A close-up of the 3700's chain trencher attachment with teeth that are hard-edged with tungsten carbide to cut through rocky and compacted soil. Photo by Erik Skindrud

Trench-digging machines come in an astonishing range of sizes, designs and capabilities. Select the right one and you'll complete the job on time and under budget.

First things first. Before you dig on any site, call the appropriate information service to determine if any gas, electric or other lines are underfoot. If you don't know where to call in your state, www.digsafely.com (888-258-0808) can put you on the right track anywhere in the country.

The Ditch Witch 3700 is powered by a 45 hp engine and is designed to work with interchangeable, hydrostatic attachments. Options include a centerline or dual-position trencher, vibratory plow, combo trencher/plow, saw and front-mounted utility backhoe.Photo by Erik Skindrud

Sizing Your Needs

The big considerations when choosing a trencher are size and weight. If you're a contractor completing a residential landscape, you'll probably want to rent a moderate-sized or small unit. Bigger jobs and harder soils call for bulkier machines that will cost more at the rental store. In most cases, rental businesses will be happy to offer advice to help you make a good choice.

Workers with Maryland's Severn River Land Trust use a Ditch Witch 1820 to claw through compacted soil during a restoration project.Photo: Severn River Land Trust
Inset: The L-2 Line-layer is a one-man operated, track-drive trencher that can place telephone, cable TV or irrigation line to a depth of 4" to 16?EUR??,,????'?? depending on the soil conditions. The self-propelled track-drive system safely passes over established lawns or rough grades. Photo: Line-Ward Corp.

Before you go to rent (or buy), ask yourself the following questions.

?EUR??,,????'???? What kind of trailer or transportation system do you have?

Brown Manufacturing's Bededger is powered by an 8 hp Honda engine that provides the power to trench through hard clay. The F-1202 model can dig trenches from 3 to 12 inches deep with widths from one-half to 3 inches. Photo:ironstonerental.com

Trencher Basics

A trencher is piece of equipment used to dig trenches, typically for laying pipes or cable, or for drainage. Trenchers may range in size from walk-behind models, to attachments for a skid loader or tractor, to very heavy-tracked engineering vehicles. Depending on the type of digging implement, a trencher may be classified as a chain trencher or a rockwheel.

Rockwheels are the heavy-duty option for deeper systems like water or sewage lines. They can cut through compacted soil like butter when chain trenchers grind to a halt. Machines like this Vermeer model are equipped with 1" shank rotary carbide teeth that can zip at tip speeds up to 750 fpm. Photo: Ky MacPherson

A chain trencher cuts with a digging chain that is driven around a rounded metal frame, or boom. The layout resembles a giant chainsaw. This type of trencher can cut ground that is too hard to cut with a bucket-type excavator.

The angle of the boom can be adjusted to control the depth of the cut. To cut a trench, the boom is held at a fixed angle while the machine creeps forward.

Sales rep Ken Vaughan with the UnderWunder horizontal boring machine at August's Texas Nursery and Landscape Association show in San Antonio. The machine bores under sidewalks or driveways, eliminating the need for demolition and resurfacing. Vaughan is holding a bit attachment that can create a hole about 5 inches in diameter.

A rockwheel, on the other hand, is a toothed metal wheel?EUR??,,????'??+effectively a giant circular saw. Rockwheels are generally heavier and more powerful than landscapers will ever need for irrigation of lighting lines. They can cut harder ground than a chain trencher, including cutting through solid stone. They are also used to cut pavement for road maintenance and to gain access to utilities under streets and roads.

Vermeer's RT100 is a compact pedestrian trencher that includes a hydrostatic trencher drive motor and hydrostatic twin wheel motors. The hydrostatic trencher drive eliminates belts, pulleys and gears, reducing maintenance time. The machine weighs about 1,000 lbs.Photo by Erik Skindrud

The teeth on a rockwheel are removable and made of high strength steel or tungsten . When the machine is under heavy use, the teeth may need to be replaced as frequently as every day.

Compact Power, Inc.'s mini-skid loader wields a 36?EUR??,,????'?? x 6?EUR??,,????'?? trencher (seen here) and other attachments.

Irrigation Line Installation

Trenches for irrigation pipes are usually 6 inches wide and up to 18 inches deep. Of course, you only have to go about 8-12 inches deep to bury irrigation pipes. Always remove any existing sod with a sod cutter before using the trencher, or the machine will rip and severely damage your lawn.

Bobcat's MT52 tracked mini-loader is compatible with the manufacturer's LT414 trencher attachment, which is available in four and five-foot dig lengths.

If you are using poly-type rolled tubing, you can use a pipe puller. This tool is similar to a trencher, but it pulls the pipe underground and leaves only a small slit in the lawn.

Sources: www.digsafely.com , www.rainbird.com, en.wikipedia.org

Gage Oetgen of Sunstate Equipment Co. in Lake Forest, Calif. shows off a Ditch Witch 1030 walk-along trencher. The machine is designed for residential and commercial installation for gas, water, sewer, electric and communications lines requiring trenches up to 6 inches wide and 30 inches deep.