Six Mile Library Regional Renovation

Summary

Kaskaskia Engineering Group, LLC (KEG) provided geotechnical engineering services for the renovation of Six Mile Regional Library in Granite City, Illinois.  KEG was contracted by Trivers Associates, the architect for the project, to explore the subsurface conditions and develop recommendations for the design and construction of the foundations and earth-related phases of the project.

Project

The 17,000-square-foot library building, originally erected in 1929, was remodeled to increase its functionality and meet current building codes. Improvements to the lower level consisted of several new spaces, including a new youth section, a 60-person capacity conference room for community use, and a local history room that doubles as a quiet study area. The circulation desk was relocated to the main floor to allow for additional stacks.

On the outside of the library, the brick and stone were cleaned and restored and handicap-accessible ramps were installed at the front and back of the building. The exterior work also included bracing the high parapet to be sure it complies with the building code.  KEG drilled two soil borings to develop geotechnical recommendations for exterior ADA-compliant handicap ramp foundations and retaining walls at the northeast and southeast building corners.

The site is located within the flood plain of the Mississippi River.  Alluvial soils were encountered, consisting primarily of sand, with some surficial cohesive soils, including high plasticity clay.  The groundwater level can rise to shallow depths as the river level increases.  Recommendations were provided for bearing capacity, lateral earth pressures for retaining wall design, settlement, seismic design, and floor slab design.  General construction considerations were also discussed in the report.