Hydro Excavation at Suburban Hospital Provides Client-Focused Solution

At Suburban Hospital’s campus in Bethesda, Maryland, Clark is constructing a 300,000-square-foot addition and renovating the existing facility. This included the difficult task of performing extensive below-grade work underneath the active and fully-operational hospital.

The project team initially planned on hand-excavating a vertical pit under the hospital through the first-floor slab, but that would have required taking more than 5,000 wheelbarrows full of dirt out the front door of the building. Additionally, hand-digging and transporting such a large quantity of soil would have been time-consuming, expensive, extremely labor intensive, and subsequently riskier from a safety perspective due to the potential for strains, sprains, or accidents.

Construction Executive Brian Hetherington stated, "I had the opportunity to reconnect with Matt Michler with Atkinson Underground last year, who I had worked with 15 years ago, and mentioned our challenge.  He came by the site on one of his trips to Bethesda and suggested excavating from the side through the foundation wall. This approach would minimize the potential for disruption to hospital's operations.”

Along with shifting to excavate via the side of the building, the team also sought to solve the time-consuming and labor-intensive hand-digging. Matt Vaughn, senior project manager for the Clark team at Suburban Hospital, reached out to Shirley’s Metro Earthworks to help evaluate an alternative solution – hydro excavation.

Hydro excavation is a system which excavates using a vacuum hose and pressurized water hoses. The process removes loose soil via the hose from the excavation area and transfers it to a truck, which then transports the material to a yard to dry. After evaluating the options with Metro Earthworks, the Clark team decided hydro excavation was the best choice for the hospital.

The project team confirmed a confined-space safety plan and set up the hydro excavator hoses to run below the emergency department, adjacent to active conference rooms on racks mounted from the ceiling in an active hallway. Grout for Clark Foundations' underpinning pits were pumped back into the space along the same racks. Rather than hand excavating and moving the soil, the project team only had to loosen the soil for the vacuum. The team broke down any rocks that were too large for the vacuum and transported them out via the hospital’s loading dock.

The project team worked with key trade contractors and several departments at Suburban Hospital to ensure everyone’s needs were known and met during this sensitive operation. In many instances, the hospital continued to hold productive meetings in their conference space with underground excavation occurring only feet away from them at the same time. 

Thanks to proactive planning and innovating thinking from the project team, there were zero unplanned disruptions to the emergency department, conference rooms, or auditorium. "This operation was a case study in leveraging Clark's extensive network of resources, including Atkinson Construction, Clark Foundations, Shirley Contracting, Metro Earthworks, and Clark Concrete, to overcome a substantial challenge." says Hetherington.