Saybrook Was First to Install PNR Septic System
The word “groundbreaking” in the Aug. 13 story “Westbrook Digs in with Groundbreaking New Septic System” turned out to be true when it came to digging through earth to install its pilot passive nitrogen removal (PNR) septic system, but inaccurate in the sense of being the first in the state to do so.
Westbrook’s neighbor, Old Saybrook, installed a similar PNR system in 2016 at its Town Garage. This system was the result of a collaboration between the town and local company Geomatrix, LLC, which engineers advanced water filtration and reuse technologies to protect the environment.
The company’s founder, David Potts, worked closely with Department of Public Works (DPW) Director Larry Bonin on the PNR project, explained Geomatrix Environmental Scientist Sara Wigginton.
“The idea was we were going to donate a lot of time and materials and in exchange for that, we were going to get to [get to work on] this experimental system,” she said.
“Geomatrix was instrumental” in implementing the pilot system, said Jim Vanoli, program manager for the town’s Water Pollution Control Authority (WPCA). “They supplied some of the equipment that remained on site, the pans, the monitoring, tubes; they designed the system. Dave Potts was super through the whole thing.”
Geomatrix took on a specialized role for the project, explained Wigginton.
“We manufacture technologies and they’re usually advanced technologies or some advancement on a time-proven technology,” she said. “We work with distributors in the region who will sell our technologies.
“We don’t usually design, but we have people who can,” she continued. “For this project, we made an exception.”
That’s because the project was experimental and an opportunity for the company to expand its knowledge.
“That’s how we stay ahead in the industry,” Wigginton said. “We like to learn and stay open to new ideas.”
PNR is an alternative to expensive advanced technology systems, which were once considered the only solution for smaller properties without adequate space for leaching systems and those near the water, where storm surges and sea-level rise can cause systems to back up.
The Saybrook system is, at heart, the same sort of system installed in Westbrook, according to Wigginton.
It’s “slightly different just in the dispersal system,” she said. Westbrook “used a super low-profile dispersal system. We used a stone dispersal system.”
It’s the layer of sawdust under a layer of sand that’s the “meat of the system,” she explained. “That’s what makes it different than other drain fields—the sawdust/wood addition.”
According to Vanoli, the town installed Geomatrix’s GST system, an adaptation on a widely-used stone leaching trench system. Beneath that, he explained, were 13 inches of manufactured sand and 14 inches of half wood, half sand by volume.
The Town Garage and dog pound had historically shared a septic system; the project split it in two, with the Town Garage “flowing into the PNR system and the dog pound into a separate system,” said Vanoli.
Geomatrix has a close working relationship with the Massachusetts Alternative Septic System Test Center (MASSTC) in Cape Cod, which researches alternative septic system technologies, including PNR.
MASSTC has installed pilot systems on site as well as at residences, and Geomatrix technologies have been used in both, according to Wigginton.
Potts “was involved with [Stony Brook University] out on Long Island and...is looking at refining a specification for [PNR systems]: the thicknesses of the layers, the size of the woodchip/sawdust, the type of tree, the age of the tree,” Vanoli said. “The wood chips or sawdust provide carbon and the microbes need the carbon for food.”
The company also monitors and tests the system quarterly, primarily for nitrogen, but also for a “whole suite of water characteristics,” said Wigginton. They send the samples to a “third-party in Barnstable to have them corroborated.”
Wigginton, who this spring earned her PhD in soil ecology and microbiology from the University of Rhode Island, worked at MASSTC monitoring these types of systems.
“I think [PNR systems] are a very, very promising technology that’s passive and affordable,” she said. They have a much “lower price tag than a lot of these tank-based systems. We’re really excited that other people are doing it and [that] it’s gaining traction.”
Saybrook and Westbrook have both faced state government mandates to address properties in low-lying areas whose septic systems are leaching nitrogen and bacteria into Long Island Sound and other public waterways.
December 2018 marked the end of Phase II of Saybrook’s Decentralized Wastewater Management project, which provided residents with state and town subsidies to replacement home septic systems. Remaining are five low-lying areas of town whose properties could not be included at all and 66 holdouts from the other areas. That amounts to approximately 800 properties that continue to have inadequate septic systems and continue to pose a hazard to public waterways.
As for how Saybrook will proceed from here, Vanoli said the WPCA is working on it.
PNR may not work for properties where the groundwater is close to the surface, as the systems require installation of thick layers of wood and sand.
We “haven’t solidified our thoughts on that,” he said. “We’re still investigating all possibilities so we provide the least expensive solution to the public.”