Salt Lake City sits on the edge of ancient Lake Bonneville, and the subsurface here tells a complicated story. You find layers of stiff, overconsolidated clays from the lakebed sitting right next to coarse alluvial fan deposits washed down from the Wasatch Range. This layering means you cannot trust a single textbook value for permeability. A Lefranc test in those silty clays gives you one number, but a Lugeon test in fractured rock along the East Bench produces something entirely different. Before designing a dewatering system for a downtown excavation or sizing a stormwater infiltration gallery near the Jordan River, you need actual in-situ measurements. We run these tests regularly from the industrial yards near the airport to hillside subdivisions in the Avenues, and the data we collect directly shapes the seismic microzonation models that factor into Salt Lake City's strict hillside development rules.
A single Lugeon test in fractured Wasatch quartzite can reveal a permeability an order of magnitude higher than what lab tests on intact core suggest.
Service characteristics in Salt Lake City
Risks and considerations in Salt Lake City
A developer we worked with on 2100 South had a stormwater retention system designed using a desktop soil survey. The numbers looked fine on paper. Three months after construction, the infiltration basin ponded water for days after each storm because the actual permeability of the Lake Bonneville silt was two orders of magnitude lower than the regional map indicated. They had to retrofit the entire system with underdrains and a pump station, which cost far more than a day of field testing would have. This scenario plays out regularly along the Wasatch Front where lacustrine deposits pinch out against mountain-front colluvium over very short distances. A Lefranc test program spaced every 100 to 150 feet across a site catches these transitions before they become change orders. For deeper projects near City Creek Canyon, skipping a Lugeon profile in the metamorphic bedrock means risking uncontrolled water inflows during caisson excavation.
Our services
Our approach to permeability testing in Salt Lake City is straightforward: we mobilize a drill rig or use an existing borehole, install the test equipment, and run the protocol that matches your geology. Every test is supervised by a licensed geotechnical engineer who understands the local stratigraphy.
Lefranc Borehole Tests
We perform variable-head or constant-head Lefranc tests in soil boreholes above the water table, targeting specific strata identified from drilling logs. Common applications include infiltration gallery design and basement dewatering analysis.
Lugeon Packer Tests
For bedrock investigations, we use single or double packers to isolate test intervals and apply five-stage pressure sequences per the Lugeon method. This identifies fracture flow behavior critical for dam foundations and deep excavations.
Combined Permeability Profiles
On sites with mixed soil and rock conditions, we run Lefranc tests in the overburden and Lugeon tests in the underlying bedrock within the same borehole, delivering a continuous vertical permeability profile.
Common questions
How much does a field permeability test cost in Salt Lake City?
A typical Lefranc or Lugeon test program in the Salt Lake Valley ranges from US$680 to US$940 per test interval, depending on depth, access, and whether we are using an existing borehole or need to drill a new one. Mobilization and engineering interpretation are additional.
What is the difference between a Lefranc test and a Lugeon test?
The Lefranc test measures permeability in unconsolidated soils above the water table using a simple open borehole cavity, while the Lugeon test uses inflatable packers to isolate sections of bedrock and applies staged water pressure to assess fracture conductivity.
When does Salt Lake City require an in-situ permeability test?
The city requires permeability data when proposing stormwater infiltration systems, when excavating below the seasonal high groundwater level, or when building on hillside lots where subsurface drainage could affect downslope stability. The Hillside Protection Ordinance specifically references hydraulic conductivity values.
How long does a Lugeon test take to complete?
A single five-stage Lugeon test interval typically requires about 45 to 60 minutes of active testing once the packer is set at depth. Factoring in drilling, setup, and multiple intervals, a full day of testing usually covers two to three intervals.