Commission reviews preliminary subdivision at 308 Melbourne Avenue amid neighbor flooding concerns

The Harbor and Coastal Zone Management Commission on Nov. 20 conducted a preliminary review of a proposed subdivision at 308 Melbourne Avenue and heard extensive public concern about local basement flooding and the location and conduct of soil/percolation testing.

Greg DeAngelis, the architect for the owners, said the proposal would split the property to create a new Lot 2 roughly 52 feet wide by 196 feet deep while leaving the existing house on a parcel of just over 10,000 square feet. DeAngelis told commissioners the plan is consistent with R5 zoning and similar divisions on Melbourne Avenue and that the owners are seeking to subdivide the parcel for economic reasons while retaining the family home.

Chris, the project civil engineer, presented the stormwater analysis for a maximum build-out scenario. He said the design counts about 2,702 square feet of additional impervious surface at maximum development and that the applicant proposes four infiltration/storage units (recorded in the meeting as "Coltec/Coltek" units) that together provide roughly 1,200 cubic feet of on-site mitigation. According to the engineer, modeled peak runoff for a 100-year storm rises from about 1.03 cubic feet per second (CFS) in the predevelopment calculation to about 1.32 CFS with the built scenario, and the proposed mitigation reduces modeled peak to about 0.9 CFS — roughly an 8% reduction versus the undeveloped-model baseline.

Chairpersons and commissioners pressed for technical detail. The chair asked specifically about pretreatment and overflow arrangements; the engineer said the design provides water-quality treatment for flows routed into the infiltration units but that additional pretreatment and a bypass will be needed so that patio and driveway flows do not pass directly through the infiltration system. "We need to add a bypass so that it goes pretreatment, and then bypasses, and then goes into the Coltec," the engineer said, and the chair listed that bypass and handling of small-patio/drainage flows among the items the applicant must address when returning.

Commission staff and the commission's reviewer from Kellard Sessions noted the design was modeled for a two-story residence and that impervious coverage in the current plan appears to be below the district maximum (the reviewer estimated the residence coverage nearer 35% with an overall potential up to 45%). The reviewer also said, after neighbors raised concerns, the village engineer went to the site to inspect test pits and confirm the applicant's reported soil characteristics.

Neighbors gave repeated, detailed accounts of basement flooding and questioned the adequacy and timing of the soil/percolation tests. Frank Schroeder of 257 Melbourne Avenue told the commission that heavy-rain events cause groundwater to rise into houses and asked that the commission consider mitigation for both the new lot and the existing lot together. "We are experiencing flooding in our homes and mostly from the water table," Schroeder said, and he asked that the village records and the consulting engineer's files be examined.

Carlo Reca of 314 Melbourne Avenue said he was present when test pits were opened and reported he saw no saturation in the hole during the work; he said he believes some observations in the public record merit further review. Kara Tannenbaum of 302 Melbourne Avenue said her basement floods on nearly every rain event and urged caution because the block is historic and "fragile."

In response, applicant representatives said they performed multiple test pits (including a second set at the owner's expense) and that plans were revised to place infiltration units directly over the confirmed test locations. The applicant also noted they will remove a long gravel driveway on the existing lot and grass that area, which would improve short-term permeability. "We shifted [infiltrators] about 20 feet to the left in the backyard so that it sits directly over where the test pit was performed," the project's engineer said.

The commission did not vote on the subdivision. Commissioners asked staff to confirm how the testing was performed and to assemble the consulting reports; they asked village engineering staff (referred to at the meeting) to appear at the next hearing so they can describe what they observed, and they directed the applicant to return with a revised plan that: documents test locations versus the plan, adds the pretreatment bypass, and provides additional mitigation for patio/driveway flows as noted by Kellard Sessions. The chair said the commission is treating the matter as a preliminary review to give the public and the commission a chance to review supporting records and to allow the applicant to make the requested changes before a vote.

Next steps: the commission will reconvene the subdivision item for final consideration after staff circulates the testing records, the village engineer or staffer able to describe on-site observations attends, and the applicant provides the revised pretreatment/bypass details and any additional infiltration units required by the updated stormwater plan.