Making Waves in Stormwater Master Planning: A Case Study on Project Prioritization in Linkhorn Bay

To combat the challenges of increased storm intensity and sea level rise, the City of Virginia Beach Public Works Stormwater Engineering Center (City) is currently developing a Comprehensive Stormwater Master Plan (SWMP). The City has used several stormwater models that contain all the major drainage networks to identify areas where flooding is occurring, known as Simulated Flooding Areas (SFAs). The focus of the SWMP is to develop and prioritize projects to improve the identified SFAs throughout the City.

The first step in the SWMP was to develop a standardized set of criteria, based on consensus from key stakeholders. The Alternative Selection Criteria (ASC) and the Project Performance Criteria (PPC) are being used to identify and prioritize improvements for each SFA.

To ensure the applicability and soundness of the criteria, they had to be tested on a sample of proposed stormwater projects. The City selected Linkhorn Bay Drainage Basin to be used as a case study to determine if the criteria developed were appropriately weighted. Linkhorn Bay was selected as it is one of the smaller drainage basins within the City.

Ultimately, 21 alternatives were evaluated with the ASC that identified 13 projects in the Linkhorn Bay Drainage Basin that were then scored with the PPC. Additionally, a cost estimate, Benefit-Cost Ratio (BCR), and Benefit Ratio (BR) were determined for each project. The last step was to calculate a combined ranking score for each project, and organize projects into tiers for implementation.

This presentation will focus on the application and results of the prioritization criteria and lessons learned in the Linkhorn Bay case study and beyond.