Plan Being Formed for Removal of White Rock Dam

A Providence engineering firm will sample sediment behind the White Rock Dam in Westerly to see if it is contaminated. A decision would then be made regarding its removal. (Chuck Horbert photos)

A Providence engineering firm will sample sediment behind the White Rock Dam in Westerly to see if it is contaminated. A decision would then be made regarding its removal. (Chuck Horbert photos)

By DAVID SMITH/ecoRI News contributor

WESTERLY, R.I. — Work has begun on a plan to remove the White Rock Dam. A contract was awarded Sept. 25 to the Providence-based engineering firm Fuss & O’Neill to first study and then draft plans for the removal of the circa 1940 concrete structure.

It would be the third dam on the Pawcatuck River earmarked either for removal or modification. The 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. About 15 miles upstream, the Kenyon Dam and Lower Shannock Falls Dam have been removed, while a fish ladder was built at historic Horseshoe Falls.

A total of $1.9 million in federal Hurricane Sandy funds is available for the White Rock project, according to Scott Comings, director of land and freshwater in the Rhode Island office of The Nature Conservancy.

A decision on how to proceed on the project will be made when the test results of soil taken from behind the dam are analyzed. If the soil is contaminated, that could add to the cost and/or change the approach.

Comings said the engineering contract is for $313,793, and will cover three phases of the White Rock Dam removal and the first phase of study regarding Bradford Dam, about 6 miles upstream.

The owner of White Rock Dam is Griswold Textile Print, 84 White Rock Road, just downstream of the structure. President Paul Bergendahl said he was “curious to see what the results” will be regarding engineering tests before he offers an opinion on the dam’s removal.

His company, which makes high-end decorative fabrics and employs 18 people, doesn’t currently use the dam. The dam was built to hold back water to feed the granite-stoned sluiceway adjacent to it. The water flow was once used to power the historic mill. While Griswold Textile Print formed in 1937, the building it occupies is much older.

The existing concrete dam replaced a wooden structure that was built in either the late 1700s or 1800s, according to Comings. Bergendahl had said that he believed that the old dam was washed out by the 1938 Hurricane.

While the dam has a 7.5-foot-high gate and let’s some water by, most of the flow goes down the sluiceway, which is about 150 yards long and now discharges back into the river.

One option is to block the end of the sluiceway if the dam is removed to let the river follow its original course.

The Nature Conservancy is under a deadline to use the Sandy funds on this project. Comings said the work must be completed by 2016. The state will only allow work in the river during the summer, so if the work isn’t completed in 2015, the next cycle would be in summer 2016.

“Fuss & O’Neill have the knowledge to get the project done in the time frame we have,” Comings said. The engineering firm worked on the three other dam projects on the Pawcatuck River.

Comings said his agency doesn’t have the permission of the dam’s owners to remove the 112-foot-wide concrete structure. The company owns the dam and an island below it that is flanked on one side by the granite-wall sluiceway and the river. He added that the project is now in the first phase and decisions will be made as information comes in. He didn’t know when the tests on the soil behind the dam would be complete.

Comings said the project’s goal is for better river connectivity. Fish are sometimes unable to swim up the sluiceway, he said. It is a barrier most of the year.

The Bradford Dam has a fish ladder that was improved several years ago. The entrance to the ladder was changed to enable fish to find it easier. But Comings said that “there are some things we could improve in Bradford.”

It’s because the dam in Bradford has a fish ladder, that the White Rock Dam was given priority. The only other dam on the river that hasn’t been the focus of a study is the Potter Hill Dam, which is between White Rock and Bradford. It has a fish ladder.