The expansion at the Rosedale WWTP required the saturated ground to be improved prior to the construction of the new thermal hydrolysis plant. The conforming design required the installation of 800mm-dia stone columns at an Area Replacement Ratio (ARR) of 18%. We offered an alternative solution for Rammed Aggregate Piers (RAPs) at a lesser ARR but due to time constraints for the design review process, we were required to install the RAPs at the 18% ARR. This resulted in the installation of 1,130 no. x 10m long stone columns and 168 no. x 5m perimeter stone columns using the Geopier RAP technique including 3 no. modulus tests.
We had to overcome the saturated ground (clay) slowing production so we introduced air into the probe to reduce the resistance this was causing. Fulton Hogan were working to a strict deadline so we provided two crews to reduce the program pressure. We completed the works ahead of schedule and received praise from Fulton Hogan’s on site staff for the manner in which we conducted ourselves on site.