Trad vs IA

Traditional Septic System vs. I/A Septic System

On Cape Cod, more than eight of 10 homes — approximately 70,000 households —  use a traditional, on-site septic system, which are commonly known as Title 5 septic systemsTitle 5 is a Massachusetts Department of Environmental Protection regulation and specifies how septic systems are to be installed, used and maintained.

As the picture above illustrates, wastewater — what comes from toilets, showers, dishwashes, washing machines — leaves the home and enters into a septic tank.  The liquid waste is then separated from the solids and is discharged as treated influent into a soil absorption system (a leaching area). What comes out of the leaching area provides additional treatment of the effluent through soil microbe activity, but dissolved substances like nitrates leach into the groundwater.  The total nitrogen (TN) level of the effluent that is released into the groundwater can range from 45 mg/L to 80 mg/L.

The take home message:  These levels of TN are too high and are the primary reason why our saltwater ocean and freshwater ponds and lakes are compromised, creating loss of eelgrass, toxic cyanobacteria, fish kill and shellfish degradation.

Ugly Note:  Homes built before the 1970s didn’t have septic tanks and wastewater went directly into a cesspool and groundwater.   If a home with a cesspool is passed on from one generation to the next (ie., with no real estate transaction), a Title 5 septic system does not need to be installed.

The picture on the right illustrates the inclusion of an innovative/alternative (I/A) septic system.  You will see the traditional septic system, but with the addition of a denitrification unit in between the septic tank and the leach area.

Denitrification units can be designed, constructed and function differently from one manufacturer to the next, but all have one goal in mind — reduce the level of TN before it reaches the groundwater.

A denitrification unit removes nitrogen by converting nitrate that is found in the liquid waste to nitrogen gas under anaerobic (ie., an absence of oxygen) conditions when sufficient organics are available.  The treated effluent that leaves the unit is much cleaner.  The standard TN reduction goal for I/A system manufacturers is to have average TN effluent levels of 19 mg/L or less.

BCWC’s Goal:  We want to work with I/A technologies that are simple to install, resilient, cost effective and can provide proven performance of 10 mg/L and less.

Visit BCWC’s Video Library - Septic Systems to learn more about Title 5 septic systems and I/A septic systems.

Over the past five years, BCWC has been working with the Massachusetts Alternative Septic System Test Center (MASSTC) to learn more about I/A septic system technologies that have been tested at the MASSTC.  In our research, we have learned about “layer cake” septic systems developed by the Center and several non-proprietary systems presented to the Center for testing by entrepreneurs, business start-ups and large manufacturers.

The desirable characteristics we are looking for in an I/A septic system include:

  • Total Nitrogen Reductions of 10 mg/L or less
  • Cost competitive as compared to municipal sewer
  • Resiliency
  • Low Maintenance
  • Real time monitoring
  • Failsafe in the event of a power loss

The I/A septic system that intrigued BCWC the most is the KleanTu® NitROE® Waste-WaterTreatment System .

KleanTu® has been operating NitROE® systems in Massachusetts since early 2017, primarily on the island of Martha’s Vineyard and the town of Falmouth. These systems have consistently shown 90% reduction or greater in total nitrogen (TN) after the initial startup period.  In 2020, the first NitROE® system was installed in Barnstable.

The NitROE® system currently has Provisional Use Approval from the Massachusetts Department of Environmental (MA DEP) and is working towards achieving General Use Approval.

Visit BCWC’s Video Library - Septic Systems to view two videos about the NitROE® system and installations that happened in 2021 as part of the Shubael Pond I/A Septic System Project.

The NitROE® denitrification unit consists of two chambers.  The Aeration Chamber contains limestone to create a favorable environment for bacteria to help convert Ammonia — a compound of nitrogen and hydrogen which is found in urine — to nitrate.  The liquid waste then enters the Denitrification Chamber which contains woodchips to provide a carbon source for bacteria to assist the conversion of nitrate to nitrogen gas. What is left is a cleaner effluent that enters a standard leach area. Average nitrogen effluent using the NitROE® system is consistenly under 10 mg/L with some systems at levels less than 5 mg/L.

If you are considering installing an I/A septic system on your property, there are several sequential steps you need to take into consideration.  The completion of all steps could take 3 to 12 months depending on the complexity of your project.

Please note that every town on Cape Cod is governed differently, but each does have its own Department of Health (DOH) and Board of Health (BOH).  Your first step is to contact your town’s DOH to understand the required process.

The steps noted on this page are specific to the town of Barnstable and can be used as a guidepost.  What is not included is the planning of any landscaping and property repair that maybe necessary after the installation.

How to Plan

Working together, your engineer and installers will be able to help you understand your
project costs and if you will need a full, partial or retrofit septic system installation.

For general project cost information, please check out the “Cost” section.

I/A Septic System Installation

Planning Steps and Project Contractors

  1. Contact and hire an engineering firm that specializes in civil engineering, land surveying and environmental permitting. It is best to work with a local firm that understands the soil conditions of Cape Cod. Their role will include surveying your property, designing the septic system layout and plan, including any variance requests necessary, and representing you at BOH meetings and, if applicable, any other town committee meetings (e.g., Conservation Commission).
  2. At the same time, and working with your engineering firm, contact an I/A septic system manufacturer and installer that offers a technology that meets your goals and budget. The Massachusetts Alternative Septic System Testing Center (MASSTC) can also help you with this selection process.  This step is important to do in conjunction with hiring your engineering firm since the I/A technology components are an integral part of the engineering site plan.
  3. Once your design plan had been completed, your engineer and I/A installer will prepare all documentation necessary to present to your town’s BOH committee for review and approval.   BOH meetings are typically monthly meetings and you do not need to present.  Upon approval, your engineer or I/A installer will work with you to secure an I/A septic system installation permit, which is issued by the town’s DOH.
  4. Upon approval by the BOH, contact and hire a licensed septic system installer/excavator, preferably one that has experiencing installing I/A systems.  They will work with the I/A installer to order all that you need for the project including the Title 5 septic tank (if a new one is needed), denitrification unit and leaching area materials. They will also sub-contract other trades that maybe necessary for the project (e.g.,electricians, plumbers)
  5. Depending on which I/A technology you have selected, system sampling and testing is required per a prescribed frequency (e.g., monthly, quarterly) by a certified System Operator.  Your I/A installer will work with you to identify a qualified contractor to do this work.