Six Days Versus Six Weeks June 2001
By taking the advice of a pumping company, Standard Aero was able to compress a difficult construction job originally projected to take six weeks into only six days.
When Standard Aero leased approximately 300,000 square feet (27,870m2) of space at Kelly Air Force Base in San Antonio, they set about modifying the facility (Building 360) to fit their specific needs. It would be reconfigured to effectively handle repairing and overhauling gas turbine engines, which are predominantly T56 engines used to power the C-130 Hercules, E-2 Hawkeye, C-2 Greyhound, P-3 Orion aircraft and an auxiliary power version used on United States Navy frigates.
The first revamping step was to fill a large 170-square-foot (52m2) hole, 12 feet (3.6m) deep in the existing building — a hole that served no purpose to Aero. To fill the hole for proper drainage, it needed a special backfilling process before a concrete slab could be placed atop it.
The initial concept was to place sand into the huge pit, using a front-end loader to haul the fill and a front-end loader in the hole to level it. They would then do 8-inch (200mm) lifts with a compaction on each lift to prevent voids. Based on these specs, the process was projected to take six weeks, working five days a week.
Liner was another obstacle However, another obstacle then presented itself. The hole required a vapor barrier or liner on the bottom and sides to prevent contamination. Therefore, no equipment could be driven on the liner or it would most likely tear with a tire's steering.
Fortunately, Concrete Pumps of Texas in San Antonio would solve the problem. They immediately provided a solution - one that not only solved the tearing of the liner dilemma but was also more cost-effective and less time-consuming overall.
Concrete Pumps of Texas recommended "washed gravel" instead of sand. Although the washed gravel cost more up-front, using it in combination with the company's Telebelt conveyor would save about five weeks in time and labor costs. The significant time savings would result because washed gravel compacts itself and thus allows work to progress in a continuous flow, unlike the sand. Plus, the exclusive design of their truck-mounted Putzmeister conveyor could move concrete and materials at high volume outputs up to 360 cubic yards an hour (275m3/hr) to get the job done extremely fast.
Wall knocked out Standard Aero and the general contractor, CCC Group, were instantly convinced. However, to get the Telebelt closest to the hole's edge for the greatest coverage area, it needed to setup at a particular spot inside the building. A wall had to be knocked out and a ramp installed over a dock area to allow the Telebelt to drive inside. The truck-mounted unit remained inside during the entire six-day process.
Although the low ceiling heights would have presented a problem for most placing equipment, the conveyor's low unfolding and operating height of only 16 feet (4.8m) didn't make this an issue of concern. However, the dump trucks couldn't deal with the low heights. They were unable to hoist up under the low ceiling to unload the gravel directly into the conveyor's hopper. Therefore, a special 3-cubic-yard (2.3 cubic meter) rock hopper was positioned over the Telebelt's feeder belt. A front-end loader kept hauling the material from piles outside the building and filling the large capacity rock hopper to maintain a constant flow of backfill.
Tony Tye, owner of Concrete Pumps of Texas, noted that "Not only was the Telebelt the most cost-effective alternative, it was the only alternative in effectively handling this particular job, especially under low operating heights."
The Telebelt ran full bore with no idle time. First, it placed backfill a foot high covering the hole's entire bottom. This made a solid foundation over the liner, which then allowed a front-end loader and skid steer to drive around in the hole and level out the material beyond the Telebelt's 105-foot reach. Delivering 1-1/8-inch (2.8cm) washed gravel at speeds faster than trucks could unload, the Telebelt filled the hole with over 300,000 tons of backfill and completed the process about 25 days ahead of schedule.
"It's a win-win situation" Mike Schultz, Sales Manager of Concrete Pumps of Texas said, "Once we outline the cost difference of buying the higher priced washed gravel which doesn't need compaction and the time saved in placing it with the Telebelt, companies and contractors better understand the substantial savings involved. It's a win-win situation for everyone."
After the backfill process was complete, a Putzmeister Thom-Katt trailer pump joined the Telebelt to simultaneously place concrete atop the 8-inch (200mm) slab. The Telebelt used its full 105-foot (32m) reach until it could extend no farther from its fixed indoor location, and the Putzmeister trailer-mounted concrete pump handled all the rest using 200 feet (61m) of 5-inch (125mm) delivery line.
The mixers couldn't keep up with the fast conveying of the Telebelt. Meanwhile, the Thom-Katt's crew also pumped the 3000-psi mix at up to the model's maximum 50 cubic yards an hour (38m3/hr) output to help finish covering the entire 30,000-square-foot (2787m2) area within a ten-hour day. The versatility and reliability of the equipment working in tandem meant a 550-cubic-yard (420m3) job completed quickly and smoothly without interruption.
The unusual project was completed in mid-April 2001, way ahead of schedule due to the ingenious use of the right material and the right equipment mix to get the job done in record time.
JOB SPECS: Owner: Standard Aero, Winnipeg, Canada headquarters General contractor: CCC Group, San Antonio Concrete contractor: H Karp Construction Company, San Antonio Pumping contractor: Concrete Pumps of Texas, San Antonio Ready-mix supplier: Ingram Ready-mix, San Antonio Equipment: Putzmeister Telebelt TB 105 telescopic belt conveyor; Putzmeister Thom-Katt trailer pump TS 2050