Sub Slab Gas Vapour Kit Installation
The Van Walt South Africa team recently installed a Sub-Slab Gas Vapour Probe Kit and trained the customer how to install the kit and use it for repeated gas sampling over time. This was the first installation of this type of equipment which we only recently added to our soil sampling range.
For the customer the existing gas sampling infrastructure on the site in Johannesburg was prone to theft and vandalism. Regular gas sampling to monitor gas leakages and soil contamination around a manufacturing plant is required for site safety but has become expensive, as additional equipment had to be purchased every time.
Van Walt’s Sub-Slab Gas Vapour Probe Kit is used to sample for volatile organic compounds (VOCs) beneath floor slabs, specifically for vapour intrusion investigations. Sub-Slab Kits provide a semi-permanent solution that allows for repeated sampling over time to assess the potential of contaminated vapour intrusion beneath the floor slab of a building. The Sub-Slab GVP Installation Kit contains everything needed to install up to five permanent sampling points with a screw-in cap to help prevent vandalism. For additional sampling points, parts can be ordered separately, but the tools in the kit can still be used to install the additional sampling points. This makes the system versatile as the sampling infrastructure can be extended over time or as expansion takes place.
This kit is user friendly, and the Van Walt SA team could easily train the team on site to install the gas vapour sample probes and to take gas samples themselves. The simple 7 step process is:
1. Create a 3.5 mm hole with a core bit so the tamper resistant cap will fit flush with the ground surface when installed.
2. Drill through the concrete or asphalt floor using the masonry bit
3. Check for obstructions in the drilled hole
4. Assemble the probe by attaching the 7.5cm stainless steel mesh implant to the stainless-steel vapor shaft tube. Slide the teflon tube plug over the vapor shaft tube, this will prevent any material from falling down the newly drilled hole and obstructing the mesh section. Lastly, cut the vapor tube shaft to the correct length and attach the female connector to the other end ensuring everything is tight.
5. Insert the assembled Gas Vapour Probe, grouting above the teflon plug as you push the probe deeper
6. Use the ball-valve and / or hose barb adapter to connect tubing and sampler to the Gas Vapour Probe and begin collecting samples
7. Screw the tamper-resistant cap in place.
The completed installation will enable the customer to replace the remaining previously installed probes that may get damaged or stolen. One of the main benefits of the kit is that it is very inconspicuous when the tamper proof cap is in place which will hopefully mean less vandalism in the future.
