The Metropolitan St. Louis Sewer District (MSD) was formed on February 9, 1954, when voters approved the Plan of the District to provide a metropolitan-wide system of wastewater treatment and sewerage facilities for the collection, treatment and disposal of sewage. MSD began operations in January 1956 in an area roughly composed of the City of St. Louis and the portion of St. Louis County located east of Interstate 270. It took over the publicly-owned wastewater and stormwater drainage facilities within its jurisdiction and began the construction of an extensive system of collector and interceptor sewers and treatment facilities. Most of the remainder of St. Louis County was annexed by MSD in 1977.
MSD's service area now encompasses approximately 520 square miles, including all 66 square miles of the City, and 454 square miles (approximately 87%) of the County. The current population served by MSD is approximately 1.3 million. MSD owns and operates the System, which consists of wastewater, stormwater and combined collection sewers, pumping stations, and wastewater treatment facilities in its service area. MSD provides sewer collection, pumping and treatment services within three major watersheds located within the MSD's service area including the Mississippi River watershed, the Missouri River watershed and the Meramec River watershed. In addition, MSD provides a variety of other services, including sanitary sewer maintenance, stormwater sewer maintenance, floodwater control, monitoring of industrial waste, issuance of pretreatment discharge permits, engineering design and specification, construction of sewer lines, plan review and approvals, issuance of connection permits, public education and customer service.
Collection and Trunk Sewers and Force Mains
As of August 29, 2016 MSD owns and maintains 9,517 miles of collection and trunk sewers and force mains, ranging in size from six inches to 29 feet in diameter. Sewers maintained by MSD range in age from less than a year old to more than 150 years old. Approximately, 524 miles are more than 80 years old and 311 miles are more than 120 years old. They are classified as one of three types: wastwater, storm or combined. Sanitary sewers accommodate household and industrial waste. Storm sewers carry rainwater and surface water runoff. Combined sewers carry both types of waste. The System currently includes approximately 4,717 miles of wastewater sewers and force mains, approximately 3,043 miles of stormwater sewers and force mains, and approximately 1,756 miles of combined sewers that handle both wastewater and stormwater flows. Maintenance of the System is controlled and conducted out of three regional facilities.
Pumping Stations and Force Mains
MSD owns and maintains 278 pumping stations and 116 miles of force mains (which are included in the sewer system totals above). Pump station and force main support is divided into three geographic regions under a pump station manager. All pump stations are maintained regularly and monitored continuously. Of the 278 stations, 37 are floodwall, overflow regulation, and wet weather relief tank stations, five are stormwater and the remaining 236 are wastewater and combined sewage pump stations which move the flow of wastewater through the system and into treatment plants.
Wastewater Treatment Facilities
MSD currently owns and operates seven wastewater treatment facilities. These facilities treat an average flow of 350+ million gallons of wastewater per day ("MGD"). The Bissell Point and Lemay wastewater treatment plants are the District's two largest plants. Both of these plants serve the Mississippi River watershed. The Coldwater Creek and Missouri River wastewater treatment plants service the Missouri River watershed. The remaining wastewater treatment plants serve the Meramec River watershed.