Figure 2. Bucket dredge Viking operating in Cook Inlet, Alaska

ERDC TN-DOER-E14

August 2001

The first event is winch noise as the dredge derrick and bucket swing outward and the bucket

is lowered. Although not classified as an event herein, a splash sound caused by the bucket

hitting the surface of the water could be detected at relatively short distances from the source.

This sound was variable depending on the speed and angle of the bucket as it entered the

water.

In the second event a sudden and often very intense impact sound is produced as the bucket

makes contact with the bottom.

In the third event, a grinding sound is produced as the bucket is closed and the dredged material

(coarse sand and gravel) is removed.

In the fourth event, a snap or clank is often audible as the jaws of the bucket close against

each other.

In the fifth event, more winch noise similar to the initial-event winch noise is audible as the

bucket is raised to the surface and the derrick swings over the barge.

Finally, in the sixth event, material being dumped into the barge may or may not produce an

audible sound depending on the level of material existing in the barge. For example, material

striking metal in an empty or partially filled barge generally produced an audible sound,

whereas material falling upon previously dumped material frequently did not.

Figure 2. Bucket dredge Viking operating in Cook Inlet, Alaska