Upper Mattese Trunk Sanitary Relief (12249)

Upper Mattese Trunk Sanitary Relief (12249)

As part of a long-term effort to reduce basement backups and sewer overflows, MSD[3] Project Clear[1] is designing a project to construct approximately 14,800 feet of wastewater pipe in St. Louis County. The project is estimated to begin construction as early as the Spring of 2024.

About the Project

Public Meeting - May 10, 2022

Project Map

Why is this project being designed?

As part of their evaluation, our team of engineers determined that the sewer in this neighborhood is undersized. During intense rainfall, the sewers become overloaded, leading to basement backups and wastewater overflows into local waterways.

What is the goal of this project?

MSD Project Clear is investing approximately $11 million to design and construct this project to increase the size of the existing sewer. This will reduce the likelihood of basement backups during heavy rainfall and prevent untreated wastewater from spilling into local waterways.

Project Facts

  • Construction is estimated to begin as early as Spring 2024.
  • MSD Project Clear will replace approximately 14,800 feet of wastewater pipe.
  • The pipe size will increase to between 8 and 36-inches in diameter, allowing a larger amount of wastewater to flow through the system.
  • MSD Project Clear will also restore impacted creek bank with gabion walls, heavy stone revetment, and vegetated earthen swales.

What can residents expect?

Though construction for this project is not estimated to begin until at least Spring of 2024, it is important to be prepared for what to expect. In the Summer of 2022, property owners from whom MSD needs to obtain new easements to construct the project will be contacted. MSD will not contact property owners with existing easements.

At this time, MSD Project Clear anticipates the contractor will use two methods to construct the project. Most of the project will likely be constructed by digging through the surface of the ground in a process known as “open-cut” construction. In the segments under Interstate 270 and Tesson Ferry, the contractor will use tunneling to avoid major traffic implications.

Traffic and Access: Because much of the construction will take place in unpaved areas, MSD anticipates minimal traffic disruptions. Drivers may experience temporary lane closures as construction crosses roadways. Traffic control will be provided as needed.

The contractor will follow all local ordinances and will notify all properties of any temporary access restrictions. As the majority of construction will take place in backyards, MSD anticipates minimal property access restrictions. The contractor will give all property owners ample notification prior to any access restrictions.

With any type of construction, residents can expect to see and hear heavy equipment and significant volumes of truck traffic during the sewer excavation process. The pictures above depict what a neighborhood will look like before, during, and after a typical project.

After all new sewer pipes are installed, the contractor will restore the construction site according to all local and District[2] requirements. This could include sodding any disturbed areas, replacing disturbed pavement, reinstalling fences, etc. In areas where the creek bank is affected, MSD will restore it using gabion walls, heavy stone revetment, and vegetated earthen swales.

At least one MSD Inspector will be on-site part of the day for every day the contractor is working.

What is the timeline?

This is the current tentative project schedule. This is subject to change based on a variety of factors including weather.

  • Complete Project Design: Summer 2022
  • Easement acquisition completion: Winter 2024
  • Estimated construction start: Spring 2024
  • Estimated project duration: Approximately 3 years


While MSD’s contractor is connecting a home’s lateral to the new wastewater sewer, they may ask residents to limit water use. In general, this process can take between two to five hours, depending on the complexity of the connection. The contractor will notify property owners in advance.

MSD does not anticipate other utility services being disrupted during this project. We will work with Missouri One Call to locate utilities before beginning construction. Occasionally, the contractor may run into utilities that were not located by Missouri One Call which could result in temporary utility disruptions. If this happens, MSD will work with the utility to restore service as quickly as possible.

Trees may need to be removed to construct parts of this project. If there are good options to avoid removing trees, MSD will make every attempt to do that. Property owners with trees that will need to be removed that are not located in already existing easements will have been compensated for the removal through the easement acquisition process.

In general, District policy is to restore affected areas to the same or better conditions than before the project. Streets that are disturbed through this project will be replaced and repaved with similar material. The project’s restoration will meet all local and District requirements.

During easement acquisition, an MSD Right of Way Agent will work with property owners to discuss restoration on their property. Most yard areas will be resodded with the same material. Driveways, walkways, and other hard surfaces will be restored using the same materials that are currently in place. In wooded ground areas, District policy is to seed the disturbed areas.

During active construction, some property owners may experience driveway access restrictions for a short period of time. The contractor will notify property owners in advance of any temporary access restrictions to allow them time to move their vehicles. The contractor will also fill trenches with gravel or place steel plates over trenches during non-working hours so residents can use their driveways during those times

MSD will instruct its contractor to keep the site reasonably clean and clear of debris. MSD will have an inspector on site every day during active construction. Prior to the start of construction, MSD will give every resident and property owner along the construction site the inspector’s contact information. Community members are encouraged to bring any concerns to the on-site inspector or any other member of the project team.

MSD constructed the St. Gemme Lane Area Relief Sewer[4] Project (S-1762) in the mid to late 1980s.  We connected the homes that were already connected, and installed wyes on the main for those not connected.  While our sewer use ordinance requires connections for properties within 200 ft of the sewer, MSD does not extend service to unserved properties. MSD will include wyes for the connections to avoid future damage to the main and to facilitate connections.

FAQs section will be updated as questions are sent in to the Project Manager.


This section will be updated with additional documents as they become available.

Stay Informed

(Please mention the Project Number: 12249)

Patricia Pride, MSD Project Manager

Terms defenitions
1. Project Clear. MSD Project Clear is a long-term initiative to improve water quality and alleviate many wastewater concerns in the St. Louis region.  It will invest billions of dollars over a generation in planning, designing, and building community rainscaping, system improvements, and through an ambitious program of maintenance and repair.
2. District. Refers to The Metropolitan St. Louis Sewer District or MSD. The District is organized pursuant to Article VI, Section 30 of the Missouri State Constitution that empowers the people in the City of St. Louis and St. Louis County “to establish a metropolitan district for functional administration of services common to the area.”
3. MSD. Metropolitan St. Louis Sewer District
4. Sewer. A sewer pipe to which building laterals are connected. Also called a collection main.