The Crossroads Mall in Boulder, Colo., opened in 1963 with nearly 400,000-square-feet of retail space. In 2006, the mall was demolished to make way for the new 29th Street Retail District. The $60-million project spans 62 acres and includes the construction of new retail, dining, entertainment, and office space in an open-air environment. Terracon performed a geotechnical investigation, construction materials engineering and testing, and Special Inspections for the project. Services included deep foundation exploration and observation, and concrete and soils testing. Layers of black organic soil were encountered below grade in some isolated areas of the site, which was not suitable for supporting foundations and slabs. Material was removed from the building foot print and an on-site granular fill was brought in. This provided a better foundation for floors and prevented collapse or potential settlement. In an effort to minimize waste from the demolition of the old Crossroads Mall, the contractor recycled material from the demolished buildings to use as fill under the new construction. Terracon provided the recommendation for recycling the rubble, suggesting it be blended with on-site soils for use as fill. This recommendation saved on the cost of having to export rubble from the site and reduced the amount of import fill required for the project. Terracon also oversaw the on-site recycling operations by methods of crushing and sieving. Recycled materials by methods, such as concrete and asphalt, were reused as base under slabs and helped in backfill of unstable utility trenches and parking areas that had pumping issues.