Alteration Septic System OWTS designs are for the alteration of existing sewage disposal systems. Alteration Septic System OWTS designs are appropriate whenever:

• Proposed change in the size of an existing Septic System OWTS.
• Modification of an existing Septic system OWTS.
• A building renovation or change of use of any structure discharging sewage into the Septic System.

A “change in size” of an existing Septic system means any physical alteration to your Septic System which will allow the system to accommodate:

1. In the case of a residence, the additional sewage flow resulting from the addition of not more than one bedroom; or
2. In all other cases, an increased flow of sewage in an amount less than or equal to twenty-five percent (25%) of the design flow.

Changes in size which will accommodate increased sewage flows resulting from more than one
bedroom or in an amount greater than twenty-five percent (25%) of the design flow (approved) must obtain a permit as a New Construction Septic Systems OWTS.

In addition to our designing an Alteration Septic System you will first need to have Soil Evaluation testing done, prior to any design, and Designers Supervision services when the Alteration Septic System is constructed and installed, which are not included.

Valid only in Rhode Island, excluding New Shoreham (Block Island) and Prudence Island. Call for pricing for surveys on New Shoreham (Block Island) and Prudence Island.