use the
waterway for private boating access.
Environmental concerns challenge project.
Eelgrass
meadows form the foundation for primary production which supports numerous
species. These meadows are very important to the coastal marine ecosystem. They
are protected by local, state and federal regulations. In these regulations,
eelgrass beds may enjoy protection under the law as "land under salt
ponds" where no project may affect "productivity of plants, and water
quality". Therefore, a 30 foot no-dredge buffer zone will protect the
eelgrass beds to the west of the commercial docks. Restrictions were somewhat
more complicated with the eelgrass beds northeast of the Paquachuck
Inn.
A dredging
window from October to January 1st (January 15th for
other parts of the project) protect spawning fish but bring bad weather and
rough seas into play for the Tripp Marine dredging crew. Other concerns are
mammal and Right Whale encounters that are monitored by on-board state
inspectors. “The dumping ground is also observed a few days in advance of the
scow arrival to ensure no Right Whales are present,” Earle said.
Overseeing
the project is the Department of Conservation and Recreation with the
assistance of the Seaport Advisory Council, State Office of Travel and Tourism,
and local conservation commission agents, among others. Westport’s share of the
$1.39 million is set at $447,567. “We’ve got the money,” Westport Town
Administrator Mike Coughlin assured us.
Click on the above photo to enlarge this panoramic view. Very large
image; please be patient! Use your browser to zoom in on image.
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