Date:September 2014

Prussian Woods: Micropiles and Compaction Grouting

King of Prussia, PA –

Prussian WoodsCGS performed compaction grouting and micropile installation for soil stabilization and sinkhole remediation at the Prussian Woods condominium complex.  Sinkholes and depressions were discovered to the rear and crawl space areas of five different units.  A common area retaining wall and depressions in other common areas were also discovered.  It was proposed to perform compaction grouting first then install micropiles at each of the units.  Micropiles were installed to carry the building loads.

Prior to starting the micropile process, CGS implemented a compaction grouting program that included installing the casings to the top of rock anywhere from 10 to 40 feet below the surface.  Voids were filled under basement slabs and improved the existing soils.  Foundation walls and slabs were monitored for movement during the process.  Once compaction grouting was complete, micropiles were installed to the rear of the units at each midpoint of the wall and corner support points.  Each micropile was installed 30 feet deep using a 40/20 Con-Tech Titan hollow bar.

Upon project completion, CGS drilled 728 linear feet at depths of approximately 30 feet and injected 114 cubic yards of grout.  Two and three micropiles were installed at each unit and the entire project was completed in four weeks using one grout crew.