Saturday, December 03, 2022

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Septic System Program’s Phase Two Nears End in Old Saybrook

As April and spring weather approaches, the town’s Water Pollution Control Authority (WPCA) is entering its final construction season under Phase II of the Decentralized Wastewater Management Project. When Phase II wraps by year’s end, the town will have overseen septic system replacement for about 1,200 of the properties the state has ordered upgraded—and then it’s on to the final, most challenging, 750 systems in Phase III.

The Decentralized Wastewater Management Project, crafted to respond to court-ordered abatement of groundwater pollution from septic systems, has been funded partially with grants and loans from the state’s Department of Energy & Environmental Protection (DEEP) under the Clean Water Act; Phase II of this program funding ends in December 2018.

In December 2017, WPCA Program Manager Steve Mongillo reported to the WPCA that “Significant progress has been made in implementing the Decentralized Wastewater Management Project. We are presently upgrading septic systems in Cornfield Point, which is the last area we plan to upgrade with conventional septic systems. All of the preliminary contract work has been done and five of the eight expected contracts have been awarded to installers. Construction will continue through the winter, weather permitting, with the expected completion date on Dec. 31, 2018.”

On to Phase III

Then starts the most difficult phase of the court-ordered project: finding a feasible solution for upgrading septic systems on the remaining 750 properties that abut waterways, Long Island Sound, or the Connecticut River. These properties were required by the court order to not only upgrade their septic systems, but also add a nitrogen removal step to minimize the amount of wastewater entering area waterways.

The plan, laid out in the original court-sanctioned agreement between the town, the WPCA, and DEEP, was to install advanced technology (AT) wastewater treatment systems on properties like those in Indiantown and Chalker Beach. AT systems add an extra active nitrogen removal step to a conventional septic system. These type of systems are already approved and in use in condominium projects that abut marshes and waterways, and in larger commercial sites like Clinton Crossing retail development.

The problem, however, is that for properties used only seasonally, AT systems don’t work very well. To work at their best, the systems need a continuous and relatively constant flow of wastewater. Seasonal properties don’t have these characteristics. So what are the options?

For some properties, the solution may be adding a passive nitrogen-removal wood chip layer below the conventional septic system leach field. Wastewater is pumped under low pressure out into the septic field and distributed evenly. From there, it drips downward by gravity into the wood chip layer, where the nitrogen is converted in a natural chemical process into nitrogen gas. Standards issued by the Connecticut Department of Public Health in January permitted this type of design for nitrogen removal only if designed by an engineer and where the property is in a court-ordered abatement areas.

To test the concept, the town’s Department of Public Works installed a passive nitrogen removal system below the new conventional septic system installed recently at the town’s Dog Pound. Monitoring wells were also installed to assess how well the wood chip layer removes nitrogen from the waste stream.

“Wastewater is stronger at the dog pound [than elsewhere] due to the animal waste,” said Mongillo. “Passive nitrogen removal is a promising technology which appears to reduce nitrogen very well, but its application is complex and site-specific.”

While this solution may work at the dog pound, it won’t work on every site. Adding an extra layer of wood chip material may not be possible on properties where the distance to ground water of a conventional septic system field is barely adequate, so passive nitrogen removal feasibility is dependent the specific site where it will be installed.

Another design concept for preventing nitrogen in a household wastewater stream from reaching waterways is to use the wood chip concept to design a barrier layer below ground to prevent wastewater with nitrogen from migrating offsite and into the waterway.

Another possible solution to nitrogen removal for the remaining properties is to design a community septic system with a nitrogen removal step or passive nitrogen removal layer, but since the court order specifies that AT systems be installed to remove nitrogen, changes would require the town and DEEP to return to the court and modify the original agreement.

So when Phase II—the installation of upgraded conventional systems—ends on Dec. 31, 2018, Mongillo and his team will work on how to best address the remaining properties.

WPCA History

The WPCA webpage summarizes the program’s history:

“The Old Saybrook Water Pollution Control Authority was established by Town Ordinance in March 1995 to create a sewer avoidance program and seek compliant with Connecticut’s DEEP. In August 2009, the town voted by a 3 to 1 margin to implement a Decentralized Wastewater Management District for the 15 focus areas and to provide the funding to proceed with the program. Construction to begin to upgrade conventional septic systems in these areas began in 2010 with Phase I funding through the Clean Water Act. The program now is in Phase II funding, which ends on Dec. 31, 2018.”

Becky Coffey covers news for Old Saybrook and Westbrook for Zip06. Email Becky at

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