Clarksburg Postal Facility

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Structural Stabilization & Rehabilitation

Since construction of the United States Postal Service sorting facility in Clarksburg, WV, the building has experienced ongoing differential settlement. As a result, damage occurred within the building. The damage was limited to cosmetic items such as cracks in the drywall, misaligned door frames, and cracks in the floor. To mitigate the ongoing settlement, a frac grouting program was specified as the method of treatment for the soils beneath the facility. ACT was the Prequalified Grouting Contractor awarded the contract for the frac grouting project.

The project involved fracture (frac) grouting of the soils beneath the existing postal facility to stabilize the soil mass and minimize future settlements. To accomplish this, we designed and fabricated custom steel sleeve-pipes and utilized a custom build hydraulic jacking unit to install the sleeve-pipes horizontally underneath the building. The sleeve-pipes were horizontally jacked into place from 4 access shafts located outside the facility. The access shafts were installed by ACT using a top down reinforced shotcrete construction method in which 5 feet of soil is excavated, steel reinforcement is installed and shotcrete in placed. A cementitious grout formulation was developed for the project to perform the frac grouting.

The postal facility was monitored in real time for heave/settlement during the frac grouting using electronic liquid level instrumentation linked to personal computers for data storage. Grouting was monitored in real time using electronic flowmeters, electronic pressure transmitters, computers and a custom software program written by ACT. The facility is a USPS postal sorting facility and remained fully operational to regular postal operations.