Potential applications

from contaminated silts on a routine basis. De Slufter managers have con-

tinuously looked for innovative approaches to sand reclamation. They are

currently investigating several different methods including a silting basin

and hydrocyclones. A sand separation basin is employed that is sized for

the velocity and quantity of material coming into the site. A small, con-

fined area at the De Slufter site expands in the direction of flow to allow

settling time for sand so that fine-

grained materials remain in turbulent

suspension and are allowed to flow into

De Slufter. The sand basin is

periodically emptied and the sand is

used for industrial purposes.

Hydrocyclones have also been em-

ployed to separate sand from fine-

grained materials at De Slufter.

According to the managers, hydrocy-

clones represent 80 percent of the cost

while supplying 20 percent of the sand;

the sand separation basin represents 20

percent of the cost, while

supplying 80 percent of the sand separa-

Figure 11. Sand peeler (Port of Rotterdam

tion. Operators at De Slufter are cur-

1999, used by permission)

rently experimenting with a device

called a "sand peeler." The sand peeler is a rectangular section of dis-

charge pipe with a flap in the bottom section (Figure 11). The peeler is de-

signed to make use of the natural zone separation that occurs within the

pipe to separate the flows. The flap is adjustable to account for different

flow regimes and sediment characteristics. The flap is intended to sepa-

rate the flow into two streams and, if successful, will allow for in-pipe

separation of sand and silt fractions. At the time of this investigation

(July 1998) experimentation had not begun.

Company/Organization(s): Access restricted to U.S. Army Corps of

Potential applications

Sand separation can be conducted as described above. All methods

listed are for reduction of contaminated materials and are not intended for

sand production. Sand has value as a by-product, but not enough value to

overcome the costs associated with separation and dewatering. Real-time,

in-pipe separation of dredged materials was not observed. The sand

peeler may prove effective in separating flow regimes; results of this

study should be available within a year. For locations with a large area

capable of relocating sand, the sand basin may save space in the disposal

area and provide recoverable sand reserves.

Chapter 4

Detailed Evaluations