Kent County Courthouse
Hillis-Carnes was contracted to design and implement a soil solidification program in conjunction with traditional underpinning methods to support the foundation of the existing Kent County Courthouse building to facilitate a 148,000 square foot addition to the original 46,000 square foot building located in Dover, DE. The 3-story addition will cost approximately $70 million once completed. A Geotechnical study indicated that the soils in the area of the proposed conventional underpinning location would be classified as OSHA Type C. These soils are loose to very loose sandy soils, which are unable to stand vertically for an extended period of time and are therefore considered to be “high risk” for working conditions. Therefore, Hillis-Carnes proposed a soil solidification program using a chemical grout product. Soil solidification is a process used to increase the compressive strength and decrease the permeability of existing soils to make them more stable without destroying the soil matrix. The purpose of the soil solidification program in this case was to modify the existing soils so that they could “stand in place” in order to facilitate excavation to construct a soil nail and shot-crete wall to underpin the existing foundation. Once the foundation has been underpinned, the site contractor can then safely excavate to construct the underground parking garage of the new addition.