GEOTECHNICAL ENGINEERING
LAREDO
HomeIn-Situ TestingField permeability test (Lefranc/Lugeon)

Field Permeability Testing (Lefranc/Lugeon) in Laredo, TX

Knowledgeable. Thorough. Resourceful.

LEARN MORE

Laredo sits at the edge of the South Texas Plains, where near-surface geology shifts from Carrizo-Wilcox sandstone to Quaternary alluvium of the Rio Grande. That transition zone creates real uncertainty in water flow paths beneath a site. The IBC requires a rational assessment of subsurface drainage, and that is precisely what a field permeability test delivers. Our crew runs both the Lefranc method for granular soils and the Lugeon method for fractured rock, following ASTM D4630 and the pressure-step protocols of Houlsby. A single boring can yield a complete hydraulic conductivity profile in less than a day, feeding directly into dewatering design or foundation drain sizing. For sites near Chacon Creek or the river terraces, we often pair the permeability data with a CPT test to correlate soil behavior type with measured k-values, giving the geotechnical engineer a continuous picture of the subsurface.

A single Lugeon test in fractured Carrizo sandstone can reveal flow paths that a dozen lab permeameter samples would miss entirely.

Our service areas

Methodology and scope

The Carrizo aquifer outcrops northwest of the city, and its sandstone fractures can transmit water at rates that surprise even experienced local contractors. In those conditions, the Lugeon test becomes indispensable: we isolate a test interval with a pneumatic packer, apply five pressure stages, and record the flow. The resulting Lugeon value quantifies fracture openness directly, which matters enormously when designing cutoff walls or evaluating grout take. Down in the floodplain, where silty clays of the Beaumont Formation dominate, the Lefranc falling-head test gives us the low-permeability numbers needed for retention pond sizing. Our lab in Laredo carries ISO 17025 accreditation for the permeability testing program, and every test run includes an automatic temperature correction to 20°C. We have seen projects where a single missed fracture zone added six figures to dewatering costs—something a properly executed in-situ permeability test catches early. The data also feeds directly into the excavation support analysis that our team performs alongside deep excavation monitoring on downtown Laredo projects.
Field Permeability Testing (Lefranc/Lugeon) in Laredo, TX
Technical reference — Laredo

Site-specific factors

Laredo's climate throws extremes at a site: flash floods in May and October, then prolonged drought that drops the water table by several feet. A permeability test run during a dry spell will yield different results than one run after a tropical disturbance, and not accounting for that seasonal swing leads to undersized drainage. The biggest risk we see is contractors skipping the in-situ test altogether and relying on lab permeameters on disturbed samples—those numbers can be off by two orders of magnitude in fissured Beaumont clay. Another risk specific to Laredo is the presence of paleochannels filled with coarse gravel lenses beneath the silt cap; a boring that misses one of these lenses will underestimate bulk permeability, and the first heavy rain exposes the error. The engineering team mitigates this by correlating permeability data with geophysical profiles and by running tests at multiple depths within each boring.

Need a geotechnical assessment?

Reply within 24h.

Email: contact@geotechnical-engineering1.org

Regulatory framework

ASTM D4630 – Standard Test Method for Determining Transmissivity and Storage Coefficient of Low-Permeability Rocks by In Situ Measurements Using the Constant Head Injection Test, ASTM D5084 – Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter (for lab correlation), IBC 2021 Section 1803 – Geotechnical Investigations (drainage and groundwater requirements), Houlsby (1976) – Routine interpretation of the Lugeon water-test, ASCE 7 – Minimum Design Loads (drainage provisions for retaining structures)

Typical values

ParameterTypical value
Test methodLefranc (variable/fixed head), Lugeon (packer)
Applicable soils/rockGranular soils, residual clays (Lefranc); fractured rock, sandstone (Lugeon)
Standard referenceASTM D4630, Houlsby (1976) pressure steps
Borehole diameterMinimum NQ (76 mm) for Lugeon; 4-6 inch bucket auger for Lefranc
Test interval length3 to 20 ft, selected from core log or CPT refusal depth
Pressure stages (Lugeon)5 stages: low-medium-peak-medium-low
Reporting metricHydraulic conductivity k (cm/s), Lugeon units (Lu), transmissivity upon request
Temperature correctionAutomatic to 20°C per ASTM D5084

Common questions

What does a field permeability test in Laredo typically cost?

A single Lefranc test at one depth interval runs US$700 to US$850, including mobilization within Laredo city limits. A Lugeon test with full five-stage pressure sequence runs US$850 to US$990 per interval. Most projects need two to three test intervals per boring to capture vertical variability. We provide a firm quote after reviewing the boring logs or site plan.

How long does a Lefranc test take on a Laredo site?

The field work for one Lefranc interval takes about 1.5 to 2 hours, assuming the borehole is already advanced to depth. A Lugeon test with five pressure stages takes longer—roughly 3 to 4 hours per interval including packer setting and stabilization. We can typically complete three intervals in a single field day.

Which test method is right for my project: Lefranc or Lugeon?

It depends on the geology. If the boring log shows granular soils, silts, or clays—typical of the Rio Grande alluvium in central Laredo—the Lefranc method is the correct choice. If you are encountering sandstone or fractured limestone below 20 feet, the Lugeon packer test is required to quantify fracture permeability. Our team reviews the existing geotechnical data and recommends the method before mobilization.

Do you provide the permeability data in a format ready for the city building permit?

Yes. Every test report includes the field data sheets, time-drawdown curves, computed hydraulic conductivity with temperature correction, and a summary table that matches the IBC Section 1803 submittal requirements. We also include the boring log with test intervals marked, so the plan reviewer in Laredo has the complete picture.

Location and service area

We serve projects in Laredo and surrounding areas.

View larger map