To meet the DNR and City Standards, this underground storm water detention system placed under a parking lot was designed to provide the 40% TSS removal as required for redevelopment sites. Corrugated Steel Pipe (CSP) was utilized on this project because of its ability to be arranged in a layout configuration that did not conflict with the building or other underground utilities while still accommodating the nearly 65,000 cf of storm water storage volume required for the site.
Many of the 96-in. pipes were upwards of 60 ft in length, which significantly reduced the amount of joints, delivered loads and installation picks that the contractor had to initiate. In addition, there was communication throughout the design process between TrueNorth Steel and Kwik Trip, along with the installing contract and engineer of record, making for a project that met all deadlines. TrueNorth Steel also fabricated slotted drain and provided flap-gates to be utilized on this project.
Just prior to fabrication, the Wisconsin DNR voiced concerns surrounding vector control. To prevent a total redesign, which would have been required if submerged inlets had been utilized, TrueNorth Steel proposed a solution in which numerous inlet pipes were reduced by directing them into nearby storm manholes which eventually led into the system. This solution reduced the amount of storm sewer piping required on the project and the remaining inlets and outlet were extended so that flap-gates could be installed. The DNR approved of this solution as it restricted clear entry of nuisance pests.
