Oldcastle Precast System Installed at Florida Living Facility

Oldcastle Precast Inc. had the opportunity to manufacture and install one of its precast products—a Storm Capture Module System, a subsurface storm water detention structure, specifically engineered and designed to accommodate both the storm water storage capacity demands and the load-bearing needs of the land use above it—at the new Horizon Bay Congregate Living Facility in Tampa, Fla. The Horizon Bay project needed to be able to capture storm water and pipe it to 6,572 cu ft of storm water detention under the parking area to absorb and detain the storm water and allow water to slowly infiltrate into the ground, assisting in recharging the groundwater.

Limited available site space necessitated the use of an underground storm water detention structure beneath the facility parking lot. Underground detention was the only practical choice, according to design engineer, Fuxan Engineering of Odessa, Fla. An overflow pipe led to storm sewers, but the majority of the storm water would be infiltrated back into the ground, a common low-impact-development (LID) practice in Florida that serves to help recharge the aquifer. According to Oldcastle Precast, the Storm Capture Module System provided a much better value proposition to the owner and engineer than the plastic underground storage chambers originally proposed for the site.

The Storm Capture Module System is suited for this type of underground detention application due to its stand-alone, traffic-bearing design that does not rely on final paving and associated stone underlayment for structural capacity. The Storm Capture Detention Modules are constructed of high-strength structural concrete. Their ability to support traffic on the parking lot allowed for a 50% reduction in thickness of base rock required between the pavement and modules, as well as a 20% reduction under the modules as compared to the originally planned plastic chambers.

The completed system design for Horizon Bay included 37 Storm Capture Modules. Each module is constructed of precast reinforced concrete with interior dimensions of 6-ft-by-12-ft-by-2.5-ft tall, with open bottoms for infiltration. Four of the modules incorporated standard inlet grates to allow storm water direct entry from the parking lot into the system. This eliminated the need for the four separate inlet structures originally designed into the project. A precast splash pad was installed below each inlet grate to prevent scour of the bedding material. In addition, the inlet grates are used for direct access to the modules for inspection and cleaning as needed. Each module has large conveyance windows into adjacent modules to allow flow equalization, as well as access for maintenance.

Source: Oldcastle Precast Inc.