Standard Penetration Test (SPT) in Port Coquitlam

Port Coquitlam sits on a mix of river-deposited silts and dense glacial till. What you hit at 2 meters is rarely what you get at 8. We see this constantly on projects near the Coquitlam River escarpment and the Pitt River flats. A Standard Penetration Test (SPT) gives you layer-by-layer blow counts that translate directly into bearing capacity and settlement estimates. No assumptions. No extrapolating from a neighbor's boring log three blocks away. The crew runs the split-spoon sampler at the depths your structural engineer needs. In deeper floodplain zones we often pair the SPT with a CPT test to fill in the continuous profile between drive samples. It makes the subsurface picture much sharper without doubling the budget.

SPT N-values are still the most widely correlated in-situ test in geotechnical practice — when done right, they anchor the entire foundation design.

Service characteristics in Port Coquitlam

Port Coquitlam's population has grown past 62,000 and older industrial parcels are converting to mixed-use. That means excavators hit urban fill over natural deltaic soils more often than anyone planned for. SPT data becomes the common language between geotechnical and structural disciplines. We run the test per ASTM D1586 using an automatic trip hammer on a track-mounted rig. The sampler drives 450 mm in three 150 mm increments. The sum of blows for the last two increments is your N-value. Refusal is set at 50 blows in any 150 mm interval. In granular soils with cobbles, we switch to a larger sampler and note the change. These details matter when you are designing footings near the floodplain boundary where water table fluctuates seasonally. The raw numbers go into a report with borehole logs, SPT profiles, and preliminary soil classification.

Standard Penetration Test (SPT) in Port Coquitlam — Soil Data That Holds Up

Parameter	Typical value
Test standard	ASTM D1586-18
Hammer type	Automatic trip (safety hammer)
Drive depth per test	450 mm (three 150 mm increments)
N-value calculation	Sum of blows for last 300 mm
Refusal criterion	50 blows in any 150 mm increment
Borehole diameter	100 mm to 150 mm (NX to HQ)
Sampler type	Standard split spoon (51 mm OD)
Reporting	Borehole log + SPT profile + soil description

Local geotechnical conditions in Port Coquitlam

The Pitt and Coquitlam Rivers laid down alternating layers of soft silt, organic clay, and loose sand across Port Coquitlam. NBCC 2020 places the city in a moderate-to-high seismic zone. Combine those two facts and liquefaction screening stops being optional. SPT blow counts feed directly into simplified procedures — Seed and Idriss, Youd et al. — to estimate cyclic resistance ratio. A raw N-value of 5 in a silty sand at 4 meters depth triggers a different conversation than N=22 in dense till. We also flag depth to groundwater. In wet winters it rises within 1.5 meters of grade in the low-lying areas. That changes effective stress. It changes blow count interpretation. A liquefaction assessment layered onto the SPT data gives the structural team a defensible design basis.

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Applicable standards: NBCC 2020 (National Building Code of Canada), CSA A23.3 (Design of concrete structures — seismic provisions), ASTM D1586-18 (Standard Test Method for SPT and Split-Barrel Sampling of Soils), ASTM D2488 (Visual-Manual Soil Description), CFEM (Canadian Foundation Engineering Manual 4th ed.)

Our services

SPT drilling anchors the investigation program. These complementary services fill in the information gaps that blow counts alone cannot address.

SPT with Sampling

Standard penetration testing with split-spoon recovery at prescribed depths. Disturbed samples bagged and labeled for lab classification.

Borehole Logging

Detailed field logs with soil description, moisture condition, consistency, and drilling notes. Compiled into CSA-format borehole logs.

Liquefaction Screening Package

Combines SPT N-values, fines content from lab, and groundwater data to compute factor of safety against liquefaction under NBCC seismic demands.

Quick answers

What depth of SPT drilling is typical for a Port Coquitlam house foundation?

For a single-family home on strip footings we usually drill to 6 meters or refusal, whichever comes first. A two-storey addition near the floodplain might need 8 meters to check for compressible silts under the bearing stratum.

How much does an SPT investigation cost in Port Coquitlam?

Budget between CA$640 and CA$1,150 per borehole depending on depth, access, and how many SPT samples are taken. Mobilization and traffic control on tighter residential streets may add a separate line item.

Do you report N60 corrected values?

Yes. We report raw N-values on the field log and apply corrections for hammer energy, rod length, borehole diameter, and overburden pressure in the final geotechnical report. The correction follows the approach outlined in the Canadian Foundation Engineering Manual.

Can you drill in a backyard with limited access?

We run a compact track-mounted rig that fits through a standard 1.2-meter gate. If there is overhead clearance for the mast and the ground can support the tracks, we can usually get the borehole in without dismantling fences.

How soon are the field logs available after drilling?

Field logs are scanned and shared within 24 hours of completing the borehole. The full interpretive report with corrected N-values and foundation recommendations follows in three to five business days.