On the first Monday in August in Westbrook, a front loader dumped a mixture of sand and sawdust into a square cavity on the side of the John P. Riggio Municipal Building; construction workers then carefully spread the mix with shovels. The seemingly simple act was one of the last steps in a long process that puts Westbrook at the forefront in a region plagued with inadequate wastewater treatment.

The Aug. 3 construction was part of the installation of a pilot passive nitrogen removal (PNR) septic system, which the town hopes will lead to the resolution of a decades-long dispute with the state over pollution of groundwater and waterways and create opportunities for business expansion, particularly restaurants, in the town center.

For several years, town officials have researched alternatives with visits to the Massachusetts Alternative Septic System Test Center (MASSTC) in Cape Cod, which researches alternative onside septic system technologies including passive nitrogen removal (PNR) systems. These are alternatives to expensive advanced technology (AT) 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.

Westbrook, along with neighboring towns Clinton and Old Saybrook, has a lot of these densely packed, low-lying areas.

Working closely with the state departments of Public Health (DPH) and Energy & Environmental Protection (DEEP), Westbrook petitioned the state agencies to consider PNR technologies standard under certain circumstances. As a result, the Connecticut technical standards that became effective as of Jan. 1, 2018 permit the use of PRN technology in standard systems “where warranted (community pollution areas),” according to a DPH summary of the revisions.

With the installation of this pilot system, Westbrook has become a state leader in addressing a problem that extends across much of the Connecticut shoreline.

“No one else in Connecticut is doing this,” said Westbrook Director of Health Zachary Faiella.

Faiella credited former town director of health Sonia Marino not only with spearheading the effort, but putting tremendous time and effort into making it a reality.

“This is all the labor of Sonia and her...passion for this in consultation” with Water Pollution Control Authority Chair Lee McNamar, Faiella said. “I tried to build off the work that she did.”

That work included monitoring water use at the Riggio Building as well as at the West Beach concession stand, the site of a second planned pilot system.

At West Beach, it was necessary to “monitor throughout the wet season how high the ground water’s going up...through tide cycles,” Marino said in a 2019 interview with Harbor News. The installation there must also be sensitive to endangered plants, such as Panicum amarum, also known as bitter panicgrass, a coastal grass on the state’s Threatened Species List.

The Riggio system was designed by Brian Curtis, P.E. and his colleagues at Nathan L. Jacobson & Assoc. in consultation with Marino, the WPCC, DPH, and DEEP.

“There’s been a large body of research done on this type of system, especially in Florida, where they have sole source aquifers for fresh drinking water,” Curtis said. “Nitrogen is of concern in those areas.”

Sole source aquifers supply at least 50 percent of the drinking water for a service area, according to the Environmental Protection Agency.

The MASSTC, which is run by the Barnstable County Health Department, researches and tests alternative system designs and makes those designs available for engineers to use and modify according to specific circumstances, Curtis explained.

“They do prototype testing and actually field installations, where they’ve monitored the effectiveness,” he said.

There are field installations at homes in the area.

In Westbrook, “The town will be following up once it’s constructed, collecting samples as [the effluent is] being treated [to determine] how effective it is in removing nitrogen,” he continued.

The system works by putting down “sand mixed with wood product, like a sawdust or wood chips, as a layer under the septic system,” he said. “This functions biologically to remove nitrogen. Carbon present in the wood products—bacteria can utilize that to remove nitrogen” from the wastewater.

“Being passive, it’s attractive from that standpoint,” he explained. “It doesn’t require chemicals or anything to be added to the system.”

Two tall PVC pipes will be cut down once the entire system is installed to enable the collection of samples for testing for nitrogen as well as pathogens.

“We’ll send samples to state testing center in Rocky Hill daily,” said McNamar. “Two to four months will [provide] a good spread on test results.”

“The things we learn here might not only be able to be applied across the state but even in other states,” said Matthew Pawlik of DEEP’s Environmental Engineering Program.