Architect: Paul Slater
Geotechnical engineer: Ground Engineering Consultants, Inc.
Structural engineer: JVA
General Contractor: FCI Constructors, Inc.
Certified Installer: Complete Basement Systems, Inc., Aurora, CO
Products Installed: 12 push piers & 22 new construction helical piers
Serving the Boulder Valley School District in Boulder, CO, the Heatherwood Elementary School has about 385 students. Classrooms, administration offices, cafeteria, and other functional spaces occupy a single large building where numerous structural issues were present.
The most noticeable of these included large cracks in the brick face and masonry columns of school walls, cracking and shifting of interior floor slabs, and exterior flatwork that had also cracked and shifted. Much of this damage was attributed to settlement, but a thorough soils analysis was done as a prelude to foundation repair work.
Test holes by soil engineers identified a thin layer of topsoil overlying man-made fill that extended approximately 3-10 feet below existing grade. Below the fill, sandy clay soil was encountered, followed by interbedded sandstone/claystone bedrock.
To stabilize and lift the settled area of the building, 12 model 288 helical piers were installed. An additional 22 new construction piers were also installed for a new addition to the school.
Although the soils report identified suitable bearing at a depth of 16 feet, pier depths ranged from 18 feet to 23 feet.
We thought we would have to predrill all piers due to the location, but fortunately, we only had to predrill 2 piers.
Once the piers were installed, L-shaped foundation brackets were positioned below and against the footings and hydraulic cylinders were used to lift the foundation back toward a level position.
The major challenges on this project were time and cold weather. Working in outside temperatures as cold as -12 degrees (F) below zero, Complete Basement Systems completed the 34-pier foundation repair job 4 days ahead of schedule.