Twin Valley Precast is part of the Spring Ridge community, a Hutterite settlement in Alberta about two hours east of Edmonton. The Hutterites immigrated from Eastern European countries to South Dakota around the turn of the last century. They thrived and expanded with new settlements in Alberta, speaking a variation of German among themselves but English otherwise. The communities farm large tracts of land in the grain belt, selling most of the crop but also using it to feed livestock and poultry for local consumption and outside markets.
The Alberta oil patch has brought much development. Twin Valley Precast saw expanded opportunities for concrete products, among them oil pump bases and insulated wall panels for residential and commercial/industrial buildings. The producer’s existing operation, housed in a 60- x 130-ft. enclosure, was no longer enough to meet increased product demand.
Twin Valley Precast’s new plant is 130- x 330-ft. with two bays, each having a 20-ton overhead crane running most of its length. The end of the building is reserved for a new, fully indoor batch plant, including sheltered aggregate storage to cope with the northern prairies’ harsh winters. During 2014 startup, the outdoor temperature plunged below zero with a howling wind fostering a -20°F chill factor; inside, the heating system, equal to operating down to -40°F, kept plant crews and equipment installers toasty.
The community enlisted Voeller Mixers Inc. for the plant equipment package: four weighed aggregate bins batching decumulatively via horizontal and inclined conveyors to 4-yd. mixer and a cement scale fed from two 40-ton silos produced by local manufacturer Meridian. Scale-Tron supplied the BatchTron control system, aggregate and mixer moisture sensors, high pressure mixer washout system and SiloWeigh system to display the weights of material in the two silos.
A precast cabin houses the control system with a connection to the offices for the reporting and inventory computer, which has an Internet connection for remote maintenance and training. The control system is a long way from the mixer; for convenience, a local control panel allows the cleanout crew to turn the batch controller offline and operate all the mixer functions, plus high-pressure washout system, from the mixer platform. The UL-certified Motor Control Center, also manufactured by Scale-Tron, includes a soft-starter for the main mixer motor as well as conventional starters for all other motors in an easily accessible sealed and interlocked panel.
The 4-yd. Voeller turbine mixer gives the plant a capacity of around 80 yd./hour at peak production. The mixer feeds the precast production bays through two chutes to buckets placed by the overhead cranes; a second discharge door can load fresh concrete into mixer trucks when necessary, using a drive-through bay with doors at each end. Two casting areas each have a heated pre-stress table and ample spare space for stacking product and forms for other jobs.
Scale-Tron’s specializes in meeting the unique needs of each precast operation to maximize efficiency by eliminating waiting time. A “demand station” near the chutes controls the batching, with automatic delivery of different formulas and batch sizes to the two bays. Interlocks prevent premature discharge if a bucket is not in place or the chute has not turned to the correct position. The control system can make up the next batch and hold it in the scales until the current batch has discharged from the mixer, with priority given to the fastest user; a secondary user’s requested batch is delivered after the priority team receives its load. A recent development allows a roving operator to view and control the batching screen from a hand-held tablet computer from anywhere in the plant—a feature that some leading precasters are already using with success.
For end of day cleanup, an automatic washout cycle, run from the batch controller, disables batching and runs the mixer while three rotating high-pressure washout heads clean all the residue from internal parts. After washing, the discharge door is opened automatically and residue is transferred into a container for disposal in the outdoor soak-away pit.
“We are pleased with the way the whole plant operates and the service during startup,” says Twin Valley Plant Manager Reuban Tschetter. “Our production is completed in a shorter time than we ever imagined, and we are still in startup mode. It will be even faster when we are settled into a regular schedule. The plant does everything we wanted and a lot more.” — Scale-Tron Inc., St. Laurent, Quebec, 800/632-7083; www.scaletron.com or www.ocmer.biz