Challenging high rise demolition for RachelPublished 15/9 at 12:02
In the US the former West Publishing complex, built in 1886, and the Ramsey County Adult Detention Center, built in 1979, in St Paul Minnesota are being demolished to make way for a $150M redevelopment.
Rachel Contracting, based in St. Michael, Minnesota, is using a Volvo EC700CHR high reach excavator on the $15M (€12.8M) demolition project, which is scheduled for completion later this year.
Work began on the 10 storey complex of seven buildings in November 2015 and covered a variety of applications. “The first step was to abate all hazardous materials, including asbestos,” said Rachel Contracting project manager Nick Bartemio. “More asbestos was uncovered than initially anticipated by the pre-engineering studies. Before any exterior demolition could begin in earnest, bluff stabilization was required to shore up the back wall facing Kellogg Boulevard.”
Rachel completed this by drilling 5,486m of grouted rock anchors into the face of the bluff. When demolition is complete, Rachel Contracting will build a 457mm to 609mm thick, 2,322m2 cast insitu concrete retaining wall along the city’s main Kellogg Boulevard.
The height of the structure, plus the location proved to be one of Rachel’s most challenging demolition projects. “The site sits between a main downtown artery and is 9m from an active rail line on the Mississippi River facing side,” said Rachel Contracting, field operations vice president Mark Kraemer. “We knew going into the bid that we could not bring it down by explosives, so the only option was to use a high reach demolition excavator. We looked at competing brands, but we felt more comfortable going with the Volvo. The support from local dealer Nuss Truck and Equipment was a big factor in our decision. We had a short lead time, and Nuss was able to provide the machine very quickly and were on site for set-up and training our operators.”
The high-reach machine has a maximum pin height of 32m with boom extension and is fitted with a Genesis GDT Razer 3t shear. It can fracture concrete and snip rebar at height, and safely lower it to the ground.
"The high reach allows us to bring this job down in a much more controlled fashion. On a building like this, with thick concrete columns wrapped around steel 1-beams, we can cut through them with the shear without jeopardizing the safety of the building, pedestrians and vehicular traffic," said Rachel Contracting general demolition superintendent Randy Shultz.
The machine is converted to a standard boom every two to three days and is paired with a Genesis DemoPro 900 for concrete cleanup. “The conversion enables the machine to work with a 5.4t attachment and use at work heights of 18m to 20m,” said Kraemer. “That height level is our bread-and-butter here in the Midwest. We have it down to less than an hour with two people. Volvo did an excellent job making this machine come apart and reassemble easily.”