GPS gets us where we're going and wireless Internet connects us everywhere else, but many projects are still accomplished by the age-old method of shoveling material into a wheelbarrow, dumping it on the installation area, and trying to spread the pile out evenly.
It takes one employee about one hour to move and spread 1 cubic yard of mulch, soil, aggregate, or compost. Material transfer systems and bark blowers allow that crew member to load the wheelbarrow in just a few seconds (see sidebar on page 34).
While bark blowers are slightly more complicated than material transfer systems, both machines are designed for intuitive use. The engine and hydraulic systems require typical maintenance, and moving parts need occasional greasing.
Material transfer systems are towable trailers with a large rear door or chute that allows them to function like dump trailers. Some models have a reversible belted floor that can unload up to 15 cubic yards of material out the back of the trailer in less than a minute. This design allows the unit to haul large items such as riprap for hard armor erosion control applications.
Smaller doors or chutes are often located on each side so users can pull up a wheelbarrow, open the door, and push a button to unload the material in a few seconds. This capability allows a crew to move soil to eroded areas without disturbing existing turf or to mulch on slopes. The machine also quickly fills sandbags during floods.
Some material transfer systems are equipped with a vacuum that sucks up leaves, grass clippings, and other debris that's dispensed into the hopper for easy unloading later.
Larger projects may demand a step up. A three-person crew operating a bark blower, for example, can complete mulching jobs otherwise performed by 10 workers.
Bark blowers shoot material through a hose at a rate of 8 to 22 cubic yards/hour, applying it much more evenly than when spread by hand. Wheelbarrows and shovels are eliminated altogether and material costs drop 25% because there's less waste.
The machines range in sizes from skid-mount and trailer models to truck-mounted units. Capacities range from 6.5 cubic feet to 22 cubic yards.
The air stream and material flow are adjusted by clicking a remote control. When switching between tight and open areas, the worker adjusts the nozzle flow without having to be near the machine.
In addition to speed and efficiency, there is also cost to consider when choosing between bark blowers and material transfer systems. The manufacturer's suggested retail price for smaller, trailer-mounted bark blowers ranges from about $44,000 to $84,000, and larger (8- to 22-yard capacity), skid-mounted bark blowers run from about $110,000 to $133,000. Meanwhile, the list price for a 15-cubic-yard-capacity material transfer system is about $53,000.
— Middendorf is senior vice president of FINN Corp., Fairfield, Ohio.
Do the math
What it takes to move and spread 5 cubic yards of mulch with a wheelbarrow and shovel. (Labor rates are figured at $15/hour.)
If it takes one person an hour to move and spread 1 cubic yard of mulch, it would take one person five hours to move and spread 5 cubic yards.
- 1 person x 5 hours x $15/hour = $75 to complete the mulching job.
Now, here's the same job using a material transfer system:
Tests have shown that one person can move and spread 5 cubic yards of mulch in approximately one-and-a-half hours.
- 1 person x 1.5 hours x $15/hour = $22.50 to complete the mulching job.
Mechanization saves $52.50, or $10.50 per cubic yard. If a crew spreads 1,000 cubic yards of mulch annually, the machine reduces annual mulching costs by $10,500.
Next, consider the bark blower. These machines have more capacity and capabilities than material transfer systems, so 20 cubic yards of mulch is used as the basis.
If it takes one person an hour to move and spread 1 cubic yard of mulch, it would take 10 people two hours to move and spread 20 cubic yards of mulch.
- 10 workers x 2 hours x $15/hour = $300 to complete the mulching job.
To calculate the cost of spreading mulch with a bark blower, consider a model capable of spreading 20 cubic yards/hour.
Three workers can spread 20 cubic yards of mulch in an hour.
- 3 workers x 1 hour x $15/hour = $45 to complete the mulching job.
Labor costs are reduced by 85%. The machine saves more than $250 and frees up seven employees for other projects.