VIRTUAL TOUR OF GPSD
Welcome to the Greater Peoria Sanitary District (GPSD). The following is a visual tour of the facilities owned and operated by GPSD. This tour briefly explains how wastewater is collected and treated to protect our environment in Peoria County; especially our creeks, streams, and the Illinois River.
The Wastewater Collection System
Wastewater leaves residences and other buildings through 4-inch and 6-inch diameter building sewers. The building sewers are owned by the property owner to the point of connection with the publicly owned sewer. Maintenance and repair of the building sewer is the responsibility of the individual property owner. The Sanitary District does have drawings of the location of many of the building sewers throughout the District. You may contact the District’s Planning and Construction Department at (309)637-3511 ext. 4844 about the availability of a particular drawing.
Building sewers empty into 6-inch and larger collector sewers. These sewers collect wastewater from within subdivisions and commercial developments and empty the wastewater into trunk sewers. The trunk sewers are generally larger in diameter and collect the wastewater from several service areas with the Sanitary District. The collector sewers and trunk sewers are publicly owned, either by the Sanitary District or the City of Peoria. The sewers owned by the Sanitary District serve Bartonville, Bellevue, Peoria, Peoria Heights, West Peoria and portions of unincorporated Peoria County.
The collector sewers are cleaned regularly using modern equipment like the Combination Vacuum/Flusher truck shown here.
Wastewater from the trunk sewers empties into two interceptor sewers owned by the Sanitary District. The Riverfront Interceptor parallels the Illinois River and collects wastewater from the east side of Peoria from the southern valley up to Peoria Heights. The Kickapoo Interceptor follows Kickapoo Creek and collects wastewater from Bartonville, Bellevue, the west side of Peoria, and the far north side of Peoria. Including collector, trunk, and interceptor sewers, the Sanitary District maintains 716 miles of sewer. Construction of the Riverfront Interceptor is shown in this 1929 photograph.
The collection system is designed to carry wastewater by gravity following the natural drainage patterns of the land. When gravity drainage is not possible, pump stations are used to push the wastewater uphill through force mains to a point where gravity flow can again be used. The collection system has a total of 17 pump stations, 16 owned by the Sanitary District and 1 owned by the City of Peoria .
The Wastewater Treatment Process
All of the wastewater collected by the two interceptor sewers flows to the District’s wastewater treatment plant located on Darst Street in the City of Peoria. The treatment plant is designed to treat an average flow of 37 million gallons of wastewater every day. However, the plant normally receives and treats 20 to 25 million gallons of wastewater each day from residential, commercial, and industrial customers. During periods of extreme wet weather, the plant can treat up to 154 million gallons of wastewater each day.
Untreated wastewater, commonly called raw sewage, enters the Sanitary District’s wastewater treatment plant at the pretreatment building.
After entering the pretreatment building, the raw sewage passes through mechanically cleaned bar screens. The screens are parallel stainless steel bars that remove large objects such as paper goods, rags, and sticks.
After it has been screened, the wastewater flows into grit removal tanks. In these tanks, the velocity of the wastewater is slowed to settle out sand, gravel, and coarse non-organic matter. All material removed by the bar screens and grit removal tanks is placed in a dumpster and then hauled to a sanitary landfill for final disposal.
Following grit removal, the wastewater must be pumped to a level to allow it to flow through the next treatment processes. Pumping is accomplished with two Archimedes screw pumps. Each pump has a capacity of 60 million gallons per day (mgd). Additional pumps are available when flows exceed 60 mgd.
The next treatment step removes about 50% to 60% of the solids suspended in the wastewater. The primary clarifier shown here is one of four used to remove these “suspended solids” and begin the process of removing organic pollutants from the wastewater. A clarifier is simply a large quiet tank that allows the light solids to settle to the bottom of the tank. The clarified water flows over the top of the tank and on to the next treatment process. The solids that settle to the bottom are removed and pumped to solids treatment.