Boise sits at 2,704 feet above sea level, perched on the edge of the Treasure Valley where the Boise Front meets the Snake River Plain. Much of the subsurface here is a puzzle of fractured basalt flows, interbedded sediments, and coarse alluvial fans deposited by the Boise River over millennia. When infrastructure projects encounter these formations, the difference between a dry excavation and a flooded worksite often comes down to a well-executed field permeability test. The Lefranc method provides reliable point measurements of hydraulic conductivity in soil and weathered rock, while the Lugeon test quantifies water loss in fractured bedrock under pressure. Our laboratory operates under ISO 17025 accreditation and follows ASTM D6391 for packer testing, ensuring the data you receive holds up under regulatory review. For dam abutments, deep foundations, or landfill siting across Ada County, slope stability analysis must incorporate accurate permeability values to model seepage forces correctly, and our team routinely pairs permeability data with seismic refraction surveys to map the top of fractured basalt before planning injection or grouting programs.
A single Lugeon test in fractured basalt reveals more about groundwater behavior than a dozen laboratory permeability runs on intact core samples.
Our approach and scope
Local ground factors
The Lugeon packer assembly is a deceptively simple piece of equipment—a reinforced rubber bladder between two steel end fittings, lowered on drill rods to the test interval and inflated with compressed nitrogen. At depth, inside a basalt fracture zone, that bladder must hold a perfect seal while water is injected at pressures exceeding 100 psi. If the packer slips or the borehole wall collapses, the test is ruined and the interval must be redrilled. In Boise's older basalt formations, clay-filled fractures can clog during drilling, artificially suppressing permeability readings and leading to an underestimation of grout take quantities. Conversely, open columnar joints may accept water so readily that maintaining pressure becomes impossible, indicating a high-transmissivity zone that demands a different engineering approach. Misinterpreting a Lugeon pressure curve—confusing turbulent flow with hydraulic jacking, for example—can result in a dam foundation that leaks or a dewatering system sized too small for actual inflows. The cost of a retest is trivial compared to the cost of redesign after excavation reveals conditions the permeability data failed to capture.
Relevant standards
ASTM D6391-11 (Standard Test Method for Field Measurement of Hydraulic Conductivity Using Borehole Infiltration), ASTM D4630-19 (Standard Test Method for Determining Transmissivity and Storativity of Low Permeability Rocks by In Situ Measurements Using the Constant Head Injection Test), IBC 2021 Section 1803.5.5 (Groundwater Investigation Requirements), USBR Earth Manual Part 2, Designation E-18 (Lugeon Permeability Test), and AASHTO LRFD Bridge Design Specifications, Section 10 (Foundations) are the applicable standards.
Other technical services
Lefranc Test (Variable Head)
Performed in soil and weathered rock boreholes at depths up to 100 feet. We measure the rate of water level recovery after a known slug injection, calculating hydraulic conductivity using the Hvorslev or Bouwer-Rice solution. Ideal for foundation dewatering design and infiltration basin characterization in Boise's alluvial terraces.
Lugeon Packer Test
Downhole packer testing in bedrock following the Houlsby five-pressure-stage procedure. Each isolated interval is subjected to increasing and decreasing injection pressures to classify flow regime (laminar, turbulent, dilation, washout, or filling). Critical for dam foundation assessment and tunnel pre-excavation grouting in Boise's basalt formations.
Multi-Zone Permeability Profiling
Sequential testing of multiple depth intervals within a single borehole, producing a vertical profile of hydraulic conductivity. We combine Lefranc tests in overburden with Lugeon tests in underlying bedrock, delivering a continuous permeability log that supports 3D groundwater modeling and cutoff wall design for Treasure Valley water infrastructure projects.
Typical parameters
Common questions
What is the difference between a Lefranc test and a Lugeon test?
Both measure in-situ hydraulic conductivity, but they apply to different materials. The Lefranc test is used in soil and highly weathered rock; water flows into or out of an uncased borehole section under a low head, and the flow rate is converted to hydraulic conductivity (cm/s). The Lugeon test is designed for competent fractured rock. A pneumatic packer isolates a specific interval, and water is injected under pressure in five stages. The result is expressed in Lugeon units (1 Lu ≈ 1.3 × 10⁻⁷ m/s). In Boise, a typical investigation uses Lefranc tests through the alluvial overburden and Lugeon tests once bedrock is encountered.
How much does a field permeability test cost in Boise?
How long does a Lugeon test take to complete?
A single Lugeon test interval, once the borehole is drilled and cleaned, takes approximately 45 to 90 minutes. The five-pressure-stage procedure requires stabilizing flow at each pressure level, and the total duration depends on rock mass permeability. Tight rock with low water take may require longer to reach steady flow at each stage, while highly fractured zones stabilize quickly. Drilling, casing advancement, and packer setup add time above the test itself. For a 100-foot borehole with three test intervals, plan on one full field day.
Which ASTM standard governs the Lefranc and Lugeon test methods?
Both methods fall under ASTM D6391-11, Standard Test Method for Field Measurement of Hydraulic Conductivity Using Borehole Infiltration. The standard covers the Lefranc (variable and constant head) procedure for soil and the Lugeon packer procedure for rock. For projects requiring transmissivity and storativity data in low-permeability formations, ASTM D4630-19 may also apply. Our field reports reference the specific ASTM method used for each test interval.