Infiltration and Inflow Program Development

  • Client

    Town of Westwood

  • EP’s Role


Environmental Partners (EP) has worked with the Town of Westwood since 2015 to develop and implement a progressive town-wide infiltration and inflow (I/I) management program that restores the long-term viability of the Town’s wastewater infrastructure.

Recognizing that infiltration is a symptom of degraded pipes and manholes, the Town has focused on addressing I/I by addressing the overall condition of its collection system. As a result, the Town is regularly one of the best performing communities in the Massachusetts Water Resources Authority (MWRA) when it comes to managing its I/I due to comprehensive and consistent improvements.

EP used wastewater pumping station flows as the initial identifier of I/I priorities, while identifying areas of old pipe, poor soils, cross-country segments, and wetlands crossings that pose a greater risk for pipe degradation and infiltration. EP conducted an alternatives analysis that resulted in the selection of high priority areas of the Town that would warrant inspection for long-term restoration of wastewater infrastructure, rather than solely an I/I mitigation approach.

The 2015 investigation program consisted of cleaning and camera inspection of 20,000 linear feet of sewer main that targeted pipelines and manholes for repair the following fiscal year. In 2016 a construction project was completed that included installing 5,020 linear feet of structural cured in place pipe (CIPP) liner; performing 112 service lateral connection repairs; raising 17 manhole frames and covers to grade; replacing 3 manhole frames and covers; and rehabilitating 19 sewer manholes via cementitious and epoxy lining. The 2017 investigation program consisted of cleaning and TV inspection of 15,000 LF of sewer main, and performing topside manhole inspections of 75 sewer manholes. In 2019, the Town is bidding another construction project that will utilize trenchless technology.

The use of trenchless technologies to resolve infiltration problems also increases the life span of the existing infrastructure, a significant cost savings as compared to replacing the pipelines and manholes entirely. Environmental Partners worked with the MWRA to obtain approval for funding this proactive inspection and rehabilitation program, and continues to work with the Town to restore its oldest wastewater infrastructure to long-term viability.

Key Team Members