CSO Public Notification Plan

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flooding on street[1] 

November 2019
City of Evanston NPDES Permit No. ILM580002

Identifying the Affected Public

The City solicited comments and feedback from the affected public in the development of the Combined Sewer Overflow (CSO) Public Notification Plan. The City considers the affected public to include governmental organizations, civic groups, recreational groups or any public citizen with an interest in or responsibility for the condition of the Chicago Area Waterway System (CAWS). Currently, the City identified the following organizations to be among the affected public: the USEPA; the IEPA; the MWRDGC; the Village of Skokie; the Skokie Park District Rowing Center; the Evanston Ecology Center; the Evanston Environmental Board; and other environmental organizations. Other groups which are to be specifically identified include the recreational and commercial users of the CAWS such as canoe or kayak clubs, high school or collegiate rowing teams, and owners of marinas.

The identified affected public was invited to the public meeting that was held on March 31, 2004. Comments and feedback were solicited at that time. Advisories about the planned public meeting were available on the City webpage, through the local news media, and direct notification when possible.

The City’s coordination with the MWRDGC

The City continues to coordinate the CSO Public Notification Plan in conjunction with the MWRDGC since the occurrence of CSOs is directly impacted by the operation of the MWRDGC sewer system. As such, the MWRDGC is aware of when CSO events occur and will display the occurrence of CSOs on their website. Additionally, the City will post signage at the City’s CSO Outfall locations, not posted by the MWRDGC, with signs similar to those being developed and in use by the MWRDGC and the City of Chicago.

Web Address Book

The District has developed an opt-in public notification system. Members of the public are able to sign up to receive e-mail and/or text notification of CSO events by accessing the District's website http://apps.mwrd.org/CSORegistration/Register.aspx. These parties will be sent an e-mail and/or text alert in the event of a known CSO or diversion to Lake Michigan. The alert contains a link to the District's CSO website where CSO discharges are displayed on an interactive map.

Web Page

The City created a web page on the City’s website that will link to the District’s website. The District has created a web page ( http://geohub.mwrd.org/pages/cso ) on the MWRDGC website to inform the general public of the occurrences of CSOs on the CAWS.  MWRD has developed a public notification program for combined sewer overflows (CSOs) into the Chicago area waterways in accordance with Special Condition 8.14 of the NPDES Permit for the O'Brien (North Side) WRP, Special Condition 13.14 of the NPDES Permits for the Stickney and Calumet WRPs, and Special Condition 14.12 of the NPDES Permits for the Kirie and Lemont WRPs.

A Graphic Information System (GIS) based map of the waterways appears on the web page depicting the occurrence of CSOs and waterway diversions to Lake Michigan. This map is updated on a daily basis seven days per week. The District includes its web address on all news releases and will also be included on those pertinent to CSOs and/or diversions to Lake Michigan.

The waterways represented on the map include the following: North Shore Channel, North Branch of the Chicago River, Chicago River, Weller Creek, Salt Creek, Addison Creek, Des Plaines River, South Branch of the Chicago River, South Fork of the South Branch of the Chicago River (Bubbly Creek), Chicago Sanitary and Ship Canal, Calumet-Sag Channel, Little Calumet River, Calumet River, and the Grand Calumet River.

Upon occurrence of a CSO in a given waterway segment, a point on the map will designate the location of that CSO discharge. Floodwater discharges to Lake Michigan at the Wilmette Pump Station, the Chicago River Controlling Works and the O’Brien Lock & Dam are indicated on the map at the respective lake outlet.

The on-line maps of CSOs are updated as the information becomes available and are typically certified within one week. The website provides the public with record of current and historic CSO/floodwater discharge events in the CAWS.

In conjunction with the above map, a CSO Synopsis Report that provides “start and stop” times for individual CSO discharge points is also available on the website. The CSO Synopsis Report allows the City of Chicago and TARP municipalities to see the time and duration of the respective CSO discharges.

A link is also established to allow users to access a table of over 10 years of CSO events at the North Branch Pump Station, the Racine Avenue Pump Station, Westchester Pump Station, 122nd Street Pump Station, 125th Street Pump Station, and the 95th Street Pump Station. (https://legacy.mwrd.org/irj/portal/anonymous?NavigationTarget=navurl://4b3d1fb27a53520a9e29c00e75beb51d ).

In addition to the graphic map display and detailed CSO information, general information regarding CSOs and floodwater discharges to Lake Michigan, along with their implications, are included for informational purposes:

What is a combined sewer overflow (CSO)?A CSO is a discharge from a combined sewer system directly into a waterway. A combined sewer system is designed to collect a mixture of rainfall runoff, domestic and industrial wastewater in the same pipe for conveyance to a wastewater treatment plant. A CSO may occur during heavy rainfalls when the inflow of combined wastewater exceeds the capacity of the combined sewer system and the wastewater treatment plant. The CSO outfalls to the waterway act as relief points for the excess flow in the sewers, thereby reducing the frequency and severity of sewer backups and flooding.

What are the impacts of CSOs?Although CSOs may contain highly diluted sewage, they may cause temporary water quality degradation in the waterways. Contact with waterways should be avoided following the occurrence of CSOs.

Why does the Chicago area have CSOs?Chicago and the older suburbs, typical of other older metropolitan areas, have a combined sewer system, in which both sanitary waste and storm water are conveyed in the same pipe. Suburbs built since 1950 have separate sanitary and storm sewer systems.

Where do CSOs occur?When CSOs occur, they impact every major waterway in the Chicago area including the following: North Shore Channel, North Branch of the Chicago River, Chicago River, South Branch of the Chicago River, South Fork of the South Branch of the Chicago River (Bubbly Creek), Chicago Sanitary and Ship Canal, Calumet River, Grand Calumet River, Little Calumet River, Calumet-Sag Channel, Des Plaines River, Salt Creek and Weller Creek. Due to the heavy urbanization in the Chicago area, CSO discharge points are numerous along these waterways.

What is being done to reduce the occurrence of CSOs?The MWRDGC’s ongoing Tunnel and Reservoir Plan (TARP) Project was implemented to alleviate the polluting effects of CSOs and to provide relief from local flooding by providing holding capacity for 17.5 billion gallons of combined sewage in its tunnels and reservoirs until it can to be pumped to the water reclamation plant for full treatment. Significant benefits have already been realized since the completion of the tunnels, Majewski Reservoir in the Upper Des Plaines System, and Thornton Reservoir in the Calumet System. It is estimated that more than 905 billion gallons of CSOs have been captured and conveyed to the water reclamation plants for full treatment between 2005 and 2014. Since TARP went online, the waterways have seen an increase in both the fish population and number of species present; basement and street flooding have been reduced; and there are fewer floodwater discharges to Lake Michigan. Completion of Stage 1 of the McCook Reservoir in 2017 and Stage II of the McCook Reservoir in 2029 will further increase these benefits. To date, over $3.8 billion have been spent on the project. The Thornton and McCook Reservoirs alone will provide over $150 million per year in benefits to the local communities. In addition to TARP, the District maintains and operates its collection system to maximize storage and optimize transportation of combined sewage to the treatment plants. This is accomplished by conducting a regularly scheduled program of maintenance which includes sewer inspection, cleaning, videotaping activities, and inspection of diversion and bypass structures.

Why do floodwater discharges to Lake Michigan occur?During extremely heavy rainfall in the Chicagoland Area, storm runoff empties into the waterways system causing the water level to rise. The water level may rise to a level sufficient to submerge the CSO outfalls, thereby reducing the rate of discharge from the outfall. This can result in basement backups and local flooding. The discharge of floodwaters to Lake Michigan occurs when the waterways reach high levels and threaten flooding of structures along the waterway and submergence of CSO outfalls. Since the initial operation of TARP in 1985, the number of times that floodwaters are discharged to Lake Michigan has been reduced. When TARP is fully complete in 2029, the number will decrease further.

How can the public reduce CSOs?During periods of high flow, every gallon of wastewater and stormwater kept out of the sewer system is a gallon that will not add to a CSO discharge. Examples of ways to reduce the wastewater load include avoiding unnecessary water usage, toilet flushing, dishwashing, clothes washing, and showering. Additionally, individuals and businesses could install rain barrels/cisterns to collect rainwater runoff from their roofs. This water would be used for garden/lawn watering and similar uses, thereby reducing both the impact of heavy rain events and the use for potable water for non-potable uses.