Skokie, known as Niles Center until 1940, was originally a small farm community. The Skokie sewer system was constructed in the 1920's and was designed to carry both sanitary flows and storm water runoff to the water treatment plant with overflows to the North Shore Channel during heavy rainstorms. The system was more than adequate for a small rural community; however, modern Skokie, developed by the post-war housing boom and the construction of the first interstate highway out of Chicago, altered the above-ground landscape and created a storm water runoff control problem. After a heavy rainstorm, Skokie's storm water receded too quickly and overwhelmed the sewer system. This created back up of combined sewage in basements throughout the Village, presenting both a health hazard and threats of property damage.

A Storm Water Relief Task Force was organized in the early 1980's. Their challenge was to find a system to control storm water runoff. The task force's research showed that a traditional solution to storm water runoff problems included separating storm and sanitary sewers or the installation of large sewers to carry storm water away from the Village to a reservoir, tunnel, or lake. Unfortunately, the cost of implementing these solutions in Skokie would have exceeded $160 million (1980 dollars). At that time Skokie's annual budget was about $30 million. Disappointed but determined to find a solution, the Village Board hired an engineering consulting firm to develop a more workable and affordable solution.

After research and analysis, the Village and its engineering consulting firm determined that the most effective program consisted of a four-phase engineering process that would eventually lead to the reduction of sewer system overload and water surcharge into homes and businesses. The phases of the project involved an engineering review of all building and sewer elevations, sewer capacity, street-ponding and alternative storm water detention areas. The resulting program was a highly engineered storm water runoff system that complements the natural flow of water (through the laws of gravity) by altering street elevations and adding water detention areas where necessary.

The Village also adopted four ordinances specifically designed to control storm water runoff. The first ordinance required all redevelopment projects (Old Orchard, Village Crossing, etc.) to contain storm water in a manner that will not adversely impact surrounding properties. The second ordinance required the disconnection of all downspouts from household sewer lines. The Village determined that approximately 30% of the rain in the Village falls on roof tops. When downspouts are disconnected from the house drains, this high volume of water is released onto grassy areas and parkways and diverted from the sewer system. The third ordinance requires overhead sewers in all new residential construction. Finally, in 2001, the Village Board adopted an ordinance which requires an engineering drainage plan for all new residences as well as large additions to existing residences.

Catch Basin: An underground structure, usually at the curb line, with an open grate cover on the surface. It collects storm water from the streets and pathways.

Combined Sewer System: A sewer system which conveys both sanitary sewage and storm water. When this type of sewer surcharges during rainstorms, combined sewage may travel down the house sanitary line into basements.

Dropshaft: A large, vertical shaft used to connect to the Metropolitan Water Reclamation District's Deep Tunnel system. During construction, dropshafts are used as an access way for workers and equipment and for removing excavation material. Dropshafts are used to convey sanitary and storm water from the Village sewer system to the Deep Tunnel.

Flow Regulators: A fixed device located in a catch basin that restricts the rate at which storm water runoff enters the Village sewer system. These regulators cannot be manually adjusted. They are fixed openings that slow down the flow of water into sewers.

Interceptors: Large sewers which transport sewage and storm water from Skokie and other Metropolitan Water Reclamation District of Greater Chicago member communities to the MWRD treatment plant at Howard Street and McCormick Boulevard.

Private House Drain: The private drain is the connection from residential property to the main sewer. The drain carries waste material from the residence to the Village sewer. Maintenance and care of this connection is the property owners' responsibility.

Relief Sewer: Sewers installed to supplement and/or relieve the combined sewer system to prevent surcharging of sewage into basements.

Roadway Berms: A section of street pavement that is constructed to create mini dams to safely maximize the ponding of storm water on the street surface.

Storm Sewers: A sewer system that only conveys storm water.

Surcharge: When combined sewers fill beyond capacity, water may flow into homeowners' basements.

Trunk Sewer: A main sewer pipeline. In Skokie, a pipe that is 60"-90" in diameter, to which smaller collector sewers drain.

Underground Storage Facilities: Large diameter concrete pipes or large concrete tanks built underground to detain storm water runoff during heavy rainstorms. The facilities drain into the combined sewer system at a rate that is designed to prevent sewer surcharging. Some of these facilities are located under Skokie parks and public parking lots.

The TARP plan was named by the United States Environment Protection Agency (USEPA) as one of the nation's top Clean Water Act success stories. 

The Program: Part One

In the 1970's, the Metropolitan Water Reclamation District of Greater Chicago, with the U.S. Army Corps of Engineers, introduced a massive area-wide storm water storage/flood and pollution reduction plan called the Tunnel and Reservoir Plan (TARP). This plan features 125 miles of deep tunnels and three quarry size storm water/sewage reservoirs. The tunnel intercepts the combined sewer overflow and carries it to to a large reservoir. Prior to TARP construction, Skokie's combined sewers overflowed directly into the North Shore Channel. By allowing Skokie's sewers to overflow into the Deep Tunnel instead of directly into the Channel, the TARP Program substantially reduced the pollution level of the North Shore Channel. The Channel water quality is now much improved. The TARP plan was named by the United States Environment Protection Agency (USEPA) as one of the nation's top Clean Water Act success stories. It has served as a model urban water management tool worldwide. It also provides the Village with a better outlet for its existing sewer system and relief sewers, allowing Village sewers to operate at full capacity. The Skokie tunnel portion of TARP is located under the North Shore Channel at McCormick Street (see photograph on back page).

The Program: Part Two

In 1982, the Village began to design and construct a comprehensive storm water runoff control system which provided a cost- effective solution to address sewer back up into basements. The program was designed to contain rainfall resulting from a rainstorm of up to 2.1" in an hour. Street elevations, sewer capacity, rainfall amounts and quantity of land-use were studied prior to determining the location of berms and detention areas. Flow regulators were installed in catch basins to restrict the rate at which storm water runoff entered the Village sewer system. Restricting this rate mitigates the potential for sewers to fill beyond capacity. Restrictors were used in concert with roadway berms so that storm water could "pond" on streets. Ponding storm water allows Village streets to serve as temporary storage areas. Another important component of the comprehensive program was the construction and installation of above-ground and underground detention facilities and relief sewers. These detention facilities temporarily store storm water. Detention facilities are located under many parks including Lockwood Park, Devonshire Park, and Gross Point Park and above-ground at locations that include Golf and Karlov, Madison School and the Old Orchard Shopping Center. Approximately 30 million gallons of water are held above ground and 30 million gallons of water are held below ground.

Where We are Now

Since construction began in 1985, 16 projects have resulted in the construction of 623 roadway berms and 93 runoff control facilities. Over 3,000 flow regulators, 104,000 feet of sewers, and 3,710,000 cubic feet of storm water detention have been constructed at a total cost of just over $80 million. Thirteen of these detention facilities were constructed on either Park District or private property which resulted in significant construction cost savings. The Program is the single largest capital improvement project ever undertaken by the Village. Five of the projects were funded with $16.8 million in low-interest loans from the Illinois Environmental Protection Agency. Permanent flow monitoring systems have been installed to monitor and to fine tune the runoff control system.

A Work-In-Progress!

The Comprehensive Storm Water Runoff Control Program is a work-in-progress with enhancements or improvements undertaken whenever possible. The Village collects and analyzes storm water data after every rainfall. Sewer surcharge reports are plotted and mapped for analysis. The Village Water and Sewer Department cleans and maintains all Village sewers and ancillary structures within the public right-of-way. The 175 miles of sewers, 3,235 catch basins and 8000 inlets are cleaned and cleared of debris on a regularly, scheduled basis. Every opportunity is taken to enhance storm water runoff control on private, as well as public property.

To assist the Village with the on-going analysis of storm water runoff control, residents who experience a sewer surcharge are encouraged to call the Public Works Department at 933-8427. In addition, please contact Public Works if during a heavy rain your street is not ponding where it normally ponds.

To assist the Village with the on-going analysis of storm water runoff control, residents that experience a sewer surcharge are encouraged to call the Public Works Department at 933-8427.

Frequently Asked Questions

There are a number of different types of valve systems to consider. All of the valve systems use a gate-like devices to prevent sewage in an overloaded main sewer line from backing up into your basement. A manual system can prevent back up during a severe storm if the valve is closed by hand prior to the main sewer backing up. The valve in an automatic system closes as soon as the water begins backing up. Most automatic systems also have an ejector pump that pumps out water on the house side of the valve against the pressure of sewer backwater in the street sewer.

Overhead Sewer

This system diverts sewage from the first and second floors to a new sewer line that runs above the basement floor. The old sewer system is sealed and drainage from the basement level is pumped up into the overhead sewer. This system is more expensive than a valve system; however, it is the most effective. Even during a power outage upstairs plumbing fixtures may still be used.

Note: A licensed plumber must install these systems. In addition, permits and inspections are required by the Village's Building Department. Please call 933-8223 for a permit.

The rainstorm has passed, why can't the Village "open the valves" and eliminate the street ponding immediately?

Answer: Their are no valves or buttons to push on this system. The system operates by gravity and the natural flow of water into the sewers. The restrictors are in place to regulate the speed in which the water enters the sewers.

Why have the neighboring communities been experiencing such high levels of flooding lately?

Answer: Rainfall is unpredictable and in the last few years major storms have produced amounts of rain that have exceeded the capacity of storm sewers. According to the National Weather Service, the Chicago area experienced the highest levels of rain in 131 years during the months of August through October 2001. In fact, during this period, Chicago received 26.34" of rain or 251% of the normal rainfall amount for the year. Expressway flooding may occur during heavy storms. The Village's sewer system can contain up to 2.1" of water in one hour. Storms with rain volumes over that amount or successive heavy rain storms may overload the Village's sewer system.

What can I do to help alleviate flooding?

Answers:

This latest revision of the Storm Water Runoff Control Program guide incorporates information requested by Village residents both during and after a storm. The brochure is a public resource guide that is available from the Village of Skokie Public Information Division and at www.skokie.org. For additional information on the Village's Storm Water Runoff Control Program please visit www.skokie.org or check out the award-winning Skokie Storm Water Runoff Control Program video at the Skokie Public Library.

Final Notes