Nowhere to go but Down

Hydroexcavation firm sucks 3,000 cubic yards of debris out of a basement and over a street for a hospital expansion.
Nowhere to go but Down
The only access to the excavation site was through crawl spaces and utility access areas in the lower level of the hospital.

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Working at a hospital presents challenges. Working under a hospital presents more challenges.

Ecotech Hydro Excavation crews learned that lesson when they took on a job to expand a Philadelphia hospital. The job required working in tight spaces and vacuuming 3,000 cubic yards of compacted soil and debris over a span of more than 400 feet.

“It was definitely a challenge,” says Ryan Frank, operations manager. “We just needed to think outside the box and get creative.”

The air and hydroexcavation company based in Quarryville, Pennsylvania, wasn’t afraid to tackle the job, which spanned nine months. The company works throughout Pennsylvania, New York, New Jersey, Delaware, Maryland and other areas of the Northeast.

“This was one of our biggest and toughest jobs,” Frank says. “It was a lot of the worst-case scenarios of every aspect of what we do.”

Taking on the job

The downtown Philadelphia hospital was undergoing an expansion, but it couldn’t go any higher than its nine stories because of ordinances, and there was no room to expand laterally. “The best option was to expand down,” Frank says. “There was an area in the center of the hospital that was just a crawl space and not a full basement, so that is where they would add extra offices.”

The general contractor was given the option of building a temporary hallway within a permanent hallway; laborers would hand-dig the soil into 50-gallon drums. The drums would then be carted out of the building and emptied into a dumpster. After the drums were cleaned out and brought back in, the process would repeat.

“One of their guys thought about vacuum excavation and they contacted us,” Frank says. “A total of 3,000 cubic yards of dirt, rocks and bricks had to be removed. Our estimate for the job was around $650,000 and the bid for doing it with the drums came in at $1.3 million, just to get the material out of the hospital. So there was a substantial cost savings going with vacuum excavation.”

Ecotech crews determined that the only way to get to where the excavation would take place was through crawl spaces and utility access areas in the lower level of the hospital. “We set up the vacuum truck outside at their loading dock area and ran 400 feet of pipe and hose into the center of the hospital,” Frank says.

The company’s GapVax HV-56 hydroexcavator was parked on the opposite side of the road away from the hospital, and its boom was stretched over the road to allow cars to pass underneath. The hose was positioned over scaffolding on the sidewalk closest to the hospital, giving pedestrians a safe place to walk.

A need for stronger pipe

Crews used 6-inch PVC pipe connected to 6-inch hoses from the hydroexcavator to the center of the hospital.

In the first few days on the job, workers were already running into issues. “Our initial problem was that everywhere there was a bend in the pipe, the pipe would want to blow apart from the rocks,” Frank says.

Crews also had two elevation changes to contend with: The hose from their hydroexcavator entered the building and dropped 17 feet into a room, then stretched across the floor and back up a 20-foot wall into the room that was being excavated.

“Trying to keep productivity up in that long-distance remote excavation was a big factor,” Frank says. “One thing we found is that the elevation changes made a tremendous difference.”

Debris going down the hose became a bigger problem than the material going back up. “You had to have so much cfm to get the material to pull 400 feet, but you couldn’t have the cfm up too high,” Frank says. “When that material would hit the downslope it would come screaming down that hill, build up too much velocity and damage everything it came into contact with.

“Anything plastic or metal on the hose was just wearing through because the material was dry and very abrasive. The pipe also had to be light enough for two men to carry it through a crawl space.”

To deal with these challenges, crews switched to 5/8-inch thick-walled pipe made for waterline installation and used heavy rubber elbows to make the bends.

Finding easier ways to work

Finding a way to break up the dirt so it could be vacuumed was another challenge.

“An air knife wasn’t a possibility and other air-spade tools like jackhammers were incredibly slow,” Frank says. “We ended up finding an electric mini-excavator that we pushed through the hallways of the hospital on a wood skid and dolly.”

Crews connected the mini-excavator to the available power source and as one worker used the machine to break up dirt, another vacuumed it.

“The GapVax kept up,” Frank says. “The material we were able to pull out of the building was going faster than what we could get broken up, so the truck and mini-excavator worked well in tandem.”

Ecotech was allowed just one truck on the job site. Two vacuum boxes were set up near the truck.

“Once we had the material in the truck, all we had to do in the middle of the day was switch hoses and move it to one of the two vacuum boxes,” Frank says. “We didn’t have to move the truck and we could just keep on working.”

Gaining confidence

The new offices in the hospital’s basement were completed in late 2015.

“Inside the hospital no one even knew Ecotech was there working or that there was construction going on,” Frank says. “We all worked really hard and did a great job. All parties involved were impressed and happy with the end result.

“More than anything it gave us confidence knowing there wasn’t a job we couldn’t successfully do.”


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