Scottsdale's build-out from a small farming community into a premier desert metropolis created unique subsurface challenges that standard lab tests simply cannot capture. The city's alluvial fans, deposited by the Indian Bend Wash and surrounding bajadas, exhibit highly variable permeability that directly impacts basement waterproofing, stormwater retention, and dewatering system design. We run in-situ permeability tests across Scottsdale because no remolded sample from a split spoon tells you how water actually moves through cemented caliche layers or interbedded gravel lenses. Complementing our field program with grain size analysis helps validate the hydraulic conductivity values we obtain from Lefranc and Lugeon procedures, particularly in the heterogeneous deposits common north of Shea Boulevard. Our laboratory maintains ISO 17025 accreditation through A2LA, ensuring every permeability value we report meets the documentation standards required by Maricopa County plan reviewers and geotechnical peer review boards.
A single Lefranc test at the correct depth replaces a dozen percolation holes and gives you a defensible hydraulic conductivity value under actual groundwater conditions.
How we work
Local ground factors
Scottsdale's projects east of the 101 face a condition we see repeatedly: decomposition of the granite bedrock creates a saprolitic transition zone that holds water unpredictably. A contractor who assumes the rock is impermeable based on a core log alone will get a flooded excavation when they hit a fractured zone at 30 feet. We have watched dewatering systems fail because the designer used a textbook permeability value for 'weathered granite' instead of running a Lugeon test in the actual rock mass. The cost of a single packer test program—typically completed in one drilling shift—is negligible compared to the change order for emergency dewatering or the structural retrofit when buoyancy forces exceed the design assumption. IBC Section 1803.5.5 and the local Scottsdale amendment to the building code require groundwater investigation when the proposed lowest floor sits within 5 feet of the seasonally high water table, and the only way to satisfy that requirement with defensible numbers is through in-situ permeability measurement. For retention basin design where infiltration is the primary outlet, we often pair the field test with an Atterberg limits analysis on the surrounding soils to confirm that fines content will not migrate and clog the basin floor over time.
Reference standards
ASTM D6391-11: Standard Test Method for Field Measurement of Hydraulic Conductivity Using Borehole Infiltration, ASTM D4630-19: Standard Test Method for Determining Transmissivity and Storage Coefficient of Low-Permeability Rocks, IBC 2021 Section 1803.5.5: Groundwater Investigation Requirements, ASCE 7-22 Chapter 8: Soil-Structure Interaction for Foundations Below Water Table
Complementary services
Lefranc Permeability Testing
Variable-head and constant-head tests performed in soil borings with pneumatic packer isolation. We target specific strata identified in the boring log, providing hydraulic conductivity values for each layer that the civil engineer needs for dewatering design, seepage analysis, and infiltration modeling.
Lugeon Testing in Bedrock
Five-step pressure testing in fractured granite and metamorphic rock following the Lugeon methodology. Each test runs at increasing and decreasing pressure stages to detect fracture dilation, infilling washout, or turbulent flow behavior. Critical for deep foundations and underground structures in Scottsdale's mountain-front developments.
Slug and Rising-Head Tests
Rapid permeability assessment in monitoring wells and open boreholes using a solid displacement slug. We use pressure transducers with 0.01-foot resolution and automated data loggers to capture the full recovery curve, then analyze the response using the Bouwer-Rice or Hvorslev solution depending on well geometry.
Infiltration Feasibility & Retention Basin Testing
Multi-depth permeability profiling specifically for stormwater infiltration design under Maricopa County LID guidelines. We combine field hydraulic conductivity with laboratory grain size curves to predict long-term infiltration capacity and assess clogging potential.
Typical parameters
Common questions
What does a field permeability test cost in Scottsdale?
A typical Lefranc test program with two to three depth intervals runs between US$690 and US$1,100 per boring, including the drilling time, packer setup, data acquisition, and the engineering report. Lugeon testing in bedrock falls at the higher end of that range because it requires a five-stage pressure sequence and longer equipment setup. The total cost depends on access conditions, depth, and the number of test intervals. We provide a fixed-price proposal after reviewing the geotechnical boring logs and project specifications so there are no surprises.
When does the City of Scottsdale require an in-situ permeability test instead of a standard percolation test?
Scottsdale's engineering design standards require in-situ permeability testing when infiltration is proposed as a stormwater management strategy and the receiving soils are deeper than the standard percolation test depth (typically 24 inches). The Lefranc test also becomes mandatory when groundwater is encountered within 5 feet of the proposed bottom of a retention basin, or when the geotechnical report identifies heterogeneous soils where a simple percolation rate would be unreliable. We coordinate directly with the city's plan review staff to ensure the test program meets the current drainage design manual requirements.
How long does a Lefranc or Lugeon test take in the field?
A single Lefranc test at a discrete depth interval typically takes 45 to 90 minutes of field time once the boring reaches the target depth. That includes packer inflation, saturation of the test zone, and running the constant-head or falling-head sequence until steady-state conditions are achieved. A complete Lugeon test with five pressure stages in bedrock usually requires two to three hours. Most test programs are completed within one working day, and we provide preliminary hydraulic conductivity values within 48 hours of demobilization.
What is the difference between the Lefranc test and the Lugeon test?
The Lefranc test measures hydraulic conductivity in soil or very soft rock using a single constant-head or falling-head stage, and it is the standard method for alluvial and colluvial deposits in the Scottsdale area. The Lugeon test is specifically for fractured rock masses and uses a five-stage pressure sequence (low-medium-high-medium-low) to characterize how fractures open, close, or erode under different hydraulic gradients. We select the method based on the material encountered in the boring. In a typical Scottsdale project near the McDowell Mountains, you might run Lefranc tests through the basin fill and switch to Lugeon once you hit the granite contact.
Can you run permeability tests in existing monitoring wells?
Yes, we perform slug tests and rising-head tests in existing 2-inch or 4-inch monitoring wells using a solid displacement slug and pressure transducer data logging. The analysis uses the Bouwer-Rice method for unconfined conditions or the Hvorslev solution for confined aquifers. This approach is cost-effective for sites that already have a well network installed, though the tested interval is limited to the well screen length rather than a discrete stratum. For new investigations where we need layer-specific values, we recommend drilling a dedicated test boring with packer isolation.