Repairing Buffalo Bayou

Buffalo Bayou, one of Houston's primary stormwater conveyance waterways, has long been susceptible to ongoing natural channel erosion. This continuing erosion process was jeopardizing the integrity of the Sam Houston Tollway over the bayou. This article discusses some of the challenges posed in controlling this erosion, and highlights some of the unique erosion control strategies that were used in the project. The goal for the design team was to develop an environmentally compatible and aesthetically pleasing erosion control plan that addressed and corrected the individual erosion problem areas, preserved and promoted existing natural habitats, and provided improved access for visitors at a nearby park. Four causes of erosion were identified: surface runoff erosion, high-velocity channel erosion, high-frequency event toe erosion, and erosion due to turbulent conditions. An integrated erosion control plan was developed to address all four causes of erosion with complementing protection measures. Highly durable erosion control measures were selected to counteract the harsh conditions and to promote the longevity of the project area. Each erosion control measure was designed and implemented to correct and/or prevent a specific erosion failure mechanism, as well as to build layers of protection against destructive natural forces. The various erosion control measures implemented include: gabion mattresses, gravity gabion walls, cantilever retaining walls with drilled secant shaft, boulder rip-rap, mortar-embedded rip-rap, articulated concrete blocks, energy-dissipating drop structures and baffles and vegetation. Another key objective of this project was incorporating improvements for the neighboring park system that complement the erosion control improvements. Aside from the complexity of designing and tying together multiple erosion control measures to provide a cohesive level of protection, challenges associated with this project included overcoming extreme constructability issues and improving the overall stream habitat. The Buffalo Bayou erosion control project, completed in September 2011, has been successful in prolonging the service life of the tollway, preserving the existing habitat, and improving pedestrian usability.