Edgartown is weighing the costs of big septic changes as the town’s wastewater treatment facility falters and the Island’s water quality continues to decline.  

The town unveiled the general outline of its 20-year comprehensive wastewater management plan this fall, a capital project intended to accommodate the town’s vast summer population growth and mitigate the rising nitrogen levels in its coastal ponds. Those plans became more urgent when earlier this year the town’s wastewater treatment facility failed, prompting officials to look into repairing or replacing the 53-year-old pipes. 

To start addressing these long- and short-term goals, the town’s wastewater commission is seeking a $3 million article on the spring town meeting warrant for wastewater treatment facility repairs. The full price tag of the 20-year plan is estimated to be $40 million.

In a presentation to the select board and financial advisory committee, Ian Catlow from the environmental engineering group Tighe & Bond outlined the need and costs to upgrade the aging wastewater facility and preserve the town's coastal ponds. A complete replacement, the most expensive option at roughly $4.9 million, would last for the next 100 years, Mr. Catlow said, while more economical options would only last another 50. The lower-tier options came in at an estimated $2.29 million and $3.65 million.

As the town’s summer population continues to rise, officials must also weigh in on what infrastructure changes could best accommodate that growth.

A complete replacement would allow the town to complete a sewer system in the dense suburban neighborhood of Ocean Heights, Mr. Catlow said, reducing the levels of nitrogen runoff in Sengekontacket Pond. Currently, a majority of homes in Ocean Heights rely on septic tanks that contribute higher levels of nitrogen runoff than a connected sewer system. Even with new septic technology that promises to treat wastewater more effectively, a centralized treatment plant is the most efficient option, Mr. Catlow said.

All runoff from the facility would go into the town’s watershed, he added, and would be much cleaner than what is currently seeping out of the Island’s septic tanks.

While no decision has been made yet, the select board and financial advisory committee have until March 4, 35 days before the April 9 town meeting, to vote on financial warrant articles. 

Regardless, the town could be looking down the barrel of significant expenditures. Oak Bluffs is currently readying itself for a $44 million overhaul of its wastewater treatment facility after approving $26 million for the project at town meeting last spring. Mr. Catlow said the town of Eastham on Cape Cod has spent roughly $16 million on septic repairs in recent years. 

If passed, Edgartown would need to borrow the $3 million, giving the select board pause. The town is not part of the Cape and Islands Clean Water Trust Fund that offers grants for septic upgrades, but it does plan to move its short-term rental tax revenue to a capital stabilization fund for the purpose of projects like these, town administrator James Hagerty said. 

As the tourist season nears, wastewater facility manager Bill Burke stressed that time was of the essence.

“The pipe is in bad condition,” he said. “If it were to break in the summer, it would be a mess.”