Directional-drilling rigs are steerable, trenchless digging machines that create tunnels for pipes or lines, which are subsequently pulled into place without disturbing surface soil, pavement or ground level structures. Trenchers are open ditch-diggers for putting pipe in the ground (whether cross-country oil lines or sprinkler systems), and laying underground power lines and telecommunication cables. Construction, industrial, municipal and landscape applications are common.
Directional drills date from the 1930s and came out of the vertical oil drilling industry. Widespread application of the principle of lateral drilling didn’t occur until the 1970s. In the 1980s and ’90s, manufacturers began to apply new electronic technologies to the steerable drills and they became a mainstay piece of equipment. Some companies, such as Ditch Witch and Vermeer, downsized the concept by creating compact models.
Trenchers were conceived even earlier, back in the 19th century, with most of them being designed for substantial excavations. Ditch Witch—Charles Machine Works as it was called then— again opted to develop machines for smaller-scale trench projects that typically were hand-dug. The company’s compact trenchers quickly became popular, both the walk-behind models and larger seated models.
The guide is laid out to systematically introduce a reader to the two types of digging equipment and to safety systems deployed in trenching.
A number of manufacturers produce horizontal directional drills and trenchers for the North American market. In evaluating the companies and products, the primary consideration should be matching a machine or system to conditions and size of your project. Some criteria to consider:
What is the level of difficulty of your project(s)?
Get what you need. A walk-behind or stand-on trencher with a 12 to 15 hp engine is perfect for burying a sprinkler system, while a 4WD 120-hp trencher with an ergonomic seat in the cab makes short work of long trenches. A 48-hp directional drill is compact and can drill under a sidewalk, whereas a 20-ton 200-hp drill 60,000-lbs. thrust can push a rod under a river. Understand the difficulty of your project or ongoing work and select a machine with enough oomph and versatility to do the job.
How critical is dealer support during the life of a machine?
HDD and trenching equipment are specialty machines highly calibrated to do the hard work of digging. They each have a long history of engineering advancement in the United States so dealership expertise is widespread. Besides the wear and tear on the primary machine, HDD units stress the extended drill stem sections operating in the drill hole. Bits wear out. Pumps and fluids and hoses are constantly utilized. Trenchers, too, operate in unforgiving conditions. All of this makes dealer support a high priority.
Even if you are a commercial HDD or trenching company, renting or leasing a drill or trencher can make sense, especially if the machine is only periodically employed. For a one-off project, renting a specialty digging machine for the duration of the job certainly makes sense. Renting a trench box also is a reasonable option unless such boxes are used regularly. Consider this:
Do not rent more machine than you need.
If a compact walk-behind trencher will do your work, don’t contract for a larger seated model… just because. Or if a 2.5-in. tunnel will handle the water lines you want to install, don’t opt for a 100-hp HDD unit that bores 4-in. tunnels. Right-sizing not only will save you money at the rental house, it is apt to lower operating costs. Also, the larger the machine, the more sophisticated it is apt to be and greater the odds some component will fail. If a dealer or rental office doesn’t have the unit you need, shop around.
Try to anticipate how terrain and space will impact your use of the machine.
Obviously, a more compact HDD machine or trencher will function better in cramped quarters, but other characteristics of a job site can come into play. Is there an embankment in the path of a trench? Where the two planes meet, the size and configuration of a trencher could recommend it over another to navigate the transition. Are there trees along the route of the trench or horizontal tunnel? The presence of roots could require more horsepower or the use of a heavier machine.
How deep a hole or trench will people be working in?
OSHA requires a protective system in any excavation 5 ft. deep and deeper. Anything shallower than 5 ft still requires OSHA check-off, even if all that is needed is benching or sloping of the sidewalls. So, if you are digging down at least 5 ft., plan on inserting some kind of protective system like a trench box to protect anyone in the hole.
What type of soil will be excavated?
Stability of the walls of an excavation are affected by the condition of the material around the hole. Sandy soil obviously is unstable, but so is earthen soil permeated by rocks which can reduce cohesion in a sidewall. Is the ground unusually moist? If so, a trench box can protect against a watery wall suddenly giving away with a whoosh.
Will the box have to deal with unusual ground pressure?
Is the dead weight of a building bearing down on the soil adjacent to a trench or pit? If so, seemingly stable walls of a new excavation can give way under the pressure. Trench boxes come in various thicknesses and heights so that an engineer or competent person can match a box to a potential pressure threat.
Do you have equipment large enough to lift and place a box?
Even if a trench or pit is relatively narrow — 4 ft. across — the type of soil and other conditions can call for insertion of a heavy, reinforced box. Can your excavator or other piece of equipment lift the box? A common formula for determining this is that a box weigh no more than one-fifth of the weight of the machine doing the lifting.
Trenchers and horizontal directional drills are not general purpose machines. It follows that pricing of the machinery — particularly heavier models — can be high-end, reflecting the relatively low volume of usage. Hereafter are categories of prices for new and used equipment:
Horizontal Directional Drills
For used machines, the year of manufacture, number of engine hours, and general condition are factors. Hereafter are some general pricing guidelines for trenchers and directional drills with 1,200 or fewer operating hours:
Horizontal Directional Drills
Unlike machines that are comprised of moving parts requiring lubrication and fueling, steel and aluminum boxes are static pieces of equipment. While they can be dented and joining pieces rusted to the point of replacement, they are not as subject to breakdowns as are machines. Pricing of used boxes is straight forward and comparisons easily made. Two examples of cost: A new 8 by 24-ft. steel trench box with 5-in.-thick walls can cost $15,000. A used 4 by 16-ft. box with 5-in.-thick walls can cost $6,000.
Prices are determined by local demand and the volume of rental competition in an area.
Horizontal Directional Drills
While these machines are rented and leased, it is not in the same volume as trenchers, so comparison shopping is sketchier. Dealers are more apt than rental agencies to have inventory for rent. Shop around.
One example of rental pricing: An 8 by 16-ft. box with 4-in.-thick walls rents for $110 a day, $320 a week and $950 a month.
These are purpose-built machines unsuitable for general utility work, so inspecting a drill involves specialty knowledge. Ask an expert along for your inspection to help you evaluate the underlying condition. Things to consider in inspecting a used drill or trencher:
Is the frame intact and not misaligned?
The forces that come into play on a horizontal directional drill are varied and unusual. The HDD carriage carries the bulk of pressure as it thrusts the rotating string forward and pulls it back in the reaming operation. Closely examine the carriage’s gearing and hydraulic cylinders for soundness. A lot depends on their integrity.
Are tracks and other undercarriage components worn out?
The tracks carrying the HDD do not propel the machine forward and back with any speed, but they do support a heavy machine and maneuver it into place. The undercarriage components and the machine’s frame are stressed during their supporting work. Look for cracks or other indications of weakness in these core components.
Examine the hydraulic system for wear and leakage.
Hydraulics gives the HDD its authority as it powers through the ground. Keeping the fluid flowing is the work of hoses, fittings and valves, all of which can fail. Hoses are worn down by rubbing against an adjacent component. Fittings lose their seal. O-rings begin to leak. If such failures seem widespread, it suggests poor maintenance.
Check anchors and stabilizers for signs of stress.
Once an HDD unit is driven into position, it assumes a working stance, which is a forward tilt toward the ground. This plane is what the drill and trailing pipe follow as the drilling process ensues. The machine is held in place by hydraulically powered anchors driven into the ground. All anchors and stabilizers should fit and slide snugly.
Examine drill pipe and down-hole tools for excessive wear.
Reamers, bits, pulling head — and the pipe itself — are the tools that make HDD functional and directional. In examining a drill, take a look at the assortment of tools that are part of the deal. If they are worn out, the expense of replacing them should be factored into the purchase price. Their condition also can be a clue about how the machine was operated.
Check the boom for condition of bearings and uneven wear.
The working end of the trencher — that is, the actual digging boom — is subject to a variety of pressures. If excessive looseness is evident, it is a sign that bearings or wear plates need replacement. If uneven wear is evident on the boom, it might indicate poor operator skill that stressed the component.
Examine the teeth and rollers on the digging chain.
The cups, or teeth, on the digging chain take the brunt of abrasive interaction with soil and, naturally, wear out. They are meant to be replaced, but it is a plus on a second-hand machine if they are not yet worn down. Examine the rollers for even wear and the chain for signs of stressed points about to give way.
Try to determine soundness of engine and hydrostatic pump.
We all know what a smooth-starting and -running engine sounds like. Take a mechanic along to help identify what ails a ragged-running engine. Stress the motor and see if it responds without complaint. Hydrostatic pumps are critical…and expensive. If pressure readings are marginal or the fluid is dirty, you might want to pass on the machine.
Was the machine well-maintained?
Grease zerks should be dirty, suggesting grease has regularly been pumped into them. Dry, rusty zerks suggest casual maintenance. A dent or gouge or another suggestion of abuse might mean nothing if the overall condition of the machine is good. Accidents happen, after all, but evident neglect in servicing the trencher can be a red flag.
Buyers and renters have lots of choices on these machines, from microtrenchers to 18-ton directional drills. But even within a certain range of trencher or HDD units, manufacturers offer variations. Hereafter are some of the variables in the market:
The popular range of engine sizes and, in the case of horizontal directional drills, the range of thrusting power is quite broad. For example, Vermeer’s lineup of horizontal directional drills runs from a 48-hp model producing less than 8,000 lbs. of thrust to a 200-hp model with 60,000 lbs. of thrust. Need something more forceful? American Augers offers, for example, a 765-hp HDD unit with 1.1 million lbs. of thrust. In trenchers, the market also is wide-ranging, from 5.5-hp models with 6-in. cuts to 275-hp machines opening trenches more than 2 ft. wide. All of which means buyers of trenchers and drills should be able to find optimum-sized equipment for their needs.
Walk-behind trenchers ride the turf either on rubber tracks or tires. As the trencher models grow larger, the choice of propulsion system changes to include quads — that is, four tracks instead of four tires. Rubber-tired machines are the original mode. Tracks spread ground pressure and can be less damaging to lawns. The tires or tracks on left and right sides of some trenchers are offset and of different sizes / lengths specifically to give a machine more maneuverability. Quad track systems on large trenchers provide additional traction, which is critical in marginal ground conditions. The more you know about how you will use your trencher, the easier the undercarriage decisions.
As trencher models grow in size and horsepower, some models evolve into purpose-built tractors with a variety of ground-piercing attachments. One tool is the vibratory plow, which is used to bury fiber communications cable and other utilities. The plow is a vertical knife-edged component that vibrates to ease its passage through soil. A rockwheel attachment is better for more problematic soils and for pavement. The wheel’s spinning, hardened blade will cut through what other systems cannot. Other attachments for large trenchers include a backfill blade and mounted reels for fiber optic lines. Trenchers are not all-purpose machines, but they can be configured for specific tasks.
Along with other construction and utility machines, trenchers and directional drills have gotten smarter—that is, engineered for more intelligent and self-regulating operation. Even the smallest walk-behind trenchers are reliably all-hydraulic. As the machines grow larger, controls automatically optimize ground speed for productivity, self-control the dig depth according to engine rpms, idle down the engine when work is paused, and so on. On smaller HDD units, operators sit in ergonomic seats. Larger directional drills have heated and air-conditioned cabs and video cameras connected to LCD monitors that immerse an operator in information. In your shopping, compare control systems.
A trench box ultimately is evaluated by how well it can withstand the force of a collapsed wall of earth. They are engineered for strength. Buyers or renters of the boxes should pay attention to:
The walls of trench boxes generally range from 4 to 30 ft. in length and in height from 4 to 10 ft. The thickness of the wall plate ranges from 3½ to 9½ in. An engineer or OSHA competent person can determine the right combination of dimensions that will produce a safe work zone for employees in the excavation.
Soil composition is the critical ingredient in predicting the potential for collapse of a side wall. Sand, solid rock, gravel, a mixture of soil and rock—and the moisture content of the material—all will dictate the level of danger is in the hole. Trench boxes are engineered for each soil condition.
Unlike shoring materials — which can be hydraulic or timber — trench boxes are fabricated of metal. Generally, they are made of steel or aluminum. Each has its place. Loose or wet soils sometimes cannot support a steel trench box and aluminum is the better choice. Steel is more suitable for deep and firm excavations.
Trench boxes and other shielding systems are sold and rented from many locations coast to coast. What doesn’t come with the boxes is a handy list of safety measures to take in using the boxes. National Trench Safety and a few other companies offer excavation safety classes for contractors. Enrolling in one is a good idea.
This Ohio company is part of the Charles Machine Works family of companies of Oklahoma, which spawned Ditch Witch trenchers. All the companies became part of Toro this year. The firm manufactures heavy-duty directional drills. Click here to see equipment currently for sale from American Augers →
Part of Charles Machine Works (see above), this American company’s HDD line ranges from a 25-hp compact JT5 model designed for shallow installations on up to the JT100 all-terrain drill, a 270-hp unit with 100,000-lb. pullback force. Click here to see equipment currently for sale from Ditch Witch →
This 105-year-old Japanese firm is a household name for turf and landscape products, but also offers two HDD models. A 72-hp model (DD2226) produces 22,000 lbs. of thrust, while the 160-hp DD4050 can thrust pipe with 40,000 lbs. of force. (Note that Toro is planning to phase out the production of its branded large HDD units, which includes DD2226 and DD4050 drills, and its RT600 and RT1200 riding trenchers.) Click here to see equipment currently for sale from Toro →
An Illinois company, Universal’s product line includes a dozen horizontal directional drills. The smallest is a 66-hp model with 12,000 lbs. of thrust requiring a 27 gpm mud pump, the largest a 44-ton, 600-hp drill creating 500,000 lbs. of force. Click here to see equipment currently for sale from Universal →
This Iowa manufacturer began in agriculture but today’s products range across various industries. It builds 12 directional drills, from a 48-hp unit with 7,800 lbs. of thrust to a 200-hp model that can push a drill string with 60,000 lbs. of force. Click here to see equipment currently for sale from Vermeer →
As noted previously, this Oklahoma firm has a special place in the compact trencher industry having invented it. Today, it builds 7 walk-behind models, one stand-on model, six ride-on trenchers, three quads and a micro unit. Click here to see equipment currently for sale from Ditch Witch →
The California manufacturer builds small auger machines and a trencher, the T-4 model, which can slice into the earth either 12 in. or 18 in., depending on configuration. The T-4 can be set up to produce a 3-in.-wide trench or a 4-in.-wide trench. Click here to see equipment currently for sale from Ground Hog →
The Japanese firm manufactures two ride-on trenchers, three walk-behinds and a vibratory plow. The largest model is the 121-hp RT1200, which rides on quad tracks. It is a 4WD and 4-wheel-steering machine that can be switched to crab steering. Click here to see equipment currently for sale from Toro →
The Iowa manufacturer has a full lineup of trenchers, including three walk-behind models, five quad-track models (one with steel tracks), two vibratory plow units and a remote-control model. They range in horsepower from 13 hp to 127-hp. Click here to see equipment currently for sale from Vermeer →
This Montana company fabricates excavator equipment, including steel trench boxes. The boxes come either in flat-bottom or knife-bottom designs and are built of 572-59 high-strength low alloy with a tensile strength of 60,000 psi. Click here to see equipment currently for sale from Felco →
This family-owned Ohio company has built boxes since 1987. It has aluminum and steel products, including a box comprised of independently moveable vertical aluminum panels that slide up and down to create pipe openings at the bottom. Click here to see equipment currently for sale from Kundel Industries →
Trench Shoring Company
This California company began building trench safety systems in 1973. It has engineered a “Flex-Shield” box with sidewalls bowed outward slightly in the middle. They reputedly are lighter than standard boxes, but as strong. Click here to see equipment currently for sale from Trench Shoring Company →
Hauling excavated materials is a big business — almost as big as the machines it employs. The industry’s bend-in-the-middle articulated model featuring a single-axle under the tractor unit is an innovative and proven engineering feat. The huge rigid-framed trucks with staircases leading up to the operator’s cab are similarly impressive in their durability. Each machine requires a big investment, but prodigious payloads can make it pay off.