By Aviva Luria / Zip06.com • 11/08/2020 1:07 PM EST
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. The construction workers then carefully use shovels to spread the mixture. The seemingly simple act was one of the final steps in a long process that puts Westbrook at the forefront in a region with inadequate wastewater treatment.
Construction on Aug. 3 was part of installing a pilot passive nitrogen removal (PNR) sewer system that the city hopes will help resolve a decade-long dispute with the state over groundwater and waterway pollution and opportunities for that country creates business expansion, especially restaurants, in the city center.
For several years, city officials have sought alternatives by visiting the Massachusetts Alternative Septic System Test Center (MASSTC) in Cape Cod, which is investigating alternative technologies for onside septic systems including passive nitrogen removal (PNR) systems. These are alternatives to expensive advanced technology (AT) 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 .
Westbrook, along with neighboring cities of Clinton and Old Saybrook, has many of these densely packed, low-lying areas.
In close cooperation with the state ministries for public health (DPH) and energy and environmental protection (DEEP), Westbrook asked the state authorities to consider the standard for PNR technologies under certain circumstances. As a result, Connecticut Technical Standards, effective January 1, 2018, allow the use of PRN technology in standard systems “where warranted (community pollution areas),” according to a DPH summary of revisions.
With the installation of this pilot system, Westbrook has become a leading state in solving a problem that stretches across much of the Connecticut coast.
“Nobody in Connecticut does this,” said Westbrook Health Director Zachary Faiella.
Faiella certified the former health director of the city, Sonia Marino, not only to take on the pioneering role, but also to invest enormous time and effort in the realization.
“This is all of Sonia’s work and her … passion for it in concert,” said Faiella with Water Pollution Control Authority chairman Lee McNamar. “I’ve been trying to expand on the work she’s done.”
This work included monitoring water usage at the Riggio building as well as at the West Beach concession stand where a second planned pilot system was being installed.
In West Beach it was necessary to “monitor how high the groundwater rises throughout the rainy season … through tidal cycles,” Marino said in an interview with Harbor News in 2019. The installation there must also be sensitive to endangered plants, such as Panicum amarum, also known as bitter panic grass, a coastal grass on the state’s list of threatened species.
The Riggio system was designed by Brian Curtis, PE and his colleagues at Nathan L. Jacobson & Assoc. in consultation with Marino, the WPCC, DPH and DEEP.
“There has been a lot of research into these types of systems, especially in Florida, where there are only aquifers for fresh drinking water,” Curtis said. “Nitrogen matters in these areas.”
According to the Environmental Protection Agency, solitary aquifers provide at least 50 percent of the drinking water for a supply area.
The MASSTC, operated by the Barnstable County Health Department, researches and tests alternative system designs and makes them available for engineers to use and modify in certain circumstances, Curtis said.
“They do prototype tests and field installations where they have monitored effectiveness,” he said.
There are field installations in houses in the area.
In Westbrook: “The city will be tracking and collecting samples as after construction [the effluent is] be treated [to determine] how effective it is at removing nitrogen, ”he continued.
The system works by “laying sand mixed with wood products like sawdust or wood chips as a layer under the sewer system,” he said. “This works biologically to remove nitrogen. Carbon in wood products – bacteria can use it to remove nitrogen from wastewater.
“Being passive is attractive from that point of view,” he said. “No chemicals or anything like that are required to be added to the system.”
After the entire system is installed, two tall PVC pipes are cut to allow samples to be taken for testing for nitrogen and pathogens.
“We will be sending samples to the state testing center in Rocky Hill daily,” said McNamar. “It will be two to four months [provide] a good dissemination of the test results. “
“The things we are learning here may have applicability across the state as well as other states,” said Matthew Pawlik of the DEEP Environmental Engineering Program.