Moline, IL's Hamilton Elementary School Gets Support from MidAmerica

Challenge

A slab-on-grade building addition was planned along the south and east sides of an existing school gymnasium. The gymnasium had experienced differential settlement at its southeast corner, evident by previous tuckpointing repair in the brick veneer. The existing gym foundation consisted of a three-foot deep foundation wall supported by a one-foot thick continuous footing. The new addition foundations planned adjacent to the southeast corner of the gymnasium included helical piles installed along the existing footings and cast into structural grade beams. These grade beams would be doweled into the existing footings and foundation walls to stabilize the existing building corner as well as support the new loads of the proposed addition. A geotechnical investigation performed in the area of the proposed helical piles identified approximately six feet of uncontrolled lean clay fill over medium stiff to stiff lean clay and silt (loess) to depths from 27 to 30 feet below grade. Stiff to very stiff sandy lean clay (glacial till) then extended to approximately 98 feet.