In Hamilton, the contact between the Niagara Escarpment bedrock and the glacial overburden creates a lot of surprises with groundwater. You hit a fractured zone in the Queenston Shale and suddenly the water inflow changes everything. Our team runs field permeability tests—Lefranc for soil and Lugeon for rock—to quantify hydraulic conductivity right where it matters. We don't just hand you a number. We give you context. A grain-size analysis on samples from the same borehole often explains why a silty clay layer at 3 m is holding water while the underlying till drains freely. And if the goal is a deep excavation near the harbour, combining permeability data with a deep excavation monitoring plan becomes essential to keep the dewatering system sized correctly.
In Hamilton's fractured bedrock, a Lugeon value of 1 means tight rock. A value of 100 means a grout curtain is likely needed. The number itself is less important than what it tells you about the fracture network.
Methodology applied in Hamilton
Demonstration video
Typical technical challenges in Hamilton
Hamilton sits at about 75 m elevation near the lake, rising to over 200 m on the Escarpment. That relief drives groundwater gradients that can destabilize slopes if you misjudge permeability. The 2008 Red Hill Valley Parkway construction showed how perched water tables in the overburden can trigger shallow landslides when drainage is interrupted. A Lefranc test that misses a thin sand seam will underestimate inflow by a factor of ten. For Lugeon testing, the main risk is bypassing the packer seal in fractured dolomite. If the seal leaks, your test data is worthless. We pressure-test the packer seal first, every time. Another risk we see often: contractors who skip permeability testing during dewatering design end up with undersized pumps and constant delays. Getting the permeability profile right on day one is cheap insurance against a flooded excavation six months later.
Our services
Our Hamilton-area permeability testing program is designed around the site geology, not a generic checklist. Here is how we typically structure the work.
Lugeon packer testing in rock
We run multi-stage Lugeon tests in NQ or HQ boreholes using single or double pneumatic packers. Each test interval is pressurized at five steps, ascending and descending, to identify fracture dilation or infilling behavior. Data is reported as Lugeon values and equivalent hydraulic conductivity. This is standard for grouting design, tunnel inflow estimates, and dam foundation assessment in the Lockport and Queenston formations.
Lefranc permeability in soils
Variable-head Lefranc tests are run inside a slotted casing with a sand filter at the test depth. We test at multiple depths per borehole to capture the vertical variation in the Halton Till, glaciolacustrine silts, and any sand lenses. Constant-head tests are used when the soil is too permeable for a reliable falling-head reading. Results integrate directly into dewatering models for building excavations and infrastructure trenches.
Frequently asked questions
What is the difference between a Lefranc test and a Lugeon test?
The Lefranc test measures hydraulic conductivity in soils. Water is introduced into a cased borehole section with a filter screen, and the flow rate is recorded under constant or falling head. The Lugeon test does the same for rock, using inflatable packers to isolate a specific section of the borehole. A Lugeon value of 1 means 1 litre of water per metre of test section per minute at 1 MPa pressure. In practice, Lefranc is for overburden and Lugeon is for bedrock.
How much does a field permeability test cost in Hamilton?
For a Lefranc test at one depth, costs run between CA$740 and CA$1,230 depending on access and whether a drill rig is already on site. A Lugeon test, which requires a packer system and longer test duration, falls in a similar range per test interval. Getting a rig mobilized for a single shallow test will push toward the upper end. The most cost-effective approach is to include permeability testing as part of the main site investigation program.
How many test intervals do I need for a dewatering design?
At minimum, one test per distinct soil or rock unit that will be intersected by the excavation. In Hamilton, that often means testing the upper weathered till, any sand or gravel stringers, and the top 5 m of bedrock. For a 6 m deep excavation near the Escarpment, three to four Lefranc tests and two Lugeon intervals would give a reliable permeability profile. More complex sites with artesian conditions or known fracture zones may need a denser test layout.