Maryland Sand and Gravel Operator Cleans Clay
from Settlement Pond
Spreads material to reclaim land
Installation of a portable hydraulic dredge has solved silt settlement problems and aided land reclamation at a major Maryland sand and gravel plant.
Silver Hill Sand & Gravel serves Maryland, Virginia, and Washington D.C. markets from plants in Silver Hill and Clinton. Silver Hill is a subsidiary of the UK-based Bardon Inc., for which is a global leader in aggregate mining. Combined, the two plants are said to be the largest sand and gravel source in the area. At Silver Hill, the gravel is scrubbed to remove a 10% clay content. After the gravel is washed, the slurry containing suspended clay and mud runs into a slurry pond where fines settle out. In the process of running 2,500 tpd, as much as 500 cu. yds. of the clay-mud mixture also are generated and added daily to the slurry pond.
For several years, management had a problem with the cleaning process. Explained Sonny Bevard, "We had a limited amount of land to use for silt settlement; we couldn't afford to let one pond fill up and simply dig another so we had to find an efficient way to get rid of the consolidated mud-clay substance and restore the settling capacity of the slurry pond."
Originally, the Silver Hill crew cleaned the pond with traditional dragline and clamshell techniques. Then the company installed a Mud Cat™ portable hydraulic dredge.
According to Bevard, the Mud Cat™ sucks and pumps the clay-mud mixture a distance of 3,800 ft. through an 8-in. discharge pipe. "We decided to reclaim and raise the level of the land," said Bevard, "and the only way to get the clay substance to dry out enough for the land to be stable is to spread to out in very thin layers. We plow furrows, much like forming ridges for a row of seeds, and direct the Mud Cat's™ pipe discharge over the furrows, pouring the substance in thin layers over the land."
Once the clay dries, the land is plowed again to further aerate it before another layer is added to the surface. After it is completely reclaimed, the land will be sold for building development.
Samuel Bevard started Silver Hill Sand & Gravel in 1939. Today, he and his sons, Marion, John, and Sonny (of Bevard Industries) own and operate two plants.
Reprinted from Pit & Quarry
