Commuter Rail Station Distressed CIP Wall 

Our Solution

Faced with signs of wall distress and drainage issues, our team approached the problem with a strong technical strategy that combined our expertise in geotechnical engineering, structural assessment, and practical construction solutions. We explored multiple repair and mitigation options, evaluating each based on long-term performance, cost efficiency, and minimal disruption to the surrounding infrastructure during construction. 

After conducting a detailed assessment of the wall conditions, we identified key issues, such as cracking, drainage failure, and soil pressure concerns. Based on the evaluation, we developed three potential solutions:

 1. Minimal Approach – A conservative option involving crack repair, sidewalk sealing, and installing weep holes draining into a trench drain. While effective in addressing surface-level symptoms, our analysis showed that wall movement could persist if the drainage material behind the wall remained clogged. 

 2. Additional Lateral Support – A more robust option that involved installing drilled shafts and anchor rods to provide lateral support to the wall, accompanied by crack sealing and sidewalk replacement. This solution would stabilize the wall more permanently but would come with higher costs and surface disruption. 

 3. Remove and Replace the Drainage System Behind the Wall – This option involves removing the existing backfill, replacing the collector drainage system, and using crushed stone as backfill. This approach would improve drainage performance and reduce lateral pressure on the wall. Additionally, with the back of the wall exposed, we proposed installing counterfort braces from the wall to the footing, further increasing wall stability. 

The Results

Our work on this ongoing project has laid a strong foundation for a successful outcome and enabled the design team to make well-informed decisions. Through a comprehensive evaluation and design process, we developed technically sound, practical, and forward-thinking solutions. Our proposed design demonstrates HVJ’s ability to blend innovation with constructability.  For example:  

• Our experienced team knew incorporating a drilled shaft and anchor system would provide critical lateral support to stabilize the retaining wall and prevent further movement. This solution is particularly important when existing drainage or backfill improvements may not sufficiently arrest wall movement independently. This system would ensure both immediate stabilization and long-term structural integrity.
• Including counterfort braces was a unique and strategic recommendation based on our team’s insight into long-term structural performance. This element was not originally part of the wall’s design, but we identified it as a proactive measure that would significantly enhance stability, especially given the signs of movement already observed.
• Selecting crushed stone backfill in the active wedge was another improvement. We selected this material not only for its drainage capacity but also for its ability to reduce hydrostatic and soil pressure, thus offering a long-term benefit that surpassed the original fill design. 

We also prioritized communication and collaboration with the design team throughout the process. We presented options, cost-benefit guidelines, anticipated construction impacts, and long-term performance outcomes.