New Standards for Nitrogen-Reducing Septic Systems in Suffolk County Starting July 1st

June 21, 2021

A recent and alarming statistic shared by the Suffolk County Department of Health Services indicates that more than 80% of nitrogen found in Long Island’s surface waters is attributable to sewage. As if the idea of sewage constituents making their way into our lakes and bays isn’t concerning enough, the environmental impacts of nitrogen on water quality are as varied as they are serious.

It is widely accepted that high levels of nitrogen in surface water leads to algae blooms that can be toxic to animals and humans. Such is the case with blue-green algae that has been appearing more and more frequently in Long Island’s freshwater bodies. Swimming in or ingesting water contaminated with the the algae can cause severe illness, neurological damage, and even death is severe cases. Pets are particularly susceptible to exposure and injury.

Even algae that is not toxic, such as brown tide, can be harmful in high concentrations because it depletes dissolved oxygen in water and blocks sunlight infiltration, both of which contribute to marine life die-off. Some may recall the series of fish die-offs in Riverhead back in 2015. Many commenters attributed those events to high concentrations of algae from sewage and correspondingly low levels of oxygen in the Peconic River.

In recognition of ongoing efforts to stem the tide of nitrogen flowing into our surface waters, Suffolk County has taken another step toward reducing the levels of nitrogen released into the environment from private, onsite sanitary systems. The new standards, approved by the Suffolk County Legislature and the Suffolk County Department of Health, largely affect Article 6 of the Suffolk County Sanitary Code. They take effect July 1, 2021, and apply to all applications submitted to the Office of Wastewater Management (OWM) after that date.

In their broadest terms, the new standards establish specified events that trigger the requirement for the installation of an “Innovative/Alternative Onsite Wastewater Treatment System” (aka I/AOWTS) in lieu of a traditional sanitary system, such as a septic tank or cesspool. The changes also expand the list of I/AOWTS technologies allowed for use on properties in Suffolk County, and modify the separation distance requirements for I/AOWTS generally, among other changes.

The triggers for the installation of an I/AOWTS are of paramount importance. In short, an I/AOWTS will be required for all “New Construction” and all “Major Reconstruction” projects. New construction for single-family residences includes:

• Construction of a new residence
• Knock-down and rebuild of a residence
• Addition to or modification of an existing residence requiring the addition or modification of a sanitary system
• The addition of bedrooms to greater than 5

New construction for “Other Construction” (i.e. commercial, multi-family, and mixed use) includes:

• Construction of a new, detached structure that requires a sanitary system
• Addition to or modification of an existing structure that requires the addition or modification of a sanitary system
• A change of use requiring the installation of a sanitary system or increase in wastewater capacity

“Major reconstruction” is universally defined for both single-family and other construction projects as any project for which the cost of the project exceeds 50% of the market value of the existing structure. Whether a project is a Major Reconstruction is determined by comparing a design professional’s construction cost estimate with an appraisal of the existing building prepared by a licensed real estate appraiser. As of July 1, 2021, any projection for which a conventional septic system is proposed will require submission of OWM’s new “Verification of Major Reconstruction Certification” supported by a constriction cost estimate and appraisal.

Triggers for Installation of an I/AOWTS for Single-Family Residence

• Construction of a new residence
• Knock-down and rebuild of a residence
• Addition of one or more bedrooms to an existing residence and the number of bedrooms will exceed 5, unless more than 5 bedrooms were already approved pursuant to a prior OWM application
• Major Reconstruction

Triggers for Installation of an I/AOWTS for “Other Construction” Projects (including commercial, multi-family and mixed use projects)

• Construction of new commercial or industrial building
• Addition to an existing commercial or industrial building requiring a new, expanded, or relocated sanitary system
• Change of use that exceeds prior approved design flow
• Major Reconstruction

There are, of course, exceptions to these rules, such as projects involving a residence or building within a proposed sewer district. Accordingly, all applications to OWM after July 1, 2021, must be compared against the new standards to determine (1) whether the project triggers the requirement for an I/AOWTS; and (2) whether an exception to the requirement applies.

On July 1, 2021, the date on which the new standards take effect, the Health Department will public new guidance documents (Nos. 8 [amended], 38, and 39), covering the triggers for referral of a single-family residential project to OWM, and when an I/AOWTS is required; triggers for requiring I/AOWTS for “Other Construction” project; and guidelines for determining whether a project is a “Major Reconstruction”, respectively. OWM will also publish its new Verification form for Major Reconstruction projects.