In January 2008, Onondaga County Executive Joanie Mahoney halted the construction of a sewage treatment facility in Armory Square. As an alternative, the County is now building this state-of-the-art, six million gallon stormwater storage facility and simultaneously investing millions of dollars in green infrastructure throughout the City of Syracuse to capture stormwater before it enters our sewer system.

Facility Details: The Clinton CSO Storage Facility Project is a 6 million gallon combined sewer overflow storage facility that will be constructed in the parking area between the elevated rail tracks and Onondaga Creek just south of the Armory Square area of downtown Syracuse (formerly known as the Trolley Lot). During wet weather events, the facility’s three, parallel 18-foot diameter, underground storage tunnels will capture flow from 9 combined sewer overflows (CSOs) in the vicinity of the former Trolley Lot. The wastewater will be stored in the tunnels until it can be conveyed via the main interceptor sewer to the Syracuse Metropolitan Sewage Treatment Plant (Metro) for treatment. The off-site conveyance piping, which will transmit the flow to the facility, was installed under the Clinton CSO Phase 1 and 2A conveyances projects completed in 2009. There will be additional on-site conveyance piping installed under this project to connect the existing sewers to the new facility. In addition to the tunnels there will be two above ground structures located at either end (east and west) of the parking lot which provide access to the tunnels and house the pumping, grit collection and odor control facilities.
Greening the Gray: To further enhance the sustainability of the facility, the project includes green infrastructure components. The stormwater runoff from the entire site that measures approximately 275,000 square feet (SF) or 6.3 acres will be managed by green infrastructure. The stormwater from the area surrounding the main structure on the western half of the site will be collected by a series of catch basins and stormwater piping that will outfall into two bio-retention basins. The bio-retention basins will allow the stormwater to infiltrate into the ground rather than immediately runoff to the creek. In addition, stormwater runoff from the eastern half of the project site, to be restored as a parking area, will be directed to a subsurface collection facility and used to flush the storage tank to clear them of grit and debris that may have settled or been left behind after the stored combined sewage was transmitted to Metro.
Construction Update: In October and November 2012, the contractor completed the installation of mini-piles for the valve house and the east side of the West Chamber; the concrete for the north and south inverts of the outfall to Onondaga Creek; the 48” casing under Onondaga Creek by micro-tunneling; and the mud mat from station 6+50 to 8+50. Construction also continued on the cast-in-basin with the installation of various transitional and mainline interior and exterior walls, invert slabs and soffits. In addition the contractor continued work on excavation and fine grading in the east chamber.
Construction Photo - October 4, 2012
Trolley Lot: When complete in December of 2013, the parking area will be restored and more importantly, this facility will prevent harmful sewer discharges into Onondaga Creek and Onondaga Lake. Onondaga County is working closely with the City of Syracuse, the Armory Square Association, and the Downtown Committee of Syracuse to ensure that the ample parking available in Armory Square is open, accessible and well-marked throughout project construction.
**UPDATE: In an effort to mitigate the loss of the Trolley Lot parking area, the the County and City have partnered to open the Washington Street Garage for extended hours & on weekends and provide parking after 4 PM on Thursdays and Fridays, and all day on both Saturday and Sunday. The Washington Street Garage is accessible from Washington Street, west of Franklin Street, or from West Water Street. Armory Square is one block from the Washington Street entrance and is accessible from the recently opened Onondaga Creekwalk.
Download Facility Specifications and Details Below:
Related media:
9 WSYR – Trolley Lot Project is Full Steam Ahead in Downtown Syracuse







