In February of this year, Tata & Howard began to look at Long Pond, the town’s primary source of drinking water, to determine what additional treatment would be needed to meet changes being made to state regulations. Funding for the $800,000 study was approved in May 2011 by voters.
It will investigate the possibility of installing a filtration plant at Long Pond as well as other options, such as enhancing the disinfectant capabilities there.
Last week selectmen were briefed on the progress of that study by Patrick S. O’Neale, vice president at Tata & Howard, and Russell Ford, vice president at CH2M Hill.
Mr. O’Neale initially focused on the characteristics of Long Pond, a surface water source, a watershed that encompasses 150 acres of protected land owned by the town.
The pond itself, he said, is subject to seasonal variations that lead to discernible differences in taste and odor.
Overall, it provides anywhere from 60 to 70 percent of the town’s drinking water during the summer, “so it is a vital piece of the town’s drinking water,” he said.
Since the early 1990s, he noted, the town has operated Long Pond with a filtration waiver from the state, using chlorine to remove pathogens from the water.
That treatment method, he said, will not meet new state regulations that go into effect in October. The new regulations will require the removal of cryptosporidium. Among the more basic options for doing so, he said, is adding ozone or chlorine dioxide treatment or passing the water through ultraviolet rays.
Additional concerns with chlorination, Mr. O’Neale said, is that it does not effectively address other contaminants such as endocrine disruptors found in personal care products that the Environmental Protection Agency could regulate in the future.
As part of the town’s study of Long Pond, Mr. O’Neale said his firm is conducting benchmark tests to assess key processes in Long Pond.
Along with that, Dr. Ford said, are pilot tests, one that will be done over the winter and another over the summer. They will analyze a variety of new treatment options that could be used on the pond.
During initial meetings with the Department of Public Works and members of the Falmouth Board of Health, Dr. Ford, said a list of 25 potential treatments were identified as possibilities for Long Pond. Those were narrowed down to coagulation, direct filtration, ozone treatment, membrane filtration or dissolved air flotation. All the equipment for the studies is currently on-site at Long Pond.
Analysis will look at the effectiveness of those options in meeting state mandates, Dr. Ford said, as well as the cost to implement them.
After the pair concluded the presentation, Chairman Kevin E. Murphy admitted that this was a topic in which the board will “really rely on your expertise as we move forward. Either that or we will have to do a lot more research.”
Department of Public Works Director Raymond A. Jack tried to simplify the conversation, first explaining that the inherent danger with a surface water source is the result of the suspended solids. Those solids, he said, essentially will settle on the bottom, but during periods of turnover they will rise to the surface and create odor and taste issues.
“The first thing you want to do is deal with the solids,” he said, as he moved to the various treatment options beginning with coagulation, which is similar to what is done with human blood. In this case, he explained, a chemical with a positive charge is added to the drinking water to counteract the negative charge, creating clots in which suspended solids can be more easily removed.
With dissolved air flotation, he said, the process moves solids out of the drinking water.
Direct filtration, he said, moves drinking water through sand to remove solids while membrane filtration is similar to reverse osmosis as it forces water through a micro-filter.
Selectman Mary (Pat) Flynn asked how complex Long Pond is compared to other sources of drinking water and how costly it would be to treat.
Mr. Jack said it would be less costly than other municipalities. The issue in Falmouth, he said, is that it is seasonal, leading to turnover, which typically occurs in the spring and fall.
As the study continues, Mr. Jack said, Falmouth will have to ask for an extension from the state in October to continue to operate Long Pond without a filtration system. He anticipated a final report from Tata & Howard and CH2M Hill will be ready at some point in late November or early December.
That report will include recommendations for potential treatment options as well as costs that Town Meeting could vote on in April.
UPDATE: This story was corrected as the original headline reported the study would begin next February. The study is already underway and is expected to be completed by December. Additionally, the story reported that the selectmen's meeting took place this week. It actually was held last week on Monday, August 27.