Edgartown wastewater authorities believe a plan to sewer hundreds of homes in the watershed of the Edgartown Great Pond can achieve the 30 per cent reduction in nitrogen pollution required to restore it to health.
A draft report of the Massachusetts Estuaries Project, obtained and published by the Gazette last week, finds the Great Pond’s water quality is significantly affected by heavy nitrogen loading. The biggest single contributor to the problem is household septic systems, the report found.
While the report detailing the pond’s poor ecological health has not been formally released yet, the town ponds advisory committee, the Martha’s Vineyard Commission and the estuaries project itself are suggesting a fix for the problem is well advanced through decisions already taken, through a combination of sewering and more frequent opening of the pond to the sea.
Two main problems remain, however: working out who will pay for the cost of connection — about $10,000 per house, on average — and ensuring that the availability of sewerage does not encourage runaway development in the area.
Edgartown wastewater superintendent Joseph Alosso said 119 homes in the Edgartown Meadows subdivision have already been approved to tie into the town sewer. A line being run from the new Field Club development at Katama to the Edgartown wastewater treatment plant would allow another 300 to 350 homes to tie in.
“I think we’ll easily exceed the 30 per cent reduction the report calls for,” Mr. Alosso said.
Even if all the homes in the area were connected to the sewer, Mr. Alosso said, the treatment facility would have plenty of reserve capacity, opening the prospect of also connecting homes in the Oceans Heights area to the treatment plant. The town board of health last year placed a moratorium on new septic hookups in that section of town out of concern for the effects of septic systems leaching into Sengekontacket Pond. Subsequently septic rules were tightened.
“The treatment plant’s capacity is 750,000 gallons per day. Peak load now is about 440,000 gallons, on July 4, and the summer average is around 300,000 for June, July and August. Once we sewer all these areas, I would anticipate that number going up less than 200,000. So there will be plenty of reserve capacity.
“I’m now looking very closely at Ocean Heights Arbutus Park [which is in the Sengekontacket watershed],” Mr. Alosso said.
Bruce Rosinoff, the Vineyard coordinator for the estuaries project, said he thought sewering was the best option, although he acknowledged the idea could be controversial.
“A number of years ago, people looked negatively on sewering because they saw the potential for additional growth,” he said, adding:
“There are people who would argue that, because anywhere you have a sewer line running, people can hook up to it and increase the density of housing and their house size. But in this case, having looked at the watershed I think it is the best approach, if we’re concerned about the pond.
“I think realistically it’s the only way we’re going to eliminate the amount of nitrogen we need to eliminate going into that system. I wish we had that option in other towns as well.”
The treatment plant removes about 90 per cent of the nitrogen from wastewater. Standard septic systems eliminate almost none, although there are now more advanced systems which remove nitrogen. But Mr. Rosinoff said they are not as effective as sewage treatment.
“People talk about these denitrifying septic systems, but the technology is not there to do a full enough job to make it worthwhile,” Mr. Rosinoff said.
He suggested the town might have to consider tightening up its regulations, through the health board or the planning board, to limit development.
“I think it is a small price to pay for being able to protect some of these ponds. That’s my personal attitude, and it seems to be the prevailing attitude with the town and even the Martha’s Vineyard Commission,” he said.
William Wilcox, water resource planner for the Martha’s Vineyard Commission, said it is fortunate the town already has infrastructure in place to address the nitrogen problem, although he conceded there were still some “hard choices to be made” about who would meet the cost.
“It will still be painful, but hopefully they’ll do as they have in the past and distribute a portion of the cost to the whole town,” Mr. Wilcox said.
Tom Wallace, who is head of both the ponds advisory committee and the Edgartown Great Pond Foundation, also sees sewer hookups as the best answer to cleaning up the Great Pond.
“It’s great the treatment facility has allocated some capacity, and now the question is how do we encourage or even subsidize that to happen,” he said.
But he also focused on the other half of the solution, opening the pond more often to flushing by the ocean. The estuaries project report recommends at least three openings per year, particularly just before summer, when the nitrogen load is heaviest and the prospect of algal blooms greatest.
He said a meeting of the directors of the Great Pond Foundation on Wednesday gave final authorization to acquire a new state-of-the-art mini dredge called Nessie, to assist with opening the pond. A contract has been signed and a deposit paid, Mr. Wallace said.
The foundation will lease the equipment for a trial period next spring, and if all goes well, will buy one.
The dredge is uniquely suited to working in the Island’s ponds because it is compact enough to be moved in and out on a trailer.
It is unclear when all interested parties will get the chance to discuss and analyze the estuaries report. The contract between the University of Massachusetts at Dartmouth and the state Department of Environmental Protection has ended, and the DEP has so far failed to agree to a new one.
Until a new contract is signed, the project cannot go ahead with a final report. DEP spokesmen had not responded yesterday to questions from the Gazette about the contract.