Within Ledge Light Health District, many homes rely on on-site sewage disposal systems to treat their waste water. These systems are typically comprised of a septic tank used in conjunction with a distribution system and leaching structure (s). The waste flows from the house to the septic tank, where the separation of solids and fats/oils/greases occurs. The solids accumulate in the bottom of the septic tank (and should be periodically pumped out) and the liquid is dispersed over a large area of soil through the leaching structures (galleries, drywells, trenches or proprietary products), where biological filtration takes place. Information about septic systems is available at the State of Connecticut Department of Public Health. Ledge Light Health District is responsible for:

• Permitting all activities related to the construction or repair of any subsurface sewage disposal system.
• Investigating any complaints related to failing septic systems.
• Reviewing and approving plans for septic systems.
• Conducting soil evaluations and percolation tests to assure site suitability.
• Retaining records for all new and repaired septic systems including as-built drawings.
• Assuring that any construction activities, or change in use of the property, do not adversely impact the on-site septic system or reduce potential repair area.

Homeowners, or their representatives (contractors), who rely on subsurface sewage disposal are required to contact Ledge Light Health District to obtain a permit if they are:

• Altering or repairing any part of a subsurface sewage disposal system.
• Constructing a new home to be served by an onsite septic system.
• Planning a project to your home that is served by an onsite septic system that meets certain criteria for review under Section 19-13-B100a of the Connecticut Public Health Code (see below).

Do I Need a B100a Review?

We are often asked when (and why) LLHD is required to review proposed projects and lot line changes on parcels that have on-site septic systems.

The regulation that governs this is Connecticut Public Health Code Section 19-13-B100a.  The stated purpose of “B100a” is to regulate building conversions; activities which would potentially increase the water usage discharged to a subsurface sewage disposal system; construction activities or lot line changes which would reduce the area available for sewage disposal purposes.

When we review a B100a application, we are looking to confirm that a code complying septic system could be placed on the property if the current septic system were to fail. We are not evaluating the status of the current system – we are just making sure that the new use, addition, lot line change or accessory structure does not leave the property without a code complying area.

B100a applies ONLY to lots where public sewers are not available and when the proposed project includes one of the following activities:

1. Building Conversions/Changes in Use to include winterization so for year-round use; any structural, mechanical or physical change that allows occupancy to increase; or any change that allows the activities in the building to expand or alter in a way that impacts water usage.
2. Building Additions to include dormers, additional building levels, finishing basement or attic spaces, moving interior walls or increasing the existing footprint of the house.
3. Installing Garages/Swimming Pools/Accessory Structures to include detached garages, pools, open decks, gazebos, barns, concrete slabs, sheds and underground storage tanks. This does not include small (<200 sq ft) portable structures without a permanent foundation.
4. Lot Lint Revisions.

If your project does not meet the above or if public sewers are available to your property, a B100a review is not required!

If you do need a B100a review, please submit a completed B100a application to [email protected]. along with a scaled site plan showing property lines, existing buildings, your septic system and well locations and the proposed project. If the project is happening inside the house we’ll also need a copy of the existing and proposed floor plans. There is an initial $25 fee for this review, which you can pay online or cash or check to our office. Once all documents have been received your application will be in the queue for review and a member of our Environmental Health Team will contact you!

Click here for information about septic safety during a natural disaster.

If you have any questions or comments, please contact an Environmental Staff member. You can view the subsurface sewage disposal technical standards on the State Department of Public Health’s website.