Central Street Culvert/Sawmill Brook Restoration Project Update
By Gregory T. Federspiel
One of the larger infrastructure projects that has been in the works for many years is the replacement of the Central Street Culvert and Restoration of Sawmill Brook. Sawmill Brook travels through the village and empties into the inner harbor next to Seaside 1 after passing under Central Street.
The old stone arch culvert and dam is failing and needs a complete replacement. Further upstream, the seawalls along the old pond are also severely compromised with sections having fallen into the water channel. While some band-aid measures have been taken to keep the culvert from collapsing, we are on borrowed time here. The Town had a scare back during the 2006 Mother’s Day storm when major flooding along Sawmill Brook caused extensive damage to homes and roads along the brook. As storms intensify and sea levels rise, improving drainage through the central part of town will be even more important.
The culvert replacement project and restoration plan for the Brook has been the focus of detailed analysis over the past four years. The hydraulics of the brook, the impacts of the old tide gate restricting water flow, and the impact on homes and wildlife have all been studied. We have been fortunate to receive grant funding for much of this and now have engineering plans about ready for bidding. Most recently permitting work has been undertaken and is nearly complete.
The cost of the extensive work is projected to be just shy of $6 million. A new dam and larger culvert are planned along with the rebuilding of a large percentage of the seawalls around the culvert and further upstream past the Fire Station. We are in the running for a federal grant under FEMA’s “BRIC” (Building Resilient Infrastructure and Communities) program. Our application for $4.5 million has advanced to the next level. We will hear by the end of the year whether we will receive this substantial grant. Representative Seth Moulton helped secure letters of support from Senator Warren and Markie. He was in town last week to gain a first-hand look at the project. We have received $500,000 from the State under their small bridge program toward the project. Local dollars will be needed to complete the funding picture.
Further complicating construction is the presence of primary electrical transmission lines that feed not only Manchester, but most of Cape Ann. These lines will need to be temporality relocated in order to allow the construction to proceed. While not as challenging, a town water line also is in the way. Building foundations that double as seawalls are yet another challenge for this project.
The goal is to begin construction a year from this September. Disruptions will be inevitable with the need for closing Central Street for periods of time during the 6 months construction will take. While details still need to be worked out, we are aiming to accommodate a temporary pedestrian passage over the brook near the construction site. Vehicular traffic will need to be rerouted during portions of the construction.
The new culvert without the tide gate will enhance water flow and prevent flooding during all but the worst of storms. The new design took into account higher sea levels as well. The new design means that instead of a large storm overtopping Central Street by over a foot of water and the subsequent flooding upstream, water will be some 4 feet lower as it flows under the enlarged culvert.
The upstream work will restore the natural flow of the brook and the former march grasses making for a more esthetically pleasing area that will be more attractive to wildlife as well.
Obviously, Central Street is a critical route for Manchester. It is essential that we maintain this route. To ensure its long-term viability, we will have to endure the pain of reconstruction. We have over a year to prepare and to develop strategies to minimize the impacts of the construction effort to the extent possible. Given the location, we will need to be as creative as possible!