Situation: The 230KV and 69KV duct banks were build on top of an existing landfill. Over time water infiltrated and caused as much as 18” in settlement.
This project included analysis of methane gases, electrical fields and drilling through debris and trash and pressure grouting the same to support the duct bank. Several methods were considered including various Piles.
Ultimately pressure grouting was chosen because the solution included grilling through the debris, trash and soil using a grout casing custom built with an auger on it. The casing was advanced using a torque drive and a water swivel so that could be injected during advancement to help clear out debris Grout was installed first on the perimeter of the areas to create containment, Volume, pressure and vertical movement criteria were established for stopping each lift of grout before lifting the casing and injecting again.