The Falmouth Water Quality Management Committee earlier this month brought in three guest speakers to give an update on the state of innovative/alternative, or I/A, nitrogen-reducing septic systems.
Chairman Eric T. Turkington said sewering the entire town to reduce wastewater nitrogen loading to the estuaries is not an option and that Falmouth is considering I/A septic systems as an alternative.
The meeting’s objective was to raise awareness on the types and status of systems that are the best candidates for Falmouth, he said.
In her presentation on the West Falmouth Harbor Shoreline Septic Remediation project, Maureen Thomas, a water resources specialist for Buzzards Bay Coalition, said the project will upgrade 30 existing septic systems within 300 feet of mean high water using the best available technologies to achieve effluent concentrations of at least 12 milligrams of nitrogen per liter.
Twenty-seven systems have been installed. The types include blackwater, Hoot, Eliminite, Layer Cake, Fast with Perc-Rite Drip Dispersal, Perc-Rite and NitROE systems.
The average cost to add an I/A system to an existing Title 5 system was approximately $24,000. Full upgrades from cesspools average $34,000, Ms. Thomas said.
These costs did not include landscaping, which is highly variable. Annual operating and maintenance costs ranged from $250 to $1,000, depending on the type of system. Monitoring, pumping and electrical costs were not included.
In presenting the most-recent monitoring data for each of the systems by type and individual installations, Ms. Thomas indicated that the median total nitrogen reduction from all 27 systems is 74 percent.
The Layer Cake and NitROE systems remove the most nitrogen, she said, adding some mechanical issues she encountered early in the project have now been worked out.
Several committee members cautioned against being too optimistic in the expectations of seeing signs of recovery too soon.
In his presentation on the Layer Cake system, George Heufelder of the Massachusetts Alternative Septic System Test Center said most systems are biological and are therefore driven by temperature: The colder the temperature, the lower the performance.
The test center’s goal is to optimize systems for the region’s climate, Mr. Heufelder said, indicating the Simple Layer Cake, the Lined Layer Cake and the Box system are the most-promising and simplest systems available.
He described how they differ from a standard Title 5 system, which for the Layer Cake system is the simple addition of sawdust to the sand layer in a Title 5 system.
The cost for electricity for all three systems is about $50 per year, Mr. Heufelder said, adding the average cost to install a Simple Layer Cake is $19,000, with $21,000 for the Lined Layer Cake and $22,000 for the Box system.
The Simple Layer Cake systems have a 66 to 89 percent annual total nitrogen removal, he said.
In his presentation John R. Smith of KleanTU LLC spoke about the design of the NitROE and SanTOE systems. He said both systems are an add-on to a standard Title 5 system and the only mechanical component is a small air pump.
To date, 12 NitROE and two SanTOE systems have been installed in the region, Mr. Smith said, notingthe only stumbling block faced was a quality issue with the aeration tubing, which has been corrected. He reported that the average total nitrogen effluent from all of the systems is 5.5 milligrams of nitrogen per liter.
The cost for the NitROE system is $21,000 to retrofit an existing Title 5, while a new Title 5 installation with a NitROE is about $38,000, Mr. Smith said, estimating the life expectancy of the system to be at least 20 years.
After the presentations committee member John B. Waterbury said four systems are most promising for Falmouth’s needs, referring to the two Layer Cake systems, NitROE and Nitrex.
Mr. Turkington said no decision has yet been made on the large-scale use of I/As, and the town and state must determine whether large-scale use of I/As at Oyster Pond is a feasible effort as a model.