City of Burnsville, MN City-Wide 2D Storm Sewer System Model, Resiliency Study, and Lake Level Analysis

Need for Analysis

The City of Burnsville selected the AE2S/WEST team to assist the City with a three-phased project to better understand the flooding risks, create a more resilient storm sewer system, and reduce the likelihood of flooding and impact to residents. The overall project can be broken down into three phases:

• Develop a City-wide 2-Dimensional (2D) XPSWMM model of the City, covering more than 22.5 square miles;
• Complete a Resiliency Study for the storm sewer infrastructure; and
• Complete a lake level analysis for the chain of lakes from Keller Lake to the Minnesota River.

The City of Burnsville was divided into six major watersheds with corresponding XPSWMM models for each. The models were developed from the ground up, integrating the latest impervious surface areas, soils, storm sewer and topography data to create an accurate model representing current conditions of the City. The purpose of developing a 2D City-wide model is to provide a clear understanding of the flood risk areas of the community with the overall goal to proactively improve the drainage for these areas to reduce the flooding.

The purpose of the Resiliency Study is to prioritize the flood risk areas as a function that takes into account the consequence of failure with the likelihood of failure. What this means is that several factors, including zoning type, service area size, critical facilities, roadway, classification, etc. will be evaluated along with the traditional “performance driven” factors, such as depth of flooding for various events. Utilizing a formula-based approach removes the subjectivity from the study and focuses the City’s attention on the most critical locations throughout the study areas.

The final phase of the project is to utilize the 2D model to analyze the lake system from Keller Lake to the Minnesota River. This lake system is prone to flooding, which impacts roadways, residential property and structures. The City is focused on understanding what improvements are possible to reduce the likelihood of flooding throughout the system.