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.
Approach and scope
Site-specific factors
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.
Service video
Applicable standards
AS 4678 (Earth-retaining structures / soakage), AS/NZS 1547 (On-site domestic wastewater management), AS 1726 (Geotechnical site investigations)
Related 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
Quick answers
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.