Demolition contractors regularly face site constraints that rule out conventional methods such as wrecking balls or explosives. When Modern Surveying Instruments and Their Uses help establish tight clearance margins around standing structures, project teams must rely on creative equipment solutions to bring down tall industrial features without collateral damage. A recent project by Veit Companies of Rogers, Minnesota, demonstrates how concrete processing attachments, custom fabricated brackets, and crane-based suspension systems can safely demolish twin smokestacks in close quarters.
Project Background and Site Constraints
The site was a former coal-fired utility plant near downtown Minneapolis that was being converted to natural gas operation. Two 248-foot smokestacks, originally built to serve the coal boilers, were no longer needed and had to be removed. The demolition challenge was severe: the stacks stood as close as 15 feet from adjacent structures, including a 90-foot-tall brick building with windows that had to remain undamaged.
Ryan Olson, Veit’s general superintendent of demolition, explained that the project owner had ruled out explosives, and the proximity of surrounding buildings made a wrecking ball approach impractical. The team needed a method that could bring down the reinforced concrete stacks piece by piece while maintaining control over falling debris at every stage.
Why Traditional Methods Were Not Suitable
- Explosives ruled out: The owner prohibited blasting due to vibration concerns and the risk of uncontrolled collapse near sensitive equipment still in use at the plant.
- Wrecking ball impractical: The swing radius of a wrecking ball would have brought the heavy mass dangerously close to the adjacent 90-foot building, risking structural impact damage.
- Manual demolition too slow: Pneumatic jackhammers and handheld tools would have required weeks of elevated work at 248 feet, with significant safety exposure for crews.
- High-reach excavator limitations: Standard demolition excavators could not reach the full height of the stacks, and setting up a machine on the limited footprint around the stacks was logistically difficult.
The solution required a technique that could reach the full 248-foot height, deliver enough force to break 18-inch-thick reinforced concrete walls, and keep debris falling within a contained zone. Veit found the answer in a method they had successfully tested on a previous tall stack demolition: suspending a concrete processing attachment from a crane.
Custom Bracket Design and Crane Setup
The centerpiece of Veit’s approach was a Genesis LXP 300 concrete pulverizer, a hydraulic attachment normally mounted on excavators. For this project, the LXP 300 was suspended from a Link Belt crane with 275-ton lift capacity, equipped with a luffing jib that gave the operator precise access to every part of each stack. Before lifting the attachment, Veit designed and fabricated a custom bracket to hold the LXP 300 securely during suspension operations.
Bracket Design Improvements
The bracket was similar in concept to one Veit had built for an earlier stack demolition, but with significant improvements based on field experience:
- Stability enhancements: The revised bracket design increased the stability of the attachment during pulverizing. Olson noted that a more stable attachment directly improved production rates, since the LXP could maintain consistent crushing force without swinging or twisting.
- Quick installation and removal: The new design allowed the LXP 300 to be installed on or removed from the bracket within minutes, reducing downtime between stages of the demolition sequence.
- Compatibility with multiple machines: The bracket was designed to work with both the crane suspension system and the excavator mounting system, allowing the same LXP 300 to transition between the two as work progressed.
Crane Configuration and Operation
The Link Belt crane was set up with a luffing jib, which allowed the operator to adjust the boom angle independently of the main hoist. This configuration provided several advantages:
- The operator could reach every section of the 248-foot stack without repositioning the crane base.
- The luffing jib maintained precise control over the suspended LXP 300, keeping it pressed against the concrete wall at the optimal angle for pulverizing.
- Once positioned, the crane processed continuously from the top of the stack down to the 125-foot level without moving.
Three-Stage Demolition Sequence
Veit executed the demolition in three distinct stages, each using a different combination of equipment to progressively reduce the stacks from 248 feet to ground level. This phased approach maximized efficiency while maintaining safety and debris control at every height.
Stage 1: Crane-Suspended Processing (248 ft to 125 ft)
The crane-suspended LXP 300, equipped with a concrete pulverizer jaw, was lifted to the top of the first stack. The pulverizer jaw was designed to crush the 18-inch-thick reinforced concrete walls, breaking the material into manageable pieces that fell straight down into the stack’s interior or directly onto the ground below. Olson reported that the LXP provided genuinely controlled demolition, with debris falling predictably without endangering adjacent structures.
Once the first stack was reduced to approximately 125 feet, the crane was moved to the second stack to begin the same process. This coordinated approach kept both stacks progressing simultaneously, reducing overall project duration.
Stage 2: High-Reach Excavator Processing (125 ft to 30 ft)
The second stage introduced Veit’s specialty machine: a Caterpillar 365C excavator fitted with a Jewell Manufacturing long-reach boom. This machine had been purpose-built for Veit by Genesis and Jewell and had become a signature tool in the region. It was equipped with a Genesis LXP 200 attachment fitted with concrete cracker jaws.
The concrete cracker jaws offered distinct advantages for this stage:
- The narrower jaw design concentrated all hydraulic force onto a smaller contact area, delivering higher crushing power than the pulverizer jaws used in Stage 1.
- A shear blade at the throat of the cracker jaw could cut through reinforcement bar encountered during demolition, eliminating the need for secondary cutting operations.
- The long-reach boom provided over 125 feet of reach, allowing the excavator to process both stacks from a single safe position without moving.
Olson noted that production rates improved noticeably once the switch was made from the crane-suspended pulverizer to the excavator-mounted cracker jaws. The excavator provided a more stable platform, and the dedicated cracker jaw was better suited to the reinforced concrete at the intermediate height range.
Stage 3: Ground-Level Processing and Recycling (30 ft to 0 ft)
At approximately 30 feet, the remaining stubs of the stacks were handed off to a standard excavator equipped with the LXP 300 that had previously been used on the crane. This machine finished the demolition down to ground level, downsized the concrete rubble to manageable sizes, and separated the reinforcing steel from the concrete for recycling.
The three-stage approach allowed Veit to maintain continuous production across all height ranges without the downtime that would have resulted from switching between completely different equipment sets mid-project.
Protective Measures, Dust Control, and Future Work
Protection of Adjacent Structures
To protect the 90-foot brick building located close to the stacks, Veit implemented a multi-layered protection system:
| Protection Method | Purpose | Location |
|---|---|---|
| Geotextile fabric | Caught small debris and prevented cosmetic damage to brick exterior and windows | Draped over the side of the building facing the stacks |
| Hay bales | Absorbed impact energy from falling concrete pieces | Placed on the building roof surface |
| Steel sheeting | Provided a hard barrier against larger falling fragments | Layered over hay bales on the roof |
| Water-based dust suppression | Minimized airborne concrete dust and silica particles | Integrated into both LXP 300 and LXP 200 attachments |
Olson noted that while Veit always takes every precaution to protect adjacent property, the controlled demolition provided by the suspended LXP attachment was so precise that much of the protective layering proved nearly unnecessary. The majority of debris fell straight down through the open top of the stack or directly alongside it, without scattering toward the building.
Dust Suppression Systems
Both the crane-suspended LXP 300 and the excavator-mounted LXP 200 were equipped with water-based dust suppression systems. These systems sprayed a fine water mist at the crushing point, capturing airborne concrete dust and silica particles before they could migrate off-site. This was especially important given the site’s proximity to other operating plant facilities and the urban environment near Minneapolis.
Project Timeline and Remaining Work
The demolition of the two 248-foot stacks was completed in approximately three weeks, with multiple additional tasks occurring simultaneously across the broader plant conversion project. However, Olson noted that the work was not finished: a third smokestack measuring approximately 500 feet remained on the site.
For the third stack, Veit planned a different approach due to its extreme height, which exceeded even the reach of their 275-ton crane with luffing jib:
- Ring scaffold construction: A crew of six to eight workers would build a ring scaffold around the 500-foot stack and begin demolition using pneumatic jackhammers from the top down.
- Crane takeover at 250 feet: Once manual demolition reduced the stack to approximately 250 feet, the Link Belt crane with the LXP 300 would take over, repeating the proven suspension technique used on the first two stacks.
- High-reach excavator finish: The Cat 365C with Jewell long-reach boom and LXP 200 cracker jaws would then complete the demolition from 125 feet down to ground level.
Veit’s experience on the twin stacks demonstrated the value of investing in custom attachments and bracket systems. The company’s willingness to design, fabricate, and refine specialized tooling for unique site conditions allowed them to complete a complex demolition safely and efficiently where conventional methods would have been ineffective or prohibited.
For demolition contractors and construction professionals planning similar tall-structure removals, the key lessons include the importance of evaluating What Is Mat Foundation Functions Uses and Construction considerations for crane setup, understanding Types of Foundation for Buildings and Their Uses Pdf for supporting heavy demolition equipment, and applying Dynamic Compaction Advantages Purposes and Uses principles when managing ground conditions around demolition sites.