A soil-stabilization spreader sailing on a pond is a sight one doesn’t see very often.
But for a crew in Catersville, GA, the water-borne spreader –– sitting atop a barge –– is the key element in a project that involves sealing a pond located on power-plant grounds without draining the water.
The body of water sits next to a stockpile of fly ash, the residue created by coal-fired power plants. When it rains, runoff from the pile collects in the pond. If the pond was to leak, the water could seep into the ground, possibly damaging the soil and water table of the surrounding woodlands.
In September, Stoltzfus Spreaders, Morgantown, PA, was contacted by Ted Hoey, senior project engineer of Environmental Specialities International Inc. (ESI), Baton Rouge, LA, to find a way to seal the pond without draining much water. Stoltzfus proposed using a truck-type spreader positioned on a barge to distribute bentonite from the deepest part of the pond to its shallowest ends.
The expansion properties of bentonite were perfect on this job, said Gary Lake, of Stoltzfus. “The clay becomes sticky like oatmeal. When it swells, it has the ability to plug leaks.”
Bentonite expands by taking in water between the layers of montmorillonite, a clay mineral that forms microscopic platy crystals with expansion properties. It weighs approximately 75 lbs. per cubic foot (34 kg per cu m) and takes approximately 10 minutes after falling from the water’s surface to begin expanding “from a couple inches to six to 10 inches thick” at the bottom of the pond, noted Lake. “It turns into something like Play-Doh and gets sucked into any potential leak.”
To spread the clay, Stoltzfus customized one of its truck-mounted soil stabilization spreaders to fit on a barge. The spreader sits almost dead center on the barge and is pneumatically loaded.
The spreader unloads onto a conveyor that moves the bentonite to a spreading auger mounted on the front starboard corner, just in front of the crew cabin. The spreader also has digital scales to monitor filling and spreading and four bin indicators, each connected to a strobe visible to the on-shore personnel. A 58-hp (43.2 kW) Deutz diesel engine powers the spreader, conveyor and auger hydraulics.
In October, the spreader and barge (from A & M Manufacturing, Old Town, FL) arrived in Georgia to be assembled and calibrated. The bentonite was shipped from Montana by rail and brought to the site with tanker trucks that moved the clay into tanks with compressors, also known as “pigs.” Set approximately 100 ft. (30.5 m) back from the pond’s shore, the pigs are connected to the site with 4-in. (10 cm) PVC pipe that runs down to the dock where the barge sits for refilling. Because of the moist consistency of the shoreline, the pigs must remain at this distance to avoid potential problems.
Before spreading began, crews lowered the water level between 6 and 8 ft. (1.8 to 2.4 m) and installed a conventional liner on the pond’s sloping edges, allowing spreading to take place up and onto the liner so that the whole thing is sealed, even in the shallow edges.
The spreader holds 25 tons (22.7 t) of bentonite and loads it into a 12-ft. (3.7 m) wide auger. Laying down a 12-ft.-wide swath, the spreader travels the length of the pond and returns on the same path. This process takes approximately 20 minutes to complete, but, with the distance between the pigs and dock, it takes two hours to refill the spreader. Once refilling is completed, the barge and spreader lay the next swath, allowing for a 1-ft. (0.3 m) overpass with the adjacent layer of bentonite.
To ensure the barge is on the correct path, Stoltzfus installed a MidTech global positioning system (GPS) with a Trimble receiver on the spreader. Inside the barge’s cabin, crewmembers keep watch over three separate electronic maps that mark their position on the pond, guaranteeing that areas aren’t skipped.
The crew works nearly 12 hours a day at the site, where challenges have popped up continuously since the project began.
After shipping the spreader from Pennsylvania to Georgia, Stoltzfus had to customize the inside of the hopper onsite to ensure that load wasn’t too heavy on the front or back of the barge, which, with its flat bottom, sits high on the water.
On each corner of the barge, ESI installed trolling motors, similar to the ones fishermen use, to stay on the GPS track during windy weather.
The project is expected to be complete this month.
“This is the first time I ever heard of a project like this,” said Lake. “It’s a great idea, I’m really glad to be a part of it.”
Lake expects that more power companies will pick up similar projects in the future.
Christian U. Stoltzfus started the Stoltzfus Spreaders in 1945 in an old water-powered feed mill just outside of Morgantown. Over the years, the company operated as Broadfall Spreaders, Willow Glen Industries and currently does business as Stoltzfus Spreaders. Its first products were truck-mounted boom-style lime spreaders, which were sold to other spreader truck drivers.
The company now offers 15 different spreader models in regular stock, including four lines of salt/cinder spreaders for highway use. Stoltzfus custom builds spreaders –– mounted on trailers, trucks, half-tracks, barges and flotation trucks –– for sludge, cement, bentonite, seashells and recycled wallboard. It also makes self-powered units for pickup trucks and dozers.
The company markets the Stoltzfus spreaders nationally through a network of 25 independent dealers. The company is still owned by the C.U. Stoltzfus family.
For more information, call 800/843-8731 or visit www.Stoltzfusmfg.com.