At several locations along Pinehurst Road, storm runoff and high flow in San Leandro Creek resulted in eroded and sloughed embankments.
Under a Task Order as part of a Structural On-Call Contract, BKF prepared civil and structural design and PS&E to repair the embankments at two locations along Pinehurst Road. The project goals were to support and protect Pinehurst Road from scour and undermining and to minimize impacts to the natural riparian environment, protecting substantial trees where possible and combining robust hardened improvements with more natural bioengineered solutions.
BKF performed a topographic survey and delivered a Preliminary Design Report (PDR) to evaluate constraints, opportunities, costs, and considerations of various erosion control and slope stability measures, including both natural bioengineered solutions and hardened embankment retaining solutions. BKF also evaluated alternatives and addressed solutions for supporting improvement details such as geometrics, vehicle barrier solutions, aesthetics, utilities, maintenance of traffic, permitting, and environmental constraints.
The design team recommended a combination of embankment hardening and natural erosion control and scour countermeasures. A soldier pile retaining wall was used to support and protect Pinehurst Road, and a rootwad revetment with brush layering and a boulder toe biotechnical bank stabilization system was incorporated along the creek embankment to provide erosion protection.
Compared to traditional wall types, the top-down soldier pile construction method promoted slope stability, minimized ground movement, reduced the risk of undermining or disturbing the riverbank, and reduced potential impacts to nearby watercourses and sensitive environmental areas. Due to the design height, the soldier pile wall was designed with ground anchors to economize the structure. Ancillary improvements included new roadway pavement and surface water drainage features.
