By Aviva Luria / Zip06.com • 9/15/2020 4:45 PM EST
The word “groundbreaking” in the August 13 story, “Westbrook digs into groundbreaking new septic system” proved correct when it came to digging through the earth to build its pilot sewage system for passive nitrogen removal ( PNR) but inaccurate i feel like the first in state to do so.
Westbrook’s neighbor, Old Saybrook, installed a similar PNR system in its city garage in 2016. This system is the result of a collaboration between the city and local company Geomatrix, LLC, which develops advanced water filtration and reuse technologies to protect the environment.
The company’s founder, David Potts, worked closely with the director of the Public Works Department (DPW), Larry Bonin, on the PNR project, said Geomatrix environmental scientist Sara Wigginton.
“The idea was that we would donate a lot of time and material and come in return [get to work on] this experimental system, ”she said.
“Geomatrix was instrumental in implementing the pilot system,” said Jim Vanoli, program manager for the city’s water pollution control agency (WPCA). “They provided some of the equipment that was left on site, the pans, the monitors, and the tubes. You designed the system. Dave Potts was great through the whole thing. “
Geomatrix played a special role for the project, Wigginton explained.
“We make technologies and those are usually advanced technologies or advances on a proven technology,” she said. “We are working with dealers in the region who will sell our technologies.
“We don’t usually design, but we have people who can,” she continued. “We made an exception for this project.”
The project was experimental and gave the company an opportunity to expand its knowledge.
“This will keep us ahead in the industry,” said Wigginton. “We like to learn and stay open to new ideas.”
PNR is an alternative to expensive, advanced technology systems that were once considered the only solution for smaller properties with insufficient space for leaching systems and those near the water where storm surges and sea level rise can secure the systems.
The Saybrook system, according to Wigginton, is essentially the same system that is installed in Westbrook.
It’s “a little different, just in the propagation system,” she said. Westbrook “used a super low profile dispersion system. We used a stone distribution system. “
It is the layer of sawdust under a layer of sand that is the “meat of the system,” she explained. “That’s what sets it apart from other drainage fields – the sawdust / wood additive.”
Vanoli said the city installed Geomatrix’s GST system, an adaptation of a widely used stone leach trench system. Underneath, he explained, was 13 inches of manufactured sand and 14 inches of half wood, half sand by volume.
The city garage and the dog pound had historically shared a septic system; The project split it into two parts, with the city garage “going into the PNR system and the dog pound going into a separate system,” Vanoli said.
Geomatrix works closely with the Massachusetts Alternative Septic System Test Center (MASSTC) in Cape Cod, which researches alternative technologies for septic systems, including PNR.
MASSTC has installed pilot systems in both on-site and residential buildings, and Geomatrix technologies were used in both cases, according to Wigginton.
Potts “was involved in [Stony Brook University] on Long Island and … trying to refine a specification for [PNR systems]: the thickness of the layers, the size of the wood chips / sawdust, the type of tree, the age of the tree, ”said Vanoli. “The wood chips or sawdust provide carbon and the microbes need the carbon for food.”
The company also monitors and tests the system quarterly, mostly for nitrogen, but also for “a variety of water properties,” said Wigginton. They send the samples to a “third party in Barnstable for approval”.
Wigginton, who received her PhD in soil ecology and microbiology from the University of Rhode Island this spring, worked at MASSTC overseeing these type of systems.
“I think [PNR systems] is a very, very promising technology that is passive and affordable, ”she said. They come at a much lower price point than many of these tank based systems. We are very happy that others are doing it and [that] it gains traction. “
Saybrook and Westbrook both faced a government mandate to deal with properties in lower-lying areas whose septic tanks are leaching nitrogen and bacteria into Long Island Sound and other public waterways.
In December 2018, Phase II of Saybrook’s decentralized wastewater management project ended, in which residents received state and municipal subsidies to replace septic tanks. What remains are five low-lying districts, whose properties could not be included at all, and 66 remnants from the other areas. This equates to approximately 800 properties that continue to have inadequate sewage systems and continue to pose a threat to public waterways.
How Saybrook will proceed from here, Vanoli said the WPCA was working on it.
PNR may not work for properties where the groundwater is close to the surface as the systems require the installation of thick layers of wood and sand.
We “haven’t solidified our thoughts about it,” he said. “We are still exploring all possible ways to offer the public the most cost-effective solution.”