Sioux Falls sits on a foundation of Sioux Quartzite overlain by glacial till, outwash, and alluvial deposits along the Big Sioux River, where perched groundwater and highly variable hydraulic conductivity create distinct challenges for excavation and foundation design. Many sites near the river—particularly in the central corridor between Falls Park and the airport—show saturated silty sands and gravel lenses at depths of 10 to 25 feet, demanding accurate field permeability values before dewatering or cutoff wall design begins. The Lefranc test provides reliable K-values in these mixed soils through variable-head measurements in boreholes, while the Lugeon method is applied in fractured quartzite bedrock where packer-isolated intervals reveal water take in Lugeon units. Our team runs these tests to ASTM D6391 standards, delivering data that feeds directly into groundwater control plans and stability models for deep excavations.
A one-order-of-magnitude error in hydraulic conductivity can double the required dewatering pump capacity—and your monthly operating cost.
How we work
Local ground factors
The most persistent mistake we see on Sioux Falls projects is running a single-stage pump test in a monitoring well and using that bulk value for the entire excavation footprint, ignoring the fact that flow in fractured quartzite is controlled by discrete joint sets with orientations that don't match the well screen. When a dewatering system is designed off a homogenized K-value, you end up with dry zones next to saturated pockets in the cut, which leads to slope instability and repeated shutdowns. Another common error is skipping the Lugeon test in the upper 20 feet of weathered rock, where fracture aperture changes rapidly—this zone often governs seepage into basements and pump stations. A complete permeability profile, with Lefranc tests in the overburden and Lugeon tests in the rock, eliminates the guesswork and keeps the contractor out of trouble during the wettest months from April through June.
Relevant standards
ASTM D6391-11 (2020) – Standard Test Method for Field Measurement of Hydraulic Conductivity, ASTM D2487 – Unified Soil Classification System, ASTM D1586 – Standard Penetration Test (SPT) and Split-Barrel Sampling, USBR Design Standard No. 13 – Embankment Dams (Chapter 8: Seepage), USACE EM 1110-2-1901 – Seepage Analysis and Control for Dams
Other technical services
Lefranc permeability testing
Variable and constant-head tests in soil boreholes, following ASTM D6391 procedures. We test individual strata within the glacial till and alluvial sequence, providing layer-specific K-values for dewatering design, seepage modeling, and infiltration analysis.
Lugeon packer testing in bedrock
Double-packer Lugeon tests in NQ or HQ boreholes across fractured Sioux Quartzite. Five-stage pressure sequences per interval quantify hydraulic aperture and fracture connectivity, essential for dam abutment investigations and deep basement waterproofing design.
Integrated groundwater investigation
Combined SPT drilling, permeability testing, and piezometer installation for complete hydrogeologic characterization. We correlate field K-values with grain-size distributions from split-spoon samples, producing defensible design parameters for cutoff walls, grout curtains, and excavation dewatering systems.
Typical parameters
Common questions
When should I use a Lefranc test versus a Lugeon test on my Sioux Falls site?
Use the Lefranc test in soil—glacial till, outwash sands, and alluvial silts—where the borehole is uncased or slotted within a single stratum. Switch to the Lugeon test once you encounter bedrock, typically the Sioux Quartzite, because the packer system isolates a specific fracture interval and applies controlled pressure to measure water take. Most projects in Sioux Falls require both: Lefranc in the overburden and Lugeon in the upper 30 to 50 feet of weathered rock.
How long does a field permeability testing program take?
A single Lefranc test can run from 30 minutes to 2 hours depending on soil permeability; low-K glacial till takes longer to equilibrate. A full Lugeon sequence on one 10-foot rock interval takes roughly 90 minutes including the five pressure stages. A typical Sioux Falls project with three soil intervals and two rock intervals can be completed in one to two field days, assuming the drilling rig is advancing simultaneously.
What does in-situ permeability testing cost for a typical project?
Field permeability testing in the Sioux Falls area generally ranges from US$550 to US$1,080 per test interval, depending on depth, access conditions, and whether we are testing in soil (Lefranc) or fractured rock (Lugeon). A complete program covering both overburden and bedrock typically falls in the mid-to-upper portion of that range per interval, with mobilization included for projects within Minnehaha and Lincoln counties.
Can you install monitoring wells or piezometers during the same mobilization?
Yes. We routinely combine permeability testing with piezometer installation, using the same borehole to set a vibrating-wire or standpipe piezometer after the test interval is complete. This provides both the K-value and long-term groundwater level data from the same location, which is cost-effective and gives you a direct correlation between hydraulic conductivity and observed pore pressures. More info.