Author(s): G. P. Van Dyk
Linked Author(s):
Keywords: Sediment sampling; Sampling plan; Sediment sampling principles; Column sampling; Grab sampling; Flowing sediment sampling; Bed-load transport; Compression; Degassing; Smearing; De-mixing; Determination of depth; Sludge consistency
Abstract: Sampling sediments must be done in an accurate way. The consequences when samples are taken in an incorrect way are enormous. Typical is the under-estimation of sludge volumes to be dredged based on samples that were taken with a system that allows compression of the layers. Pollution levels can severely be over-or under-estimated when top layers are missed; a case typical for gravity operated grab samplers that sink through the most liquid top layer before closing. In this article an overview of sampling principles, sampling possibilities and sampling problems is given for both sediments in suspension as sediment deposited. An overview of commercially available sediment samplers is given with images and sketches. Small sized samplers may be applicable operated from a small (preferably flatbottomed) boat. Large size samplers will require a very serious logistical operation with a full size ship equiped with compressor, davit, GPS, sufficient anchors or poles to be driven into the submerged soil prior to sampling. Apart from that, statistical variations and dynamic processes in the sediments require a lot of samples to be taken for a representative analysis result. The article focusses on currently applied solutions for these problems.
Year: 2003