Project Overview
Russo Corporation constructed a new 44-lot residential subdivision on a 13.5-acre wooded parcel in Hoover, Alabama. The development includes public roads, 1+ acre lots, and two at-grade detention ponds. Each detention pond was designed using Automated Outlet Structures (AOS) for water quality treatment and peak-flow attenuation for the 2–25-year storm events in accordance with City of Hoover stormwater regulations.
Site Challenges
Major site constraints—including shallow rock and strict stormwater requirements—initially required the project team to provide about 125,000 cubic feet of detention storage and perform up to 8 feet of rock excavation. The subdivision is located within a well-established residential neighborhood with sensitive downstream conditions, so both over-excavation and under-performance were concerns.
Automated Outlet Structure Solution
To improve constructability and performance, Flood-Con evaluated the use of an AOS on each pond. The AOS actively manages release rates and optimizes use of available storage in real time, instead of relying on fixed passive outlets.
The AOS design was developed to:
- Meet City of Hoover peak-flow attenuation requirements (2–25-year events)
- Maintain water quality performance
- Protect downstream properties and infrastructure
Results
Key Benefits
• 35% reduction in required detention volume from 125,000 cubic feet down to about 80,000 cubic feet
• Rock excavation cut roughly in half
• $250,000 in construction cost savings
• Shortened construction schedule by several months
• Smaller basin footprint, reducing land-disturbing activities and stabilization needs
Performance in the Field
Since installation in October 2021, the site has already experienced a 25-year, 24-hour storm event, and the AOS units performed as designed. Rainfall data from this event and subsequent storms is logged on site to document performance and maintain code compliance. Annual inspection reports are uploaded to confirm that the stormwater management facilities continue to function properly.