Texas State Highway 99 extending over the Brazos River has experienced severe erosion on its north bank since record flooding during the summer of 2016. There were concerns that if the bank erosion continued, it could not only cause instability of the bridge but could also affect the levee system behind the bridge, which protects a large population of residences. To detour the bank erosion, a drilled shaft tangent pile wall protection system was designed utilizing shafts measuring 66 inches in diameter and 120 feet deep. The design also included seal shafts measuring 24 inches in diameter to be installed in between the tangent piles.
During installation of the protection system, the area suffered impact by Hurricane Harvey and another round of record flooding that caused even more bank erosion, further affecting the as-designed work area. Due to this new erosion, the design was modified with the addition of tangent wall shafts measuring 10 feet in diameter and 130 feet deep. All shafts were installed using wet construction methods with bentonite slurry to stabilize the excavations.
GENERAL CONTRACTOR: NBG Constructors Inc.
OWNER: Fort Bend County Toll Road Authority