Stormwater Management Plan

JBW was contracted to assist the client in applying for and complying with a Land Disturbance Permit Variance within Duluth Township. The total impervious surface for the existing parcel had been expanded and was no longer within the 25% maximum limit.

The scope of services included a half-day site visit for one individual, a hydrologic analysis of the existing site, and a review of stormwater discharge for Total Suspended Solids (TSS) and Total Phosphorus (TP). The civil design tasks involved determining impervious surface area, historic and developed stormwater runoff, whether a detention facility was required, and identifying Best Management Practices (BMPs) to manage stormwater runoff.

JBW created a Permanent Stormwater Management Plan to adhere to the Duluth Township “Stormwater, Erosion, and Sediment Control Ordinance Number 1” and the Minnesota Pollution Control Agencies’ “Technical Support Document for the Post-Construction Stormwater Management Conditions.” The final design included a small settling pond and a 7,000 ft2 sand filter with a network of 4” PVC underdrains. The final design was completed to bring the effluent flow, TSS, and TP back within the required pre-construction rates.