Plans are in the works to shore up a 500-foot-long stretch of riverbank that threatens the Merrimack Valley Regional Transit Authority’s garage and offices on Railroad Avenue.
Consultant Daniel Bourdeau told the Haverhill Conservation Commission last Thursday that erosion is significant enough to cause damage to the building. He presented photographs, showing the bank has eroded, in some spots, up to the foundation of the parking garage.
“When we first started the project, there had been some movement in the building, some cracking, so we teamed with a geostructural firm to do an assessment of the building and make some recommendations on stabilizing the building,” he said.
Bourdeau, of Portsmouth, N.H., -based Geosyntec Consultants, told commissioners the company was hired by the Transit Authority and has been studying the problem for the last two years. The firm teamed up with Boston based engineering firm, Thornton Tomasetti, to find a solution.
“The MVRTA Facility, located along the Merrimack River, has experienced extreme erosion and so they put out a project in 2019 to solve this problem that they have,” he explained.
Bourdeau told the Commission, while there are several issues involved, the primary goal is to shore up the stream bank in a way that will last. He said that will involve both man-made construction and the use of vegetation.
“So, we have a combination of riprap, sheet pile, block wall and then a vegetated slope on the upper portion of that. Our plan includes a restoration component and monitoring plan, using native species to replace trees on the slope,” he said.
Asked how long it would take to complete the project, Bourdeau explained this portion of the river is an important habitat for short nosed sturgeon, meaning any construction must cease in April. Because the project is being federally funded, money also will not be available until early 2022, making a short window of opportunity to get it done.
While Bourdeau said he believes the plan will solve the current problem, he added erosion could occur again further down the river. The Commission agreed it will require close monitoring.