Woburn conservation commission continues review of riverfront house plan after questions on wall, elevations and runoff

WOBURN — The Woburn City Conservation Commission on Nov. 7 continued a public hearing on a proposal to build a smaller single‑family house on a lot that previously hosted a house and barn, after commissioners asked for more detail about riverfront alteration limits, floodplain elevations and stormwater controls.

Mark Slager of Allen Engineering described the plan as substantially the same as a prior approval that expired in March but with a reduced roof footprint — "about 650 square feet smaller than what was proposed before" — and a larger infiltration system designed to collect all roof runoff. Slager said a trench drain is proposed across the frontage to prevent driveway runoff from reaching Lexington Street, which he described as a state highway.

Commissioners probed whether shifting the driveway to the left (to avoid relocating a telephone pole), adding an integrated block retaining wall and raising a portion of the yard back to lawn would count as an alteration in the riverfront zone under local rules. One commissioner noted lawns are not categorized as "degraded" under the riverfront regulations and questioned whether the project could exceed the allowable alteration amount (the commission discussed a 5,000‑sq‑ft threshold vs. a percentage cap tied to total riverfront area).

There was also detailed discussion about FEMA floodplain elevations. Slager initially referenced an elevation of 72 but corrected that the relevant flood elevation is about 52; he said the bottom of the proposed wall would sit roughly two feet above the floodplain elevation and that, in his assessment, the wall would not divert floodwaters onto neighboring properties. Commissioners asked Slager to reconcile datums and confirm elevations on plan sheets.

Members asked whether the existing block wall had required a building permit and whether the proposed new wall over 4 feet would need a structural design and building permit; Slager said he would check permit records. The commission also sought a numeric calculation of how much riverfront would be disturbed and asked the applicant to add preliminary FEMA floodplain mapping to the plan for clarity.

Because commissioners requested additional information and said the application will likely need further review, the commission voted to continue the public hearing to its Nov. 21 meeting. The applicant indicated willingness to supply requested floodplain cross‑sections, the riverfront disturbance calculation and any necessary supporting surveys.