Malcolm’s first diaphragm wall (“D-Wall”) project in Oregon was for a pump station and associated water treatment plant in Hillsboro. A diaphragm wall is a reinforced concrete wall, excavated under bentonite slurry. This wall was part of Malcolm’s innovative, value engineering proposal to substitute the original design which was based on two sunken caissons with 20-foot thick tremie plugs. As designed for this project, the circular diaphragm wall acts as a compression ring and serves the dual purpose of a temporary shoring wall as well as part of the permanent structure for the pump station. There were many challenges presented by this job site: high ground water levels, poor soil conditions, and rainy weather just to name a few. Event with all of these challenges, Malcolm was able to offer major cost and time savings because their design build proposal eliminated the need for a massive concrete bottom plug and dewatering.
