HARWICH — The Cold Brook project is at about the 50 percent design stage, Harwich Conservation Trust Executive Director Michael Lach informed selectmen in a presentation on the ecological restoration initiative at the Robert F. Smith Cold Brook Preserve.
The Massachusetts Division of Ecological Restoration, U.S. Fish and Wildlife Service, HCT and the town are working together in the planning, design and permitting phases that will lead to restoration work in the more than 60-acre wetland and bog preserve owned by HCT on the east side of Bank Street.
There are three major goals associated wit the effort, Lach told selectmen last week. They are enhancing the quality and diversity of wildlife habitat; enhancing water quality; and enhancing the visitor experience. The town's participation in the project relates to water quality improvement, focusing primarily on nitrogen removal from groundwater in the Saquatucket Harbor watershed, which moves through Cold Brook and Carding Machine Brook into the harbor and Nantucket Sound.
The project is part of the town's comprehensive wastewater management plan which has a major goal of reducing nitrogen in groundwater generated primarily from septic systems from degrading the marine environment.
Town Administrator Christopher Clark pointed out marshes, streams and ponds are nitrogen attenuators. The town is working with HCT to provide additional ponding in the preserve to hold nitrogen, which moves through the groundwater, allowing the extraction of upward of 55 percent of the nitrogen as gas before it reaches the marine environment.
The nitrogen reduction feasibility study conducted on behalf of the town in 2015 and 2016 determined nitrogen reduction was a co-benefit with the HCT ecological restoration project, Lack said. Nitrogen reduction in the watershed helps the town improve harbor water quality in compliance with the comprehensive wastewater management plan.
He also said reducing nitrogen through eco-restoration within the watershed helps reduce the need for sewering, which will save future wastewater treatment costs for the taxpayers.
Lach pointed out town meeting approved $2 million in 2017 for the design, construction and implementation of the project. He said since that time, the working group was formed to study design options and has agreed on a conceptual design. Grants to fund the design phase have been received from the Massachusetts Environmental Trust.
The Massachusetts Environmental Policy Act permitting process, has also begun, a state review requirement for the project because it contemplates changes to bordering vegetated wetlands. Lach also said a grant application for $1 million was submitted to the National Coastal Wetlands Conservation grant program.
Discussions have begun with the town on governing site access during restoration, construction, monitoring as well as governing the contracting process for restoration implementation, he said.
“We don't own the property and there has to be an access agreement,” Clark explained. The next stage, Clark added, is further discussion about design ad construction.
To date, $35,000 of the $2 million appropriate has been spent on the nitrogen reduction study. Clark said more may need to be spent on experts as the design stage continues, and there will also be costs associated with monitoring.
“Are we close to an agreement?” Selectman Michael MacAskill inquired. Lach said there is a conceptual design.
Selectman Larry Ballantine had questions about the sizing of the proposed ponds, noting they are more shallow than initially proposed. “The bottom line is that is how the nitrogen is removed,” he said. Ballantine wanted to know how the conceptual design compared to removal from bigger ponds.
Clark said the ponds are bigger in this design. However, they are not as deep. The town's CWMP consultant, David Young of CDM Smith, Inc., said the proposed ponds will remove the nitrogen. The UMass Dartmouth School of Marine Science and Technology, which served as a consultant, is still involved in the design concept, Lach said.