Description of Demonstration Project
Two bioretention cells are constructed in East Tampa to serve as a research site and a demonstration project. Our community partner, the Corporation to Develop Communities of Tampa, Inc. (CDC), is a non-profit organization that provides community and economic development services in East Tampa. In working with the CDC and locating our bioretention cells on their property, the Audrey Spotford Youth and Family Center, we are able to engage with the participants and students in their programs, who are also residents of East Tampa. Middle and high school students from the Youth Leadership Movement have participated in rain barrel workshops, painting rain barrels and a mural, planting of the rain garden, and other stormwater and nutrient management related activities. The two bioretention cells and signage at the site were constructed with the help of participants from the Tampa Vocational Institute, a job training program. The integration of university research with job training and youth programs within local communities provides a unique opportunity for research and education on green infrastructure for stormwater and nutrient management in the Tampa Bay watershed while addressing sustainable livelihoods.
The two full-scale bioretention cells were constructed in parallel, located in the grassy area between the building and parking lot of the Spotford Center. The cells are encased in a wooden frame with an impermeable geomembrane liner. The PVC effluent pipes were configured to also be used as sampling ports for research activities. One cell is a conventional bioretention system, while the second cell is a modified bioretention system designed for denitrification with an internal water storage zone containing eucalyptus woodchips. The modified cell was first tested in the lab with promising results for nitrogen removal from urban stormwater at USF by Dr. Thomas Lynn and is now being researched in the field by Emma Lopez, PhD candidate.
Details of Bioretention Cells
The modified bioretention system is designed for denitrification with an internal water storage zone. It has dimensions of 1.5’ W × 4’ L × 3’2” D. The top layer consists of 1 ft of 250 paver sand wrapped with geotextile fabric, followed by 2 in of pea gravel, and 1 ft of a 2:1 (vol/vol) mixture of pea gravel and eucalyptus wood chips. The bottom layer containing the underdrain is 1 ft of #57 limerock. The bottom two layers containing the gravel-wood mixture and the #57 limerock are always saturated with water from the discharge pipe with an upturned elbow. The treated stormwater discharges to a trench that is located underground. The second cell is a conventional bioretention cell a foot shorter than the modified system with dimensions of 1.5’ W × 4’ L × 2’2” D. The top layer consists of a foot of 250 paver sand wrapped with geotextile fabric, followed by 2 in of pea gravel, and 1 ft of #57 limerock at the bottom. Each cell is topped off with a thin layer of river rock mulch instead of wood mulch. Florida native and friendly plants are planted above the trench area where the effluent is discharged and around the cells.