Field Permeability Testing (Lefranc & Lugeon) in West Valley City

West Valley City’s expansion onto the Lake Bonneville lakebed sediments created unique subsurface challenges. What was once farmland and marshland now supports subdivisions, commercial corridors, and light industrial parks, all over complex sequences of clay, silt, and sand lenses. The saturated fine-grained deposits underlying much of the 8400 South corridor demand accurate hydraulic conductivity data before any deep excavation or foundation drain design. The field permeability test, conducted as the Lefranc method in soils or the Lugeon method in rock, measures in-situ water flow through these formations at discrete depths. Our team runs these tests across West Valley City using wireline packers and constant-head setups calibrated to ASTM D6391 procedures. For projects near the Jordan River or Decker Lake, where groundwater fluctuates seasonally with snowmelt, we frequently combine the permeability test with grain-size analysis to correlate field hydraulic behavior with laboratory particle distribution curves.

In-situ permeability measurement captures secondary porosity and macro-fabric effects that lab tests on small specimens simply cannot replicate.

Process and scope

West Valley City’s semi-arid climate masks a shallow water table that surprises many contractors. Summer irrigation return flows and winter snowpack melt from the Oquirrh Mountains recharge the unconfined aquifer, raising pore pressures in the silty overburden. This seasonal shift directly impacts the reliability of infiltration rates and dewatering estimates. Our field permeability testing program addresses this by running tests in both wet and dry cycles when project schedules allow. We measure hydraulic conductivity across the full range expected for the Lake Bonneville sediments—from 10⁻⁷ m/s in fat clays near 3500 South to 10⁻⁴ m/s in sandy interbeds. The data feeds directly into dewatering system design and seepage analyses. When boreholes encounter gravel stringers, the Lugeon test protocol using five pressure stages identifies fracture flow behavior that steady-state Lefranc tests alone would miss. For deep foundation evaluation, the results support pile design by quantifying the lateral drainage conditions that affect skin friction development in saturated silts.

Local geotechnical context

IBC Chapter 18 and the West Valley City engineering standards require site-specific hydraulic conductivity for any project with a permanent dewatering system or an infiltration basin. The region’s layered stratigraphy creates a particular risk: thin sand seams between clay layers act as confined aquifers that, when punctured by an excavation, trigger sudden base instability. A site on Parkway Boulevard experienced exactly this scenario in 2018, requiring emergency dewatering that could have been avoided with pre-construction permeability profiling. The Lugeon test also serves dam safety evaluations for detention basins in the city’s flood control network, where internal erosion through foundation rock poses a long-term failure mode. Our reports include the Lugeon criterion for grouting decisions—values above 3 Lugeon units typically indicate a need for curtain grouting, directly triggering the scope for grouting programs.

Technical parameters

Parameter	Typical value
Test standard	ASTM D6391 (packer method)
Soil method	Lefranc constant/variable head
Rock method	Lugeon (5 pressure stages)
Measured property	Hydraulic conductivity k (cm/s or m/s)
Typical k range in basin silts	10⁻⁶ to 10⁻⁴ cm/s
Borehole diameter	NX to 8-inch (depending on depth)
Packer type	Single or double pneumatic
Reporting output	k per test interval, Lugeon values, transmissivity

Other technical services

Lefranc Test Program

Constant-head and falling-head tests in soil boreholes. We install monitoring wells or use direct-push tooling to isolate specific strata within the Lake Bonneville sequence.

Lugeon Pressure Testing

Five-stage pressure test in bedrock using single or double packers. Applied to dam abutments, tunnel alignment investigations, and deep shaft construction where fracture flow dominates.

Dewatering Feasibility Package

Combines field permeability data with analytical modeling to estimate steady-state inflow rates, well spacing, and drawdown timelines. Required by West Valley City for projects with excavations below 8 feet.

Common questions

What is the difference between Lefranc and Lugeon testing?

Lefranc tests measure hydraulic conductivity in soil using a constant or falling head in an open borehole section. Lugeon tests apply to rock, using a packer to isolate a test interval and pumping water at five increasing pressure steps to assess fracture flow and the need for grouting.

How much does a field permeability test cost in West Valley City?

A single Lefranc or Lugeon test typically ranges from US$680 to US$980, depending on depth, number of test intervals, and mobilization requirements. Multi-depth profiling across several boreholes reduces the per-test cost.

How long does a Lefranc test take to run in the field?

A single constant-head Lefranc test takes 30 to 90 minutes once the drill rig reaches the target depth. The time depends on soil type: low-permeability clays require longer stabilization. We typically schedule one to two tests per drilling shift.

Do I need a permeability test for a residential foundation in West Valley City?

Most single-family homes do not require it. However, if your lot is within 500 feet of the Jordan River or a mapped wetland, or if a basement will extend more than 4 feet below the seasonal high water table, the city may request hydraulic conductivity data for drain design.

What borehole diameter is needed for these tests?

Lefranc tests can be performed in boreholes as small as NX (3-inch) diameter, though 4- to 6-inch holes provide more reliable results. Lugeon tests in rock typically use NQ or HQ core holes with a pneumatic packer seated in competent rock above the test interval.