by Michelle Christensen 

The Town of Plymouth is taking proactive steps to protect its natural water resources, public health, and scenic coastline. Partnering with engineering consultants Weston & Sampson, the Town’s Department of Public Works and Engineering Department are developing a 20-year Comprehensive Wastewater Management Plan (CWMP).

Supported by a five-member Citizens Advisory Committee appointed in July 2025—led by Chair Mike Hanlon, Vice Chair Michelle Christensen, and Clerk Sara Greenberg and committee members Don Williams and Roger Janson—this initiative establishes a strategic roadmap to modernize Plymouth’s water infrastructure.

What is a CWMP?

A Comprehensive Wastewater Management Plan evaluates a community’s current infrastructure to forecast and solve future wastewater needs over two decades. Its goals are straightforward: safeguard public health, ensure regulatory compliance, maintain financial sustainability, and preserve Plymouth’s ponds, bays and groundwater.

Currently, over 80% of Plymouth relies on private septic systems rather than town sewer. The existing municipal infrastructure encompasses over 50 miles of gravity sewer pipes, 17 miles of force main, and 8 town-owned pump stations that serve roughly 2,800 lots. Treatment takes place at the municipal plant at 131 Camelot Drive, which currently processes an average of 1.5 million gallons per day (MGD) out of its permitted 2.5 MGD capacity. Because more than 40% of this collection system is over 50 years old, planning for upgrades is essential.

Identifying Unsewered Priority Areas

Even well-maintained traditional septic systems can gradually release nitrogen and phosphorus into nearby groundwater, feeding unwanted algae blooms and placing aquatic ecosystems at risk. We are experiencing this in our Herring Pond Watershed, with phosphorus streaming underground from the Ponds of Plymouth area into Little Herring Pond, and ultimately into Great Herring Pond via the Carter River.

To protect vulnerable water bodies, Plymouth has evaluated four primary unsewered neighborhoods in Cedarville. High-priority Buttermilk Bay includes 500 lots averaging under 0.25 acres with homes mostly over 50 years old. Medium-priority areas include Big Sandy Pond and the Ponds of Plymouth/Great Herring Pond areas. Big Sandy Pond has 730 total lots (600 potential sewer connections), an average lot size of 0.40 acres, and 20 septic variances, while Ponds of Plymouth and Great Herring Pond area features 1,000 total lots (800 potential connections) averaging 0.85 acres adjacent to impaired waters. Finally, Cedarville is designated as a low-priority area, encompassing 500 residential and commercial lots near Cape Cod Bay.

Smart Solutions & Next Steps

Engineers are evaluating customized solutions for each area rather than a “one-size-fits-all” approach. Options include installing Enhanced On-Site Systems (advanced septic units that remove 25% or more of nitrogen and phosphorus), extending main sewer infrastructure, creating new localized treatment facilities or connecting to existing localized treatment facilities such as Red Brook.

By planning ahead rather than waiting for state-mandated environmental requirements, Plymouth positions itself advantageously. Establishing a state-approved CWMP could position the town for state and federal grants and low-interest infrastructure funding.

Community participation is vital to the project’s success. Residents are encouraged to share their feedback and learn more by visiting plymouth-ma.gov/1577/ComprehensiveWastewater-Management-Plan.