Frozen Ground Excavation: The Contractor’s Guide to Excavating

Frozen ground excavation can be a challenge. When a deep freeze sets in, even the softest of soils can quickly turn into a stubborn and concrete-like barrier to making progress with your earthmoving job and hitting your targets on time. Ground density depends on several factors, including moisture content, grain size, and surface temperature. Excavation equipment and trenching machines with tools that can generate high forces, and attachments that have a narrow (or sharper) contact patch with the ground that create greater penetration have the best chance of working through coarse frozen material.

At ShearForce Equipment, we provide excavator attachments for sale in Ontario, British Columbia, Alberta and other provinces throughout Canada that are built for frozen ground excavation. We asked our frozen ground excavation experts to weigh in with some tips to avoid job delays this season and look at some of the most effective tools and methods for excavating frozen ground.

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What are the biggest implications to contractors who run into deep frozen ground while already on the job? 

When you hit unexpected delays, it can impact other aspects of the project down the road. Delays make the ground crews less efficient when waiting for trenching and digging to actually take place, and overtime costs for equipment operators can quickly add up. Operator health and safety concerns arise from the constant jarring of the equipment being transferred back to the operator while working in these unforgiving conditions. The equipment also suffers when frozen ground becomes a hard reality; equipment stress, damage, or breakage is more likely to occur, including boom, stick, or attachment cracking or gouging.

What are the typical traditional methods of excavating frozen ground? Which is most effective? Which is least effective?

• Dig bucket – Without sharp bucket teeth designed for excavating frozen ground, using a regular dig bucket is likely the least effective method for frozen ground excavation. Very hard on the operator and machine.
• Frost bucket – Frost buckets have sharp digging teeth but the constant banging digging motion is hard on the operator and machine. Very slow production in hard ground.
• Static ripper – A single tooth ripper makes penetration easier but the clawing motion is jarring on the operator and machine and works slowly in permafrost and frozen soil. Larger machines are also necessary with static rippers as you would rely solely on the machine’s brute force to break frozen ground.
• Hydraulic hammer – Produces an additional impact with hydraulic force penetrating the ground but hammers tend to punch holes in frozen ground, and using the tool bit to pry chunks of hard ground loose will cause damage to the chisel point.
• Rotary cutter – Chipping away layers of solid frozen ground using hydraulic rotational force is sometimes a viable option. Depending on how solid the material is, rotary cutters produce small spoils and work very slowly, especially in deeply frozen ground.
• Hydraulic rippers – Most effective hydraulic attachment for excavating frozen ground due to vibrations creating space between the ripper tool and the frozen material. A relatively new technology in the equipment sector that has been proven to outperform other hydraulic attachments significantly in frozen ground removal. Minimal stress on the machine and operator.
• Hydrovac (daylighting) – Requires highly specialized equipment and team on site, and relies on pumping hot water into the ground for suction removal. Concerns include potential water contamination on site and ensuring proper disposal of excavated materials.
• Heating the ground with a self-contained heater – Effective in a closed or small space, it can be expensive to bring in dedicated equipment and time consuming to wait for the ground to thaw before excavation.

How can contractors who think they might encounter frozen ground on their upcoming projects prepare themselves to hit the ground running?

Excavating frozen ground is a harsh reality in many parts of Canada such as British Columbia and Alberta; therefore, contractors working in cold climates need to be prepared for whatever conditions they may encounter. Ensuring that you have the correct tools before landing on site is key to minimizing downtime once the project is in full swing.

• Ensure you have proper low temperature oils in your excavator and excavator attachment tools.
• Inspect excavator boom, stick, and attachments for cracks before moving the equipment to site. Repairs in the field are often much more costly, cause unplanned delays, and are typically lower quality than repairs made in a shop with the most appropriate conditions and tools on hand.
• Stock a sufficient supply of wear parts on site. Frozen ground is more abrasive and frigid temperatures increase the likelihood of cracked hoses and broken seals.
• Contact us well ahead of time to consult our sales team for an equipment solution tailored to your application.
• New equipment installations can be challenging in busy winter months. Book technicians for setups well ahead of time.

How do hydraulic rippers work in frozen ground? What makes it unique to other attachments?

Hydraulic rippers produce high frequency vibrations that impact into the ground and the ripper shank lifts up the frozen ground from below the frost. The ripper hammers and vibrates into the ground to below the frost line and gives the excavator the ability to lift up the frozen ground. If the ripper shank is longer than the depth of the frost, it creates an almost popping like action. If you have an open trench with an open void to break material into, you would use the ripper to shave off incremental pieces of frozen material. If the frost is deeper than the length of the shank, the operator can create a trench as deep as possible and create a bench for a 2^nd pass.

The wedge shape of the ripper arm is also a major factor in effectively removing frozen ground. As the weight of the machine and the vibration and impact of the ripper drives the tool into the frost, its wedge shape actually splits the frost apart, allowing for easier breakup and removal.

Hydraulic rippers like Xcentric Ripper produce much less jarring motions for the machine and operator compared to all other techniques for excavating or trenching frozen ground. They require minimal maintenance versus a hydraulic hammer with less frequent greasing (grease every 100 hours of use vs. hourly with a hammer), and fewer moving parts that require maintenance during use. In fact, hydraulic rippers have proven to be up to 5x more productive than a hydraulic hammer, and up to 10x more productive than a static ripper when excavating frozen ground.

• Hydraulic rippers have 3x the impact rate of a hydraulic hammer
  • XR30 impact rate = 1300 bpm
  • SM30 hammer impact rate = 300-450 bpm

If your job requires tearing your way through thick frozen ground this winter, let our equipment solutions experts help set you and your crew up for success. We have plenty of experience with frozen ground excavation and are here to help answer any questions you may have. Contact us for more information, including purchase and rental rates and availability, and keep your projects on track this season.