In 2008, the city of Lakewood, Calif., in conjunction with the Los Angeles County Department of Public Works, used an innovative design approach to widen a portion of Paramount Boulevard, which was located in a high-density urban area near the center of downtown Lakewood.

As one of the first projects funded through the SAFETEA-LU surface transportation bill passed by Congress in 2006, the Paramount Boulevard road-widening project was selected to demonstrate the viability of retrofitting certain street and sidewalk locations with various bioretention tree well filter systems, which are designed to capture and biologically filter storm water pollutants prior to discharging treated runoff into the local storm channel.

Storm water runoff from public roadways is one of the leading contributors of storm water pollution to our nation’s waterways, impairing our nation’s health, water quality and natural habitats. Due to the dense, urban environment of the city of Lakewood and the subsequent high volume of trash generated along Paramount Boulevard, storm water pollution is of particular concern to local residents.

Tasked with providing a solution to remediate the adverse impacts of polluted storm water runoff, the Los Angeles County Department of Public Works and the city of Lakewood chose to install several Filterra Bioretention Systems, a package flow-through planter box system manufactured by Americast Inc. The system consists of a specially designed engineered soil media that supports local native trees and shrubs inside a catch basin-like structure. The system is designed to capture, remove and metabolize a variety of pollutants of concern before treated water enters the storm drain. Pollutants of concern conveyed in runoff include trash, debris, sediment, metals and bacteria.

Under this roadway retrofit design scenario, Filterra was the natural choice for the project designers. The modular design requires very little space along sidewalks and is inherently well suited for dense urban environments. Based on independent third-party data and verification, the Filterra system has proven performance and removal effectiveness for various pollutants such as trash, debris, sediment, petroleum, heavy metals, phosphorus, nitrogen, TSS and bacteria. Once Filterra was chosen by the project designers for retrofit locations, the Los Angeles Department of Public Works was able to proceed with completing construction documents and project implementation in a timely manner.

The Paramount Boulevard Retrofit project was completed in March 2009 using two Filterra Bioretention Systems designed to capture runoff generated from an area of approximately 3 acres of high-density roadway. The selected trees chosen by the city of Lakewood for each system are Majestic Beauties that require minimal watering and no irrigation system.  

These particular systems provided a compact, green storm water treatment solution that incorporates local trees and shrubs placed along the roadway. In addition, maintenance is simple, safe and inexpensive to the city. The system only requires maintenance once or twice per year by removing collected sediment and debris inside the Filterra planter area and replacing the mulch layer. 

For further information about this project, the city of Lakewood produced a video that can be viewed here.