A common mistake we see with Carlow projects is assuming the gravel layers along the River Barrow drain freely. They often don't. The glacial till that sits underneath the town centre and stretches out towards the Killeshin hills has a maddening variability—lenses of silt stop water dead, then a metre over you hit open gravel. Contractors who skip the in-situ test end up with undersized soakaways that back up in the first wet winter, or basement tanking that floats because the water table was higher than the desk study suggested. We run both Lefranc and Lugeon tests across the county, from one-off house sites in Palatine to commercial developments on the Athy Road, giving you the real permeability of the ground rather than a lab estimate. For deeper strata or rockhead assessment we often pair the permeability test with SPT drilling to correlate the hydraulic conductivity with the logged stratigraphy.
A falling-head test in Carlow's glacial till can take forty minutes to stabilise. If the contractor tells you it only took ten, the reading is wrong.
Methodology applied in Carlow
Local geotechnical conditions in Carlow
Eurocode 7 (EN 1997-2:2007) requires that ground investigation cover permeability when seepage or uplift can affect stability. In Carlow this isn't a tick-box clause. The River Barrow floodplain and its buried channels create a perched water table that rises fast after sustained rain—we've measured a 1.2 m rise within a week during a wet October near the town park. If the building envelope hasn't been designed for the actual field k-value, you get groundwater ingress through floor slabs or lateral pressure on retaining walls that the drainage system can't relieve. The Lugeon test on the underlying limestone is equally sensitive: open joints and solution cavities can transmit water far faster than a rock core sample suggests, turning a routine excavation into a dewatering nightmare. Ignoring field permeability in this landscape means designing blind, and the cost of remedial drainage after the fact runs many times the price of a day's testing.
Our services
We run field permeability campaigns across Carlow and the wider southeast. Every test is supervised by a senior geotechnical technician and the dataset is reviewed before it leaves the van. Two configurations cover most project requirements.
Lefranc permeability test (soil)
Constant-head or falling-head test in cased boreholes. Suited for the glacial till, sandy gravel, and alluvial deposits typical of Carlow. We log stabilisation flow rates every minute and report hydraulic conductivity k (m/s) with full borehole context and water level monitoring.
Lugeon packer test (rock)
Single or double packer test for limestone bedrock. Five pressure stages per interval, ascending and descending, to detect fracture dilation or infilling. Standard Lugeon value reporting, with correlation to RQD and core recovery when drilling data is available.
Questions and answers
How much does a Lefranc or Lugeon test cost in Carlow?
Budget between €600 and €850 per test setup, depending on depth, number of intervals, and whether you need a Lefranc in soil or a Lugeon in rock. A full-day campaign with multiple test intervals will naturally push the total upward, but we always provide a fixed quote before mobilising.
Which test do I need for a basement project in Carlow town?
It depends on what the boreholes hit. If the formation is glacial till or gravel above rockhead, a Lefranc falling-head test gives you the design k-value for drainage and waterproofing. If the basement cuts into the limestone, we add a Lugeon test to check joint conductivity. Most town-centre projects end up needing both across different horizons.
Do you need a drilled borehole already on site?
We can either test an existing open borehole that meets the casing and backfill requirements, or we can mobilise our own drilling crew to put down a dedicated test hole. The borehole diameter needs to be at least 76 mm for a standard Lefranc setup and 96 mm for a double-packer Lugeon. If the hole is already there, we'll inspect it first to confirm it's fit for testing.
How long does a field permeability test take on site?
A single-interval Lefranc test typically runs 30 to 60 minutes once the casing is set. A five-stage Lugeon test on one rock interval takes closer to 90 minutes. The real variable in Carlow is the till: if it's silt-rich, the falling-head stabilisation can drag past an hour. We never cut a test short before the flow-rate criteria are met—that defeats the purpose of being on site in the first place.