The triumph of human ingenuity has led to many discoveries that make our lives easier, more enjoyable and productive. If it weren't for entrepreneurs and researchers asking "what if" and challenging conventional wisdom, we would not be reaping the benefits of satellites, GPS systems for construction equipment and the Internet. Rather, we would still be communicating by carrier pigeons and eating by candlelight and not by choice.
By challenging the conventional method for cutting new development roadways to grade, Miami, FL-based grading, utility and paving contractor, Persant Construction Company Inc., is proving to be one of those entrepreneurial companies. It's blazing a new method for dealing with an old soil problem, which allows the company to significantly increase efficiency.
Much of the soil in Dade County, a market staple for Persant, consists of large amounts of lime rock and very dense cap rock, which makes building new development roadways a long and arduous process. "The soil in Dade County is some of the hardest stuff there is," comments Jorge Pernas, civil engineer for Persant.
Tough soil conditions is the reason why many equipment manufacturers, according to Pernas, test the performance of their new products in this county. It's also why Persant has helped to introduce and test no less than 13 different machines in the region over the years. However, the company's latest test consisted of finding a new way to use a proven piece of equipment. An experiment designed to address an old problem is proving to be very beneficial for the company, helping the contractor to build a better rapport with its customers.
Cutting time by 2/3
Working as a subcontractor for site developers, Persant often must bring high grade lime and cap rock to final grade for a development's roadways and housing. The current pace of new construction demands that the 30-year-old business continually examine the ways it performs its duties in order to get the job done quicker.
Cutting the existing terrain to grade is one of the most time-consuming aspects of the work. For years, Persant removed the rock with a dozer equipped with a plow attachment. Lumbering along with the 1 1/2-foot-wide attachment, the dozer chiseled away at the soil and rock at six-inch depths. A second dozer closely followed to push the chucks of lime and cap rock to the side for eventual removal off site. This time-consuming process would take weeks for final road grade to be achieved.
That is until some of Persant's crew started to ask some "what if" questions in order to find a more efficient way. These questions ultimately led them to Nortrax Equipment Company — Southeast, the Bomag distributor in south-central Florida.
In an effort to find a better method for removal of the rock, Nortrax salesman, Carlos Rodriguez, demonstrated the Bomag MPH122 recycler/stabilizer to Persant. "This is an entirely new application for the MPH122, and we wanted to ensure that it would handle it more efficiently than the dozers," says Rodriguez.
Although not built specifically for this task — it's typically used for full-depth reclamation of asphalt roads and to cost-effectively stabilize or improve existing soils — the recycler/stabilizer worked extremely well for Persant, exceeding the company's expectations. "We now cut an 8-foot-wide pass at a 1-foot depth with the MPH122," says Pernas. "For every pass we make with the MPH, it would have taken us 16 passes with the dozer."
By using the recycler/stabilizer instead of the dozer, a job that used to take Persant three weeks can now be finished in about one week, a substantial time savings and competitive advantage for the small contractor.
More than efficient
However, the time factor is simply not the only efficiency gained through the use of the Bomag MPH122. When using the dozer with plow attachment, large chunks of rock were generated, which were then trucked off site. The recycler/stabilizer, on the other hand, pulverizes the soil and rock together to deliver a well-graded soil that can be reused as subbase for development roads.
The MPH122 features a 92-inch-wide, center-slung universal rotor that can be used for asphalt reclamation as well as soil stabilization. "The center-slung rotor holds an even cutting depth, which is exactly what Persant needs for this application," explains Mickey Cereoli, landfill and soil stabilization specialist for Bomag Americas Inc. Although Persant cuts to a depth of only one foot per pass, the machine's 48-inch-diameter rotor is capable of cutting to depths reaching nearly 20 inches.
One machine feature that drew Persant to the Bomag is its hydraulics system. Hydrostatic drive not only powers the steering and four-wheel-drive but also the cutting drum's rotation. A built-in hydraulic relief system automatically stops the rotor's rotation when an obstruction is encountered, preventing damage to the drum and rotor drive system.
"The other machines we looked at had planetary drives, which were designed to be the weakest point of the rotor," says Pernas. "These rotors will break at the planetary, which costs about $24,000 to replace." Persant's high utilization need for a recycler/stabilizer — logging nearly 200 hours within the first three months of ownership — combined with the dense lime and cap rock places a lot of stress on the machine's rotor. Pernas estimates that the company would have had to replace at least one planetary each year, if it were to have chosen a stabilizer with a mechanical drive system.
One of Pernas' initial concerns in this application, however, was if the MPH122 had enough horsepower to cut through the dense rock. He recalled some manufacturers stressed that high horsepower requirements would be necessary. But Pernas quickly discovered that the Bomag had more than enough power due to its hydrostatic drive system.
"The MPH122 has a proportional power system that enables the operator to manually dial in the power requirements," explains Cereoli. "This system allows the machine to use available horsepower more efficiently."
The new application for the recycler/stabilizer saves Persant manpower as well. It still requires the use of a dozer to move the blended soil and rock off to the side of the road. However, according to Pernas, "We can now use the same operator to run both the MPH and dozer, whereas the old way required us to have two dozers and operators."
Elimination of the additional operator, the need to truck excess soil off site and a lengthy process to cut the existing terrain to grade is only the beginning of the benefits for employing the recycler/stabilizer. When Persant encounters a site with questionable soil content, the company can use the MPH122 for its originally-intended purpose, soil stabilization.
Dade County has certain soil specifications for new development housing pads. If areas of questionable soil exist within a development, Persant can bring the soil to meet spec with the MPH122. "If a pad was to have about six inches of out-of-spec soil, we will run the rotor down a foot to blend the soil and bring it to spec," says Pernas.
This is a money saver for the contractor, since there is no need to remove the questionable soil and replace it with virgin aggregate. The versatile machine will also allow Persant to make soil improvements by blending in additives like lime or Portland cement, should the need arise. And with the recycler/stabilizer's universal rotor, the company can expand its paving side of the business by offering low-cost, full-depth reclamation services for deteriorating roads.
However, most important to Persant is that using the MPH122 in this new application has turned a time-consuming, inefficient process into a quick method of cutting high grade lime and cap rock into new roadways. "We now get more jobs done quicker, which helps to build a better rapport with our customers," says Pernas. Something that will help keep this small, Miami-based contractor successfully conducting business for another 30 years.