BS 5930 and Eurocode 7 (EN 1997-1:2004) set the standard for ground investigation in the UK. In Liverpool, with its dense Victorian infrastructure and clay-rich glacial till, a GPR (Ground Penetrating Radar) survey is especially relevant for detecting buried services and voids before excavation. Liverpool's port history means many sites have backfilled docks or old tunnels that surface radar can map quickly. We combine this with calicatas exploratorias for ground-truth calibration and ensayo CPT where continuous soil profiles are needed. The result is a comprehensive, non-invasive assessment that reduces project risk from day one.
A 400 MHz GPR survey in Liverpool's docklands located undocumented sewers and bedrock at 4.2 m depth in just two days — zero excavation.
Process overview
A typical Liverpool project involves a 12-storey residential block near the Albert Dock. The client needed to locate historic masonry foundations and buried fuel tanks before piling. We deployed a 400 MHz antenna array towed behind a survey vehicle. The unit transmits electromagnetic pulses into the ground and records reflections from buried objects and soil layers. For this site, the GPR (Ground Penetrating Radar) survey identified three undocumented brick sewers and a sandstone bedrock interface at 4.2 m depth. We cross-referenced anomalies with placa de carga tests to verify bearing capacity assumptions. The survey covered 2,800 m² in two days, with real-time data processing on site. No digging, no traffic disruption, no delays.
Technical reference image — Liverpool
Local context
The GPR (Ground Penetrating Radar) survey unit itself is a compact wheeled cart with a control laptop and battery pack. In Liverpool's narrow Georgian streets, we use a smaller 200 MHz antenna for tight alleyways. The main risk on site is interference from overhead power lines or metal gratings. We mitigate this by pre-scanning a calibration line and adjusting gain settings. Another risk is misinterpretation of saturated clay as a void. Our team has processed over 300 GPR surveys in Merseyside alone, so we recognise the signature of Liverpool's glacial till versus backfill. We always flag ambiguous anomalies for intrusive follow-up, never guess.
Up to 8 m in dry sand/gravel; 3-5 m in Liverpool clay
Vertical resolution
2-5 cm (at 900 MHz)
Data acquisition speed
Up to 50 km/h (road surveys)
Grid size for utility mapping
1 m x 1 m (standard); 0.5 m x 0.5 m for rebar
Post-processing software
GPR-SLICE v7.0 & RADAN 7
Additional services
01
Utility & Service Location Survey
Detect buried water pipes, gas lines, electric cables, and telecom ducts. We map them in plan and depth with ±5 cm accuracy. Ideal for Liverpool's congested city centre pavements.
02
Concrete & Rebar Scanning
Locate rebar, post-tension cables, and voids in concrete slabs. Used for core drilling safety on Liverpool's many listed buildings and retrofit projects.
03
Void & Cavity Detection
This service complements our laboratory testing work for a complete project analysis.
Relevant standards
BS 5930:2015 (Code of practice for ground investigations), Eurocode 7 – EN 1997-1:2004 (Geotechnical design), BS 5930 (Standard guide for using surface GPR on subsurface investigations)
Common questions
How deep can a GPR (Ground Penetrating Radar) survey penetrate in Liverpool?
Depth depends on soil type. In Liverpool's dry sands and gravels we reach up to 8 m. In the common glacial till clay, expect 3-5 m. Saturated clay reduces penetration to around 2 m. We always test a calibration line first to confirm site-specific depth range.
What is the cost range for a GPR survey in Liverpool?
A standard utility survey on a 2,000 m² site costs from £780 to £1,250 inc. VAT. Smaller scans or concrete surveys start at £480. The final price depends on grid density, antenna choice, and site access. We provide a fixed quote after a quick site visit or plan review.
Can GPR detect plastic pipes or clay drainage?
Yes, but with limitations. Plastic pipes are visible if there is a contrast in dielectric constant with the surrounding soil. In Liverpool's clay, we detect PVC pipes down to 1.5 m depth. Clay drainage pipes are harder, but we can identify them when backfill material differs from natural ground. We always cross-check with ground truth.
