By: TrueNorth Steel
To meet the DNR and City Standards this underground stormwater 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 unique layout configuration that did not conflict with the building or other underground utilities while still accommodating the nearly 65,000 cf of stormwater storage volume required for the site.
Many of the 96” pipe lengths were upwards of 60ft in length which significantly reduced the amount of joints, delivered loads, and installation picks that the contractor had to initiate. In addition, abundant communication was had throughout the design process between TrueNorth Steel and Kwik-Trip, along with the installing contract and engineer of record, making for a successful project that met all project 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 actually 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.
