April 7, 2021 ITS Money: Marco Fellin, P.E.

Marco Fellin, P.E. | Tetra Tech | ECA Geotechnical Group

Benefits of a Pile Testing Program During the Design Phase

A bridge replacement project in Helena, MT consisted of replacing two 12-span interstate bridges with two 4-span bridges in an area with complex subsurface conditions. Several foundation options were evaluated, which showed that the preferred option was the use of shallow driven piles. A test program was then performed during design to determine the axial, lateral and uplift capacity to demonstrate the feasibility of this option. The program also produced more precise soil properties, which allowed further optimization of the design.

Findings

• Test Pile Program cost $200,000.
• Using the test results the foundation design was optimized by using shallow pipe piles to save approximately $3 Million in construction cost (pre-bid estimate) over drilled shafts.
• The shallow pipe pile foundation was estimated to reduce construction duration about 2 months.