Ipswich River Sewer Interceptor Biostabilization Protection Project

ENSURING RESILIENCE OF SEWER SYSTEM

The sewer interceptor piping was originally installed in 1958 along the northeast bank of the Ipswich River between Choate Bridge and the Green Street Bridge.  Over time, both installed stones and the underlying bank have washed away, leaving the interceptor pipes vulnerable. Improvements to protect the sewer system are crucial to the safety of the Ipswich River, its surrounding environment, and the community. Failure of the sewer siphon could cause sewage to discharge into the river, flowing downstream to shellfish beds and bathing beaches or backup into residential and commercial properties causing creating damage and potential business closures. This risk will be intensified by increased storm events.

Figure 1- North bank of Ipswich River showing exposed sewer interceptor and eroded bank.

Figure 2 - Erosion Along Bank of Ipswich River. Site of Biostabilization work.

The Town received Municipal Vulnerability Preparedness (MVP) Action Grant funding in 2020 to complete the final design for the sewer interceptor and siphon resiliency improvements, and MVP Action Grant funding in 2021 to construct the biostabilization component of the project.

In the spirit of collaboration that is the foundation of the MVP program, many partners supported obtaining this funding or implementation including:

• Massachusetts Executive Office of Energy and Environmental Affairs MVP Program
• Ipswich Water and Wastewater Department
• Ipswich High School Environmental Club
• Ipswich Conservation Commission 
• Ipswich River Watershed Association 
• Ipswich Council on Aging

PROJECT DESCRIPTION 

The Town is committed to restoring the Ipswich River bank and protecting the sewer piping, implementing nature-based solutions where possible. 

This project consists of the following elements:

• Replacing the existing sewer siphon near the Choate Bridge with a new triple-barrel siphon and installing watertight sewer manhole cover
• Rehabilitating and physically protecting the sewer interceptor from climate hazards
• Stabilizing the shoreline through the use of coconut coir wrapped lifts combined with salt tolerant native plantings to reestablish the riparian area and provide habitat while also protecting the critical sewer infrastructure
• Removal of invasive species and re-vegetation with native plantings, shrubs and forbs that will improve air quality, stabilize the soil and bank, provide habitat, and further enhance the waterway as a scenic community asset. 
• Stabilizing the bank from erosion and protecting the interceptor and siphon with habitat stones to compliment the coir wrap lifts and native plantings will harden the infrastructure and banks against future more intense and frequent storm events, increased river flows and sea level rise in the river. 

The Project improves resiliency to a portion of riverbank along the Ipswich River, where increased river speed and debris from sea level rise and intense rain events have eroded and will ultimately expose and compromise the infrastructure. This nature-based bank protection is designed to ensure that the infrastructure, adjacent environment, and properties will be more resilient to extreme weather-related events.

These improvements provide multiple environmental co-benefits by promoting biodiversity, restoring the project site, improving water and air quality, and carbon sequestration.

Native species include shrubs, perennials, grasses and forbs that have been selected to withstand the fluctuations in water levels, salinity, and the variable climate conditions found along the Ipswich River. Over time, seeds from some of these plantings will spread to other areas along the riverbank, softening the hard edges of the stone, providing valuable habitat for wildlife, and an attractive resource for the public to enjoy. 

MVP PROGRAM

The Municipal Vulnerability Preparedness (MVP)  grant program, created in 2017 as part of Governor Baker’s Executive Order 569 establishing an integrated climate change strategy for the Commonwealth, provides support for cities and towns in Massachusetts to identify climate hazards, assess vulnerabilities, and develop action plans to improve resilience to climate change. The goals of the program are for each town and city across the Commonwealth to gather together a diverse group of community stakeholders to:

• Define top local natural and climate-related hazards of concern.
• Identify existing and future strengths and vulnerabilities.
• Develop prioritized actions for the community.
• Identify opportunities to collaboratively advance actions to increase resilience.

The Town of Ipswich became an official Municipal Vulnerability Preparedness (MVP) community in 2019, receiving funding through the state’s MVP program to complete a Community Resiliency Building workshop and adopt priority actions to increase the community’s resilience to climate change. Participants in the MVP planning process overwhelmingly agreed that the Ipswich River Sewer Interceptor and Siphon was one of the greatest current concerns and challenges presented by the Town’s top natural hazards (coastal storm surge and sea level rise; inland flooding; extreme cold/winter storms; and heat/drought/fire). 

The Ipswich River biostabilization project is designed to meet the MVP Program’s 9 core principles to address climate change impacts:

• Furthering a community identified priority action to address climate change impacts
• Utilizing climate change data for a proactive solution
• Employing nature-based solutions
• Increasing equitable outcomes for and supporting strong partnerships with Environmental Justice Populations and Climate Vulnerable Populations
• Conducting robust community engagement
• Achieving broad and multiple community benefits
• Committing to monitoring project success and maintaining the project into the future
• Utilizing regional solutions toward regional benefit
• Pursuing innovative, transferable approaches

Community feedback has helped shape the design of this project, particularly regarding nature-based design solutions including:

• Native species plantings selection along the coconut coir wrapped lifts will let the plantings’ root structure develop to stabilize the bank. 
• Originally proposed permanent gravel or paved access road (heat sink), replaced with nature-based geo-fabric supported native grasses for permanent access road. Removal of this heat sink is a climate mitigation environmental co-benefit that is under construction under the base bid construction contract.
• Habitat stone placement to support marine habitat.