Field Permeability Testing (Lefranc/Lugeon) in Wichita’s Sedimentary Formations

Wichita sits on a thick sequence of Permian shales, siltstones, and interbedded limestones belonging to the Wellington and Ninnescah formations. The Arkansas River cuts through the city’s west side, leaving alluvial deposits that complicate every dewatering plan. When a geotechnical report only estimates permeability from grain-size correlations, it misses the fracture flow that dominates in these weathered shales, and that’s exactly where a field permeability test (Lefranc/Lugeon) provides the numbers a desktop study never can. The USGS monitoring well network in Sedgwick County shows static water levels that fluctuate seasonally between 10 and 35 feet below grade, a range that makes packer placement and test stage isolation critical for reliable data. Whether it’s a commercial excavation near the river or a stormwater infiltration basin on the east side, we run these tests following ASTM D6391 and the USBR earth manual procedures so the hydraulic conductivity you receive holds up under peer review.

Fracture flow in the Wellington Formation can produce hydraulic conductivity values two orders of magnitude higher than what a lab test on an intact core would suggest.

Our approach and scope

Around the Delano District and anywhere within half a mile of the Arkansas, we see clean sands and gravels where the Lefranc constant-head method works fast, but move two miles east toward College Hill and you’re into tight, fractured claystone that demands the Lugeon approach with a pneumatic packer. The test isn’t just about pumping water and watching a gauge. It requires isolating a specific interval, applying stepped pressures, and interpreting whether the flow is laminar, turbulent, or influenced by fracture dilation, exactly the behavior Bishop and Lugeon documented in the 1930s and that still drives dam foundation assessments today. We often pair the permeability test with a CPT soil profiling run to confirm the stratigraphy before setting the packer depth, especially where the contact between alluvium and bedrock is irregular. When the site will eventually carry a mat foundation or a deep basement, combining these results with excavation monitoring data gives the structural engineer a complete picture of both inflow rates and pore pressure dissipation during construction.

Local considerations

Downtown Wichita and the Riverside area present two completely different permeability problems. Downtown excavation in shale may encounter minimal seepage until a fractured zone connects to the alluvial aquifer, at which point inflow jumps from a nuisance to a safety hazard in minutes. Riverside, built on coarse Arkansas River deposits, often requires wellpoint dewatering from the start, and assuming a textbook permeability value instead of running an in-situ test leads to undersized pumps, trench instability, and OSHA violations during deep utility work. The biggest liability we observe isn’t the test cost. It’s the cutoff wall or dewatering system that gets designed from a lab permeability number on an intact sample, while the field-scale fracture network transmits groundwater at a rate the drained design never anticipated. A Lefranc or Lugeon test anchors the groundwater model in measured reality, which matters when you’re signing off on a shoring plan under IBC Chapter 33.

Reference standards

ASTM D6391-11: Standard Test Method for Field Measurement of Hydraulic Conductivity Using Borehole Infiltration, USBR 7310: Pressure Testing of Foundation Rock (Lugeon Method), IBC Chapter 18 & 33: Soils and Foundations / Excavation Safety, ASCE 7-22: Minimum Design Loads for Buildings and Other Structures

Typical values

Parameter	Typical value
Test standard (Lugeon)	ASTM D6391, USBR 7310
Test standard (Lefranc)	ASTM D6391, ISO 22282-2
Borehole diameter used locally	NQ (75.7 mm) to HQ (96 mm)
Typical test stage length	3.3 ft to 16.4 ft (1 m to 5 m)
Pressure range applied in shale	0.5 to 5 bar, stepped in 3-5 increments
Reported hydraulic conductivity (k)	cm/s, ft/day, or m/s
Water source requirement	Potable or site-sourced, 500-2,000 gallons per test

Frequently asked questions

How much does a Lefranc or Lugeon permeability test cost in Wichita?

A single-stage Lefranc or a basic Lugeon test in one borehole typically falls between US$610 and US$1.000, which includes the technician’s time, packer equipment, water supply coordination, and the interpretive report. The final cost depends on how many stages you need, whether we’re testing in soil or fractured rock, and the depth of the test interval. A multi-level Lugeon profile in deep bedrock will push toward the upper end of that range due to the extra time for packer repositioning and pressure stabilization.

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

It comes down to the material. Lefranc works in soil, sand, gravel, and highly weathered rock where the borehole stays open without casing. Lugeon applies to competent rock and stiff claystone where you can isolate a section with inflatable packers. In Wichita, many sites start as soil, then hit shale at 15 to 25 feet, so we often run a Lefranc in the overburden and switch to a Lugeon setup once we’re into the Wellington formation.

How long does a field permeability test take on site?

For a single Lefranc test in granular soil, expect one to two hours of active testing once the borehole is prepared. A Lugeon test with five pressure stages in rock usually requires two to four hours per test interval, because each pressure step needs time for flow to stabilize. If we’re profiling three or four zones in the same borehole, the full log can run a full day. We coordinate the drilling and testing schedule to minimize standby time for the rig.

Field Permeability Testing (Lefranc/Lugeon) in Wichita’s Sedimentary Formations

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Our approach and scope

Local considerations

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Reference standards

Typical values

Frequently asked questions

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