Stormwater Management/MS4 – Chicago Skyway

Skyway’s Municipal Separate Storm Sewer System (MS4) Program

What is a MS4 permit?

Under the Clean Water Act, municipalities and entities in urbanized areas are under a federal mandate to obtain a National Pollution Discharge Elimination System (NPDES) permit for discharges of Small Municipal Separate Storm Sewer Systems (MS4). Throughout the state of Illinois, the NPDES General Stormwater permit is issued by the Illinois Environmental Protection Agency (IEPA), also referred to as the ILR40 (MS4) permit. The MS4 permit requirements include a stormwater management program for reducing impacts from stormwater runoff by issuing MS4 permits.

What is stormwater runoff?

Stormwater runoff occurs when precipitation from rain or snowmelt flows over the ground. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater from naturally soaking into the ground. Click for more information.

What is included in a MS4 permit?

As part of the MS4 permit, the permittee is required to implement a stormwater management program with six minimum control measures and special conditions to be included in the program. These six minimum control measures are as follows:

Six (6) minimum control measures

1. Public Education & Outreach: The public education and outreach consists of measures and programs to educate the public about the impacts of stormwater discharges to receiving waterways and management practices to reduce pollution in stormwater.

2. Public Involvement/Participation: The public involvement and/or participation consists of meetings, resources, and events to promote the public participation in environmental programs.

3. Illicit Discharge Detection and Elimination: The illicit discharge detection and elimination consists of developing, implementing, and enforcing a program to detect and eliminate stormwater pollution.

4. Construction Site Storm Water Runoff Control: The construction site storm water runoff control measure consist of developing, implementing, and enforcing a program to reduce pollutants in storm water runoff from construction activities with 1 acre or more of disturbance.

5. Post-construction storm water management in new development and redevelopment: The post-construction storm water management measure consist of activities to reduce pollutants in storm water runoff, including best management practices and maintenance.

6. Pollution Prevention/Good Housekeeping for Municipal Operations: Pollution prevention and/or good housekeeping measures consist of educating and training Skyway staff to prevent and reduce stormwater pollution from Skyway owned operations.

How is the Skyway managing stormwater?

The Skyway developed a stormwater management program to reduce pollutant impacts in stormwater runoff. The MS4 permit required monitoring, record keeping, and reporting documents consists of the following:

Notice of Intent (NOI)–NOI is available to the public by IEPA or contact to request a copy.
Storm Water Pollution Prevention Plan (SWPPP)-SWPPP is available to the public by IEPA or contact to request a copy.
Salt Usage-Yearly salt usage during the winter months is available in the SWPPP or contact to receive a copy.
Storm Water Management Plan (SWMP)–SWMP is available to the public by IEPA or contact to request a copy.
Annual Report–2018 Annual Report and/or Annual Reports for subsequent years are available to the public, contact to request a copy
Monitoring–Monitoring results are included in the annual reports, in accordance to the latest permit requirements.
Annual Training–Training of Skyway employees on storm water management is conducted annually. The 2019 training was completed in October.

In a continual effort to improve the way the Skyway manages the reduction of pollutant impacts in stormwater runoff, we encourage public involvement and comments on the above information. Please direct all comments to environmental@chicagoskyway.org.

How is the Skyway managing chlorides?

In the Chicago region, elevated chloride concentrations in receiving streams during the winter season is primarily due to road salt. Implementing control measures is important to reduce chlorides discharged into receiving waterbodies. The Skyway’s commitment to proper management of chlorides includes the following activities:

Participation in an active watershed group-The Skyway participates in the Chicago Area Waterway System (CAWS) Chloride Initiative Workgroup
Salt storage-The Skyway covers its salt pile with a tarp when salt is not being distributed. Additionally, the Skyway is actively identifying a location for a more permanent enclosed storage structure for the salt.
Tracking Salt Usage-The Skyway tracks average annual salt usage for de-icing purposes per calendar year.