Hayward Baker's ground improvement program was completed 1.5 weeks ahead of the anticipated contracted schedule.

The project

New proposed structures — a 16,000-square-foot aeration basin and two 5,000-square-foot clarifiers — were to be constructed within an approximately five acre site. Near-surface alluvial soils consisted of lean clay, silty clay, and clayey sand.

The challenge

The anticipated structural loading ranging from 1,600 to 3,500 per square foot would have caused significant compression of the upper strata, resulting in intolerable differential settlement between facilities. Removal and replacement of the upper 12 to 15 feet of site material would have required approximately 14,000 cubic yards of imported fill.

The solution

In lieu of removal and replacement of compressible soils, HBI designed and installed a ground improvement program consisting of over 1,000 Vibro Piers that would keep differential settlement to less than 0.75 inches. This program improved the allowable bearing pressures of the in-situ soils by increasing bearing capacity and reducing anticipated settlements to tolerable values.

The PCL team appreciated Hayward Baker’s expertise in pier construction. The team’s knowledge and expertise was instrumental in our early talks with the design engineers to help develop a work plan to deal with our challenging soil conditions.

Jared Rubinoff, Assistant Project Manager at PCL Construction, Inc.  

Project Facts


Town of Marana

Main Contractor(s)

PCL Construction, Inc.

Keller Business Unit(s)

Hayward Baker


Carollo Engineers