We worked on a large commercial excavation near the Boise River where the water table sat just 4 meters down. The design team assumed a simple drainage system would suffice. By running a field permeability test (Lefranc/Lugeon) on three distinct strata, we found a silty sand layer with hydraulic conductivity two orders of magnitude lower than expected. That single data point saved the project from a costly groundwater control failure. In Boise Idaho, where the alluvial deposits of the Snake River Plain mix with cobble layers from ancient flood channels, relying on textbook values is a gamble. Direct in-situ measurement removes that guesswork.
A single Lefranc test in Boise's alluvial gravels can reveal hidden clay lenses that block drainage — saving months of groundwater trouble.
Method and coverage
- Hydraulic conductivity (K) in m/s or ft/day
- Lugeon value (LU) for rock mass permeability
- Pore pressure dissipation rate
- Anisotropy ratio between horizontal and vertical flow
Regional considerations
In Boise Idaho, many engineers assume the local soils drain uniformly. They don't. The Boise River floodplain deposits contain discontinuous silt and clay beds that create differential seepage paths. If you place a subgrade without a field permeability test (Lefranc/Lugeon), you risk hydrostatic uplift under a slab or unexpected inflow into an excavation. We've seen a parking garage near downtown Boise require emergency shotcrete because nobody checked the permeability profile beforehand. That cost the owner six figures in delays. A simple test before construction avoids that.
Standards that apply
ASTM D5084 (Flexible Wall Permeability), ASTM D4630 (Lugeon Test in Rock), USBR 7300 (Lefranc Test Procedure)
Related services
Lefranc Test (Variable Head)
Constant or falling head test in a cased borehole, ideal for Boise's silty sands and gravels. We measure hydraulic conductivity at the exact depth of your foundation or retaining wall.
Lugeon Test (Pressure Packer)
Packer test for rock or stiff clay, using stepwise pressure increments. Essential for grouting design in the fractured basalt layers found beneath Boise's Bench neighborhoods.
This service complements our laboratory testing work for a complete project analysis.
Typical parameters
Top questions
What is the difference between the Lefranc and Lugeon tests?
The Lefranc test uses a constant or falling head in a cased borehole, measuring permeability in soils. The Lugeon test isolates a section of rock with inflatable packers and applies multiple pressure steps to assess fracture flow. In Boise Idaho, we use Lefranc for alluvial deposits and Lugeon for basalt or sandstone bedrock.
How much does a field permeability test cost in Boise Idaho?
The typical range for a single test is US$640 – US$1,080, depending on depth, access, and number of pressure stages. A Lugeon test with three pressure steps and packer setup falls at the higher end. We provide a firm quote after a site visit.
When should I schedule a permeability test during my project?
Schedule it after the geotechnical borehole is advanced but before final foundation design. In Boise Idaho, testing during the dry season (June–September) gives representative results because the water table fluctuates with snowmelt. Testing in spring may overestimate drainage capacity.