Commission closes Walker School hearing after engineers present larger recharge system, invasive-species plan and waivers

Brandon Lee of Kelly Engineering Group told the Conservation Commission the Walker School project team prepared an updated wetland resource evaluation, invasive species removal and treatment plan, and revised recharge calculations to include both the existing roof and the proposed addition. He said the updated recharge volume increased to approximately "2,000 cubic feet" and that the drainage design was modified by adding nine chambers to bring the total from 15 to 24.

Brandon also explained that, to limit disruption to school operations, the applicant requested a waiver to conduct soil-test pits prior to construction rather than during site work; the commission attached preconstruction soil-test requirements as a preconstruction condition and approved the waiver request. Staff supported the planting plan and invasive-species management protocol and said those items will be included in the draft order of conditions and the monitoring schedule.

Commission staff described the project footprint as partly in riverfront area and noted compensatory planting and invasive-species management (including targeted removal of garlic mustard, Japanese knotweed and others) as mitigation. The commission voted to close the hearing and later approved the order of conditions, including a multi-year monitoring plan for the invasive-species work.