The most significant topic of the meeting was the stormwater management plan for a proposed development on Monponset Street, which includes two multi-unit dwellings for senior housing with amenities such as a pickleball court and pool house. The commission, represented by members including Kathy Evans and Edward Lane, emphasized the necessity of an approved septic plan before proceeding with stormwater management discussions. Concerns were raised about the completeness of the submission due to the pending approval of the septic plan. The board expressed a preference for conditioning any approval on the requirement that any changes in grades resulting from the septic plan would necessitate a return to the commission for re-evaluation.

A representative from JDE Civil presented details about the drainage systems designed to comply with stormwater management standards. Multiple revisions had been made to address previous comments from the commission. The representative highlighted various changes incorporated into the plans, including the construction of infiltration basins with appropriate specifications for loam depth to ensure efficient drainage. The representative detailed that four inches of loam would enhance infiltration rates while allowing grass to thrive, thus removing contaminants.

Pat Brenan, an engineer, summarized the revisions made in response to the commission’s comments. He noted that the stormwater management plan had been enhanced to ensure compliance with local regulations, with a significant capacity for stormwater storage exceeding required levels. Concerns were raised about the potential for effluent to return to Monponset Street, to which the representative confirmed that the design included multiple catch basins to manage water flow across the site effectively. He stated, “We have plenty of stormwater collection for the previous surfaces to the site,” indicating the thoroughness of the design.

Throughout the discussions, there was an emphasis on ensuring that the approval of the stormwater management plan would not preclude necessary adjustments based on the outcome of the septic plan review. The board sought to maintain a cautious approach, ensuring that any future changes would be adequately addressed, thereby streamlining the development process while upholding environmental standards.

The meeting also addressed the potential impact of the stormwater management system on nearby condominiums. Concerns were raised about how the water from the development would flow into the adjacent wetlands and whether it would affect the groundwater levels at the condominiums, particularly in the context of previous flooding incidents in the area. A technical explanation was provided regarding the design of the stormwater management system, which includes deep catch basins and proprietary units that separate solids from the water. The discussion included specific details about the infiltration basins, rain gardens, and the overall drainage system, with emphasis on ensuring that water would be treated effectively before discharging into the wetlands.

Joseph Telo, a resident of 284 Monpon Street, raised a question about the number of bedrooms in the proposed units, asserting that understanding the water flow from these bedrooms was vital for assessing the potential impact on groundwater. It was noted that the septic design plans submitted to the Board of Health outlined the flow rates, which include a total design flow of approximately 9,980 gallons per day from 72 units, and that there were no three-bedroom units planned. The concerns regarding the impact of unit water flow on the groundwater systems were reiterated, with emphasis that the board’s primary concern was stormwater management, rather than the septic plan, which had yet to be approved.

Further clarifications were sought about the elevations of the proposed development in relation to the condominiums. The elevations were discussed in detail, indicating that the condos were at a higher elevation than the proposed basins, which would be designed to collect and manage water effectively. There was a discussion about whether the project would raise the grade of the property, which was confirmed to an extent, with some portions of the property intended to be raised. The potential for groundwater infiltration from the basins into the condos was raised, with a suggestion that rubber barriers could be implemented to mitigate this risk. However, it was explained that rubber barriers would not be effective for groundwater issues, as the primary concern was the infiltration of groundwater rather than surface water, and that the project was operating within wetlands regulations that would not allow for such barriers.

The distinction between retention and detention basins was explained, highlighting that a detention basin holds water without allowing it to recharge groundwater, while an infiltration basin allows for the recharge of groundwater. This distinction was reinforced with the assurance that the design would meet the requirement of not increasing post-development runoff off-site. The participants expressed ongoing concerns about the adequacy of the proposed stormwater management systems and their ability to handle the anticipated water flow, especially given the area’s history of flooding and groundwater issues.

Another discussion involved a proposed development project at Shelby Plaza. Concerns were raised about the project’s elevation and the potential for water runoff to impact surrounding properties. Participants questioned the accuracy of the existing conditions survey and the number of parking spots for the development. A representative confirmed that there would be a total of 60 parking spots for the project’s 30 residential units. However, concerns lingered regarding whether this number would adequately serve the proposed mix of one- and two-bedroom apartments.

The issue of drainage from the development site was a focal point, with participants emphasizing the need to prevent water from flowing onto neighboring properties. The conversation included the acknowledgment that discrepancies in elevation could lead to significant problems and the necessity of a proper survey to clarify elevations. Concerns about the septic system’s proximity to the proposed development were also raised, with worries about water saturation and flooding, particularly for properties that had previously experienced basement flooding.