Restricted-access ground investigation: options for difficult sites

Difficult access rarely stops an investigation - it changes the method and the plant. The job is to match the rig to the site: small enough to get in, light enough to leave the ground as it found it, and still able to recover the samples and tests the scheme needs. The earlier we know about the access, the more options we have.

What makes a site restricted

• Basements, plant rooms and low-headroom interiors.
• Back gardens, courtyards and positions reached only through a building or a narrow gate.
• Embankments, cuttings and steep or uneven terrain.
• Live highways, verges and operational sites with tight working room.
• Soft, waterlogged or sensitive ground that will not take a heavy machine.

The rigs that get in

Our window sampling fleet is built for this - light, tracked and manoeuvrable, driven by a hydraulic jackhammer, and relatively non-intrusive compared with a larger rig. Where even that cannot get in, handheld window sampling can be used in virtually any situation where a driller can obtain access on foot, recovering soil in clear plastic liners to depths in the order of 5-8m. So a restricted site still gets its samples, its SPTs and DPTs, and its monitoring wells - not a compromised investigation.

Getting the kit to the working position is often half the job. The Norcar A7545 4T tracked telehandler is designed to leave little to no sign of having been near a site - it carries up to 1500kg across rough or waterlogged terrain and tows up to 3500kg, which overcomes the age-old problem of getting compressors and bowsers in and out. Where nothing can drive in, we hand-work equipment into position.

Protecting the site while we work

Track mats and boards spread the load on finished surfaces and soft ground, and our own vacuum systems take care of drilling fluids, so we can work in gardens, on live sites and on sensitive ground and leave them close to how we found them. On operational sites we bring the segregation, signage and permits the setting demands.

Talk to us early

The best outcomes on tight sites come from planning access before mobilisation. Send us photos, a site plan and the constraints - headroom, gateway widths, ground conditions, working hours - and we will tell you honestly what is achievable and recommend the right rig and approach.