Information and Frequently Asked Questions about Disinfection Byproducts
Modernizing Our Water System for the 21st Century

A New West Parish Filters Water Treatment Plant

Looking west from Springfield Water and Sewer Commission's West Parish Filters Water Treatment Plant in Westfield, MA in 1909 (left) and in October 2022 (right).
The History: Water Treatment at West Parish Filters

West Parish Filters in Westfield has been the site of water filtration and treatment for drinking water supplied to the City of Springfield since the early 1900s. Original construction of the plant was completed in 1909 and featured slow sand filtration facilities (common in New England at the time). More slow sand filters were added in the 1920s, and chlorination was added in the 1960s.

With the passage of the Safe Drinking Water Act in the 1970s, new science, technology, drinking water regulations, and substantial federal funding drove a modernization effort at the plant. In 1974, construction of a new rapid sand filtration facility was completed at West Parish Filters.

The rapid sand filters have been the primary form of drinking water treatment ever since, with the slow sand filters remaining in use to meet peak and emergency demand.


Pictured above: (Top) Slow sand filters under construction at West Parish Filters in the 1920s. (Bottom) The Rapid Sand Filtration Facility at West Parish Filters was constructed in the 1970s and is still in use today. 

Planning and Design of a New Treatment Plant

In 2012 the U.S. Environmental Protection Agency (EPA) and Massachusetts Department of Environmental Protection (MassDEP) updated its regulations related to disinfection byproducts (DBPs), which were first adopted in 1998.

DBPs form when chlorine (required for safe disinfection) reacts with dissolved natural organic matter (NOM) found in surface water bodies such as the Commission’s Cobble Mountain Reservoir, the main source of the drinking water supply. Data indicates that the more intense and extreme precipitation patterns observed in recent years are increasing the amount of NOM in the reservoir.

The Commission recognized that the 1970s-era rapid sand filters were not capable of removing the amount of NOM now necessary to consistently meet the new DBP regulations. In addition, many other components of the plant were at or beyond the end of their useful life, increasing the risk of failure. Therefore, in 2015 the Commission initiated a comprehensive planning process to modernize the drinking water treatment plant.

The West Parish Filters Facility Improvements Plan was completed in 2021 and identified a multi-phase approach to replace aging infrastructure and maintain regulatory compliance for DBPs. The planning process also identified that an added step of clarification of the raw water – known as “dissolved air flotation” – is required to meet modern drinking water standards.

Projects included in the West Parish Filters Facility Improvements Plan:

  • Clearwell and Backwash Pump Station Replacement – to replace obsolete infrastructure and protect water quality
  • New Chemical Storage and Feed Building – to support new treatment processes
  • New Dissolved Air Flotation Facility – to more effectively remove NOM prior to filtration
  • New Electrical System – to support new treatment processes
  • Rapid Sand Filter Upgrades and Expansion – to more effectively filter out NOM
  • Elimination of Slow Sand Filters

As part of the planning process, isolated pilot testing completed on-site at West Parish Filters from 2018-2020 identified Dissolved Air Flotation (DAF) as the new treatment method to most effectively limit the formation of DBPs. Pictured above is the outside of the pilot testing facility at West Parish Filters and (below) the small-scale DAF filters used as part of pilot testing. 

Currently Underway: Building the Next Era of Water Treatment

Planning, design, and construction of a new drinking water treatment facility of this size is a complex and lengthy process (the original construction of Borden Brook Reservoir, Cobble Mountain Reservoir, and West Parish Filters took more than 30 years to design and complete). The Commission is accelerating and advancing this process as quickly as possible with plans to complete construction by 2027.

The first phase of construction began in 2021 and includes:

    • Clearwell and Backwash Pump Station Replacement – The replacement of the existing 1925 clearwell and 1974 backwash pumps with more modern, efficient, and reliable equipment is underway. Construction of the new clearwell and backwash pumps is on schedule and expected to be complete in 2024.
    • New Chemical Storage and Feed Building – Upgrades include improved safety measures such as sprinkler and fire protection, as well as improvements to the storage of the plant’s primary coagulant. The project started in 2021 and is expected to be completed by summer 2022.

Exterior panels being lowered by crane to the new clearwell, October 2022.

Demolition of 1909 slow sand filters began in December 2021 to make way for the new clearwell structure. 

Backwash pumps dating from the 1970s will be replaced with modern, redundant backwash pumps.

Upcoming: Design Approval and New Treatment Plant Construction

Water treatment plants are carefully calibrated to the specific chemistry of the water source and must receive multiple regulatory approvals.

The engineering and design firm selected by the Commission is currently designing the treatment plant upgrades, including the dissolved air flotation clarification process. Final designs of the new treatment plant must be approved by MassDEP before construction can begin. Following MassDEP approval, construction of the DAF facility and treatment plant upgrades is anticipated to start in 2024 at an estimated cost of $238 million. Completion of construction is expected in 2027.

Conceptual rendering of new treatment plant (rendering by AECOM)


In fall 2021 the Commission announced it had received a $250 million low-interest loan from the highly competitive U.S. Environmental Protection Agency’s (EPA) Water Infrastructure Finance and Innovation Act (WIFIA) Program. WIFIA Program financing will advance all plant upgrades on an accelerated schedule and save ratepayers approximately $60 million in borrowing costs over the next 30 years.

The new water treatment plant is estimated to cost $238 million. WIFIA financing will allow the majority of construction to occur simultaneously over the next six years.

Matching funds for the WIFIA Program are being financed in part by the state’s competitive Drinking Water State Revolving Fund (DWSRF) program, which provides low-interest loans for drinking water projects. One DWSRF project is the Clearwell and Backwash Pump Station Replacement project, which received $25.08 million in SRF financing. In 2022 the Commission received a $4.96 million grant in the form of loan forgiveness for this project from the Clean Water Trust.

Click here to learn more about the WIFIA Program financing and other projects included in the Commission’s portfolio of WIFIA projects or view an interactive map which highlights the planned water and sewer improvement projects and their locations throughout our region.

Executive Director Josh Schimmel, Acting Regional Administrator Deborah Szaro (EPA Region 1), Congressman Richard Neal (MA-1), EPA Assistant Administrator for Water Radhika Fox, Springfield Mayor Domenic J. Sarno, Commissioner Vanessa Otero (SWSC), MA DEP Commissioner Martin Suuberg, Commissioner Daniel Rodriguez (SWSC), Commissioner William Leonard (SWSC), and Agawam Mayor William Sapelli appear at a funding announcement at the site of the Connecticut River Crossing Project on Bondi’s Island.