Facility Information

 With the Fresh Pond Reservation as a dramatic backdrop, the Walter J. Sullivan water purification facility is located on the former site of the old water works buildings. The consolidated facility footprint - the purification, maintenance and administrative operations are under one roof. Vegetation and plantings are primarily native species designed to create an "urban wild" appearance.

The building relates to the site's natural surroundings, using complementary exterior materials of granite, brick, slate and cast stone. A two-story interior main lobby was designed with arched windows that allow natural light and unobstructed views of Fresh Pond. The stone entrance and two stone medallions of the state and city seals were saved from the former water treatment plant to become part of the new lobby. They form the background for the lobby's water fountain, designed in materials of granite, terrazzo and stainless steel. Art within the building lobby, designed by a local artist, celebrates water by way of a unique terrazzo floor design and an 11-foot glass water column that is an interactive display for the public. The column is connected to an exterior drinking fountain and comes to life with lights and bubbles when the drinking fountain is used.

The Treatment Facility produces drinking water from the raw water of Cambridge reservoir system. The drinking water from the plant is provided to the City of Cambridge. The staff includes a Production Manager, an Instrumentation and Maintenance Manager, Laboratory Manager, two Water Quality Supervisors, and eight fully licensed Drinking Water Operators classified as Team Leaders and Plant Operators.

The plant includes various intake structures and aeration equipment that extend into the pond. The rest of the treatment process is contained inside the Walter J. Sullivan Water Treatment Facility. The raw water is treated to State and Federal drinking water standards.

The processes that accomplish this include:

Aeration: The bubbling of air from the bottom of the pond keeps the waters of Fresh Pond mixed, preventing stratification by temperature. The mixing prevents and controls the release of manganese into the water.

Pre-treatment: This includes the pre-oxidation, rapid mix, coagulation and dissolved air flotation (DAF). These processes with the application of ozone and a coagulant chemical, alum, remove: manganese, natural color, particles, algae, protozoa, viruses and bacteria from the water.

Intermediate Ozone: In this step fine bubbles of ozone are dissolved into the water and disinfect the water by killing bacteria, viruses, and protozoa. The ozone in generated in the plant and introduced into the water in a series of chambers that allow contact and mixing of the ozone with the water. At the end of this process all the ozone introduced is removed from the water.

Granular Activated Carbon (GAC) Filtration: This step follows the ozone application to help remove any organic compounds that may have been rendered biologically active or useable by the ozone step. The filters further polish the water by removing additional particles, color and protozoa from the water.

Chlorination: The chlorination after the filters kills bacteria that may develop during the normal operation of the filters. The chlorination step also provides a level of redundancy in the overall disinfection process.

Post Treatment Chemical Addition: This includes the adjustment of pH for corrosion control, the addition of fluoride for dental health, and chloramination to provide a disinfection residual in the distribution system.