Figure 1. Time-history of cutterhead position

ERDC TN-DOER-I4

August 2000

accurate results. Magnetic flowmeters are superior to Doppler-based flowmeters but cost consid-

erably more. Density meters typically use a nuclear source and measure the attenuation of the

nuclear particle flux through the pipe. They require a licensed technician to handle the source and

documentation. Despite these drawbacks, most larger pipeline dredges have them.

Production meters can only measure production through the pipeline. Some production may occur

from the transport of sediment dislodged during the dredging process, especially in fine sediments.

When comparing production meter output to survey volumes, the best results are usually obtained

in sands where the in situ density is well known.

Additional parameters can be measured to fully characterize the limiting factors affecting dredge

performance. The most important of these are pump-related parameters, such as revolutions per

minute, suction vacuum, and discharge pressures. Important for some projects are dislodgment-re-

lated parameters, such as cutter motor and swing winch loads. Furthermore, projects that require

extensive use of booster pumps may need to monitor them as well.

Provide Trustworthy Facts. The increase in construction claims and litigation during the past

decade emphasizes the need to document the facts that may be used as evidence in negotiation and

litigation. Sanderson succinctly related this need in his presentation at the Texas A&M 1992

Dredging Engineering Short Course: