ASTM D4630 and the USBR Earth Manual specify field permeability testing as the most reliable method for determining in-situ hydraulic conductivity—a parameter that laboratory tests on small specimens often misrepresent due to sample disturbance and scale effects. In Aurora, Illinois, where the shallow subsurface consists of glacial outwash sands interbedded with lacustrine silts and clays, the Lefranc method provides accurate point measurements in soil boreholes, while the Lugeon test characterizes rock mass permeability when exploratory drilling encounters the underlying dolomite bedrock of the Galena Group. For projects requiring a complete stratigraphic characterization, this test complements data from SPT drilling to correlate hydraulic conductivity with blow count profiles, particularly when evaluating dewatering requirements for excavations that penetrate the permeable Fox River Valley deposits.
A single Lugeon test in fractured dolomite reveals more about grout take and cutoff wall design than a hundred lab permeameter runs on intact core samples.
Technical details of the service in Aurora
Demonstration video
Local geotechnical conditions in Aurora
Aurora sits at an elevation of approximately 720 feet above sea level, with the Fox River bisecting the city and creating a hydraulic gradient that drives groundwater flow toward the stream channel. Construction dewatering in the dense urban core, near structures like the Paramount Theatre or the Santori Library, generates drawdown cones that can induce settlement in adjacent buildings founded on compressible lacustrine clays if the radius of influence is underestimated. An incomplete permeability profile—one derived solely from grain size correlations without field verification—routinely overestimates or underestimates flow rates by an order of magnitude. The Lefranc test eliminates this uncertainty by measuring the actual soil mass response, including the effects of stratification, fissures, and sand lenses that laboratory tests cannot capture. In rock, the Lugeon test distinguishes between laminar flow through tight joints and turbulent washout in open fractures, a distinction that determines whether a cutoff wall will succeed or whether extensive grouting is required before excavation reaches final grade.
Our services
Our field permeability program in Aurora covers the full range of in-situ hydraulic testing, from shallow soil boreholes to deep rock investigations, supported by our accredited materials laboratory for post-test verification.
Lefranc Variable Head Tests
Conducted in soil boreholes during routine geotechnical investigations. We isolate the test section with a slotted casing and measure head dissipation over time in granular and cohesive soils, providing point k values for dewatering design and seepage analysis.
Lugeon Packer Tests in Bedrock
Performed in NQ or HQ core holes drilled into the Galena Group dolomite. Single and double packer configurations isolate fractured intervals; five-stage pressure testing evaluates hydraulic conductivity and joint condition for deep foundation socket design and grouting programs.
Combined Permeability and Monitoring Programs
Integrated service that pairs Lefranc/Lugeon testing with piezometer installation and aquifer response monitoring, delivering a complete hydrogeological model for Fox River corridor projects where groundwater control is critical.
Quick answers
What is the difference between a Lefranc test and a Lugeon test?
The Lefranc test measures hydraulic conductivity in soil by injecting water into an open section of a borehole and recording the rate of pressure decay or flow under a constant head. It is defined in ASTM D4630 and is used in unconsolidated deposits like the outwash sands common in Aurora. The Lugeon test, specified by USBR 7310-89, is a packer test for rock—it isolates a borehole interval with inflatable seals and records water take at stepped pressures. A Lugeon value of 1 Lu equates to approximately 1×10⁻⁷ m/s and indicates tight, intact rock, while values above 20 Lu suggest open, potentially groutable fractures.
When is field permeability testing required instead of laboratory tests?
Field testing is specified when the soil or rock mass contains structural features—fractures, fissures, sand lenses, or gravel seams—that control hydraulic conductivity at a scale larger than a lab specimen. In Aurora's glacial stratigraphy, thin sand partings within till units can dominate the overall seepage regime; a lab permeameter test on a 2-inch sample would miss these features entirely. Regulatory agencies and the IBC also require in-situ permeability data for dewatering permit applications when the proposed excavation extends below the groundwater table.
How much does a Lefranc or Lugeon test cost in Aurora?
How long does it take to get results from a field permeability test?
The field execution for a single Lefranc test takes approximately 30 to 60 minutes per interval, depending on soil type—clean sands drain rapidly, while silty clays require longer observation. A complete Lugeon test with five pressure stages typically requires 60 to 90 minutes per test zone. Raw data plots showing flow versus pressure are available within 24 hours of field completion. The final interpretive report, including calculated hydraulic conductivity values, Lugeon unit plots, and flow regime classification, is delivered within three to five business days.