Monitor Dredge Position

ERDC TN-DOER-I4

August 2000

The inspectors ensure that the contractor's operating procedures and dredging equipment adhere to

safety requirements and United States Coast Guard regulations. They must also maintain records

and submit progress reports and daily logs for the dredging project. These reports document various

parameters for payment purposes and aid in contract quality assurance. The dredge's time is

distributed into various categories, such as time spent actually dredging, moving, breakdowns, and

various types of delays. The inspector periodically checks the position of the dredge to assure that

the dredge is operating within the designated site. Inspectors investigate controversial issues

created by the progress of work and submit a written report of the findings. As the situation requires,

they supplement the regular reports with various types of narrative information. This information

can include field conditions, recommendations to facilitate dredging progress, matters pertaining

to safety, or general material concerning the dredging project.

Within these broad requirements, Corps dredging personnel identified the following specific

inspection objectives that might be better met with the assistance of a SI system

Monitor dredging position (xyz coordinates).

Monitor dredge production status.

Provide trustworthy "facts" for dispute resolution.

Monitor Dredge Position. This objective is intended to satisfy several user needs. One need

is to ensure that dredging operations do not stray into environmentally restricted areas. Another

need is to assure dredging managers that the contractor is maximizing his effective dredging time

by operating only within the designated prism and cut. A time-history of cutterhead or dustpan

position in three dimensions is invaluable to the inspector in meeting these needs. The inspector

needs to be able to review these data on the dredge, but back in the office as well (Figure 1).

Monitor Dredge Performance (Production Status). On-dredge performance monitoring is

important in Corps contract management because it assists in:

Verifying contractor claims of changed conditions affecting production.

Knowing when the dredge was actually dredging.

Having an alternative to surveys for dredge production estimation.

Improving estimates by providing detailed parameters to dredge performance models.

Providing timely feedback to the Corps and contractors on production efficiency.

Two main operational parameters can be practically monitored to describe the dredge's activities

in time and space. The two parameters are the cutterhead's (dustpan) 3-dimensional position and

a production indicator. Monitoring results can feed directly into automated reporting of dredge

position and dredge production.

Production is typically monitored onboard the dredge by measuring the flow velocity and density

in the pipeline. These two measurements are usually combined into another instrument called a

production meter. If installed correctly and calibrated (Pankow 1990), these meters can give