Key Considerations for Managing Risk When Implementing Vibratory Caissons

Vibratory caissons (circular or multi-sided, tubular, smooth wall steel piles) are increasingly utilized as a preferred foundation type for transmission line projects in poor subsurface conditions due to their limited spoil generation and ease of installation with the proper application. However, without a thoughtful approach, the use of vibratory caissons can lead to significant project schedule delays and increased project costs. How do we get the information necessary to reduce the risk of design or construction issues for projects with very challenging environmental or construction access conditions? How do we effectively coordinate with the various stakeholders involved in the successful implementation of vibratory caissons? How do we improve the likelihood of accurately predicting the performance of vibratory caissons? How do we set up contractors for installation success? This paper will answer these questions while discussing key considerations to select, design, and construct vibratory caisson foundations as a suitable alternative to traditional direct embed or drilled shaft foundation systems. Based on project experience with multiple utilities along much of the East Coast and Southeast parts of the country, the authors will discuss how project teams can identify when vibratory caisson foundations are favorable over traditional foundation systems. In addition, the authors will discuss important design methodology, fabrication, and installation elements that require consideration for improved probability of successful implementation of vibratory caissons.