When the Eagle Mountain/Saginaw Independent School District realized it needed additional elementary school facilities, time became a big concern. The school district would have to have the facilities ready to open by the spring of 2008.
The 6-acre (2.4 ha) building site is located directly across the street from a heavily populated residential area in Fort Worth, Texas. The earthmoving segment of the project required that 8 ft. (2.4 m) of limestone, which existed beneath 2 ft. (0.6 m) of North Texas “black gumbo,” a clay type soil, be removed.
The project subsequently required 70,000 cu. yds. (53,500 cu m) of material to be moved on the job. Within the site, 20,000 cu. yds. (15,200 cu m) of basic soil and clay had to be moved from one location to another, an additional 30,000 cu. yds. (22,900 cu m) was to be moved off-site and 20,000 cu. yds. of “select fill,” approximately 90 percent rock and 10 percent clay, for the building site had to be installed before any permanent structure could proceed. The 20,000 cu. yds. of “select fill” was produced on-site from materials obtained from the site.
Both the 65,000 sq. ft. (6,000 sq m) building site and preparations for the parking facilities had to be completed within 30 days. The overall site prep project presented quite a challenge for all bidding dirt contractors.
Herter Enterprises LLC was determined to win the bid. Herter specializes in school and church building projects.
“Due to the time restraints, the close proximity to residential housing and the multiple restrictions for not using explosives in any North Texas incorporated area, we determined that we would have to bring in two excavators, one to remove some of the stickiest ’black gumbo’ you have ever encountered and the other to break up the limestone to be stockpiled and removed from the site,” Al Herter said. “We realized that we would have to pay to have the stockpile of fractured limestone removed and then we would have to pay to bring ’select fill’ onto the site to complete the site-prep.”
After considering all the cost factors, he indicated that the building budget would be very tight with little or no chance of any increases. Herter said that he had seen ads in the Western edition of Construction Equipment Guide about the IronWolf attachment that was installed onto a wheel loader. He had learned that the IronWolf could attack most any type of rock including limestone and reduce it to a minus 2 to 3 in. (5 to 7.6 cm).
In one operation with the proper amount of clay mixed in the limestone, the IronWolf could produce “select fill.” He also realized that the IronWolf would alleviate the need for one of the excavators, the costs of the spoil removal and the majority of the “select fill” purchase.
“I had studied the engineering soil sample reports and determined that there looked to be enough of the limestone and clay mix that I might not have to purchase any ’select fill’ since the IronWolf was totally capable of producing it given the proper combination of ingredients,” Herter said.
Herter contacted IronWolf and was directed to Hoss Equipment, the local IronWolf dealer. Hoss representative Phil Lanman along with Dave and Rusty Griffis of the local IronWolf distributor, R&D Equipment, met with Herter and determined that once the 2 ft. (.6 m) of “black gumbo” was removed, the IronWolf could handle the job of removing the limestone and crushing it into “select fill” in one simple operation.
A Kawasaki 115 Z IV with the IronWolf 840 Heavy SS Crusher unit was recommended. The crusher is powered by its own Cat C15, 540 hp 402 kW Tier III engine.
“After evaluating the project, we were very confident that the combination of the Kawasaki and the IronWolf 840 Heavy with its new hydraulic ’split system’ could efficiently handle the project within the time restraints,” Dave Griffis said.
The “split system” hydraulics allow for more efficient hydraulic flow, which lowers the operating temperatures and allows for more horsepower. Due to the heavy duty fracture boards, the 8 ft. (2.4 m) crusher unit weighed 25,000 lbs. (11,300 kg).
With the hydraulic motors on either end of the crusher receiving its own direct hydraulic flow, the “split system” meets the fines measurement of 2 to 3 in. and time restraints.
“We realized that this combination provided a most efficient system by taking 9-inch deep cuts across 8 feet of the limestone. The fines, in this case ’select fill’, was picked up using a Kobelco 250 wheel loader and dumped into either an A25C or A35B Volvo articulated haul truck and moved to stockpiles, then make another cut of 9 inches until we reached our 8-foot required depth,” Herter commented. “We also realized that the fill we might not use was a very sellable material for other projects. In the long run, after making all my calculations, I came in $400,000 less than the next bidder for the project.
“I miscalculated the amount of ’select fill’ that could be made on-site due to the excess amount of clay that was present in some of the limestone; however, we were able to produce the required fill using the IronWolf at $2 per cubic yard and had to purchase very little ’select fill’ at $10 per cubic yard,” Herter said. “I was hoping to have an excess of the ’select fill’ when the job was finished and since there is actually only one ’select fill’ pit left in this area, it would be very sellable.”
When the purchased ’select fill’ was delivered, Herter used a John Deere 330 to fill the delivering haul trucks to transport the spoil back to the pit for depositing.
Herter had multiple reasons to incorporate the IronWolf aside from the economics. One of these reasons was the environmental aspect. There was only one ’select fill’ pit left in this part of north Texas. When it is gone, there are no others available. By using the IronWolf to create on-site “select fill” he felt that he was helping to establish another method of using local resources instead of having to bring them in from another location. Not only did it work in this fashion environmentally, but also economically for the school district.
“The IronWolf performed exactly as planned, even after over 25,000 cubic yards of limestone had been processed, we never had to change any of the teeth,” Herter said. “I cannot say enough about the IronWolf crusher and its performance and the help of the associates with IronWolf, R&D Equipment Sales and Hoss Equipment.”
Herter started in business in 1981 and the company has 13 employees, including Al Herter. Herter used a total of 8 machines on the project not counting the haul trucks that removed the spoil piles. The IronWolf was the only rented machine. Herter used a Kobelco 250 to move the black gumbo within the job site and help load the fill into the haul trucks. The job used two Volvo rough terrain trucks, a 25C and 35C to haul the spoil and the “select fill” to stockpiles. A John Deere 330 excavator was used to load the “select fill” into the Volvos and the spoils into the haul trucks to be removed from the job site. A Cat D7H dozer was used to level the “select fill,” an Ingersoll Rand SE-1000 smooth drum roller smoothed and compacted the “select fill” as an International 4000 gal. (15,000 L) water-wagon continued to pour water onto the fill in order to create the proper compaction for the building site.
For more information on this project, call 817/866-4382. CEG
Today's top stories
