The Challenge
NHSA faced considerable regulatory and community pressure to address CSOs and flooding. With nearly 190,000 customers in one of the most densely-populated urban areas in the U.S., limited land availability for stormwater runoff storage, and a constantly changing environment and watershed, the Authority needed to consider a new approach to advance their mitigation and water quality goals.
The Results
Since 2018, Opti has been actively controlling several stormwater assets. Using weather forecasts, inflow models, and real-time data, Opti active controls improve wet weather capture and minimize peak flows to the combined sewer system, thereby mitigating CSOs and flooding. Over the course of two years, Opti-controlled sites fully captured 86% of storms with no outflow, saving capacity at the downstream treatment plant during peak loading times.
The Solution
With a dense urban service area and limited right of way, traditional approaches to create additional system capacity for addressing flooding and CSOs were not feasible. Instead, NHSA partnered with commercial developers to maximize storage and wet weather capture with smart detention.
In 2018, NHSA implemented new stormwater design and connection rules requiring automated flow controls on new developments disturbing 10,000 SF or greater. The rule accelerated an integrated network of continuous monitoring and adaptive control (CMAC) sites across the sewershed, helping NHSA protect people, property, and environment while meeting regulatory compliance requirements.
Storage Reduction
NHSA’s new stormwater regulations put an emphasis on more storage. Meeting peak flow requirements with an undersized system could only be met by integrating active controls or constructing comparable storage elsewhere. With Opti active controls, a building’s detention tank could be downsized by an estimated 30% and continue to meet NHSA’s volume capture requirements. This smaller, more efficient storage approach saves money and space in constrained projects. Opti’s continuous monitoring and adaptive controls (CMAC) is now the primary smart active controls solution used by area developers.
