TXI 's new Wade Sand & Gravel plant operates in two states on both sides of the Red River, with Ellicott Dredge

It flows unvexed to the Gulf of Mexico as it has for thousands of years. Choctaw Indians call it Ohammabok, meaning Red River. As the boundary between Texas and Oklahoma, the Red River has flooded and meandered across countless acres of land to deposit its bounty atop these basins.

It is for this bounty that TXI bought the property for Wade Sand & Gravel in 1994 and 1995. In all it encompasses more than 2,400 acres, with 2,300 of it in Oklahoma and 100 of it in Texas. The Texas property was purchased almost solely for distribution purposes due to the remoteness of the Oklahoma deposit. The processed material serves the northeast quadrant of the Dallas/Ft. Worth market and all of east Texas.

Construction of the Wade Operation began in May of 1998 on the Texas side. More than 300,000 cu. yd. of material was moved from the hill, near the present office, to the current plant location to provide a buffer between the plant and the untamed Red River. After raising the Texas Plant elevation 18 ft. to that of the 100-year floodplain, earthmoving began in Oklahoma.

TXI's Wade Sand & Gravel Plant

Initially, construction on the Oklahoma side required less material to be moved, but earthmoving is a constant operation for production to continue. And the most challenging operation in setting up the plant was boring multiple pipelines underneath the Red River (see sidebar below). "Using the pipeline drastically reduced the environmental impact any of the other options would have had," says Chris Rahn, Wade Sand & Gravel production superintendent/mining engineer.

Primary processing in Oklahoma

The whole production process begins at the cutterhead on the Ellicott dredge (named the Ohammabok), located in a dredge pit that has been constructed east of the plant. Zero material and only supplemental water comes from the river. Material and water are picked up at the dredge and pumped to the Oklahoma plant for primary processing.

TXI's Ellicott Dredge "Ohammabok"

The dredged material is first sized over a 6-ft. x 16-ft. Svedala two-deck horizontal screen. Material larger than 1 in. is conveyed to the oversize pile. Material smaller than 1 in. but greater than 38-in. is fed to a coarse material washer for cleansing and stockpiling. The smallest particles, smaller than 38-in., are fed to the 12-ft. x 48-ft. Eagle Iron Works Classifying Tank. Here the sand is separated into salable product and settling pond filler.

On to Texas

After leaving the classifying tank, salable product finds its way to an 11,000-gal. sump to be sucked up by a 12-in. x 14-in. GIW pump and pushed with a 1,000-hp DC drive motor on its journey to Texas. 3,300 ft. later the slurry enters another 12-ft. x 48-ft. Eagle Iron Works Classifying Tank in Texas. All material is separated into three products, by gradation. The primary product, concrete sand, is dewatered by an Eagle Iron Works Double 54-in. fine material washer and conveyed on a 36-in. Peerless 75-ft. transfer conveyor.

The product is stockpiled by a 36-in. Peerless 150-ft. elevating stacker to be loaded for sale. The second product, masonry sand, is processed and dewatered through a system identical to the concrete sand system on the east side of the Texas Plant. TXI's specialty products are processed in the third system at the Texas plant. Sand is dewatered in a single Eagle Iron Works 44-in. sand screw, conveyed on a 30-in. Peerless 75-ft. transfer to a 30in. Peerless 120-ft. elevating stacker. All process water is returned to the Oklahoma plant for further processing by a 10-in. x 12-in. GIW slurry pump.

This pump is controlled by a radar level meter that controls a 300 hp-variable speed drive on the pump. Loadout occurs at the stockpiles by one Caterpillar 980C and one Caterpillar 980G front-end loaders. The trucks then proceed to a Mettler Toledo DigiTol Truckmate scale for weighing.

Automation

Being a greenfield operation, TXI spared little expense when it came to making the plant as automated as possible. There is no operator at all on the Texas side, all operations are controlled by one person based on the Oklahoma side. A few examples of the automation in place includes Milltronics Zero Speed switches on all the conveyors, variable speed sump pumps and radar level detectors in the tanks and Ramsey belt scales on all the belts.

All this information is communicated to an AutoSpec III PLC for processing and display. Information from the Texas side is relayed to Oklahoma by radio frequency. As TXI continues to increase the amount of automation Rahn says the next step will be to install a fiber optics line that will be placed in the pre-bored communication line that runs under the river.

"With the installed automation the operator can monitor, and see, (at the river pump) tph, the velocity of the material in the pipeline, and the specific gravity of the material in the pipeline," says Rahn. "He can see the level of water he has in his tank and add fresh water from two fresh water pumps down at the pit if he needs to."

This is all automatically controlled by two air-operated butterfly valves and the PLC controls. As the water in the sump goes up the water at the valves is stopped and vice-versa. On the screen, he can also see the density of the material in the pipeline; the discharge pressure, which runs anywhere from 80 to 140 psi; any faults that are occurring on that motor, the speed the motor is turning, the power it is pulling in kWh and the vacuum on the suction side. It also shows tons per hour that is going over to Texas.

"The vacuum is important because if his velocity starts to get too low or the pressure or density gets too high it will open another valve and introduce fresh water only into the sump, bypassing the material, so it can clear the pipeline out," says Rahn. The automation allows the controller on the Oklahoma side to move the stackers on the Texas side. This currently is not being done as there is no visual feedback on the Texas side but TXI plans on installing video that will the operator to move the stackers. "That will help out a lot," says Rahn.

Besides all the control, the automation also aids in production by keeping track of daily production as well as month-to-date and year-to-date. It will also compare to last year's figures once they have been running long enough. "The automation we have installed at this facility is pretty slick," says Gary Allen, plant manager for TXI. "It is a totally automated flow from Oklahoma to Texas."

As of press time, TXI was still evolving its operation, adding a Nordberg VS1680 crusher, an Eagle Iron Works 36-in. x 30-in. log washer, five additional conveyors, two hoppers and a Tyler 4-ft. x 8-ft. single deck screen. Being added to the Oklahoma side, this addition is taking the smaller rock (less than 1-in. but greater than 38-in.) off the bottom deck of the screen, crushing it to sub 38-in. size and reintroducing it into the coarse sand system going to Texas. PQ.

If you can't go over it ...

Crossing the Red River presented one of the most challenging phases in the construction of TXI's Wade Sand and Gravel operation. Three options were originally considered - a conveyor system, bridge or pipeline.

"The pipeline consideration was two-fold," says Chris Rahn, Wade Sand & Gravel production superintendent/mining engineer. "Using the pipeline drastically reduced the environmental impact any of the other options would have had, which was our number-one concern. We are very concerned about doing anything on or around the Red River and in order to reduce and just about eliminate any kind of impact we would have, directional drilling was the way to go," says Rahn. "Permitting was also easier and the cost was unbeatable."

The boring began in October 1998 by the Davis Corp. of Healdton, Okla. The bores are 90-ft. below the surface, on an arch going down at 12-deg. When they get to 90 ft. they start the curve, coming back up to the other side. This puts them significantly below the surface of the river, which at a maximum is 20 ft. deep.

Upon its completion in December 1998, Wade now had a method to transport material from Oklahoma to Texas. Four bores were completed in three months. The first is used to transport material to Texas, the second is to return water to Oklahoma, the third is a spare transport line, and the fourth is a communication line for future use. Construction of the Texas and Oklahoma plants was completed in March of 1999.

Excerpted from Pit & Quarry By Chad A. Dorn