Baden Cityshed Mitigation Basins (Calvary, Frederick, Partridge and Tillie) – Separation Sewers (12847)

Baden Cityshed Mitigation Basins (#12847)

As part of a long-term effort to reduce basement backups, MSD Project Clear is constructing a project to install approximately 10,700 feet of sewer and separate storm and wastewater sewers in the City of St. Louis, west of Halls Ferry Road, East of Riverview Boulevard and north of Cavalry Cemetery.

The Contractor selected for this project is Unnerstall Construction Co.

Project status as of 2/14/24

Partridge Basin:

  • Basis is complete

Tillie Basin:

  • Piping installation continues on Halls Ferry, north of McLaran
  • Restoration beginning this week on alley between Newby and Church; restoration will follow at intersection of Halls Ferry and Church

Frederick Basin:

  • Basin is complete with punch list items remaining

Project Map

Project Map

What is the goal of this project?

MSD Project Clear is investing $5.8 million to construct this project to install separate sewers for stormwater and wastewater in this area. Additionally, this project will also direct stormwater flows to the newly installed detention basins in the neighborhood. Ultimately, this project aims to remove stormwater from the wastewater system to reduce instances of the system becoming overcharged and causing basement backups.

What work is being done?

  • MSD Project Clear will install approximately 10,700 feet of sewer
  • The pipe size will range between 12 to 48 inches in diameter
  • MSD Project Clear will remove the stormwater from wastewater sewer in this neighborhood
  • Stormwater will be directed to one of the MSD-constructed detention basins in the area

Why is this project being constructed?

Part of MSD’s service area has a combined sewer system, where stormwater and wastewater flow through the same pipes to one of our treatment facilities. During heavy rain events, stormwater can overcharge the system in these areas which leads to basement backups and increased treatment costs.

Over the last several years, MSD Project Clear has spent considerable resources and time engaging the community to install several detention basins in this neighborhood. With this project, MSD will be installing new stormwater sewer to separate the system in this neighborhood and direct the stormwater to one of the detention basins. The basins will collect and hold the stormwater and release it at a regulated rate to help prevent instances of overcharged sewers.

How will it be built?

MSD’s contractor, Unnerstall Construction Co., will install the pipe by digging through the surface, a process known as “open-cut.” The contractor will dig a trench several feet into the ground and install new stormwater sewer.

Under Halls Ferry Road, the pipe will be installed underground through a process called “tunneling”. Tunneling is being used for this part of the project to prevent traffic disruption at the surface.

What can residents expect?

With any type of construction, residents can expect to see and hear heavy equipment during the sewer excavation process. The pictures above depict what a neighborhood will look like before, during, and after a typical “open-cut” project.

MSD Project Clear does expect traffic disruption, and street and lane closures as a part of this project. MSD’s Contractor will inform affected residents prior to starting construction. The Contractor will also be required to have a Traffic Control Plan to mitigate traffic disruption.

MSD expects temporary access issues to properties during construction hours as well. The Contractor will work to restore driveway access after construction hours every evening, or when notified by the homeowner within a reasonable amount of time.

Residents and/or property owners along the construction path should move small portable items outside of the easements and inform MSD of dog fences, sprinklers, and other underground assets.

After all new sewer pipes are installed, the contractor will restore the construction site according to all local and District requirements. This could include sodding any disturbed areas, replacing disturbed pavement, reinstalling fences, etc.

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

What is the timeline?

  • Construction start: Summer 2022
  • Construction end: Late 2023 to early 2024

Previous milestones:

  • Project design completion: November 2020
  • Easement acquisition completion: November 2020


MSD does not anticipate sewer service or 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.

Yes, MSD does anticipate that construction will temporarily affect access to driveways and properties as a part of this project. The Contractor will work to restore access to affected driveways/properties each evening, by either backfilling with gravel or plating over the trench. Residents with specific concerns are encouraged to reach out prior to construction so that the Contractor can work with you as much as possible.

Because much of the work will be on roadways, MSD does not expect extensive tree removal. However, 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.


Stay Informed

Kent Rollins, Unnerstall Project Manager

Andy Day, MSD Construction Supervisor