Field Permeability Testing (Lefranc/Lugeon) in Waterloo, Ontario

A recent multi-storey mixed-use development near King Street North in Waterloo encountered groundwater seepage at a depth of just four metres during excavation. The project geotechnical engineer halted work immediately and ordered a series of in-situ permeability tests to quantify the hydraulic conductivity of the silty sand till underlying the site. This scenario repeats itself across Waterloo Region as the urban core expands into areas with complex glacial stratigraphy. The in-situ permeability assessment — specifically the Lefranc test in granular soils and the Lugeon test in fractured limestone bedrock — provides direct measurements of water flow through subsurface materials. Unlike laboratory tests on small samples, field methods capture the influence of fissures, joints, and macro-scale heterogeneities that dominate mass permeability. Our technical team executes these tests following ASTM D6391 for the Lefranc method and the Houlsby procedure for Lugeon assessments, delivering data that drainage designers, dewatering contractors, and structural engineers can rely on for infiltration calculations and basement waterproofing decisions.

A single Lefranc test can reveal more about actual groundwater behaviour than a dozen laboratory permeability runs — because in the field, soil structure and fissures control flow.

Service characteristics in Waterloo Ontario

Waterloo sits on a sequence of glacial deposits — predominantly Port Stanley Till overlying Silurian dolostone of the Lockport Group — where hydraulic conductivity can vary by three orders of magnitude across a single site. The water table across the city typically fluctuates between two and six metres below grade, influenced by seasonal recharge to the Waterloo Moraine aquifer system. In the till matrix, Lefranc tests are performed in boreholes at discrete intervals to isolate specific strata, measuring permeability in the range of 1×10⁻⁷ to 1×10⁻⁴ m/s typical of silty clay tills. Where the borehole encounters the weathered bedrock surface — often between eight and fifteen metres depth in Uptown Waterloo — the Lugeon test evaluates rock mass permeability using packer-sealed intervals under staged pressure increments. The results are interpreted using the Lugeon coefficient, where one Lugeon unit equates to approximately 1×10⁻⁷ m/s under laminar flow assumptions. For projects requiring a broader stratigraphic context, these tests are frequently paired with triaxial laboratory testing on undisturbed Shelby tube samples to establish the soil-water retention curve, and with grain size analysis to correlate permeability with particle size distribution using Hazen and Kozeny-Carman empirical relationships.

Field Permeability Testing (Lefranc/Lugeon) in Waterloo, Ontario

Parameter	Typical value
Test depth range (Lefranc)	2–30 m below grade in soil
Test depth range (Lugeon)	5–80 m in fractured rock
Borehole diameter	76–150 mm (NX to PQ core)
Pressure stages (Lugeon)	5–10 increments, max 1 MPa
Permeability range measured	1×10⁻⁸ to 1×10⁻³ m/s
Applicable standard	ASTM D6391-11 (Lefranc)
Reporting parameter	k (m/s) and Lugeon units

Demonstration video

Risks and considerations in Waterloo Ontario

With a population exceeding 130,000 and growing at over six percent annually, Waterloo’s construction footprint is pushing into areas where groundwater management failures carry steep consequences. The regional bedrock aquifer supplies drinking water to more than half a million residents, making any uncontrolled connection between surface contaminants and the groundwater table a serious environmental liability. Underestimating in-situ permeability during dewatering design can trigger excessive drawdown, settlement of adjacent structures founded on shallow footings, or catastrophic base heave in deep excavations. The Ontario Building Code, through reference to the NBCC, requires site-specific geotechnical investigations where groundwater affects foundation performance. A Lugeon test that reveals high conductivity in a dolostone fracture zone — values exceeding 30 Lugeon units are not uncommon in the Lockport — can fundamentally alter excavation support design, requiring cutoff walls or extensive grouting programs. Regulatory compliance under the Clean Water Act and local source water protection plans demands defensible hydraulic conductivity data, not textbook correlations.

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Applicable standards: ASTM D6391-11 (Lefranc field permeability), NBCC 2020 Division B Part 4, CSA A23.3 commentary on groundwater effects, Ontario Regulation 903 (Wells)

Our services

The permeability testing program is tailored to the stratigraphy encountered in each Waterloo borehole. The following configurations cover the range of conditions typical in the region.

Lefranc variable-head test in overburden

Performed in soil boreholes prior to rock coring, this method measures hydraulic conductivity in the saturated zone by recording water level recovery after a sudden change in head. Suitable for silty tills and sand lenses above the bedrock interface.

Lugeon packer test in bedrock

A double-packer assembly isolates a test interval in the rock core hole. Water is injected at five sustained pressure stages following the Houlsby method, plotting flow versus pressure to identify laminar, turbulent, dilation, or washout behaviour.

Combined Lefranc-Lugeon logging program

A continuous permeability profile from surface soil through weathered to competent rock. Each test interval is logged for stratigraphy, RQD, and fracture characteristics, producing a unified hydraulic conductivity log for hydrogeological modelling.

Frequently asked questions

How long does a Lefranc test take in the field?

A single Lefranc test interval typically requires 40 to 90 minutes of field time, depending on soil permeability. Fine-grained tills like those across Waterloo can exhibit slow recovery, extending the observation period. A complete borehole with three to four test intervals usually occupies half a day of rig time.

When is a Lugeon test required instead of a Lefranc test?

The Lugeon test applies specifically to rock masses. Once the borehole advances into the Lockport dolostone or Guelph Formation limestone beneath Waterloo, packer testing becomes the standard method. Lugeon testing is mandatory for dam foundations, tunnel alignments through rock, and deep shafts where fracture flow dominates the groundwater regime.

What is the typical cost range for field permeability testing in Waterloo?

Budgeting for in-situ permeability testing in Waterloo generally falls between CA$830 and CA$1,360 per test interval, with the final figure dependent on borehole depth, access conditions, number of intervals, and whether a Lefranc or Lugeon setup is used. Mobilization and reporting are typically quoted separately.

How do the results influence dewatering system design?

The hydraulic conductivity value from a field test feeds directly into analytical and numerical groundwater models used to size dewatering wells, specify pump capacities, and predict drawdown radii. Underestimating conductivity can lead to under-designed systems and construction delays, while overestimating inflates costs unnecessarily.