Test pit
A test pit is a shallow excavated hole that exposes the soil profile for the geotech to log and sample, feeding the soil report and AS 2870 site classification.
Ask Chalkline about this →A test pit (or trial pit) is a shallow pit excavated during site investigation to expose and log the soil profile, sample the layers, and check for groundwater before footings are designed. It is one of the two common ways to investigate a residential site; the other is a drilled borehole that produces a bore log.
Where it’s used: dug by excavator or hand auger, usually to a few metres, for a quick and cheap look at the near-surface soils on a residential block. The geotechnical engineer logs the layers, takes samples for shrink-swell testing, and records the findings in the soil report.
What it feeds: the soil report and, through it, the site classification under AS 2870, which sets the footing system and beam depths.
Test pit vs borehole: a test pit is open, so the engineer sees the soil profile directly, but it is limited in depth. A borehole reaches deeper and suits multi-storey or deep-footing work. Most straightforward residential investigations use test pits.
Common limitation: a test pit only tells you about the spot it is dug. Soil can vary across a block, so the number and spread of pits matters; a single pit can miss a soft patch or fill.
Also known as: trial pit.
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Last updated: 2026-05-24. Verified: 2026-05-24. Quarterly review for currency.