A proposed 38-home subdivision dominated discussion at this month’s Canandaigua Planning Board meeting, with officials ultimately holding off on a decision after a lengthy, technical debate over stormwater management and downstream impacts.
The April session, which included multiple routine approvals, centered on the Ashton Place South subdivision off County Road 16 — a project that has drawn sustained scrutiny from both board members and nearby residents concerned about flooding, drainage, and long-term environmental impacts.
While the board approved a minor terrace expansion project near Canandaigua Lake early in the meeting, the tone quickly shifted as engineers, consultants, and residents spent more than an hour dissecting whether the subdivision’s stormwater plan adequately accounts for runoff in increasingly intense storm events.
Subdivision plan faces renewed scrutiny
Developers returned seeking preliminary subdivision approval, presenting updated engineering reports and stormwater analyses intended to address earlier concerns. They argued the design meets — and in some cases exceeds — state and local requirements, including reductions in peak runoff compared to existing conditions.
But board members and third-party reviewers were not convinced the analysis fully reflects real-world conditions.
A key point of contention was the project’s reliance on a “bypass” system that diverts a significant portion of upstream runoff around the proposed detention pond instead of capturing it. Critics argued that approach could accelerate water flow, increase peak discharge, and worsen downstream flooding — particularly during high-intensity storms.
Board member Tim Schneider raised concerns about core assumptions in the engineering model, including runoff coefficients, soil classifications, and time-of-concentration calculations — all of which influence how much water the system is expected to handle.
Independent consultant Kevin O’Brien echoed those concerns, suggesting the model likely underestimates runoff due to soil compaction that occurs during construction and the effects of channeling water through bypass systems rather than allowing natural absorption.
Residents highlight ongoing flooding issues
Public comment reinforced those technical concerns with real-world examples.
Neighbors described worsening erosion, repeated basement flooding, and stream overflow during recent storms. Several pointed to an already constrained drainage system downstream — including undersized culverts and clogged channels — arguing the development could exacerbate existing problems.
One resident said floodwaters during a recent storm backed up into his home through a basement drainage system, while another described stream banks eroding by several feet over time.
City staff acknowledged that portions of the drainage system are already compromised by vegetation, debris, and inconsistent culvert sizing — issues that are outside the scope of the current application but directly tied to broader flooding concerns in the area.
No decision as board seeks more analysis
Faced with conflicting analyses and unresolved questions, the board opted not to act on the subdivision.
Instead, members directed the applicant to revisit the stormwater design, coordinate further with the city’s engineering consultant and watershed experts, and provide clearer modeling — including how runoff behaves during extreme storm events and whether additional mitigation measures, such as a second detention basin, are warranted.
The applicant agreed to continue working with consultants and return with revisions.
Beyond stormwater, the board also flagged additional considerations, including conservation subdivision requirements, potential infrastructure extensions, and long-term maintenance responsibilities.
Routine approvals move forward
Outside the subdivision debate, the board handled several smaller items outlined in the agenda, including historic alterations, signage updates, and site plan reviews for local businesses.
A terrace expansion project near Canandaigua Lake was approved with minor conditions, including adjustments to erosion control measures and submission of additional structural details.
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