MEASURING DRY MATTER IN TRAILING HOPPER DREDGERS
Of the various ways of determining payment for dredging work on the basis of measurement, the method which measures the quantity of dredged material in the means of transport is the most suitable for maintenance dredging operations using trailing suction hopper dredgers because siltation during dredging operations can be disruptive. The current 'half-ball and centrifuge' method has its limitations. These include dependence on the type of soil being dredged, dependence on manual actions and the fact that that payment is not proportional to the actual amount that was dredged. This has led to the testing and evaluation of a number of new methods aboard various trailing suction hopper dredgers. The weight measurement method appears to be the best way of meeting the shortcomings of the current method. The unit of measurement is 'tons of dry matter.' This is determined by using the weight and volume of the load. The weight of the load is established by using two levels of draught and the Carene diagram. A number of level sensors and the Level Table are used to determine the volume of the load. This method is the only one that is independent of the type of soil transported. Moreover, the method presents possibilities for improving the performance which may be profitable for the contractor and may decrease the expenditure of the principal. From measurements taken in practice, it appears that total accuracy is considerably better than for the currently used method. Besides this weight measurement method, other methods are recommended for specific purposes. One of these is radioactive measurement in combination with a flow meter. This method is preferred in cases where the slurry is being pumped into a disposal site via a pipeline.
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- Journal article
- Rokosch, W D
- Publication Date: 1989-12
- Pagination: 8 p.
- TRT Terms: Dredged materials; Dredging; Labor; Measurement; Prices; Volume; Weight
- Uncontrolled Terms: Suction dredges; Work
- Old TRIS Terms: Dry matter
- Subject Areas: Economics; Finance; Marine Transportation;
- Accession Number: 00659069
- Record Type: Publication
- Source Agency: Maritime Technical Information Facility
- Files: TRIS
- Created Date: Jul 21 1994 12:00AM