The Sacramento Valley's hot, dry summers and wet winters create dramatic swings in groundwater conditions that directly impact foundation design. With the city sitting at the confluence of the American and Sacramento Rivers, alluvial deposits dominate the subsurface—layered silts, sands, and gravels deposited over millennia. Measuring in-situ hydraulic conductivity becomes essential, not optional. A CPT test can map soil stratigraphy efficiently, but when you need direct permeability values for dewatering design or seepage analysis, the Lefranc test in soil and the Lugeon test in rock provide the data engineers actually trust. Our field crews run these tests across Sacramento County, from Natomas basin clays to the fractured metamorphic rock encountered in foothill projects near Folsom. With over 525,000 residents in a seismically active region, accurate groundwater characterization supports everything from basement waterproofing to levee stability assessments.
Lab permeability on a 3-inch sample misses the gravel seam that drains your excavation in 20 minutes.
Scope of work in Sacramento
Risks and considerations in Sacramento
Sacramento contractors learn this lesson fast: pumping tests alone don't reveal anisotropy. Horizontal permeability in river-deposited sands often exceeds vertical permeability by a factor of 5 to 15. Design a dewatering system assuming isotropic conditions and you'll either undersize the pumps or miss a perched water table entirely. We've seen excavations flood in the Pocket-Greenhaven area because a thin gravel stringer wasn't identified during exploration. The Lugeon test also catches something critical in rock—hydraulic fracturing. If the injection pressure exceeds the in-situ minimum stress, the measured permeability spikes artificially. Our technicians follow the Houlsby interpretation method, plotting flow versus pressure to identify laminar, turbulent, dilation, and washout regimes. This prevents overestimating the grout take in foundation rock or underestimating uplift pressures beneath a mat foundation. For deep excavations near existing levees, accurate permeability data feeds directly into the slope stability analysis and determines whether cutoff walls or relief wells are necessary.
Our services
Permeability characterization often requires complementary field and lab work. These are the services our Sacramento teams execute most frequently alongside Lefranc and Lugeon testing.
In-Situ Permeability Testing
Direct measurement of hydraulic conductivity in soil and rock using variable-head Lefranc tests and staged-pressure Lugeon tests. We provide test intervals at any depth, with real-time data plots and final interpreted k-values for dewatering design, seepage modeling, and grouting programs.
Pumping Tests and Slug Tests
Larger-scale aquifer characterization using observation wells and high-capacity pumps. We design the test layout, instrument the wells with transducers, and analyze drawdown data using Theis or Cooper-Jacob methods to determine transmissivity and storage coefficient for the Sacramento aquifer system.
Soil and Rock Laboratory Testing
Flexible-wall permeameter tests (ASTM D5084) on undisturbed samples, grain size distributions (ASTM D6913/D7928), and Atterberg limits (ASTM D4318) to correlate field permeability with index properties and support seepage model parameterization.
Quick answers
What is the cost of a field permeability test (Lefranc/Lugeon) in Sacramento?
For budget planning, a single Lefranc test interval typically ranges from US$630 to US$960, assuming the borehole is already advanced. Lugeon testing in rock runs toward the upper end due to packer setup and multi-stage pressure sequences. Mobilization, borehole drilling, and reporting are priced separately. A site-specific proposal after reviewing the project location and depth requirements will give you a firm number.
When do I need a Lugeon test instead of a Lefranc test?
Use the Lefranc test in soil and very soft rock where the borehole wall stands open or can be cased. Switch to the Lugeon test when you encounter rock that requires a packer to isolate the test interval—typically in the Mehrten Formation, metamorphic bedrock, or any material where the borehole won't collapse. The Lugeon also gives you information about rock mass fracturing behavior under pressure, which the Lefranc cannot provide.
How long does a field permeability test take on site?
A single Lefranc test in soil usually completes in 30 to 60 minutes once the borehole is at depth. A full five-stage Lugeon test in rock takes about 90 minutes per interval. We typically run multiple intervals per borehole, so a full day of testing might cover three to five intervals depending on access and ground conditions.
Can field permeability values replace lab permeameter tests for a dewatering plan?
They should complement each other—not replace. Field tests capture the bulk mass permeability including fissures, gravel lenses, and macro-scale heterogeneities that a small lab specimen misses. Lab tests on intact samples provide the matrix conductivity. For dewatering design in Sacramento's layered alluvium, we recommend both: field values for the system-scale model and lab values to understand the fine-grained layers that may act as aquitards.