Miami Valley Hospital In Dayton, Ohio Gets Entire New Wing

The Problem

In September of 1998, Cutting Edge Services, Corp. was called upon to remove a reinforced concrete stair tower, 70-feet high, 12 feet across and extending 15 feet off of the face of a building, to make way for a large, new wing to Miami Valley Hospital in Dayton, Ohio. This job was made more challenging because it had to be done quietly. The tower was adjacent to critical care patient rooms and sensitive operating rooms.

Cutting Edge Services was one of the first contractors to pioneer diamond wire construction sawing for North America in 1983. The company was glad to be called to perform these services. The company's strengths were perfectly matched with the job that needed to be done.

Any time there are large facilities or very thick structures that require precision removal, projects that require limited access, heights or very unusual thicknesses, Cutting Edge Services can be of help.

The portion of the work that needed to be done at the hospital was to make room for a 221,000 square foot addition.

The expansion provided more space to encompass a new emergency department, surgery, recovery and outpatient surgery as well as a new central service distribution.

The hospital chose Cutting Edge Services because they wanted a firm that had the capability of removing the existing materials without making any great noise to interrupt the patient care in the building. This work was accomplished in an area adjacent to patient care rooms as well as the operating and emergency departments.

The Solution

Cutting Edge Services came up with a scheme to cut the tower from the top down and cut through the walls, stair sections and other concrete attachments with one single wire cut. Our company's pricing was most likely in line with other techniques that might have required more labor. Wire sawing required less use of labor and more use of the equipment.

It is precisely this increase in productivity that has helped the number of wire saw jobs mushroom. Jobs are completed in less time with less manpower than required by conventional demolition. Such conventional methods as jackhammers, hoe-rams, and explosives create a considerable amount of noise, dust and vibration. The diamond wire saw, on the other hand, creates very little noise, no dust and does not weaken surrounding structures because of vibration. Additionally, the length of the wire is virtually unlimited -- any size cut can be made.

In operation, the diamond-embedded wire is driven and guided by a pulley system. The guide wheels or pulleys are mounted near the structure to be removed and generally are no larger than 16 inches in diameter. The power unit can be placed several yards from the work area. The pulley system allows for the removal of heavy reinforced concrete where the work space is limited or in areas that pose a safety hazard for the operator.

In a typical cut, a small hole is drilled at each end of the cut to be made. The wire is passed through the two holes and then coupled together. It is placed on the drive wheel and around idler wheels that guide the wire. Water is used to cool the wire and to wash away the slurry created by the cutting operation. Wire tension is maintained via a hydraulic "stroke" motor that pulls the main drive wheel along its sliding carriage assembly. The main drive assembly is a simple fly-wheel that is hydraulically driven.

This job presented several challenges. Cutting Edge was blocked from access inside the hospital, so the only access was from the outside. Also, as the structure was being cut free, it had a tendency to become unstable. Since the cutting for this job started at the top, the biggest challenge was that there wasn't room to really run a wire saw at the various elevations, so they had to run the wires from the ground up. In addition, with diamond wires, the longer they get, the more complicated projects become. For this job, it took a 250-foot length of wire to make the initial cuts by running the wire up along the side of the building and transitioning to a horizontal cut at each elevation.

Also, there were approximately 40 two-inch diameter wire access holes that were drilled for the wire access points. For rigging, there were approximately 60, four-inch diameter holes drilled through the composite section, consisting of four inches of brick and then an air space and 12 inches of reinforced concrete.

Diamond wires used were the center type cable, 11 millimeters in diameter. A separate contractor was responsible for the crane lifting and the removal of the concrete. The company utilized an 80-ton capacity truck-mounted hydraulic crane. All-terrain mobile lifts were used for the drilling crews and technicians to access the elevated points.

The structure came off as a three-sided shape that had to be handled carefully. A spreader bar was used to apply even vertical loads to the pieces on the wall so the structure didn't collapse when it was picked up as any type of significant movement or loss of a large section of the piece could have caused damage to facilities and equipment below.

There was a limitation on the size of the pieces that could be picked up with the crane, so Cutting Edge Services helped size the sections that were coming down. They also planned the layout, starting from top down, to determine where all the horizontal cuts would be made. The whole cut was done in eleven pieces, each weighing up to 35,000 pounds each.

Once most of the holes were drilled, Cutting Edge Services proceeded with the horizontal wire cut and worked its way down. After removing the first two pieces, the structure was stable enough with this method of cutting so the crane could be moved off site while the remainder of the horizontal cuts were completed.

This left the structure attached to the hospital only on the vertical face. From there the company finished the project with the second of two wire saws that made flush cut against the hospital face and freed those stair tower sections. Then each section of the tower was cut through, lifted off and lowered to the ground for removal.

The Result

The hospital was quite satisfied with the results. What they really enjoyed was the fact that the wire cutting was extremely quiet. Cutting Edge Services didn't even need OSHA ear protection to be able to work adjacent to the wire cutting operation. Also there was no vibration or dust.

Another advantage for the wire saw was that it didn't take up much space. The contractor was able to keep the equipment in a small pad adjacent to the hospital. Excavation around the stair tower to the west and to the south of the staging area was very close to where the wire sawing was performed.

In appreciation for its good work, Cutting Edge Services was invited back to complete the second phase, which involved the cutting of a second, similar tower.