Board delays action on stormwater changes after concerns over redevelopment costs and existing-site assumptions

The Somerville Planning Board on May 13 debated proposed stormwater ordinance changes that would broaden treatment requirements and add inspection obligations for major developments.

Planner Mike summarized four primary proposals from the Environmental Commission: regulate all impervious surfaces over 5,000 square feet as major development; require water-quality polishing for runoff from those surfaces; adopt a presumption that existing-site conditions are wooded when calculating volume-control obligations; and introduce annual inspections with an associated borough fee for major developments. Mike also noted the Environmental Commission produced a short video and planned a written revision of several items for council consideration.

Board members expressed concern that the presumption of wooded existing-site conditions and treating roofs like vehicle areas could make redevelopment on tight downtown lots infeasible. One board member, who identified themselves as the county emergency-management director, said the board’s focus has consistently been protecting residents and the master-plan vision and cautioned against rules that would halt redevelopment. “If you add too much for redevelopment ... no developer in their right mind is gonna be able to do that,” the member said.

Another member with experience on municipal stormwater working groups said components of the draft (points 1 and 4) may already be addressed under the borough’s MS4 permit and questioned whether the additional inspection language duplicates existing obligations. The board discussed practical exceptions, waivers or hardship provisions for constrained downtown parcels and raised the challenge of where to store stormwater volume on lots with no room for infiltration.

Given the outstanding questions and the Environmental Commission’s intention to further revise its proposal, the board requested written clarification from the commission and asked staff to circulate the marked-up language. The board tabled further action until members receive a written revision and additional technical detail to evaluate redevelopment impacts.