Integrated Water Management

Technical Assistance, John J. Carroll Water Treatment Plant


Technical Assistance, John J. Carroll Water Treatment Plant

Marlborough, MA


About this Project

After completing a number of successful Technical Assistance contracts for MWRA, FST was selected for a similar contract at the new Carroll Treatment Plant, providing services on an as-needed basis. FST makes available a wide range of engineering specialties to facilitate the smooth operation of this new facility. It began operations in 2005 to treat drinking water for 2.3 million people in 41 Metropolitan Boston communities, from Arlington to Boston, Swampscott to Quincy. Its capacity is 275 MGD average and 405 MGD, peak. Ozonation is used for primary disinfection and chloramination, for residual disinfection. Corrosion control and fluoridation are also used.

Bubbled through the water supply, ozone, which occurs naturally in the atmosphere, degrades and destroys the cell walls of bacteria, germs, and other organisms, including cryptosporidium, a waterborne pathogen that comes from animal waste. The ozone is highly effective against organic matter or contaminants.

In a lab analysis and taste test conducted by the local newspaper, MWRA's tap water was compared with various bottled waters. Participants in the taste test, which included panelists with sophisticated palates, all agreed that there was essentially no difference between bottled water and the MWRA tap water. But in price, MWRA's cost a half-cent a gallon comparing quite favorably with bottled water at 79 cents to $6.82 a gallon.

Sample task order assignments for FST included:

  • Shorten Treatment Plant Restart Time
  • Ultraviolet Disinfection Fouling Study
  • Design of Leak Repairs in Storage Tank
  • Entrance Security Study
  • Construction Administration Services for Ozone Cooling Water Upgrade
  • Design of Second Gaseous Oxygen Pipe
  • Final Design of Ammonia Feed Piping Upgrades
  • Design of Additional Instrumentation for Chlorine Residual Entering Storage Tanks


More Information

Owner: Massachusetts Water Resources Authority

Location: Marlborough, Massachusetts

Highlights: Since MWRA officials started using ozone, customer complaints about the taste of the water have plummeted from about 50 a day to just next to nothing. The amount of chlorine in the water has been reduced by about a third, along with chlorine byproducts, contributing to the greatly-improved taste.