A view down the road carved through the woods from Cherenzia
Excavation Inc. on the Rhode Island side of the Pawcatuck River. Building the
road was the project’s first step. (David Smith/ecoRI News photos)
WESTERLY, R.I. — Heavy equipment and material have been moved into
place and work has begun removing White Rock Dam.
A 70-yard road was pushed through the woods July 29 from a gravel
bank on the Rhode Island side of the Pawcatuck River. Large trees were ripped
from the ground and laid on their side at the beginning of the road.
The dirt road ends at the river, where riprap has been laid on the
soft, muddy bank in anticipation of continuing the road to an island on the
east side of the dam. Each side of the graded roadway is lined with staked
fabric to contain erosion.
The road will bridge the sluiceway but still allow water to flow
down it via pipes. It will give the crew of SumCo Eco-Contracting LLC of Salem,
Mass., access to the river below the dam. The initial work will include grading
the riverbed below the dam, followed by the building of a cofferdam to dewater
the dam. That will allow SumCo remove the dam.
The final piece in the Rhode Island permitting process was the approval
of a wetlands permit July 2. A corresponding wetlands permit is also needed
from Connecticut. Scott Comings, associate director of the Rhode Island chapter
of The Nature Conservancy, said that is expected in the next few weeks.
A cofferdam is expected to be in the river by the first week of
August. Comings said building the road was the project’s first step. What
follows will be extending that access to the island adjacent to the dam.
“It is a huge step to start,” he said. “The conditions are perfect.
The water is low and there has been no rain. It’s ideal.
”
The permit application in Connecticut was started about six weeks
after the Rhode Island application, Comings said. He was told by Connecticut
officials that the public comment period has ended and “there was nothing but
positive comments.”
The work in the river is expected to take 90 days, and is
scheduled to be finished by the end of October.
“We believe there is enough time to get it done,” Comings said,
“but there are some things out of our control such as rain, flooding and
hurricanes.”
The sluiceway is on the left and White Rock Dam is on the right.
A contract to remove the 112-foot-wide concrete dam was awarded to
SumCo in April for $710,869. The Nature Conservancy had expected to move
supplies into place in June and be in the river in by July, but the work was
held up by the necessary wetland permits from Rhode Island and Connecticut.
The Nature Conservancy is working to maintain the level of the
river below the dam so that it doesn’t change the potential for flooding. There
will be signs on the river notifying boaters of the construction project and to
direct them to a path for safe portaging.
The granite sluiceway, which is a
favorite of kayakers and canoeists, will not be removed. A barrier will be
built in front of it on the upriver side and water will only flow into it
during high water.
The first dam at the site was built in 1770. It was rebuilt
several times over the centuries. When the dam was washed away in the 1938
hurricane, it was rebuilt using concrete.
Comings said that if excavation reveals parts of the original rock
and wooden dam, work will be halted for a few days so it can be recorded. He
said it’s possible that when it was rebuilt workers used the same stone
foundation.
Nils Wiberg, an associate with Fuss & O’Neill Engineering of
Providence, said earlier this year that because the level of the river is so
flat in that area, the water levels will drop from 2.5 to 3 feet at the dam,
from 1.5 to 3 feet upstream at the Boom Bridge Road Bridge and up to a
half-foot at Potter Hill Dam, more than a mile upstream.
Wiberg said tests on the sediment behind the dam show the usual
levels of volatile organic compounds and metals expected to be found in a river
system dotted with mills.
He said the levels are all below exposure levels
established by the Rhode Island Department of Environmental Management. That
means the sediment will stay on-site and be used to form the new river channel
or distributed in the old canal and capped with rock.
White Rock is the fourth dam on the Pawcatuck River earmarked
either for removal or modification.
This effort is designed to improve fish
passage on the 20-plus-mile waterway that stretches from Worden’s Pond in South
Kingstown to Little Narragansett Bay. The work also is expected to reduce
flooding above the site.
About 15 miles upstream, the Kenyon Dam and Lower Shannock Falls
Dam have been removed. A fish ladder was built at historic Horseshoe Falls.
A total of $1.9 million in federal Sandy money is available for
the White Rock project, according to Comings. He said the engineering contract
for the project is $313,793 and will cover all three phases of the White Rock
Dam removal and the first phase of study regarding Bradford Dam, about 6 miles
upstream.
Fuss & O’Neill has done the work on the two dam removal
projects and the building of the fish ladder at Horseshoe Falls Dam.