The term “rock-hard” takes on an entirely new meaning when you’re talking about utility work. Few other ground conditions pose quite the same challenge as rock. Estimating productivity, even for seasoned crews, can be extremely difficult, making planning and equipment selection all the more important. Choosing the right machine for the job can help ensure your project’s success.
Get to know the ground
Utility trenchers and rockwheels are designed to endure some of the most difficult and varied ground conditions. While they are capable of handling an array of rock formations, operators still need to rely on geological background and equipment upkeep to capitalize on the capability of these machines.
Rock sampling is the easiest test a contractor can perform that will provide extensive information on the ground conditions of a project. A core sample from the jobsite will help identify what type of rock is in the path, as well as the pressure it’s under, and its hardness and abrasiveness.
“The most important characteristic to know is what kind of rock the contractor can expect to cut through, followed by the hardness. The hardness will help determine weight and power, because a harder rock typically indicates the need for a heavier machine with more horsepower,” says Jon Kuyers, senior global product manager at Vermeer.
Consider the specs
The specifications of a project also help determine what method is most suitable for a job. The type and size of pipe being placed in the ground will influence whether the contractor chooses between a rockwheel or a tractor equipped with a trencher chain outfitted with teeth specifically for cutting rock.
For utility lines that are less than 6 inches (15.2 cm) in diameter and less than 4 feet (1.2 m) deep, installation can be done with a rockwheel. Rockwheels are designed to cut through rock, concrete and other tough surfaces with ease. Plus, a rockwheel provides a clean trench and suitable backfill.
If a project calls for a wider or deeper trench, using a chain trencher is recommended. A digging chain can offer the flexibility to cut a wider trench, plus these machines offer increased horsepower and weight to help with productive cutting. A chain trencher will also produce a clean trench and suitable backfill.
Trenching tips
The ground conditions can go a long way toward influencing tooth selection. The teeth and tooth patterns on the digging chain and rockwheel need to be aligned properly to allow for maximum productivity and efficiency. Cost versus performance also needs to be balanced.
“Different types of teeth and carbide tips have varying costs. You will need to determine the desired rate of production, how much your consumables (teeth) will cost, and how much time and how often you need to change the teeth to determine the best solution,” Kuyers says.
Additional tips
Machine and tooth maintenance cannot fall by the wayside. Operators need to regularly examine all wear parts and components of the machine. Pushing a trenching unit too hard or too fast is another surefire way to cause excessive, unnecessary wear.
When a trencher or rockwheel is working, watch the material it is producing. A strong, sharp tooth with the machine operating within the optimum working range should create smaller chips, not just powder or dust.
Contact your local Vermeer dealer, as their understanding of the area ground conditions makes them a valuable asset in helping you pick the right machine and tools.
For more information on Vermeer rock trenchers and rockwheels, visit vermeer.com.