To be successful, demolition contractors must be able to identify and solve unusual challenges. On a project in downtown St. Paul, MN, Rachel Contracting is doing just that as it brings down a massive 700,000-square-foot complex that was not only built into a bluff, but also faces a pair of busy St. Paul thoroughfares and, in places, is just steps from an active rail line.

The former West Publishing headquarters, built in 1886, and the Ramsey County Adult Detention Center (ADC), built in 1979, were mainstays of the St. Paul riverfront. Sitting on 3.9 acres, the seven structure complex had outlived its usefulness when West relocated to a suburb, and the jail was quickly deemed inadequate. Repeated efforts to sell the property were hindered by the daunting thought of demolishing the existing structures, which rise up to ten stories from the base of a riverside bluff, and years of on again, off again government tenants that finally led to the entire complex sitting vacant for the last several years. Recognizing the property’s tax revenue potential, Ramsey County committed to undertaking the demolition.

The eight story ADC is the first structure slated to come down. Work on it started in August 2015 with interior demolition, according to Mark Kraemer, Rachel’s vice president of field operations.

“The interior work included asbestos abatement, followed by removal of any remaining hazardous materials as well as municipal solid waste and other debris,” he said. “What makes this job different from most others, however, is the fact that the structures are essentially built right into the side of a bluff alongside the Mississippi River. So, with the preliminary interior work completed, we moved into a bluff stabilization phase. For that, we had crews core drill into the back wall of the building, install 40-foot threaded rods, and inject each core with grout to secure the structure to the bluff during demolition. Once demo is complete, a new concrete wall will be built and backfilled to keep the bluff face intact and ready for new construction.”

The height of the structures, more than 90-feet in most areas, coupled with their proximity to active pedestrian, vehicle and train traffic, eliminated the use of any of the more traditional demolition techniques such as implosion or a wrecking ball. The solution, a high reach excavator outfitted with a GDT Razer 290 from Genesis Attachments.

“We have the GDT mounted on a Volvo EC700C HR, a 195,000-pound base machine with the high reach package,” he said. “That configuration affords us just over 105-feet of reach, more than enough for even the uppermost reaches of the ADC structure. Our options were definitely limited by our surroundings. An active Amtrak line runs as close as 25-feet to one side of the jail, and one corner of the structure is just feet from the heavily travelled Wabasha Street Bridge.”

Material encountered during the ADC portion of the demo included 10-inch thick two way concrete slabs reinforced with No. 4 rebar at 10-inches on center each way. The structure also included a parking garage which had 12-inch concrete slabs.

“We also processed 1.5-foot square reinforced concrete columns, and concrete waffle slabs measuring 12-inches deep, with a 19-inch dome, 5-inch wide ribs and a 3 5/8-inch topping slab,” said Kraemer.

As the project continues, the company will eventually be far enough into the structure that they will be at street level and facing Kellogg Avenue, a major east-west artery in downtown St. Paul, and still another logistical challenge. Remaining highly controlled in every aspect of the demolition process, said Kraemer, has not only been key to their production, it’s helped ensure a safe operation.

At 7,000-pounds, the GDT Razer is light enough to be very maneuverable, even at peak heights, yet still provide the power needed for effective concrete cracking. According to Rachel’s project superintendent, Jim Jude, that maneuverability is being put to the test on the ADC facet of the job.

“The jail’s overall footprint is a strange zig-zag shape, but the interior of the structure also has hallways and walls that seem to run in every direction,” he said. “Through a combination of the attachment’s rotation and its design, the GDT Razer is able to easily access every area we need to get at, then crack and drop the concrete material. It will also be great to have that degree of control when we are at the part of the structure where the tie backs are present. Being able to trim in these areas without fear of messing with the tie backs will be a real plus.”

For added versatility, the number and location of crushing teeth on the GDT Razer can be customized to meet Rachel’s project needs. In addition, the bolt-on teeth can be interchanged and reversed front to back, increasing their life and lowering the cost of operation. Jude said the position of the pin centers on the tool make it easier for him to roll it back to get under a beam. “That alone has helped keep things moving out here.”

While the GDT Razer has four way indexable blades for cutting any rebar encountered in the structures, the bulk of the actual material processing is being done using a combination of additional Genesis tools. These include an LXP^® 300 Logix Processor and a GDR 300 Demolition Recycler, each mounted on a Cat 336E; and a DemoPro 900 on a Cat 349.

“The other attachments will be pulling double duty on this project,” said Kraemer. “In addition to processing the more than 100,000 tons of concrete and brick we expect to encounter here, they will also be doing actual demolition on some of the lower, more accessible areas of these structures. We like that they are multi-faceted in what they can do and use it to our advantage whenever possible.”

Kraemer said Rachel Contracting’s relationship with Genesis extends back about eight years and, while they obviously appreciate the job the tools do, the commitment centers around service and support. “We like that Genesis is always there when we need them, treats us well and keeps us in the loop with new developments as they arise,” said Kraemer. “They have the whole package, and we like that.”

The St. Paul project includes far more than just the Ramsey County Jail. Next on the list is the one time West Publishing complex, now called the Ramsey County Government Center, RCGC. The RCGC sits adjacent to the jail, is roughly three times its size, and presents the same logistical challenges as the ADC.

“The RCGC complex represents the bulk of the 700,000-square-foot of demolition,” said Rachel’s Kraemer. “And, because it was added onto repeatedly in its 130 year history, there are different types of construction, some with much more structural steel, for example. However, because of who we are as a company and the way we approach projects like this, we are equipped to tackle anything we encounter.”

The $13.1 million demolition is slated for a Spring 2017 completion.