Below is a brief summary of the steps required to set up an effective soil vapour sampling event.
- Install soil vapour or sub-slab probe
- Cover surface area around soil vapour probe
- Check potential vacuum in probe (should be less than 10 inches water)
- Determine volume of sampling well (volume of sand pack and tubing)
- Determine volume of sampling train
- Perform shut-in test on sampling train
- Attach sampling train to soil vapour probe
- Cover sampling train and probe with shroud
- Add helium into shroud (target 20 to 40% helium)
- Purge three well/tubing volumes into Tedlar bag in vacuum box
- Using the filled Tedlar bag test for helium
- Helium in bag should be less than 1% of the helium level under the shroud
- Also test Tedlar bag for other gases (O2, CO2, CH4, total TPH)
- If all indicators are within criteria, begin soil vapour collection