Understanding Mount Prospect Sewer Systems

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A Brief History...

When the Chicago area was initially settled by pioneers in the early 1800s, outdoor privies were utilized for sanitation and drinking water was pumped from shallow wells. However, due to the flat topography of the area, and the sandy soil near Lake Michigan, settlers were soon plagued by waterborne diseases caused by privy water contaminating nearby drinking water wells. To correct this problem, settlers decided to start drinking water from the lake.  The separation of drinking water from wastewater was an elegant solution that worked well for a few years. However, the early settlers were also plagued by large rainstorms and frequent flooding; as is the case until this day. After all, most of early Chicago was constructed on an area that had formerly been marsh land. To solve the flooding problem, early Chicagoans laid sewers that drained the marsh areas and discharged to the Chicago River. At that time, the Chicago River discharged into Lake Michigan.

The new sewers worked extremely well. They not only drained the land, they also drained the outdoor privies as well. However, by that time, Chicago had grown so much that outdoor privies were no longer tolerated. Instead, homes and buildings were simply connected to the new sewers. All wastewater (both sanitary and industrial), as well as all storm water, was discharged to the local river system via sewer pipes.

These first sewers were "combined" sewers; both sanitary waste and storm run-off were collected and conveyed in the same pipe.

Certainly, city leaders of the time realized that their new sewer system was ultimately discharging into the source of their drinking water (Lake Michigan). However, they embraced a common belief of the time that "dilution was the solution" to avoid contamination of their drinking water. That is, they believed that the large volume of fresh water in Lake Michigan, along with the curative characteristics of sunlight, would cleanse their wastewater flows. Unfortunately, this belief was proven misplaced time and again resulting in frequent outbreaks of waterborne diseases such as cholera, typhoid, and dysentery.

By the late 1800s, as the city rebounded from the Great Chicago Fire of 1871, a plan was drawn to separate wastewater from drinking water by more effectively reversing the flow of both the Chicago and Calumet Rivers. This plan resulted in the construction of the Sanitary and Ship Canal as well as the Calumet Sag Channel. These waterways utilized a series of locks to climb and descend the drainage divide. They permanently reversed the flow of both the Chicago River and the Calumet River. The project was extremely innovative requiring the development of new techniques and equipment. Much of what was learned during the construction of these channels was later applied to the excavation of the Panama Canal.

To manage these massive projects, and operate the expansive sewer and drainage systems associated with them, the Illinois legislature created the Sanitary District of Chicago in 1889. This agency would become known as the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC). Although its name implies association with the City of Chicago, it is actually a creature of state government. Today, in addition to operating the canals, the MWRDGC is responsible for wastewater treatment and flood management throughout most of Cook County.

In response to the Supreme Court ruling, the MWRDGC began constructing wastewater treatment plants. 

One of the first plants constructed was the "north side" plant situated on the Skokie/Chicago border. This plant began operating in 1928. To feed this plant, the MWRDGC constructed large diameter transmission sewers to intercept existing local sewers just before they discharged into waterways. On dry days, these "interceptors" carried most of the wastewater to treatments plants. When it rained, the interceptors would quickly fill and the local sewers would discharge directly into local waterways as they had for decades.

This was the state of affairs when the first sewers were constructed in the Village of Mount Prospect during the 1920s. Finger-like interceptor sewers stretched out from the MWRDGC Skokie plant and intercepted Mount Prospect sewers just before they discharged into Weller Creek and the Feehanville Ditch.