Due to heavy rains last night and today, crews and contractors with the Metropolitan St. Louis Sewer District (MSD) have been forced to suspend repairs to the underground force main sewer break in Chesterfield, Missouri. Heavy rains moving through the area have created unsafe work conditions at the repair site. Additionally, the rain has resulted in higher volumes of wastewater traveling through the force main, further hampering repairs and hindering efforts to control the flow of wastewater into surrounding ditches that lead to the Missouri River.
The location of the break is just west of where Cordovan Commons Parkway turns into Howard Bend Station Road in Chesterfield, Missouri. The break was reported to MSD at approximately 5:00 AM on Monday, September 8. A temporary dam and pumping system remains in place at the site of the break to help prevent direct discharge to a drainage ditch that leads to the Missouri River. However, the rains have temporarily overwhelmed these measures and the discharge from the break has resumed entering the Missouri River.
To properly repair the force main, crews and contractors must find solid, durable pipe on either side of the break – a 12-inch gash along the top of the force main. In essence, the section of damaged pipe is cut out of the force main and replaced with a section of new pipe. For the new pipe to properly take hold, it must be connected to existing pipe that is not compromised or weakened in some way. Now that MSD personnel and contractors have been able to visually inspect the damaged pipe, it has been determined that approximately 100 feet of force main will need to be replaced. However, the pipe replacement must wait for dryer weather. Thus, repairs will not be complete until, at the earliest, this coming weekend.
Additionally, to visually inspect and repair the pipe, the force main sewer had to be temporarily shutdown. The shutdown caused several overflows from manholes along the force main route. Affected areas include:
• 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.
• Portions of Caulks Creek.
• Portions of Bonhomme Creek.
Shutdowns of the force main will continue intermittingly throughout the repair effort.
MSD has placed warning signs in these areas, advising the public of the overflows. While there is no immediate threat to public health or safety, the public is asked to heed the signs and avoid contact with the affected areas. If a member of the public should come in contact with these areas, they should immediately and thoroughly wash with soap and water.
MSD will continue to monitor manholes in the area. If a member of the public should come across what they suspect to be an overflowing manhole, they should contact MSD’s 24-hour Customer Service Center at (314) 768-6260.
Once full operations of the force main sewer resume, cleanup at the break and associated locations will commence. While an exact timeframe is dependent on how long the force main takes to repair, cleanup will take at least several days.
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 in question was built in 1983 and a replacement is currently under design. Construction of the replacement force main is expected to start in 2016 at an estimated cost of $6.5 million.
The force main sewer break and associated manhole overflows have been reported to the Missouri Department of Natural Resources, as required by law.