West Parish Filters Facilities Plan

Raw water from Cobble Mountain Reservoir is filtered, treated, and disinfected West Parish Filters Water Treatment Plant located in Westfield, MA, before flowing through the distribution systems to homes and businesses in Springfield and several surrounding communities. The plant was originally built in 1909 and last underwent significant upgrades in 1974 with the addition of the rapid sands direct filtration plant.

With systems, equipment, and machinery at West Parish Filters nearing the end of their useful life, the Commission recognized the need modernize the facility to provide reliable drinking water service and comply with drinking water standards set by the Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MassDEP).  

In 2015 the Commission initiated a comprehensive plan for modernization upgrades to West Parish Filters. Planning and design for this type of large scale project takes many years and requires a special approval process.  

The West Parish Filters Facilities Plan includes plans for:

  • Dissolved Air Floatation (DAF) Clarification Process or Pre-Oxidation Treatment – to more effectively remove suspended particles and dissolved NOM prior to filtration
  • Rapid Sand Filter Upgrades – to more effectively capture and filter out dissolved NOM
  • New Electrical System – to support new treatment processes
  • New Chemical Storage and Feed Building – to support new treatment processes

The addition of a clarification process or pre-oxidation treatment will improve water quality and compliance with drinking water standards, including standards for haloacetic acid 5 (HAA5). HAA5 is a disinfection by-product that forms when chlorine reacts with dissolved natural organic matter (NOM) found in surface water supplies, such as Cobble Mountain Reservoir. Dissolved NOM enters the reservoir from rain and snow melt from the surrounding forest. Both the amount and types of NOM in the reservoir impact the levels of HAA5 in the treated water. As part of the treatment plant upgrades, a new treatment method will be added to remove more of the NOM present in the raw water.  

As part of the planning process the Commission launched a pilot testing site in the fall of 2019.  Water treatment plants are carefully calibrated to the specific chemistry of the water source and must receive multiple regulatory approvals. At the pilot site, researchers conduct testing and gather data to analyze what types of treatment methods would work best with the unique composition of the raw water in Cobble Mountain Reservoir, the source of the Commission’s drinking water.  The pilot testing results are being analyzed by a Commission team including a panel of national experts, and will inform the new treatment upgrades. Upon completion of the pilot testing, in September 2020, the Commission will immediately begin design of the treatment plant upgrades.

The design phase is scheduled to begin in 2021. After the design is approved by MassDEP, construction will begin in FY24.

An exterior view of the pilot plant installed at West Parish Filters, Fall 2019.
An interior view of the pilot plant installed at West Parish Filters, Fall 2019.