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From the Mayor’s Desk
By Mayor Katjana Ballantyne

Violent storms have dominated the national news, putting a stark focus on the resilience of our communities and our stormwater infrastructure. While Somerville hopefully never experiences something as tragic or devastating as the hurricanes that just battered the Southeast United States, we can’t ignore that climate change will bring us more unpredictable and heavier storms in the future.

Somerville is a growing community that has older infrastructure, and that, combined with threat of more powerful storms makes upgrading our sewer system a priority. It’s easy to forget about the sewer system when it is working, but it is critical to public health and safety. Providing a system that handles sewerage and stormwater runoff is a best practice for a city. We do not have the luxury of hoping our aging pipes can handle the challenges of what will be thrown at them in the years to come. I can however report that – even with much more to do – Somerville has made notable progress in the generational overhaul of these critical systems.

Our sewer system is old and outdated. Some of our sewer system along Summer Street is made out of brick and mortar “pipes” that were built in 1886. That makes them 15 years older than the Boston Red Sox. Sports fans in those days were still wearing tailcoats and top hats.

I don’t think I need to get graphic about what goes into our sewers other than to say people deserve to have full confidence that, when they flush their toilets, it’s the start of a one-way journey to the Deer Island wastewater treatment facility. But climate change and the age of our system are making that less of a sure thing. Modern systems route stormwater and sewer flows through separate pipes. Our older system collects all the runoff from rainstorms and puts it into our combined sewer pipes in many parts of our city.

We’ve seen street flooding and basement backups throughout the city and particularly in Union Square during heavy downpours when the system got overwhelmed. With more intense storms, we have also seen an increase in Combined Sewer Overflows (CSOs) that discharge sewage-contaminated stormwater to Alewife Brook and the Mystic River.

But we are using innovative solutions to address these issues. For the past five years, we’ve used robot cameras to inspect our 181 miles of pipes and then repair them before they collapse; and begun the long process of separating the stormwater from the sewage, running those flows through two parallel lines. Often, we use what is known as trenchless technology that costs a fraction of what emergency digging efforts cost, avoids midnight sewer service interruptions, and digging up entire sections of streets.

For the southern two-thirds of our city, stormwater and sewage separation work has involved a massive three-stage project.

The first stage started with the Somerville Avenue sewer and streetscape work in Union Square. That work wrapped up last year and included a massive stormwater pipe designed to carry flows from as far away as Davis Square. We’re nearly done with the second stage: the Spring Hill sewer separation project. For that, we’re lining the old pipes to prevent leakage and collapse, as well as installing new parallel lines for stormwater collection and removal. This Spring Hill work is scheduled to wrap up in late 2025.

It will all culminate with the third stage: the Poplar Street Pump Station project, which involves the installation of a four-million-gallon underground tank. Thanks to an agreement we made as part of the Green Line Extension project, this pump station will link Somerville’s runoff with an MBTA-owned set of pipes and will be able pump 50 million gallons of stormwater per day.

I cannot overstate how important it is that these projects also include Green Stormwater Infrastructure (GSI) in addition to the traditional “gray” infrastructure. This means that all three stages of projects, as well as our most recent pipeline rehabilitation project in West Somerville, include bio-basin bump-outs and underground tree wells that collect, store, and treat stormwater before it enters the system, which helps both our stormwater management and the environment.

However, once in a generation infrastructure like this comes with a price tag. The Somerville Avenue project cost $72 million, the Spring Hill project will cost $38 million, and the Poplar Street Pump Station will cost $113 million. The Turner Building Cost Index, which is a measure of construction and labor prices, estimates that project costs have increased over 50% in the past decade. As costly as this work may be today, it will be even more expensive tomorrow, and we have reached our legacy infrastructure’s operational limits.

These investments create a system that will serve us for another 100-plus years. But we are not done. Additional sewer separation is needed to further reduce legacy flooding and leverage the full potential of the Poplar Street Pump Station. More significantly, Somerville is partnering with Cambridge and the Massachusetts Water Resources Authority (MWRA) to develop a plan to reduce and potentially eliminate CSOs to the Alewife, Mystic, and Charles Rivers. To be clear, CSO mitigation is a regulatory requirement, and the state and federal agencies will mandate those system improvements; however, Somerville is fully embracing this effort as a roadmap to update our system.

While we all can clearly see the above-ground construction sites for these projects, it’s easy to miss the scale and importance of the work that is being done underground. It is also important to appreciate the complexity of that underground work. It must be coordinated with maintenance or replacement of other utilities including water, gas, electric, and telecommunications – all while avoiding or minimizing service interruptions to our residents and businesses.

So, when you get slowed down by a detour or construction site as we do this work, know this is us, the Somerville community, at work adapting our sewer system for basic and changing needs. We are the generation ensuring Somerville will remain a healthy, well-operating, more resilient city long into the future.