Field Permeability Testing (Lefranc/Lugeon) in Des Moines

Q: What does a field permeability test cost in Des Moines?

Mobilization and traffic control in downtown Des Moines can add to the total.

ASTM D4630 and the USBR 6510 procedures govern how we measure hydraulic conductivity in situ across Des Moines. The city sits on a complex transition zone between Pennsylvanian bedrock and thick Wisconsin-age glacial drift, with surficial deposits ranging from tight glacial till to alluvial sands along the Des Moines and Raccoon Rivers. Designers working on central Iowa infrastructure quickly learn that lab permeameter values rarely match field behavior. A Lefranc test in granular lenses within till, or a Lugeon test in the fractured Cherokee Group shale, exposes flow paths that remolded lab specimens completely miss. For the East Side interceptor tunnels and downtown Des Moines deep excavations, we typically pair site-specific permeability profiling with in-situ permeability verification at multiple depths to satisfy IBC Section 1803 groundwater requirements. Getting the flow rate wrong in Des Moines is not a paperwork error — it is a dewatering system that fails mid-excavation.

A 5-stage Lugeon test in Des Moines shale can reveal fracture dilation thresholds that a single-stage packer test would miss entirely.

How we work

Des Moines presents a specific set of subsurface conditions that make Lefranc and Lugeon testing indispensable. Glacial till in Polk County frequently contains sand lenses and silt seams that act as preferential flow paths. You cannot detect these with a Shelby tube sample. A constant-head Lefranc test in a cased borehole at 5 to 15 feet captures the real bulk permeability of those thin water-bearing layers. Deeper, where the Des Moines lobe deposited dense pre-Illinoian till over weathered shale, the Lugeon test becomes critical. We run five pressure stages per USBR recommendations, and the resulting Lugeon unit pattern tells us whether we are dealing with laminar flow, fracture dilation, or hydraulic fracturing. For projects near the Raccoon River levee system, these results feed directly into dewatering pump sizing and cutoff wall design. We often recommend comparing borehole data with grain-size distributions from split-spoon samples to calibrate the permeability model against soil texture.

Local considerations

The test setup itself is straightforward: a drill rig advances the borehole to target depth, we seat a pneumatic packer above the test interval, and water is injected under controlled pressure. In Des Moines, the rig choice matters. The glacial till here contains erratic boulders from the Canadian Shield — a lightweight auger rig will refuse exactly where you need the test. We mobilize track-mounted CME-75 or similar rigs with hollow-stem auger capability. For Lugeon testing in the Cherokee Group, we switch to rotary drilling with a mud program that does not clog the fractures we are trying to measure. The biggest risk we see in Des Moines is running tests too shallow in bedrock without casing off overburden, which produces artificially high Lugeon values that lead to oversized and expensive dewatering systems. We always measure groundwater level before and after each test run.

Typical values

Parameter	Typical value
Test standard	ASTM D4630 / USBR 6510
Lefranc test depth range	3–45 ft below grade
Lugeon test depth range	25–200+ ft in bedrock
Packer type	Single or double pneumatic
Lugeon pressure stages	5 stages (USBR method)
Permeability range measured	1×10⁻⁷ to 1×10⁻² cm/s
IBC groundwater compliance	Section 1803.5.4

Other technical services

Lefranc constant-head test

Borehole permeability measurement in soil using a cased test section. Ideal for glacial till, alluvial sands, and silt lenses at depths up to 45 feet. Directly calculates k-value for dewatering design.

Lugeon packer test

Five-stage pressure test in bedrock following USBR 6510. Applied to Pennsylvanian shale, limestone, and sandstone beneath Des Moines. Identifies fracture flow regime and hydraulic fracturing pressure.

Falling-head variable-head test

Alternative method for low-permeability soils where constant-head flow is too slow. Used in the tight glacial tills common across northern Polk County.

Questions and answers

What does a field permeability test cost in Des Moines?

Which test do I need — Lefranc or Lugeon?

Lefranc is for soil; Lugeon is for rock. In Des Moines, if your foundation or excavation stays within the glacial drift (top 20–40 feet), Lefranc is the correct choice. If you are socketing caissons into the Cherokee Group shale or designing a deep basement that cuts into weathered bedrock, you need Lugeon testing.

How long does a single test interval take?

A complete 5-stage Lugeon test in Des Moines bedrock takes approximately 45–60 minutes per interval once the packer is set. A constant-head Lefranc test in soil typically requires 20–30 minutes to reach steady-state flow. We can usually complete 3–4 test intervals in a standard field day.

Can you run these tests inside an existing building in Des Moines?

Yes, with a limited-access drill rig. We have performed Lefranc tests inside warehouse slabs and industrial facilities in Des Moines using portable track-mounted rigs with less than 8 feet of headroom. Lugeon testing indoors is rarer but possible if bedrock is shallow.

Field Permeability Testing (Lefranc/Lugeon) in Des Moines — ASTM D4630 Compliance