City of Worcester Water Treatment

Faced with urbanization in watershed and aquifer areas, an aging and deteriorating infrastructure, and stricter water quality standards, the City of Worcester, in 1984, began planning to protect, preserve, and expand its supply of potable water. The city set its sights on construction of a new water filtration plant to filter ---for the first time ever---the drinking water for the 200,000 people it serves. The Safe Drinking Water Act Amendments of 1986 dictate that all surface water supplies must use filtration to treat drinking water if they cannot meet highly stringent water quality and reliability criteria.

Worcester’s Water Treatment Basics

• Plant Flow - 50 Million Gallons Per Day (MGD)
• Reservoir System - The treatment plant utilizes a series of ten surface water reservoirs located in Leicester, Paxton, Rutland, Holden, and Princeton. The ten reservoirs combined, hold over 7 billion gallons of water.
• Primary Disinfection - Ozone, generated by four ozone generators (one standby) from air with a system capacity of 834 pounds per day. The applied ozone averages 1 mg/L, with a design maximum of 2 mg/L.
• Rapid Mixing/Coagulation - Two-stages, utilizing vertical shaft radial turbine mixers. Coagulant chemicals are aluminum sulfate (alum) and cationic polymer.
• Flocculation - Three stages, having a total of 15 min. detention time and utilizing vertical- shaft, axial-flow flocculators. nonionic polymer is provided as a filtration aid.
• Filtration - Eight filters having a design filtration rate of 8 gpm/sf. Filter media consists of 60 inches of anthracite coal over 12 inches of sand. The filters are designed to accept activated carbon media if needed in the future.
• Corrosion Control - pH adjustment using lime, followed by an application of a blended orthophosphate corrosion inhibitor.
• Final Disinfection - Chlorine
• Treated Water Storage - Two, 2.75-million-gallon storage tanks.

This internship placement includes learning equipment operations (both field and lab equipment), chemical distribution, and water testing.  Some computer analysis also occurs.Thus, Worcester began the process of building a new 50-million-gallon-per-day plant to comply with federal regulations and, more importantly, meet the water quality and public health needs of the area.

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