Window sample drilling is a cost effective and quick way to collect samples of cohesive and granular strata. Typically it is used to sample the upper 6m or so of the sub-surface (made ground and natural strata); however it is possible to sample to greater depths (depending on ground conditions). 

Metal sample barrels are driven into the ground using a drop weight (hammer) on the mast of the rig. The 1m long barrels are lined with a plastic sleeve (liner), which collects a continuous sample of soil. When the full length of the barrel has been driven into the ground it is pulled out using the rig.  The liner containing the sample is then pulled out of the barrel.  

The liner can be opened immediately for logging on site by the engineer, who can also collect disturbed and bulk samples. Alternatively, the ends of the liner can be sealed up and the sample logged later.  

The borehole is continued to the required depth by adding 1m long drilling rods to each sample barrel. Our rig can extract up to 5m of drilling rods at any time, increasing the speed we can complete a borehole. Metal casing is used to keep the borehole open in granular strata. The casing is driven in at the same time as the sample barrel, helping minimise cross contamination. 

Standard penetration tests (SPTs) can easily be completed in the borehole.  A 50mm thick-walled sampler is driven into the base of the borehole using the 63.5kg hammer. The sampler is driven in for a seating drive of 150mm, after which the number of blows required to drive the sampler 300mm is recorded (the 'N' value).  We record the number of seating blows and the 'N' value on our drillers log.  

After drilling we can install the borehole with a monitoring well for groundwater and / or landgas, securley completed at the surface with a metal cover.  Alternatively, the borehole is backfilled and the ground surface reinstated.  Well / backfill installation details are recorded on our drillers log.

Our rig and necessary equipment is transported to site in a trailer towed by a 4 x 4.  

The compact track mounted rig can easily be driven between borehole positions and can access hard to reach areas, including through standard size doorways, up slopes and close to walls. We can also set up the rig within buildings (additional ventilation may be needed, which we are happy to provide if requested).  

We have experience working at sites with sensitive access requirements including:

• residential gardens
• sites with ecological designations (including sites of special scientific interest (SSSIs), special protection areas (SPAs) and special areas of conservation (SACs))
• operational petrol filling stations
• schools
• hotels
• places of worship

Please contact us if you have any questions about the rig dimensions or access considerations.