Union Park CSO Detention/Treatment Facility (MWRA # 6265)

Location: South Boston, Massachusetts
Contract Value: $45,081,577
Project Dates: April 2003 – October 2006

This project involved construction of the Union Park Combined Sewer Overflow Detention-Treatment Facility complex in the middle of a Boston residential neighborhood.

We received high marks from the Owner, neighborhood businesses and residents, and local community groups for our ability to perform heavy construction in their midst without major disruption to their daily routines and with a minimum of impact to their quality of life.
The existing Pumping Station provides flood control and the new Detention/Treatment Facility (DTF) provides CSO detention and treatment for the South End of Boston.  The operation of the Pumping Station was maintained throughout the duration, and portions of the new work were delivered prior to completion of the project to maintain operation.

The abandoned 90-year-old pump station foundation was located beneath the site of the proposed DTF.  Discovered within the foundation was the station’s machinery and oil tanks.  The contaminated soil, old pumps, equipment and tanks were removed from the site; approximately 20,000 gallons of contaminated water and 60,000 tons of contaminated soil were tested, excavated, sorted, handled, transported and disposed of.
Excavation for the 140’ x 260’ detention tanks reached a depth of 40’.  The extensive earth support system included sheeting that was driven adjacent to active city streets up to the back edge of sidewalks, and abutted the circa 1915 landmark brick building which housed the current pumping station.

The underground detention basins with a combined storage capacity of 2.2 million gallons were topped with a newly constructed building to house the treatment facility equipment including new pumps, screening, disinfection and odor control systems.