Concrete Products Group parlays precast rain garden
- Published: Thursday, 17 February 2011 16:37
- Written by CP Staff
The 11th Street Pilot Project recently brought downtown St. Louis an urban rain garden, the market’s first design-build project of its kind. Built with the proprietary Freno Modular Rain Garden System, the precast concrete rain garden is a shallow depression filled with water-prone plants in a prescribed profile of soil, sand, and aggregates. The structure uses the technique of bio-retention to help manage stormwater by capturing runoff, storing it briefly, and filtering out pollutants through natural processes.
Midwest Products Group fabricated the system at a wet cast plant it opened in early 2010, adjacent to its Jefferson City, Mo., headquarters operation. Midwest Products is the U.S. licensor of Freno and distributes the system through St. Louis-based Midwest Block & Brick and other producers in the Concrete Products Group LLC network.
The Freno allows rapid placement of rain gardens in urban settings. Rain gardens, bioswales and bio-retention cells—designed to intercept and reduce runoff, filter pollutants, replenish groundwater, and enhance the surrounding street-scape— are relatively inexpensive and require minimal excavation, labor, and material. Thanks to performance characteristics and aesthetic appeal, notes Midwest Products, rain gardens have become a popular Low Impact Development technique for urban streetscapes, where they are typically paired with concrete enclosures or planters.
The Freno Modular Rain Garden System was developed as an alternative to traditional cast-in-place methods, providing Midwest Products engineers note is a higher level of quality and durability at a lower cost, and with less construction time. The 11th Street Pilot Project system offered a cost-effective, modular method of building an urban rain garden for the City of St. Louis.
Freno is made up of a set of three precast concrete pieces – called the T, the N and the S Modules, based on their shapes. They link together and can be arranged in a nearly limitless number of configurations. Other accessories under development have the potential to serve as benches, bike racks, or decorative fencing.
“Freno is an innovative system designed to reduce stormwater runoff, improve water quality and promote groundwater recharge, while creating landscape enhancements in urban settings. It was conceived to provide high-quality green infrastructure with a reduced installed cost due to the speed and convenience of modular construction,” says Midwest Products Sales Engineer David Mudd. “Freno is simply a tool to make it easier and faster to build bio-retention systems with predictable quality, and offers the same design options that any bio-retention system has.”
The system works in all soil types, from sands to clays, and can adapt to local engineering, soil and planting requirements. In the case of the 11th Street Pilot Project, the system was specifically designed to exfiltrate and was installed without an underdrain. In impervious soils, the Freno system can accommodate an underdrain, and be designed as a filtration system, much like any bio-retention structure. The cost is competitive with existing methods, Midwest Products notes, while offering superior speed of construction, and quality consistency.
System benefits include maximum flexibility, simple constructability, superior durability, enhanced aesthetics and the advantage of pre-cast manufacture. “With Freno, landscape architects, civil engineers and people involved in those functions within municipalities will find they can specify a high-quality, durable recycled-content product with a beautiful architectural finish,” notes Mudd. “The components can be specified and used again and again over time with certainty, regardless of the unknown factors of location, season or installer. Freno eliminates the need for specialty labor required with cast in place systems.