Stormwater systems constructed 20 to 40 years ago were designed using rainfall data, land use assumptions, and regulatory frameworks that no longer reflect current conditions. Increased precipitation intensity expanded impervious surfaces, sedimentation, evolving compliance standards, and aging materials have collectively created a growing disconnect between original hydraulic design capacity and present-day performance expectations.

This session examines how municipalities and private asset owners can systematically evaluate and modernize legacy stormwater infrastructure without defaulting to full system replacement. Drawing from field-based assessments and applied hydraulic analysis, the presentation will explore methodologies for identifying true conveyance constraints, evaluating hydraulic grade line conflicts, restoring detention storage capacity, and prioritizing retrofit interventions that improve system reliability.

Attendees will gain a structured framework for distinguishing between maintenance deficiencies and fundamental capacity limitations, along with practical strategies for phased improvements that align with capital planning, regulatory compliance, and long-term watershed resilience. Case applications across municipal systems, residential communities, commercial developments, and recreational properties will demonstrate how legacy infrastructure can be repositioned from reactive liability to managed asset.

Learning Objectives:

· Evaluate how changes in precipitation, land use, sedimentation, and aging infrastructure impact the performance of legacy stormwater systems.
· Differentiate between maintenance deficiencies and true hydraulic capacity limitations using field assessments and hydraulic analysis.
· Apply retrofit and modernization strategies to improve stormwater system performance, regulatory compliance, and long-term resilience.