About the Project
John Rolfe Square was developed on a 10-acre lot in Richmond’s desirable West End. Eagle Construction worked with a Richmond engineering firm and Colonial Construction Materials to find a space-saving stormwater management solution that would meet Virginia’s stormwater runoff and detention requirements.
The team selected an underground chamber system rather than a traditional above ground stormwater pond. By moving the stormwater BMP underground, the developer was able to maximize land space and eliminate the visually unappealing detention pond.
The underground stormwater detention system was constructed from a series of 5-foot and 8-foot aluminized corrugated steel pipes. Aluminized steel pipe is strong, corrosion resistant and an economical alternative to HDPE which can be costly in large-diameters.
The corrugated steel pipe system features two chambers, nicknamed Alpha and Beta. Alpha and Beta was installed in an 88′ x 70’ space, wrapped in six-ounce nonwoven geotextile fabric and backfilled with 3,800 tons of Bluestone gravel.
During construction, the storm chambers acted as a temporary detention system. The corrugated steel pipe chambers retained stormwater runoff, allowed for sedimentation and promoted positive drainage. Once the site was 80% developed, the bulkheads that separated the chambers were removed. At that point, the underground stormwater detention system was converted to a permanent stormwater management system.
Runoff and rain flows from drop inlets through concrete pipes and into the below ground system. As water flows into the system, geotextile fabric and stone pre-filters out debris. As water builds up, it infiltrates the backfilled aggregate and finally flows into a system of eight-foot diameter corrugated steel pipes. From there, the water is released downstream at controlled rates.
There is now a shared green space over Alpha and a rain garden over Beta.
