Micropile Design and Construction in a Limited Access Wetland Habitat

This paper will discuss the use of micropiles as a specialty deep foundation solution to limited construction access challenges within the Troy Meadows wetland portion of PSE&G’s 500 kV Susquehanna to Roseland Electric Reliability Project. Micropile foundations were constructed utilizing primarily helicopter access for seven 500 kV double-circuit tubular steel pole structures within the protected habitat. The successful implementation of a design-build strategy between the overhead design team and the contractor led to significant refinements in the foundation design. Value engineering efforts focused on refinement of tower loading geometry and load cases, assessment of geotechnical conditions, and reduction of foundation footprints within the wetlands environment. The paper will detail design and routing of the overhead alignment, as well as permitting restrictions and area of impact limitations. It will then provide an in-depth analysis of concrete cap micropile design and detailed construction methodologies.