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ELGL’s Best of Water

Lower Footprint Biofiltration to Increase Efficiency in Right of Way Stormwater Capture

Houston, TX, USA

At a Glance

Part of a broader redevelopment effort, Bagby Street - a ten-block corridor in a dense, urban neighborhood of Houston - was redesigned to improve mobility for vehicles and pedestrians, and add aesthetic appeal to the road. Improvements led to Bagby Street being named one of Texas' first certified Greenroads.

Problem Addressed

During the roadway redesign, one top priority was to provide street trees within the right of way while also removing pollutants such as heavy metals, floatables, sediment, and oil and grease from the roadway stormwater runoff before it was released via outfalls to nearby Buffalo Bayou. However, due to the robust root system of most street trees, the design team did not have enough space to integrate a typical biofiltration planter box without damaging and clogging the underdrain of the biofiltration system, causing the planters (and street eventually) to flood.

Houston used/is using FocalPoint High Performance Modular Biofiltration systems to address this/these challenge(s).

Solution(s) Used

Ultimately, the design team chose to use the high performance small footprint FocalPoint HPMBS which allowed them to place the biofiltration area outside the drip zone of the street trees. Because of the systems' high flow-rate engineered media, the design team didn’t need to fill the entire planter box with a bioretention media and underdrain system. Instead, they could place the FocalPoint HPMBS between two v-notch weirs and away from tree roots.


  1. $25 million of private development encouraged by project
  2. 33% of stormwater enters into rain gardens, removing 75% bacteria, 73% phosphorus, 93% oil and grease, 43% nitrogen, and 85% total suspended solids from leaving the site
  3. 165% increase in the amount of trees within the corridor

Something Unique

The unique biofiltration system installed used only 1/20th of the space need for a typical system.

Who Should Consider?

Any roadway redevelopment that is working to solve a stormwater flooding challenge but faces right of way footprint constraints.

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