Falmouth seeks DEP modification to raise treated discharge while pursuing outfall; environmental groups urge offsets and monitoring

Amy Lowell, Wastewater Superintendent for the Town of Falmouth, updated the Water Quality Management Committee on the town’s application to modify its groundwater discharge permit to accept additional treated wastewater flow for the Great Pond Phase 1 sewer project.

Lowell told the committee that the town has an existing groundwater discharge permit and "we are proposing to discharge an additional 200,000 gallons per day of flow from the Great Pond Phase 1 Sewer Project, to the existing open sand beds 14 and 15. Those beds have the capacity to handle that additional flow within their existing footprint." She emphasized the application proposes increased flow to existing disposal beds without expanding their physical footprint and that the application follows a hydrogeologic report and subsequent modeling requested by the Department of Environmental Protection (DEP).

The DEP has requested additional modeling of groundwater mounding and potential wetland interactions since the Maui court decision on groundwater discharge and wetlands protections has prompted conservative evaluation methods. Lowell described the current permitting sequence: town staff submitted the hydrogeologic report and permit modification application, the DEP requested further modeling and wetland evaluation, the town is completing those tasks, and when DEP issues a draft modified permit it will be published for public review and comment in the Environmental Monitor.

Lowell gave capacity figures: the town’s current permitted total discharge is 710,000 gallons per day and the modification requests a total limit of 910,000 gallons per day (an increase of 200,000 gpd). She characterized the proposed change as a short-term measure while the town continues to pursue a marine outfall as the long-term disposal solution.

Environmental and neighborhood groups pressed the town for offsets and monitoring. Corinne Peterson of the Buzzards Bay Coalition said that existing discharge to Beds 1 through 13 (permitted at about 450,000 gpd) generated an estimated 4,100 pounds of nitrogen to West Falmouth Harbor annually and warned that the proposed increase would raise the town’s discharge footprint into Crocker Pond and Herring Brook. "This increase will exceed what the town discharges to West Falmouth Harbor," Peterson said, and urged that, if the town increases flow to Beds 14 and 15, it should secure offsets in other watersheds to prevent net increases in nitrogen loads down-gradient.

Matt Hanley of the Surfrider Foundation urged clearer visual and mapping materials for residents who are potentially affected and requested an explicit schedule for when town meeting funding and permitting steps will occur. Lowell confirmed an article is on the April town meeting warrant to fund planning and that the permit review and modeling steps were ongoing; she estimated the town should know more about the outfall feasibility within a year or two and said borings for the outfall will be done in early months (February-March in the schedule discussed).

Lowell described DEP’s process as conservative and iterative: DEP has asked for additional modeling approaches for groundwater mounding that account for wetland sensitivity. The committee discussed monitoring well networks and long-term monitoring requirements that would likely accompany a modified permit; Lowell said the town has a substantial monitoring well network in place but the DEP may require additional long-term monitoring and wetland community assessments.

Next steps recorded in the meeting: complete DEP-requested hydrogeologic modeling, respond to DEP on wetlands evaluation, await issuance of a draft modified groundwater discharge permit and participate in the public-comment period, and continue parallel work on the outfall project (borings, USGS inputs and marine-permitting steps). The town framed the 14/15-bed increase as an interim option to serve sewer expansion while the outfall is pursued as the long-term solution.

Ending: The committee recommended that staff prepare clear, public-facing maps and a professional presentation of where additional discharge would go and what monitoring and offsets the town would use to avoid legacy impacts to downstream ponds and marshes.