Bioretention Systems
Description
Bioretention systems capture and infiltrate stormwater in shallow, vegetated depressions. Stormwater pollutants are removed through physical, biological, and chemical processes, including adsorption, filtration, plant uptake, microbial activity, decomposition, sedimentation, volatilization, and infiltration. Bioretention facilities typically include a pretreatment biofilter (vegetated swale or strip) to reduce velocities and filter out particulates, a sand trench to augment the infiltration capacity of the planted bed and to evenly distribute incoming runoff, and a ponding area to collect and store runoff prior to infiltration. Common constituents that are removed include total suspended solids (TSS), total nitrogen and phosphorus, pesticides, total and dissolved metals, microbiological constituents, and litter. Bioretention systems can also reduce peak discharge and runoff volume by detaining water through surface ponding and storage in soil and gravel layers, and by allowing it to infiltrate into the subsoil or dissipate through evapotranspiration.Experience
Caltrans District 12 State Route 73 Pilot Program – Bioretention
The District 12 State Route 73 Pilot Program was a multi-year field study conducted in Orange County. The primary objective was to assess the effectiveness of twenty-four pilot Best Management Practices (BMPs) for treating stormwater runoff from freeways. Included in the program was a Bioretention Area BMP. For the Bioretention Area BMP, influent and effluent water quality samples were collected and compared, and operation and maintenance activities, including vegetation management, were recorded to develop maintenance protocols.
OWP Tasks
OWP Contacts: David Alderete
OWP Tasks
- Assisted in Study Planning
- Reviewed Design of the Bioretention Area BMP
- Provided Review of Installation/Construction Activities
- Provided Monitoring Assistance
- Reviewed Data Assessment and Reporting
OWP Contacts: David Alderete
Caltrans San Francisco–Oakland Bay Bridge (SFOBB) Bioretention Pilot Study
The SFOBB Bioretention Pilot Study was a multi-year study conducted in Alameda County to assess the effectiveness of a Bioretention Area BMP. The Bioretention Area BMP consists of six bioretention cells. Design parameters, including drainage area, ponding depth, and vegetation coverage, varied among the six bioretention cells to assess their effects on performance. Influent and effluent water quality samples were collected and compared, and operation and maintenance activities were recorded to develop maintenance protocols.
OWP Tasks
OWP Tasks
- Assisted in Study Planning
- Reviewed Designs of the Bioretention Area BMP
- Provided Review of Installation/Construction Activities
- Provided Monitoring Assistance
- Reviewed Data Assessment and Reporting
