Trench safety through advanced processes with zero excavation.

It was my pleasure to work with United Rentals and Mortenson Construction at the Lutheran Hospital in Wheat Ridge, CO on this challenging project.  Personnel from Concrete Stabilization Technologies (CST), United Rentals and Mortenson Construction coordinated a safety plan to address loose sandy soils running parallel to a new trench being dug in the central energy plant of the 50 plus year old facility.  CST was contacted to address loose sandy soils that collapsed during excavation into the trench from under the existing slab.  The 4' wide trench was to be excavated down to 12' below top of slab elevation.  Loose soils were located at roughly 3'6" below top of slab elevation.  CST's solution was to use the patented Uretek Deep Injection method to create a below grade retaining wall below the slab and parallel to the trench to support the loose soils.  2 staggered rows of penetrations were injected from -3' to -13' with patented expanding structural polymers to create 2 back to back "retaining walls" below grade with no excavation.  Due to the tight quarters of the area, solutions were very limited.  This process was performed in 1 1/2 days total and saved considerable time and costs over any other alternative.  The excavation has since been finished and with no danger to the excavators.  Shoring was used and dropped in place in 2 foot lifts during the excavation process.  Special thanks to: Kris Graham - United Rentals Trench Safety Specialist, Boone Cervantes - General Foreman for Mortenson Construction, Ryan May - Project Manager for Mortenson Construction and Telsche Jaderlund - Safety Engineer for Mortenson Construction.