Ground investigation techniques vary depending on the objectives of the investigation, the strata, and logistical factors such as access.
To assist with understanding what factors contribute to the decision on which technique to use, we have prepared a briefing note on the use of dynamic sampling techniques. Further techniques will be discussed, so keep an eye open for them!
Summary: A specialist piece of equipment that strikes a tube into the ground providing both a soil core and a groundwater and ground gas monitoring installation possible. Often the “go to” piece of equipment for a contamination and basic geotechnical investigation.
Equipment: Dynamic sampling rig (often called a window or windowless sampling rig). Requires a crew of at least two operators, plus a site Engineer.
Time: A lead in time of around two to three weeks.
Costs: A relatively modest cost per day, though labour costs for the operators and site engineer make up the majority of the costs.
Depth: Normally 5m deep is possible. This may be shallower in sand and gravel, or up to 10m deep boreholes feasible in clay (such as London Clay).
Coverage: Good coverage across the site, with up to 6 locations per day feasible (fewer if deeper boreholes are required or complex ground conditions).
Constraints: Access for the rig is generally good, but can be challenging if it has to pass through narrow gates (though the rig can pass through a standard doorway with a lot of disassembly). Requires headroom of around 3.5m.
Best used when: The site is open for equipment to access. Due to the relatively low disturbance of the sampling location, and the ability to place a stopcock type flush cover over any monitoring installations, this is a preferred method in sensitive locations (such as in a car park).
agb Environmental has a team of geo-environmental (contaminated land) and geotechnical specialists that can assist with ground investigations and assessments for development projects. To discuss what ground investigation technique may be suitable for your development, call Simon Pike (Principal Consultant) on 01638 663226 (Newmarket office) or email email@example.com.