Innovative Systems Could Play Role In Falmouth Wastewater Planning

The view of an Innovative Alternative system from above the surface. The green lid covers a pump for the system. The design has been discussed as an option for nitrogen mitigation.SAM HOUGHTON/ENTERPRISE - The view of an Innovative Alternative system from above the surface. The green lid covers a pump for the system. The design has been discussed as an option for nitrogen mitigation.

Innovative Alternatives, or I/A systems, have been listed as possible tools for nitrogen mitigation for both the West Falmouth Harbor watershed as well as Oyster Pond.
Local researchers and designers of the technology are “cautiously optimistic” that the systems will help to reduce nitrogen loading of water systems.

George R. Heufelder, director of the Barnstable County Department of Health and Environment, is confident that an I/A system can reduce the nitrogen load from a house by 50 percent, with an additional 10 percent eliminated in a leaching field. Any more than that, he is not confident about, but he remains optimistic. “They are another tool in the toolbox,” he said.

Current I/A systems are installed on the property of a homeowner in addition to a septic system and leaching field. Installation costs range from $15,000 to $25,000. Most of a system is installed underground but a part that houses a pump that operates the system protrudes above the surface of the ground.

advertisement

Falmouth, through the Water Quality Management Committee, has applied for a grant that would help fund the installation and monitoring of I/A systems in 20 homes near West Falmouth Harbor. Eco-toilets will be included in that grant as well. The project, in partnership with the Buzzards Bay Coalition, would also act as a demonstration of the effectiveness of the systems.

Last week, a consulting firm presented six options to mitigate nitrogen loads into Oyster Pond. Two of those options included the use of I/A systems.

I/A systems essentially add another step to a traditional Title V septic system. As wastewater exits a house, it passes into a septic tank, where a liquid eventually turns to ammonia. For a Title V system, or what most homes use today, the liquid then travels into a leaching field where some of the nitrogen is removed before it flows into the groundwater.

I/A systems attempt to treat the ammonia after it flows from the septic tank and before it reaches the leaching field. The ammonia travels through the I/A system where it is nitrified by bacteria, which turn the nitrogen in it into gas. The treated water is then pumped into a leaching field where more nitrogen is taken out.

There are numerous types of I/A systems. According to the Barnstable County Department of Health website, there are 38 varieties installed on Cape Cod. There are 156 I/A systems installed in Falmouth. The most common type in Falmouth is the FAST Treatment System. It is chosen often because it is a cheap option and has little visual impact, Mr. Heufelder said. In Falmouth, there are 38 FAST systems installed. There are also Bioclere technology, OMNI recirculating sand filter, RUCK, and others, all varying  in size and cost.

To mitigate the total maximum daily load of nitrogen into a pond, Mr. Heufelder said I/A systems could be more effective than sewers, depending on the location of the homes and a sewer treatment plant. For a remote home far from a sewer plant, I/A systems make sense as the installation of sewer pipes over large distances could outweigh the costs. In a dense neighborhood, I/A systems might not be as cost-effective as sewers.

Mr. Heufelder also said that the initial price of an I/A system is not the only cost to consider. There are yearly electricity costs, maintenance costs, service charges and monitoring costs associated with them. The electricity bill could cost $1,000 a year; servicing the system, based on two site visits, would cost about $500 a year; monitoring the daily load of nitrogen out of the system can cost another $2,000 a year, he said.

The systems can also be visually unappealing, Mr. Heufelder said. A FAST system features an approximate two foot by one foot, green cover that protrudes from the ground.

Improvements are being made, however, Mr. Heufelder said. He runs the Massachusetts Alternative Septic System Test Center on Joint Base Cape Cod.

A number of the I/A systems sit inside closed sheds. The test center is mostly outdoors, approximately the size of a football field and surrounded by a chain-linked fence. Companies from across the country install their systems for six months while the county department monitors each one’s effect at mitigation.

Sections of bright green grass surround the center where different leaching fields are tested. A trailer serves as the office. In one area, Mr. Heufelder said, they are testing the effect of different soils in leaching fields on nitrogen removal. Sand is the most common substance used for leaching fields.

Inside one shed, the California Institute of Technology has installed an electric toilet that could potentially reduce nitrogen. A company from Oregon, which Mr. Heufelder said he could not identify, is testing the ability to monitor its I/A systems remotely. If effective, employees could monitor their system  anywhere in the country from their Oregon office.

Eric T. Turkington, chairman of the Water Quality Management Committee, said that I/A systems are the “Holy Grail” of nitrogen mitigation and sewage treatment. “There are a lot of people who say, ‘If I can come out with something that is affordable and easy to operate and reduces the right amount of nitrogen from septic systems, there will be a huge market for this,’” Mr. Turkington said.

He said there is yet to be one system that has been designed that can capture all nitrogen from homes that enter a water body. Regardless, the I/A systems can help mitigate nitrogen levels from some water bodies. He added that I/A technology is still in its infancy.

Mr. Heufelder is currently testing a system with funding from the Cape Cod Commission and the state Department of Environmental Protection. The design works similarly as a horizontal, and smaller, permeable reactive barrier (permeable reactive barriers sit vertically and use wood chips and other substances to remove nitrogen from wastewater flowing from multiple septic systems into a water body). The system would be similar to a leaching field, an approximate 10-foot by 10-foot space and a foot deep. It would be constructed at a home with a layer of sand, followed by a concentrated layer of a sawdust, sand and water mixture, which would be followed by another layer of sand.

The design works in the same way that other I/A systems work. The sawdust is a carbon source. As the nitrogen flows from the initial top layer of sand through the wood chips in the second layer, the nitrogen interacts with the carbon, where it sticks. As bacteria feed on the nitrogen, they release it as a gas. The treated water would then flow into the third layer before exiting into the groundwater.

Mr. Heufelder said because there is an abundance of water on the Cape, there is little incentive to conserve it and to reuse wastewater from homes. In places where water is scarce, like Florida, he said, engineers have created systems that reuse water for lawn fertilization and even re-use it in toilets.

“I have grandkids and I would like to see them in a world where wastewater is not wasted,” Mr. Heufelder said. “I want to see it reused.” He pointed to a section of grass in the test center that is bright green, where nitrogen from wastewater has acted as a fertilizer.

Comments

Please sign in to leave a comment.

  • peter

    How well do permeable reactive barriers work? Why not scale up these barrier systems that don't have machinery and require ongoing energy and expense to operate? I know nothing of the engineering challenges, but why not fit a septic system with a surrounding permeable reactive barrier, like a sock on a foot?Instead of dropping new septic tanks into a big hole in the ground,drop them into a big hole lined with a barrier system. As for already installed systems, figure out the water flow direction out of the system and install a barrier to "intercept" the effluent before hitting the ground water. Is this possible? Has anyone attempted to utilize barriers in this manner?
  • BostonSteve

    The carbon source in a permeable reactive barrier (saw dust) would deplete over time. Groundwater monitoring just down gradient of the PRB would indicate this. The PRB would then have to be dug up and replaced with another carbon source. Depending on the depth and length of a PRB, this can be costly. In the mean time, nitrogen rich waste is being discharged. Some other issues with PRBs is they can become plugged and channeling can occur. If not properly designed, and more importantly not properly installed, one doesn't know if the PRB is working until after it has been installed.