Ipswich River Siphon and Interceptor Project

The Ipswich Wastewater Department is working on a project to upgrade the sewer interceptor pipe and siphon located along the Ipswich River by the historic Choate Bridge. Both the interceptor and siphon were constructed over 60 years ago and remain in original condition.

The 18-inch sewer interceptor collects sewage flow from the Union Street and Market Street areas and travels from west to east under the Choate Bridge along the northern bank of the Ipswich River. The pipe, which is constructed of cast iron and supported by concrete support piers, is exposed at this location and vulnerable to damage from river flow and the elements. 

The 12-inch sewer siphon is located approximately 300 feet east of Choate Bridge. Sewage flow from the South Main Street and Elm Street areas travels beneath the Ipswich River through the sewer siphon, which then connects to the interceptor along the northern bank of the river. The siphon is a 130-foot long single-barrel cast iron pipe that was recently discovered to be exposed in the riverbed.  

The first phase of the project was to evaluate the existing sewer interceptor and siphon. Information gathered during the evaluation was then used to develop the second phase of the project, design of improvements. The project was fully designed, permitted, and bid in Fall 2020.  

The construction contract was awarded to N. Granese & Sons and began in December of 2020. Throughout the winter and spring, N. Granese & Sons, set up a temporary by-pass system to allow the interceptor and siphon to come off-line to complete the work. The siphon was replaced by setting up a cofferdam on the south side of the riverbank to divert river flows while pipe was installed 5-feet below the riverbed. The same process was repeated on the north side. 

Once the siphon work was complete through the river, the interceptor rehabilitation begun along the riverbank on both the west and east sides of the Choate Bridge. Using a sandbagging technique to create dry working conditions, the Contractor was able to replace the old cast iron pipe and damaged supports with a preferred material known as High density polyethylene (HDPE). This pipe was then encased in concrete and protected by appropriately sized rip-rap to protect from river flows and the elements.

In August of 2021, construction and restoration of the rehabilitated sewer interceptor and new triple barrel siphon was substantially completed.

The Department worked closely with project abutters to discuss construction details and obtain easements to allow for the construction in a very sensitive and constrained area.  We'd like to thank all abutters for their cooperation and patience during this process.

For project details and updates, refer to the documents below or contact our office at (978) 356-6635. Thank you for your patience and cooperation during this important project.