The Challenge
The Kingsmill resort was renovating and expanding the existing marina and restaurant building but needed to salvage the existing deck along the rear of the building adjacent to the James River.
A special foundation system was required due to poor bearing soils near the surface of the site and erosion and scour caused by tidal surges along the river’s shoreline.
The Solution
The design Geotechnical Engineer and design Structural Engineer determined that a deep foundation was required in order to properly support the new building. Timber piles and helical piles were evaluated for this project, however helical piles were determined to be the more appropriate pile system.
The helical pile system was recommended because of its relative ease of installation in a limited site space and long term stability. The helical piles required to meet structural specifications were designed by the JES engineering staff and consisted of 2.875” outside diameter and 3.50” outside diameter hollow round shaft piles with ASTM A572 Grade 50 x 3/8-inch thick helix blades.
The piles were designed to provide 13 kips to 55 kips allowable compression capacity and 10 kips of tension capacities. The torque required to achieve the design capacities ranged from 7,600 to 15,886 ft-lb. The helical pile components were hot-dipped galvanized in accordance with ASTM A123 [Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products].
Project Summary
JES installed 29 Helical Piles to support the foundation system of the new marina structure. The helical piles consisted of fifteen (15) FSI Model HP288 Helical Piles with a lead section with 10”/12”/14” helices and fourteen (14) FSI Model HP350 Helical Piles with a lead section with 10”/12”/14”/14” helices.
The piles were installed to a typical depth of 26 feet to 31 feet. Select piles were subjected to compression and tension load testing using a “Pro-Dig C440 Torque Transducer” to determine that the piles were capable of supporting the design workloads of 13-55 kips compression and 10 kips tension.
New construction steel brackets (caps) were bolted to the top of the pile shaft and were embedded in the concrete grade-beam type footings and pile caps. To ensure proper bolt-hole alignment, the JES field crew used a “Magna-Drill” attached to an engineered guide system.
The Team
JES Project Engineer: David E. Stinnette, PE
Architect: OZ Architecture
Structural Engineer: The Structures Group
Geotechnical Engineer: GETS, ECS Ltd. Mid-Atlantic
General Contractor: Brasfield & Gorrie, LLC, Tauer Group
