Sampling of soil Flashcards
Explain how soil collection from a screw should be done.
You should remove the outer layer of soil from the screw since this originated from the up pulling of the screw. Then you can take a sample directly from the screw, using your hand if you have rubber gloves.
What is sulfide soil? Why should you be concerned about it?
It is soil that contains sulfides, for example iron sulfides. When these come into contact with oxygen (which they do after land rise and weathering for example) the chemical reaction gives cause to acid drainage due to sulphuric acid
When is it recommended to sample from pits? What are the main advantages and disadvantages?
It’s recommended when you have till with rock or heterogeneous composition. The main advantage is that you get a good overview. Disadvantages are that you can only go max 3-4 meters down, deeper than 2 meters gives big security risks. It is not suitable below groundwater table and it changes the grounds stability.
When is it recommended to sample with a screw? What are the main advantages and disadvantages?
When you at the same time want to install groundwater pipe or do a geotechnical investigation this method is good. The main advantages are that it’s low impact and safe. The disadvantages are that it provides disturbed samples, it’s difficult to get an overview and difficult with coarse materials, rock, waste etc.
When sampling soil from a profile, when is it allowed to mix soil and when it is not?
Don’t mix type/texture, consistency, colours, odors, from above and below the watertable.
Don’t mix cohesive soils with friction soils. Don’t mix natural soil with backfilled soil. Don’t mix soil from above and below the groundwater table.
What is good to do to choose a representative sampling site?
Look at background information. Talk to people who know the place.
What is one way to reduce laboratory costs?
Take samples in different bags depending on the material (sand, gravel…) –> send your finest particles to lab (metals are bound to clay) –> wait for analysis and see if other particles sizes also should be analysed.
