Falmouth Water Quality Management Committee heard a number of options with cost estimates to heal Oyster Pond of its daily nitrogen load and phosphorous levels.
Edward J. Leonard of Wright-Pierce, an engineering firm in Andover, reported on the options to the committee at its meeting last Thursday. The town hired Wright-Pierce in February of last year to develop a plan for the estuary.
The options include connecting homes to the existing sewer system, off-site sewer treatment plants, and innovative septic systems to serve homes in the area.
Alternatives that the committee has considered before such as shellfish, permeable-reactive barriers, and inlet widening were not presented as options because of Oyster Pond’s characteristics compared to other town estuaries.
Eco-toilets, however, are an option as an alternative in Mr. Leonard’s report.
The report was presented to the committee as a preview to a public hearing to be held on Wednesday, July 30, at the SEA building on Woods Hole Road. A time has yet to be determined for that meeting.
“We really need the comments of all the [Oyster Pond] watershed residents at the workshop to help us select the best plan for them and best for the town,” said Steven B. Leighton, a member of the committee.
“We have no deadline here. We are not under the gun,” said chairman of the committee, Eric T. Turkington. “We are looking to explore the best way to do this.” He said that the report is on the town website for the public to better educate themselves prior to the public meeting.
Mr. Leonard said that 72 percent of nitrogen entering the pond now is from septic tanks. He said that there was a total of 243 dwelling units in the immediate watershed.
Mr. Leonard said one option is to connect homes in the area to sewer mains that are already installed under the Shining Sea Bikeway, which abuts Oyster Pond. The mains carry wastewater from Woods Hole to the Wastewater Treatment Facility on Blacksmith Shop Road.
Mr. Leighton said that this was not necessarily the first choice of the committee but an obvious choice because the mains and plant are already in place. He said that the committee was still unsure if the West Falmouth plant had the capacity to handle the additional load. He said that members of the committee would confirm that the plant could handle the load before any decision was made.
Mr. Leonard estimated that the cost to homeowners would be $27,800 for each dwelling unit, or $1,800 annually, to connect to the sewer system.
Another option he said was to connect homes to an existing treatment plant at the Woods Hole Oceanographic Institution, which he estimated would cost $49,000 per dwelling unit or $3,610 per year.
Another possibility, he said, was to create a new treatment facility, which he estimated to cost $62,800 per household.
Mr. Leonard said that these prices did not include a likely share that the town would pay.
Other options he offfered included on-site, individualized treatment systems also known as I/A systems. The I/A systems are more effective at reducing nitrogen than septic tanks but, like septic systems, they would be placed on the grounds of homes.
Because Oyster Pond is brackish, meaning it is a mix of salt and fresh water, inlet widening was not considered, Mr. Leighton said. River herring are a federally protected species, and spawn in the brackish water.
Conservation Commission members as well as the neighbors of Oyster Pond hope to keep the herring in the estuary, Mr. Leighton said.
Oysters and other shellfish were not considered an alternative to nitrogen removal because they do not survive in brackish water.
Permeable reactive barriers were not considered by Wright-Pierce because, Mr. Leonard said, there are large boulders that would hinder installation. He said that there are also limited rights of way for the installment of the barriers.