Williamsburg Landing – The Challenge
The Williamsburg Landing Assisted Living Facility building in Williamsburg, VA, was expanding the existing cafeteria (Cove Café), which would extend into the building’s interior courtyard. The new construction consisted of structural steel framing, CMU walls and a slab-on-grade floor.
Prior to construction it was determined that a deep foundation system needed to be installed to prevent future settlement issues associated with uncontrolled and unsuitable fill which covered the proposed building limits.
Williamsburg Landing – The Solution
The geotechnical engineer (ECS Mid-Atlantic) and the structural engineer (The Structures Group) recommended the installation of helical piles to transfer the weight of the structure onto stable soil. JES Foundation Solutions was selected as the Helical Pile installer (Specialty Contractor). The helical pile system was recommended because of its relative ease of installation and long term stability. Helical pile installation does not generate spoils or create vibrations which could adversely affect directly adjacent structures.
Since the new construction would take place within a courtyard, limiting installation vibration was critical. Additionally, the smaller installation equipment could access and easily maneuver in the limited access space. The helical pile required to meet structural specifications was designed by the JES engineering staff and consisted of 2- 7/8” outside diameter by 0.203-inch wall hollow round shaft with ASTM A572 Grade 50 x 3/8-inch thick helix blades. 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].
Prior to production pile installation, representative piles were load tested in both compression and tension. Load testing was performed in accordance with ASTM D1143 (Standard Test Methods for Deep Foundations Under Static Axial Compressive Load) and ASTM D3689 (Standard Test Methods for Deep Foundations Under Static Axial Tensile Load). A steel “I-Beam Load Frame,” reaction anchors and hydraulic load cylinder were used to test the load capacity of the piles.
Williamsburg Landing – Project Summary
JES installed seventeen (17) Helical Piles. The helix configuration consisted of a 7’ Lead Section with 8”-10”-12” helices. The piles were installed to an average depth of 25 feet. Load testing and torque verification using a “Pro-Dig C440 Torque Transducer” during pile installation determined that the piles were capable of supporting the design working loads of 18 kips compression and 10 kips tension. New construction steel brackets (caps) were bolted to the top of the pile shaft. To ensure proper bolt-hole alignment, JES field crew used a “Magna-Drill” attached to an engineered guide system.
JES Project Engineer: David E. Stinnette, P.E.
Architect: Guernsey Tingle Architects
Structural Engineer: The Structures Group
Geotechnical Engineer: ECS Mid-Atlantic
General Contractor: Henderson, Inc.