Town Designs Flood Mitigation Strategy at DeFazio

May 30, 2025
• Identified as a problematic flooding area last year, a section of DeFazio Field’s parking lot could be remediated with a rain garden.

For those attending sports games, walking their dogs or visiting the Tot Lot, one area of the DeFazio Field parking lot has remained off-limits. The southwest corner of the lot reliably floods and holds water, even days after rainfall.

A developing town project aims to mitigate that flood risk by installing “green infrastructure” said Gabby Queenan, Needham’s sustainability manager. That means using nature-based solutions, such as restoring wetlands or a rain garden, where native plantings can capture and retain precipitation.

The area, adjacent to Alder Brook, is one of several in Needham identified through a Charles River flood model, developed in 2020 by the Charles River Watershed Association. A $125,000 grant from the Office of Coastal Zone Management — through the CRWA — is funding the engineering design phase of the project, which is expected to conclude by the end of June. The town has yet to receive funding for the actual construction.

Floods occur in the area, in part, due to compacted gravel, Queenan said, and the project would drop the grading in that section by up to two feet to allow water to naturally flow down through designated outlets. A bioretention basin, or “engineered rain garden,” will both store and treat water before it’s discharged into the brook and eventually the Charles River, she said.

“There’s a depression in the ground where water will collect and it will be treated and then infiltrated into the ground through plants, so using a nature-based solution,” Queenan said in an interview.

An assortment of native grasses, shrubs and other plants are included in the current design.

The basin would trap phosphorus, which is one of the town’s outstanding sustainability goals. At the Select Board’s Tuesday meeting, officials from BETA — a stormwater and groundwater company working with the town — said Needham has about 425 pounds of phosphorus to reduce by next year, which could cost an estimated $31.9 million total. Each pound of phosphorus reduction costs about $75,000, they said.

The DeFazio project would account for just a 1.4-pound reduction and cost about $180,000, BETA said.

“This is not a low-budget option,” said Phil Paradis of BETA. Installing infiltration systems underground would be cheaper, but Paradis said the rain garden serves additional purposes by beautifying the area and providing a sign detailing the importance of the site.

Instead of relying on catch basins — considered “grey solutions” — the CRWA prioritizes natural elements, Community Organizer Arrianna Proia said. More frequent flooding occurs due to the increase in impervious surfaces, which is infrastructure that cannot absorb water, she added.

“Flooding is something that’s going to affect all of us. It’s happening, and as we develop our cities and towns, we’re going to have to live with that, and it will affect not just the biodiversity, but also it will eventually affect humans’ ways of life,” Proia said in an interview. “So, it’s really important to address this now, because climate change is happening, and we really want to get in front of that and adapt and do some adaptation and mitigation.”

As part of the project, officials plan to place two inlet control structures to treat sediment. The basin would also treat about half an inch of emergency overflow. While the plans may not prevent flooding in severe storms, Chris Brainard of BETA said the ponding in the site would be treated and better controlled, without losing any parking space.

“It’s not really a project that’s going to solve any major flooding that the town has, as this is only phase one of the project,” Brainard said at the meeting, “but it’ll help to manage that half-inch flow.”

The town solicited public feedback on the project in February, followed by a community survey that ran earlier this month. From that survey, which generated about 150 responses, Queenan said there’ll be a bigger push to educate residents on the mitigation strategies.

“There’s a lot of people who might walk by a bioretention basin and not realize the value of what it’s doing, and they might not know that this is Alder Brook over here,” Queenan said while on site. “So there’s some opportunities for us to do some education as well about the value of these kinds of systems and think a little bit more holistically about how we can integrate education with some of our projects.”

For those concerned about attracting mosquitos, Queenan said water in the basin would be dispersed within 24 hours so as to prevent the insects from living there.

The project is one phase of a multi-phased work at Alder Brook.

Paradis from BETA told the Select Board that the area is heavily impacted by flooding, and that water appears to converge at DeFazio and its fields. They’re also working on the culvert on the opposite side of Dedham Avenue, which is susceptible to floods.

“It’s a pretty critical area. You close Dedham Ave., that’s a major artery in your town,” Paradis said.

Select Board member Josh Levy spoke to that concern, adding that he feels the project is worth the added expense.

“We have a long way to go to tackle stormwater issues in town, not just phosphorus reduction, but also flooding,” Levy said. “The neighborhoods around here, like around Alder Brook, were hit really hard.”

DeFazio has also been eyed as the potential future site for Pollard Middle School, which the town expects to renovate and expand in the coming years. Queenan said they plan to wait to move the project forward until the school’s location is determined. Paradis suggested storage facilities beneath the fields could absorb water to lower that risk.