Milford agency continues public hearing on 34 Buick Avenue after new stormwater, construction concerns

The Milford Inland Wetlands Agency on Oct. 1 continued a public hearing on a proposed redevelopment at 34 Buick Avenue, asking the applicant and municipal reviewers for additional technical responses about permeable paver design, construction-phase soil protection and nearby drainage before the agency will deliberate further.

The agency left the public hearing open until its Oct. 15 meeting and added a requirement that the applicant and city reviewers analyze (1) potential impacts to the wetland that receives flow tributary to Stubby Plain Brook from changes in overland flow and (2) drainage coming from Sunnyside Court to the site and whether additional treatment is required.

The applicant’s design team described revisions submitted in late September and in the days before the meeting. Engineer Robert Weiwei said the plan now raises the permeable-paver reservoir to provide a two-foot vertical separation from modeled groundwater and includes construction sequencing, concrete curbing with slotted inlets on Buick Avenue and a new biofiltration area adjacent to existing culverts. “In my opinion, this results in an ultra conservative design,” Weiwei told the agency when explaining the decision to base separation on modeled depths rather than the groundwater elevations observed during soil testing.

The project team also presented details intended to reduce surface runoff that reaches Buick Avenue: Weiwei said the plans will reduce surface flow to Buick Avenue from roughly 6.9 acres under existing conditions to “less than a half acre” by collecting and infiltrating runoff from parking and roof areas into the reservoir beneath permeable pavers. The team proposed a short biofiltration swale and underdrain behind slotted curbing on Buick Avenue and a catch basin with a 4-foot sump to trap sediment before water is conveyed to an existing headwall outfall at Cherry Street.

Expert witnesses from the applicant’s team described the proposed assembly and mitigation. Landscape architect and erosion-control specialist Jeff Gordon said the design follows low-impact development guidance and includes permeable pavement, vegetated swales, biofiltration cells and native plantings intended to protect soils and reduce runoff. Wetland scientist Matthew Popp summarized field visits and the mitigation planting plan, saying the permeable pavers are approximately 90 feet from the wetland and about 110 feet from the main channel of Stubby Plain Brook and that the mitigation will convert roughly 5,300 square feet of unmanaged lawn into a planted buffer and meadow. “In my opinion, there won’t be any adverse impact to the wetlands or to Stubby Plain Brook,” Popp told the agency after describing site conditions and his biological surveys.

Several neighbors and residents testified with technical and operational concerns. Longtime area resident Bill Silver raised questions about construction sequencing and how contractor staging and heavy equipment will be kept off the infiltrative stone beds that support the reservoir cells; he argued that “overburden is undefined and there's no way of managing the construction process” unless the commission requires tighter field oversight. Silver urged the agency to consider requiring an on-site, daily field engineer or similar third-party observer. Willis Morris and Wiley Blake focused on long-term maintenance of permeable pavers and the biofiltration swale, asking who will store and operate specialized vacuum sweeping equipment, who will replace joint aggregate if it is displaced by maintenance, and whether the town will assume responsibility for care of the roadside treatment area. Morris asked whether the commission will require a long-term bond to guarantee maintenance across ownership changes. Blake noted that existing stone trenches in the neighborhood are often clogged by leaves and yard waste, and she asked how the new trench and bioswale will be kept functional after storm events that overtop the headwall.

LandTech, the agency’s peer reviewer, told the commission that the applicant has addressed many of its initial comments but that a full review of the late-submitted materials remains outstanding. Rob Prior and Tom Ryder of LandTech noted that the Connecticut DEEP stormwater manual generally recommends a three-foot separation between infiltration elements and seasonal high groundwater but allows a two-foot separation in some circumstances (including certain residential/multifamily contexts and where groundwater is classified GB). Prior recommended that the commission consider a spill-prevention/response plan as a condition and suggested the value of third-party oversight during construction and certification of the completed infiltration systems.

The agency discussed scheduling and deadlines. Staff reminded commissioners the statutory deadline to close the hearing is Oct. 24; the agency voted to continue the hearing to Oct. 15 to allow time for the city engineer and the peer reviewers to complete their reviews and for the applicant to respond. The agency also voted to add explicit review points — impacts to the tributary wetland downstream of the site and the Sunnyside Court drainage route — to the scope of the follow-up responses.

The hearing will reopen Oct. 15. The agency said it expects the applicant’s team to provide focused written responses to the city engineer’s and LandTech’s outstanding comments and to address the construction-phase protections and maintenance questions raised by neighbors. If reviewers request redesigns after that submission, the agency indicated it may require additional time or special meetings to ensure full technical review.