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Sacred Heart Senior Apartments

Saint Francis, Wisconsin

Stormwater Detention and Stormwater Treatment


Sacred Heart of Jesus Parish


The Sigma Group


A.W. Oakes & Son


August 2001

Technical Description:

  • CMP Detention
  • 644-in. of 142-in. x 91-in. CMP

The Sacred Heart of Jesus Church, originally built in the early 1960s, was renovated to include a new senior living apartment community. The community, called the Sacred Heart Senior Apartments, is a non-denominational facility and seniors of all faiths are welcome.

The renovated sanctuary and rectory are 19,058 sf of the 113,735 sf project. The apartments occupied 84,081 sf in the renovated space above the church, which were formerly school classrooms, and also in the newly-built addition on what was parking lot. There also is a 10,595 sf common room shared between church and apartments

“We’re trying to reinvent ourselves,” said Eric Stemwell, Sacred Heart Parish Core Team. “It’s kind of an experiment, teaming up with a developer to offer senior housing. Senior citizens are a very vital part of any community. What we’re trying to do is create an environment where senior citizens can thrive.”

The church contacted The Sigma Group of Milwaukee to design the civil portion of the project which included the stormwater management plan for the site.

The state Department of Natural Resources (DNR) requires Total Suspended Solids(TSS) reduction in stormwater leaving the site of 80% for new developments and 40% for redeveloped projects. The 4.0-acre senior apartment complex project was considered partially new development and partially redevelopment; resulting in a weighted TSS reduction requirement of 50%.

Because the project was located in an urban setting, The Sigma Group did not have the option of an aboveground stormwater pond for the required TSS removal. Instead, they looked at “mechanical” options that would be contained beneath the parking lot.

The Sigma Group contacted Contech Engineered Solutions for assistance in providing an economical solution to meet the DNR requirements. The project covered 4.0 acres. Of that, 2.83 acres were treated and 1.17 acres were taken offsite with 0% removal. Contech proposed an underground stormwater detention system utilizing corrugated metal pipe (CMP) to treat the 2.83 acreage because it could achieve the weighted 50% TSS reduction requirement. This solution also met all of the project requirements while keeping within budget.

Utilizing WinSLAMM (Source Loading And Management Model for Windows) to evaluate sediment loading of the project site, the Sigma Group determined that the underground system needed 7,390 sf of surface area at the water line and 48,035 cf of active detention storage.

The CMP detention system was constructed out of 644 feet of 142-in. x 91-in. CMP coated with aluminum to fulfill the surface area and active storage area requirements. Aluminized, ALT2 coating was chosen to meet the 75 year service life required by the owner. The system was designed with a 3.5’ permanent pool of water in a serpentine configuration to maximize the settling time. The calculated TSS removal rate from Contech’s “underground wet pond” solution was 76.61% - resulting in a net TSS removal of 56%, greater than the 50% required, for the entire 4.0 acre site.

Technical Description:

  • CMP Detention
  • 644-in. of 142-in. x 91-in. CMP

800-338-1122 |


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