Infiltration Test for Stormwater Design in Chatham-Kent

Setting up a double-ring infiltrometer on a residential lot near the Thames River in Chatham-Kent, we first drive both rings into the topsoil with a steel ring driver to ensure a tight seal against side-wall leakage. The inner ring, typically 30 cm in diameter, is kept at a constant head of about 10 cm using a Mariotte bottle, while the outer ring buffers lateral flow. We record the drop in water level every minute for the first ten minutes, then at increasing intervals until steady-state flow is reached. For clayey till soils common in the Chatham-Kent area, this often takes 90 to 120 minutes; sandy deposits along the Lake Erie shoreline can reach equilibrium in under 30 minutes. Before the test we always run a calicatas exploratorias to verify stratigraphy and identify any restrictive layers at depth.

Illustrative image of Infiltracion in Chatham-Kent

Steady-state infiltration rates in Chatham-Kent’s clay tills can be one to two orders of magnitude lower than in its glacial outwash deposits – a spread that makes site-specific testing non-negotiable.

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Ground improvement

Unsaturated soil analysis ›Stone column design ›Dynamic compaction design ›Deep Soil Mixing (DSM) design ›Geotechnical drainage design ›

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Slopes & Walls

Soil erosion analysis ›Slope stability analysis ›Slope failure analysis ›Debris flow analysis ›Factor of safety (FS) calculation ›

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Foundations

Differential settlement analysis ›Settlement analysis ›Bearing capacity analysis ›Foundations on fill (analysis) ›Shallow foundation design ›

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Methodology and scope

ASTM D3385 is the governing standard for double-ring infiltrometer testing in Chatham-Kent, and we adhere to its requirement of a minimum 300 mm inner ring diameter and a constant head maintained within 10 mm of the target. The procedure produces a direct measurement of saturated hydraulic conductivity (Ksat) at the test depth, which is the key parameter for designing infiltration basins, rain gardens, and perforated pipe systems under the Ontario Building Code and NBCC stormwater provisions. In Chatham-Kent’s lacustrine clay plains, Ksat values often range from 5 × 10⁻⁷ to 1 × 10⁻⁶ m/s, while the sandy beach ridges near Erieau yield values above 1 × 10⁻⁵ m/s. We complement each infiltration test with a densidad cono arena to correlate field density with permeability, and we always record the soil classification per CFEM for the test horizon.

Technical reference — Chatham-Kent

Local considerations

Chatham-Kent sits on the floor of the former glacial Lake Whittlesey, where thick sequences of low-permeability clay till dominate the upper 6 to 10 m of soil. A common design error in the municipality is to assume a single infiltration rate from a desktop review of regional maps, which can overestimate the actual Ksat by a factor of three or more. When that happens, stormwater facilities designed for 25‑mm/h infiltration may only achieve 8 mm/h, leading to surface ponding during a 5‑year storm event. The municipality’s own drainage criteria require a safety factor of 2 applied to the field‑measured rate, so an overestimate of 15 mm/h can result in a system that is nearly 50 % undersized. We have seen this problem on commercial developments along Grand Avenue West, where post‑construction infiltration failed until we performed a second round of double‑ring tests at the actual invert elevation.

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Explanatory video

Applicable standards

ASTM D3385 – Standard Test Method for Infiltration Rate of Soils in Field Using Double‑Ring Infiltrometer, Ontario Building Code (OBC) 2012 – Section 7.4.6 (Stormwater management), NBCC 2020 – Division B, Subsections 4.1.6 and 4.1.7 (Foundation drainage and groundwater control)

Technical parameters

Parameter	Typical value
Inner ring diameter	300 mm (ASTM D3385)
Constant head maintained	100 ± 10 mm
Measured parameter	Saturated hydraulic conductivity (Ksat)
Typical test duration (Chatham-Kent clay)	90–120 min
Typical Ksat range (clay till)	5×10⁻⁷ to 1×10⁻⁶ m/s
Typical Ksat range (sand)	1×10⁻⁵ to 5×10⁻⁵ m/s
Reporting standard	ASTM D3385 with field log

Frequently asked questions

How long does a double‑ring infiltrometer test take in Chatham-Kent’s clay soils?

In the clay till that covers most of Chatham-Kent, the test usually runs between 90 and 120 minutes until steady-state flow is achieved. Sandy deposits along the Lake Erie shoreline can reach equilibrium in less than 30 minutes. We always include setup and ring seating time in the field schedule.

What is the typical cost range for an infiltration test in Chatham-Kent?

For a standard double-ring infiltrometer test on a single test pit, the field service plus reporting typically falls between CA$480 and CA$550. If multiple test locations or pre-test soil classification are needed, the total may increase depending on the scope and access conditions.

Why can’t I use a regional Ksat value from a soil survey map for my stormwater design?

Regional maps in Chatham-Kent average values over large areas and often miss local variations such as clay lenses, till crusts, or sand pockets. We have measured differences of more than 200 % between adjacent test pits on the same lot. A site-specific infiltration test gives you the actual rate at your invert elevation, which is what the municipality requires for a stormwater permit.

Location and service area

We serve projects across Chatham-Kent.

Location and service area