On site building expansion required foundation under-pinning of an existing 8-story tower. A12” drainage pipeline, located directly beneath the building, was struck during drilling and subsequently filled with 5,000 psi grout. This problem was discovered during the height of COVID and during the Christmas holiday when building roof drains and mechanical rooms were not draining during overnight rain.

• Excavation and shoring of an entry shaft beside the building foundation extending appr 18’ deep.

• Hand-tunneling 50LF under the building while exposing the grout-filled pipeline and construction a tunnel shoring system.

• Hydro-blasting the remaining pipeline at 55,000 psi

• Installation of a new 12” DIP to an exterior junction manhole.

• Pressure-grouting the remaining tunnel to fortify the building foundation.

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The project involved multiple trades and extensive design while maintaining the safety of project personnel and building residents.  Charlotte Fire/Rescue were heavily involved due to the unique nature of the project.

​The project was a huge success as stormwater flows and the building foundation remains intact to this day.