Midland overflow abatement project, Onondaga Lake Improvement

In its efforts to improve water quality in both Onondaga Lake and Onondaga Creek, Onondaga County is building the Midland Regional Treatment Facility (RTF) and 2 miles of conveyance piping.

Between Newell and Tallman streets, twenty-one overflow points discharge combined sewage to Onondaga Creek fifty to sixty times per year. The overflows create human health risks because they contain bacteria and degrade water quality, and they are the source of odors to the area.

Nine of these CSOs will be connected to the Midland overflow abatement facilities now under construction. The remaining twelve are being eliminated through sewer separation projects.

Work underway (April 2007)

Phase II construction continues

The specialty metals subcontractor worked on installing walkways and stairs in the vortex separator room. The plumbing contractor continued to install roof drains and leaders in the RTF. The HVAC contractor continued to install supply and return water lines for the unit heaters in the RTF. The electrical contractor continued to install switchgear and conduit in the RTF, lighting in the underground storage tank, and conduit and panel boxes in the underground disinfection tank.

Total amount of concrete poured to date is 19,885 cubic yards of an estimated 23,000 yards for the completed facility. Concrete work this month included the chemical room floor, tank retaining walls, and equipment pads.

For the exterior walls and the interior walls, 100% of the concrete masonry units (CMU) have been installed. Work has begun on the exterior brick.

Geotechnical monitoring instrumentation reports continue to be compiled and submitted to the County and consultants for review.

Upcoming work

For Midland Phase III this month, bids were advertised on April 23 and will be opened June 6.

Objectives

Onondaga County's will meet or exceed federal and state water quality requirements to reduce CSOs and make improvements to the area affected by construction. The RTF project will significantly improve water quality of Onondaga Creek and Onondaga Lake. It will reduce human health risks associated with discharge of untreated sewage into the Creek and Lake and eliminate odors caused by discharging overflows.

Project description

Existing collector and trunk sewers in the Midland service area can store 74% of the average annual wet weather flow. The piping now under construction will store another 18%. All of this stored flow will be conveyed to the Metropolitan Syracuse Wastewater Treatment Plant (Metro) for treatment and disposal. The remaining 8% (about 77 million gallons annually) will be handled by the RTF.

This 8% of the total flow will be treated at the RTF by swirl concentrators (vortex units), disinfected, dechlorinated, and discharge to Onondaga Creek. Besides the vortex units, the RTF will include a pumping station, odor control and ventilation equipment, electrical and control equipment, chemical storage (liquid sodium hypochlorite and liquid sodium bisulfite), and a small office. The aboveground portion of the RTF will be 24,000 square feet and 24 feet high.

The RTF is not a sewage treatment plant. Sewage treatment plants typically operate 24 hours per day everyday and usually include a biological treatment process.The RTF will operate infrequently. It will fully operate and discharge only when the 7.2 million gallons of storage—included in the large diameter conveyance pipes, underground storage tank, and RTF influent wet well—is exceeded. Even then, a treated discharge to Onondaga Creek will only occur when the total 8.45 million gallons—including inherent storage in the vortex units and disinfection tank—is exceeded, approximately nine times per year.

Timeline

Onondaga County has been working to reduce combined sewer overflows in the Midland area for several years:

1969 Ownership of Midland Avenue and Elmhurst combined trunk sewers transferred from the City of Syracuse to Onondaga County.

1978 Tallman Street and Bellevue Avenue trunk sewers transferred from City to County.

Mid-1980s Onondaga County undertook a series of best management practices to improve the combined trunk sewer system and significantly reduced the incidence and volume of combined sewer overflows. Through the County's efforts, a number of CSOs were closed, and the volume of sewer overflows released to Onondaga Creek and Onondaga Lake was reduced by 90%.

1991 Onondaga County began plans to address and abate remaining CSOs with a 1991 facilities plan.

1996 Proposed municipal compliance plan (MCP) specified a CSO abatement project at the Blaine-Oxford streets site.

1998 The Amended Consent Judgment signed by the County, State, and Atlantic States Legal Foundation includes a regional treatment facility with vortex separation at the Blaine-Oxford streets site for the Midland sewer area. Design and construction of the project had required milestone dates for the County to meet.

1998-2000 As part of the planning and environmental review for the Midland project, Onondaga County re-evaluated potential locations for the Midland facilities and the technologies to be employed.

2000 Phase I: A 900-ft conveyance pipeline was installed to bring the Tallman Street CSO to the RTF site.

Fall 2000 Construction documents for the Midland RTF and related Phase II conveyances submitted to NYSDEC

Fall 2001 City of Syracuse Common Council voted to refuse to sell necessary City-owned and -controlled land to the County for the project.

Nov 2001-Aug 2002 Onondaga County, independently and in cooperation with a mediation efforts of NYSDEC, identified and evaluated further alternatives to the proposed RTF.

Aug 2002 Onondaga County adopted a modified project plan reducing the number of vortex units from four to two and added 2.5 million gallons of underground storage—thus increasing the amount of CSO captured and reducing the amount to be processed through the RTF and discharged to Onondaga Creek after treatment.

Oct 2002 Onondaga County sponsors workshop on disinfection of wastewater with chlorine to demonstrate the effectiveness and benefits of this technology. Speakers included USEPA, NYSDEC, and Syracuse Research Corp.

Nov 2002 U.S. District Court rules that Onondaga County may condemn property owned by the City that is needed for the Midland project.
Engineers begin preliminary design for the County's preferred option.

Jan-Feb 2003 Revised and updated facilities plan submitted to NYSDEC for the Midland Avenue RTF and conveyances project.
Onondaga County Legislature authorized acquisition of property for construction, operation, and maintenance of Phase II Midland Avenue RTF and conveyances.

Mar 2003 Onondaga the County further modified its plan by locating most of the RTF and the underground disinfection tank on CENTRO property adjacent to the bus garage.

May-Jun 2003 Federal district court judge supports Onondaga County's right to use eminent domain with just compensation to acquire a City-owned property. City files appeal. County proceeds to purchase needed private properties and assists property owners in finding new homes and provides compensation for moving.

Jun 2003 Amended facility plan and revised engineering design report forwarded to NYSDEC for review.

Nov 2003 NYSDEC approves updated facilities plan and engineering design report.

Feb 2004 Contract for building demolition put out for bid.
Bids advertised for construction of Phase II Midland RTF and conveyances.

May 2004 Demolition contract awarded. Site demolition begins.

Aug 2004 Notices-to-proceed issued to general contractor and electrical contractor.
Demolition of structures on the construction site completed. Under agreement with the Syracuse Housing Authority, public housing residents located in the Blaine-Oxford area are assisted in finding new apartments. Relocations are to be completed by November 15, 2004.

Sep 2004 Construction begins with site preparation work. Perimeter fencing is installed, office trailers arrive on site, and the former apartment building at 115 Oxford Street is demolished. In all, seven structures are demolished, including five houses, purchased from their owners, an abandoned garage, and one apartment building.

Oct 2004 Oxford Street bridge is demolished. Work begins to relocate utility lines before relocating Main Interceptor Sewer which crosses the construction site.

County officials meet with area residents at a meeting of SUN-Tallman Action Council. Questions are asked and responded to regarding construction and the proposed schedule of construction activities.

Test wells are installed for dewatering.

Mar 2005 One segment of MIS on the Midland construction site replaced. Excavation begins for disinfection tank.

Jun 2005 Completed replacement of the 48-inch brick-and-concrete MIS segment across the Midland construction site with 54-inch high-density polyethylene plastic pipe.

Jun 2006 Conveyance line to Bellevue Regulator crosses Onondaga Creek.

Aug 2006 Onondaga County Legislature authorizes issuance of an additional $49,890,420 in bonds to pay increased cost of improvements for Midland facility. The Legislature also authorizes $218,100 for acquisition of real property for the construction, operation, and maintenance of the Midland project.