ADU proposal at 47 Walnut Street continued after board flags square-footage, septic and drainage issues

Evan Brooks presented a proposal to add a 900-square-foot detached accessory dwelling unit (ADU) at 47 Walnut Street for an immediate family member. The board identified a key discrepancy: the main dwelling’s square footage listed in materials was unclear (transcript discussion centered on whether the primary dwelling was 1,680 square feet), which affects ADU eligibility because the ADU cannot exceed 50 percent of the primary unit or 900 square feet, whichever is less.

Board members also raised concerns about the septic system (Title 5) and whether the existing leach field and soil conditions can support the additional unit; they asked whether the applicant had obtained Board of Health review and noted that a new or revised leaching field may change site topography and drainage. The board requested clearer site-plan notation about how runoff and erosion will be managed during and after septic work (siltation barriers, riprap where needed) and suggested the applicant secure Board of Health confirmation and a revised engineered site plan that accurately shows drainage mitigation.

The board voted to continue the ADU hearing and to make any future approval contingent on submission of corrected square-footage calculations, Board of Health correspondence (Title 5 determination), and an engineered drainage/septic mitigation plan. The applicant was given the opportunity to call the builder to confirm house area and to resubmit a revised plan for administrative review or conditional approval.