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Cleanup: Municipal Wastewater

Onondaga County has implemented several projects that have resulted in cleaner discharges of wastewater to Onondaga Lake. Its projects include improvements to the sewer collection system and improved treatment.

Collection System Improvements

Regional storage & treatment facilities
The Midland RTF and the Hiawatha RTF are complete and operating. Facility plans are available for the Harbor Brook CSO Abatement Facility and the Clinton CSO Abatement Facility.
Sewer separation
Where RTFs are not feasible—economically or hydraulically—the sewers in some CSO basins have been separated. The following are complete: West Water Street north, Taylor Street, Tallman Street West, onondaga Avenue (two), Marguerite and Hunt streets, West Brighton Avenue, South Avenue around Bissell, and Parkway-Rockland. The following are in design: Wallace and West Genesee streets, Tully Street, and Hudson and West Castle streets.
Floatables control facilities
FCFs have been installed at Maltbie Street, Franklin Street, Harbor Brook, and Teall Brook. In addition, a skimmer boat removed debris from the mouth of Onondaga Creek and the Inner Harbor area during spring and summer months.
Storage & transport improvements
Siphons under Onondaga Creek were rehabilitated. Storage under Erie Boulevard was revamped. The Kirkpatrick Street Pump Station was replaced, and a force main was built from the pump station to Metro. Phase I of a pipeline to serve the Midland RTF is complete.

Treatment Improvements

Advanced phosphorus removal
Onondaga County is reducing the phosphorus that reaches the Lake to extraordinarily low levels (0.12 mg/L as a 12-month rolling average). Onondaga County has met its first required 12-month rolling average (April 2006-April 2007) for Stage II phosphorus limits in its Metropolitan Syracuse Wastewater Treatment Plant effluent. The ACJ limit is 0.10 mg/L total phosphorus. In the future—by 2012—Onondaga County will reduce the phosphorus it discharges to Onondaga Lake to 0.02 mg/L. This is the most restrictive in the U.S. and perhaps in the world. The limit has been set low because Onondaga Lake is small and because it receives phosphorus from other sources (mostly from nonpoint source pollution).
Ammonia reduction
The final stage of the Metro improvements for ammonia treatment came on line in early 2004. The Biological Aerated Filter (BAF) system has resulted in year-round nitrification (conversion of ammonia to nitrate) in wastewater. Metro had reduced its annual discharge of ammonia from an average of 1210 metric tons (MT) from 1990-1997, to an average of 521 MT from 1998 to 2003. In 2004, the annual Metro ammonia discharge was reduced to 152 MT as the BAF system came on line. In 2005 the Metro contribution fell to 21 MT. As of 2005, Metro is no longer the largest source of ammonia N to Onondaga Lake. Lake ammonia concentrations in 2005 were the lowest ever measured, and remained at safe levels for even the most sensitive aquatic organisms.
General plant improvements
Several projects were undertaken to enhance the ability of Metro to treat wastewater, including insulation of the roofs of digesters #1 and #3, replacement of three waste-gas burners, ventilation improvements in the digester control house, installation of new instrumentation, replacement of a sluice gate, installation of new piping, and overflow weirs in the diversion structure.
Odor control
In the late 1990s, major improvements were made to the plant's headworks, the place where sanitary sewage enters the plant. A treatment building was constructed to house the system that controls odor-producing gases.
Improved aeration
In 1998, Onondaga County upgraded the entire aeration treatment system. A diffused air system was installed. Now, the aeration system pumps air through more than five thousand ceramic diffusers that cover the floors of the eight aeration tanks. This improvement in treatment corresponded to lower levels of ammonia in Onondaga Lake.
Improved communication & control
The Supervisory Control and Data Acquisition (SCADA) system was completed in 2001 to expand and improve Onondaga County's ability to monitor and control treatment at at six wastewater treatment plants and twenty-eight pump stations. It enhances the efficiency of the collection system and treatment processes.
Improved chemical storage
Onondaga County revamped its chemical feed system to meet new New York State chemical bulk storage regulations in 2000. It constructed a new chemical storage building and feed system along with the ancillary facilities of a new gas compressor station, new sludge polymer feed pumps, and related piping.
Digester modifications
Onondaga County upgraded sludge-handling at Metro in 2001. It made improvements to sludge digester tanks, the settling lagoons, and the gas compression system.
Biosolids handling
Onondaga County upgraded the handling of biosolids in 2007. A major component of the work was energy conservation through cogeneration.

Ambient Monitoring Program

Onondaga County conducts an annual program to evaluate the water quality conditions of Onondaga Lake, the lake tributaries, and a portion of the Seneca River. An Amended Consent Judgment signed in 1998 requires Onondaga County to complete three major tasks: to upgrade treatment at the Metropolitan Syracuse Wastewater Treatment Plant (Metro), to mitigate the combined sewer overflows (CSOs), and to implement an Ambient Monitoring Program (AMP) to track the effectiveness of these improvements to the wastewater collection and treatment infrastructure. The AMP builds on Onondaga County's historical monitoring program, which provides a basis for evaluating trends over time. Each year the County prepares an annual report of its findings.

The AMP is designed to identify sources of materials (nutrients, sediment, microorganisms, and chemicals) to the lake, evaluate in-lake water quality conditions, and examine the interactions between Onondaga Lake and the Seneca River. In addition to the water quality-related program, the AMP examines many levels of the biological community of the lake and its watershed. The AMP includes an assessment of zebra mussels, benthic macroinvertebrates, aquatic plants, phytoplankton, zooplankton, and fish.

A rigorous quality assurance/quality control program is in place. Results of internal and external audits, blanks, and duplicates are presented in the annual AMP report. Samples are collected by trained technicians and analyzed in a state-certified laboratory. The annual AMP work plan is subject to NYSDEC review and approval. Technical experts (the Onondaga Lake Technical Advisory Committee) review the program findings and interpretive reports each year.

Technological advances enable the County to monitor water quality on a near-real-time basis. A water quality buoy with an array of probes that measure physical and chemical characteristics of the lake water is deployed on the lake at its deepest point (referred to as the South Deep station). Data from the buoy provide a window into how the lake quality changes in response to winds and waves. Acoustic Doppler devices, installed at the lake's outlet by the U.S. Geological Survey, provide data needed to assess water exchange between the lake and the Seneca River.

As part of the annual AMP, Onondaga County tests over 20,000 water samples and examines several thousand biological samples. Data are appended to the custom long-term database developed by Dr. William W. Walker Jr. The database, which merges the County's tributary and lake data from 1968 to the current year, has greatly improved data management and reporting tasks.