Better retention

Replacing a wheelbarrow and shovel is a back-breaking, labor-saving, revenue-driving relief, particularly for jobs like building retaining walls.

Compact equipment is a workhorse for projects that call for hauling heavy soil, grading, tamping and lifting. It’s like adding a pint-sized Hercules to the crew– with limits, of course.

“We do most of the groundwork with equipment rather than by hand because, obviously, it’s faster that way,” says Ben Polzin, vice president of operations at Down to Earth Garden Center in Eau Claire, Wisconsin. “Whether that’s digging trenches, backfilling or the initial site prep, we do all of this now with compact equipment.”

Polzin keeps a range of attachments on hand at his business: augers, trenches, a tree spade, bucket, fork, pallet attachment and a rock bucket that can pick up and move heavy stone and boulders. For walls, he generally sticks to the bucket. And, Down to Earth usually uses both a skid-steer loader and mini excavator on retaining wall projects.

“We do everything from decorative walls to extremely functional walls that are holding back a lot of earth,” Polzin says. “So, our equipment use depends on what the project entails.”

At Parker Landscaping in Wilmington, N.C., President John Parker says his equipment lineup is a “1-2-3 punch” that includes full-size tractors for grading large areas of land, large skid-steer loaders for hauling soil, site prep and moving materials and mini excavators for fine grading and getting into tight spaces.

Indeed, size can be everything when it comes to equipment for building retaining walls because these structures are commonly built in back yards, which means moving materials over finished landscape and around the sides of homes to the project site. “You can’t bring a tri-axle dump truck on to a homeowner’s driveway because it will shatter the concrete like it’s glass,” Parker says. “We need to have the materials dumped at the road and use a mini skid-steer to move it to the back of the house.” Parker will drive his equipment over boards set down on yards and concrete to avoid damage. “We have to protect their investment and everything else they’ve put into their landscapes,” he says.

Retaining wall rights.

There are several variables to consider when creating a strategy to build a retaining wall. Those include soil conditions, accessibility and what lies beneath (power lines). For Parker, the sandy soil in his region means actually moving the material and lifting it away from the ground is not difficult – but creating a solid, sustainable foundation on which a wall can be built is another story.

“Clay soil is harder to dig but easier to level, and sand continues to fluctuate,” he says. “The struggle is with trying to establish and compact a base. The compaction rates here are poor, so you have to be careful with how you build a wall.”

For Parker and his crews, this means deadheading walls that are made from wood. (This is not necessary for keystone block walls, he says.) “We deadhead wood walls every 8 to 10 feet,” he says.

Soil preparation for building walls in Wisconsin where Polzin’s business is located can include dealing with wet soil. “We often have to excavate more to make it a stable environment for the wall,” he says. “More excavating means more equipment – but the equipment definitely saves time vs. manual labor. Any time you are moving dirt, it’s more efficient to use some type of equipment.”

Site conditions also come into play. Is the retaining wall holding back lots of soil, or is it mainly decorative? What’s behind the wall? In North Carolina, Parker is building walls against bulkheads along the beach. “The bulkheads are on the ocean and we are doing retaining walls behind those (on homeowners’ properties) because behind those there can be 12 feet of fall,” he says. This usually means working within tight spaces, Parker says. “We have to get materials to the back side of the house.”

Polzin might be creating walls that hold back hills of earth. Regardless of the wall’s surroundings, controlling water runoff is key. “You want to control where water goes and what water does, otherwise a major rainstorm could make or break the wall,” he says. “Water can run down the back of the wall and cause it to fail.”

Parker adds that preventing hydrostatic pressure is critical to maintain the integrity of the wall. Therefore, proper drainage must be planned. “We use a mini excavator to dig out the footer, then tamp in the soil so we can then put in drainage solutions for the wall to avoid hydrostatic pressure,” he says.

These steps must be reviewed with crews before a project begins. “We go over the project with crews, identify the grade points and discuss the purpose of the wall,” Polzin says. “We then review what the wall will look like and go over the plans before beginning any initial site prep.”

An important factor to remember is power lines, Parker adds. Call the local utilities before digging. Mark gas, power and water lines. “If you are in a development, power lines often run along the back sides of houses and they are not always buried 3 feet as required by regulation,” he says.

Powering up the job.

The scope of a retaining wall project – establishing a base, installing drainage, hauling soil and materials – calls for equipment that can make the job more palatable. Adam White, president of Adam’s Landscaping and Lawn Care in Elizabeth City, North Carolina, says the versatility of compact equipment means the machine stays busy.

“We like the flexibility of having a bucket on the front and a box blade on the back so we can rip out shrubs, push up stumps and then grade down the land without changing out attachments,” he says. Site prep for wall-building or any landscape task can require removing existing trees, shrubs and infrastructure.

What should a contractor look for when deciding what compact equipment and attachments to use? White’s advice is to buy more power than you think you need. “It always seems like you need a bit more power, so I’d rather have that than get caught needing more power,” he says.

Weight capacity is a priority for Parker, as well. “We try not to exceed using 60 percent of the total capacity,” he says.

He also considers the linchpin height, how high a skid-steer can lift its “arm.” “Linchpin height is important because we need the machine to lift high enough to get materials on to trucks,” he says.

The clearance space between the bottom of the equipment and the ground is also key. His compact equipment allows for enough clearance that his crews can avoid scraping or damaging existing surfaces.

As for attachments, Parker uses a “small thumb” to tamp and smooth out soil. A trencher will do the job as long as there are no power lines in the way, he says. He is investigating a footer attachment for digging as opposed to using a trencher. “We are intrigued by the footer attachment because it has a wider blade to the left or right so the operator can see everything he is doing and get exact lines,” he says. “That is very important because if we are building a retaining wall against wetlands, the wall has to be just on the other side of the wetland. We have to be perfect, and if we are 1 inch over, the state will make you move the wall. We won’t be making that mistake.”

Compact equipment is a tremendous labor saver when it comes to building retaining walls. But, there is still a lot of handcrafting that goes into these jobs, Polzin and Parker note. “Building up the block is mostly manual,” Polzin says. “But the backfilling and compacting behind the wall can be done with equipment.”

Parker adds, “We are using compact equipment for retaining walls, but we are not to the point where the machine can lay the foundation, tamp it in and move on to laying brick. But, it does replace using wheelbarrows.”