Repairs by the Metropolitan St. Louis Sewer District (MSD) to a break in the existing force main sewer in unincorporated St. Louis County were completed late Thursday evening. The location of the break was 673 Water Works Road, which is located near the Monarch Chesterfield levee. MSD has determined that pipe corrosion caused the force main sewer to break.
The break was first reported on Monday afternoon to MSD by Missouri American Water. MSD had a contractor working onsite to construct a new replacement force main sewer to run alongside the existing in-service force main sewer. Because the existing force main has experienced recent breaks, the contractor on the project is required to conduct daily visual inspections of the entire length of the existing force main for the duration of the project. This requirement allows for a rapid response by the contractor that is already onsite. The construction of the new force main was accelerated due to a history of breaks along this line, which was built in 1983. Construction began in March on the two-phase replacement project that is estimated to cost $6.5 million.
To properly repair the existing force main sewer, crews and contractors worked to find solid, durable pipe on either side of the break – The section of damaged pipe then had to be cut out of the force main and replaced with a section of new pipe. For the new pipe to properly be repaired, it had to be connected to existing pipe that is not compromised or weakened due to age. Approximately 60 feet of 24-inch diameter ductile iron pipe was replaced.
MSD will complete cleanup activities at the site of the break and other affected areas over the next 24 hours. The public is encouraged to avoid these effected areas:
• Caulks Creek near the intersection of Crystal Spring Drive and Brighthurst Drive in Chesterfield.
• Portions of the walk/bike trail that runs along the Monarch Chesterfield levee south of Chesterfield Commons.
• Other portions of Caulks Creek.
• Portions of Bonhomme Creek.
A force main sewer is a sewer line through which wastewater is propelled by the force of pump stations located along the path of the sewer. Pump stations are sometimes necessary to overcome gravity and allow for the transport of wastewater to area treatment plants. Force mains are made of cast iron and can last anywhere from 25 to 50 years, depending upon the amount of flow the line handles and the corrosive properties of the wastewater.
The force main sewer break and associated manhole overflows have been reported to the Missouri Department of Natural Resources, as required by law. The total volume lost from the force main and associated manholes is being calculated and will also be reported to the Missouri Department of Natural Resources, as required by law.