Project expected to be completed by October
By DAVID SMITH/ecoRI News contributor
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.
On the opposite side in Connecticut, access to the site will be realized from property owned by the Wescon Corp., a provider of concrete and asphalt.
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.”
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.