The Challenge
The city of Harrisburg, like many older cities, has ongoing CSO issues due to its aging combined sewer system. Approximately 60% of Harrisburg is served by this system which, during heavy rains, overflows into Paxton Creek and the Susquehanna River, contributing to pollution and flood risks downstream. Capital Region Water needed to retrofit existing stormwater pond infrastructure to address these issues while maintaining community aesthetics and value.
The Results
CSO and flood mitigation: the adaptive system reduced stormwater entering the combined sewer, alleviating CSOs into Paxton Creek and the Susquehanna River. Community benefits: the project maintained aesthetic water levels while creating storage, preserving the ponds' community value. Real-time insights: continuous monitoring provided data for performance adjustments and optimizations.
Performance Highlights
During Tropical Storm Debby in August 2024, both ponds performed well under extreme conditions, showcasing the resilience and adaptability of the CMAC system:
- Willow Pond: Pre-event drawdown was activated, reducing overflow and managing stormwater effectively.
- Spruce Pond: Overflow remained minimal despite the high precipitation volume. CMAC maintained control for 90.2% of the storm duration.
The Solution
Opti, in partnership with Jacobs, implemented its Continuous Monitoring and Adaptive Control (CMAC) system at the Bellevue Park ponds. This system allows for forecast-based pre-event drawdown, real-time control of water levels, and modulated wet-weather releases. Capital Region Water used the system to achieve multiple goals: optimize stormwater capture, reduce CSO volume, and balance the aesthetics requirements of the community.
