Sampling of soil Flashcards
Explain how soil collection from a screw should be done
- Remove the outer layer
- Take the samples directly from the screw
- Use your hand, with rubber gloves on
What is sulfide soil? Why should you be concerned about it?
- Contains S
- Binds trace elements, problem when it oxidizes
- Can cause acidic water when oxidating
When is it recommended to sample from pits? What are the main advantages and disadvantages?
+ Good overview
+ Possibility to take samples from the excavator
+ Better in till with rock or heterogeneous composition
- Reach only 3-4 meters into the ground
- Difficult to take out samples deeper than 2 meters without safety risks
- Not suitable below groundwater table
- Changes the ground stability
When is it recommended to sample with a screw? What are the main advantages and disadvantages?
+ Low impact
+ Few safety risks
+ Provides the ability to install groundwater pipes at the same time
+ Can be combined with the geotechnical investigation
- Provide disturbed samples
- Difficult to get an overview
- Difficult in areas with very coarse material, rock, waste etc
What are the common on site analysis that can be done when samping soil?
- PID
- XRF
- Size of material
- Colour
- Odour
When sampling soil from a profile, when is it allowed to mix soil and when is it not?
If there is any form of layering or natural soil you are not allowed to mix, most soil types are not allowed to be mixed, because the size and composition will vary
Describe how the xrf works
- Metal concentrations in the soil
- X-ray is sent out and bounced against the material, the reflection is then measured by the machine calculating what element it is from the reflected rays
Describe three different sample preparations that can be used for XRF analysis. what are there pros and cons? How can you compensate for the cons?
- Dry it?
How can you plan your sampling procedure to reduce the cost for sampling and analyzing? How to choose representative sampling sites?
- Look at background information
- Talk to people who have worked there
- Look at maps, soil type etc.
How can you plan your sampling procedure to reduce the cost for sampling and analyzing? Field measurments (pH, XRF, PID)
- Bring a pH-meter to the site
- XRF will not give you as precise values as if done at the lab but will still give you results. Based on those results you may choose which samples to send to the lab
How to reduce analysis cost in the laboratory?
- If there is a contaminant, send in the clay and silt layers first, since they have the highest values
- Send the right amount/weight to the laboratory
- Do the measurments that you can make on your own, do them
- Write down exactly what you want to get analysed and how precise….