In Albury-Wodonga, the local AS 4678 standard governs the assessment of soakage rates for on-site wastewater systems, and that is exactly where our infiltration test becomes essential. The region's clay-rich subsoils and variable alluvial deposits mean a single percolation estimate can be misleading. We run the double-ring infiltrometer and Porchet methods to deliver design-level hydraulic conductivity values that actually hold up under local conditions. Before finalising any septic layout or stormwater infiltration trench, we recommend combining this test with a permeability field test to cross-check results, and a soil classification to understand texture and structure influence on flow.
A single-ring test in duplex soils can overestimate lateral flow by 40% — use double-ring for vertical-only readings near the Murray River floodplain.
Methodology and scope
Local considerations
If you compare the alluvial flats near Wodonga Creek with the higher clay terraces around Albury's Lavington, the infiltration rates can differ by a factor of three. Relying on a single percolation hole from a previous project on the other side of town is a gamble that often leads to undersized absorption trenches or failed septic systems. We have seen developments where a missing infiltration test meant a 50% cost overrun on drainage redesign. Getting the numbers right early on avoids that entirely.
Explanatory video
Applicable standards
AS 4678 (Earth-retaining structures / soakage), AS/NZS 1547 (On-site domestic wastewater management), AS 1726 (Geotechnical site investigations)
Associated technical services
Double-Ring Infiltrometer Test (Full Setup)
We install inner and outer rings driven 150 mm into the ground, maintain constant head with a Mariotte bottle, and record readings every minute until steady flow is achieved. Suitable for clay, silt, and sandy soils.
Porchet (Falling-Head) Test
A cost-effective alternative for preliminary assessments. A 150 mm auger hole is pre-soaked for 2 hours, then water-level drop is measured at 1, 2, 5, and 10-minute intervals. We calculate Ksat using the Porchet equation.
Field Permeability Profiling
When a project requires multiple test locations across a site, we can run a grid of infiltration tests and produce a contour map of Ksat values. This is especially useful for subdivision drainage design.
Typical parameters
Frequently asked questions
How long does an infiltration test take in Albury-Wodonga?
A single double-ring test typically takes 2 to 4 hours including the pre-soak phase. The Porchet method can be completed in about 2 hours. If we run a grid of tests for a subdivision, we usually schedule a full day on site.
What is the difference between a Porchet test and a double-ring infiltrometer?
The Porchet test uses a single auger hole and measures falling head; it is simpler and cheaper but can overestimate rates in layered soils. The double-ring infiltrometer isolates vertical flow with a buffer ring, giving more accurate Ksat values for design — especially important in Albury-Wodonga's duplex soils.
Why do I need an infiltration test for my new house in Albury-Wodonga?
Local council requirements for on-site wastewater systems (septic tanks, aerobic treatment units) mandate a soakage rate under AS/NZS 1547. Without the test you cannot size the absorption trench correctly. We provide the certified report that council accepts.
How much does an infiltration test cost?
For a standard double-ring infiltrometer test with reporting, you can expect between AU$ 430 and AU$ 570. The Porchet method is slightly lower. Volume discounts apply when testing multiple locations on the same site.