Located at the Hamner Avenue Bridge over the Santa Ana River in Norco, CA. Malcolm Drilling was awarded the ground improvement work to enhance the safety, stability, and serviceability of the bridge approaching embankment.
Malcom designed and installed stone columns to mitigate the site liquefaction and lateral spreading hazards below the planned retaining wall footprint. To densify the liquefiable sands, Malcolm Drilling designed the treatment layout, diameter, and depth based on our experience and analysis. The customized vibrator penetrated 30-feet below the working platform, densified the loose sand, bottom filled with crushed rock, and formed stone columns back to the ground surface. An average of 36-inch diameter stone columns were installed in an eight-foot square pattern with a 11% replacement ratio. Malcolm used a real time data acquisition system to monitor and record the vibro replacement stone column installation parameters, including the vibrator penetration depth, electric current, air pressure, and interpolate stone column diameter as a function of depth. This system provided a reliable field quality control record to the design engineer and the client. As part of the quality assurance process, 20 post-treatments cone penetration tests (CPTs) were performed and analyzed, conformed all the design densification criteria achieved.