Annex D
(informative)
Vacuum bottles for groundwater sampling
When sampling groundwater through a filter tip, this and the extension pipe should be installed by pushing, percussion or pre-drilling. The filter tip shall penetrate groundwater unaffected by the drilling process. When using vacuum bottle sampling, the filter tip should be provided with a flexible rubber disc in its upper end preventing water from entering the extension pipe (see Figure D.1). The sampler contains a housing, an evacuated sample container with a flexible rubber disc in its lower end, a double-ended hollow hypodermic needle with sharp ends and a wire with a measuring tape. The sample container and its different parts shall be thoroughly washed and if necessary sterilised by boiling or autoclaving for 10 min at 105 °C. When coolish and dry, the container can be reassembled and mounted in the sampler. Before lowering the sampler, the sample container should be evacuated and the hypodermic needle mounted thoroughly so it doesn’t penetrate the sampler rubber disc before entering the filter rubber disc. The sampler is lowered to the filter and the needle isbrought to penetrate first the rubber disc in the top of the filter and then the rubber discin the sample container. Due to the vacuum in the container, the groundwater is sucked into the container. It shall be checked that the container is filled to the required amount. The time for filling depends on the permeability of the soil. It can take a few minutes in sandy soils but 30 min in clays. The sampler shall be slowly pulled out and the rubber discs in the container and the filter tip are automatically closed. The sampling can be repeated if required otherwise the extension pipe with its filter tip is pulled out.
Key
- 1 wire
- 2 container housing
- 3 evacuated sample container (vial)
- 4 flexible disc of rubber
- 5 double-ended needle
- 6 flexible disc of rubber
- 7 extension pipe
- 8 filter
- 9 filter tip
