Gordon Family YMCA, Sumner WA

During the construction of the Gordon Family YMCA in Sumner, Washington, unforeseen offsite dewatering activities for new utility installations led to settlement issues in the under-construction building. This posed a significant challenge, particularly for the planned pool area, which required excavation below the groundwater level. Traditional dewatering methods risked further settlement, potentially compromising the structure’s integrity.

To address this, Mr. Rohrbach devised an innovative solution employing deep soil mixing (DSM). This technique involves mechanically blending the in-situ soil with a cementitious binder, resulting in soilcrete—a material with enhanced load-bearing capacity and reduced permeability. By creating a low-permeability zone beneath the pool area, the DSM approach effectively sealed the subgrade against groundwater intrusion. This eliminated the need for additional dewatering, thereby mitigating the risk of further settlement.

The successful implementation of this technique not only ensured the structural stability of the YMCA building but also allowed the project to proceed without significant delays. Today, the pool serves the community, standing as a testament to the efficacy of advanced geotechnical solutions like deep soil mixing.