History

The Downriver Wastewater Treatment Facility is owned by 13 Downriver communities and operated by the Wayne County Department of Environment. The interceptor and trunk sewers leading to the plant are also owned and maintained by the Department of Environment on behalf of the thirteen Downriver communities. The thirteen communities own the lateral and collector sewers that lead into the interceptor sewers. Each community has a contract with the county to discharge a specific amount of wastewater into the county's interceptor sewers. This is frequently referred to as purchase capacity.

The origins of the Downriver Wastewater System can be traced back to the World War I era and the early 1920s, when sewers were constructed by Wayne County to serve communities along the Detroit River. In the late 1920s, these sewers were extended to serve the Wayne County Drainage District No. 5 and the Le Blanc Drainage District. During this period, most of the sewage discharged directly to open drains and the Detroit River without treatment.

Down to a science: The staff of the Wayne County Wastewater Treatment Plant are continuously monitoring influent and effluent sewage, and performing rigorous tests to ensure the safest treatment of wastewater.

The wastewater treatment plant and the River Drive Interceptor were constructed in the late 1930s. This system, as originally constructed, provided primary treatment for a flow of 30 million gallons of sewage per day. As the area grew, so did the need for additional treatment capacity. During the 1960s the plant was expanded to provide additional primary treatment. The geographic area served by the system was also enlarged at this time; interceptors were constructed to service most of the present Downriver area.

In 1975, the wastewater treatment plant was again expanded, and secondary treatment facilities were added. The expanded plant had a capacity of 100 million gallons per day.

Significant improvements were also made to the collection system by local communities during the 1970s and 80s. These improvements include:

• Extensive renovation to the Southgate-Wyandotte Sewer System, including the construction of relief sewers and the Pine Street Pump Station to improve transportation of wastewater within the sewer pipes. CSO treatment facilities were also added to handle flows beyond the treatment plant capacity.
  
  
• The city of Taylor separated their combined sewers.
  
  
• Dearborn Heights and northern portions of Taylor constructed an excess flow storage facility.
  
  
• The cities of Allen Park and Lincoln Park separated their combined sewers and constructed excess flow storage facilities.
  
  
• The city of Riverview constructed the Riverview Interceptor.

The late 1980s and early 1990s also brought a number of process improvements at the wastewater treatment plant aimed at complying with changing NPDES permit requirements.

Ultraviolet disinfection processes were put into service in November 2001. This technology uses ultraviolet light to perform the task of disinfection, replacing the chlorine processes previously in use. At the time of installation, the Downriver Wastewater Treatment System was the largest application of this technology in the United States.

Downriver Wastewater Plant Improvements

Treatment processes were completed in 2001, allowing the plant capacity to more than double. The plant now has a treatment capacity of 150 million gallons per day under normal conditions, and 225 million gallons per day under extreme wet weather conditions. This capacity enables the plant to effectively treat sewage and accompanying high flows during severe rain storms. 

The improvements and expansion were constructed in four phases. The first phase, completed in 1995, included improvements to immediately upgrade plant equipment and facilities in several critical areas. These improvements included new piping, replacement of portions of the plant grit removal and screened effluent systems, and construction of dechlorination facilities. Dechlorination is the final step of the treatment process where chlorine left over from the disinfection process is removed from the final effluent. 

Under the second major improvements phase, four belt filter presses were added to improve and increase solids dewatering and sludge handling. Sludge is the solid that is removed during the treatment process to clean the wastewater before discharging to the river. The plant now has six belt filter presses to dewater sludge before being transported to a landfill. Six sludge cake pumping units were also installed to transport the dewatered sludge (called sludge cake). Improvements were also made to the dewatering process. 

A new 30,000 square foot maintenance facility was also constructed as part of the second phase. This facility houses shops for machining, welding, sanding, painting, electrical, instrumentation and pump repairs. Finally, an 8,000 square foot addition to the existing Administration Building was constructed to provide space for increased activities and personnel. All construction for the second phase was completed in September 1996. 

Under the third phase, instrumentation and control improvements were constructed throughout the entire plant. New internal and external plant power lines were installed to provide all equipment with two sources of power (called redundant power). The main pumping station pumping units were upgraded to include better pumps and a new metering system. 

Improvements and expansions to the primary treatment process included the addition of a seventh primary settling tank, preliminary screening improvements, outside solids receiving facility, aerated grit and screening expansion.

Secondary treatment process expansions included the addition of a fifth aeration train (increased secondary treatment capacity from 100 to 125 million gallons), chemical feed facilities improvements and expansion, and chemical addition for pH control of the final treated effluent. The oxygen dissolution system was upgraded through new equipment that improves the oxygen mixing in the secondary treatment process. This gives the pollutant-destroying bacteria used in the treatment process more oxygen so they can better remove pollutants.

The fourth phase included a new disinfection system, a new low lift pump system, and a new outfall. The disinfection system provides increased capacity to disinfect treated wastewater. An ultraviolet system was selected as a cost-effective improvement upon current disinfection using chlorination and dechlorination systems. The Wyandotte plant now has the largest UV disinfectant facility in the United States. The low lift pumping system now has new pumps and improved controls to lift treated flow from the primary system to the secondary system. Lastly, the existing plant outfall capacity, previously limited to 120 mgd, has now been increased to 225 mgd capacity. Construction of this fourth phase has now been completed. 

The division is currently working on a State Revolving Plan (SRF) project plan to identify the capital needs for the future. This plan will be developed over the next several months and submitted to the Michigan Department of Environmental Quality in July of 2004.

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