This page is not intended to be a substitute for professional geotechnical advice and should not be relied on as geotechnical advice by individuals or other professionals to make site-specific decisions. Always seek advice from professional geotechnical engineers.

Hydraulic conductivity or permeability testing is a measuring of water that how it passes through soil or rock. The high value will show a permeable material by which water passes but low values show a less permeable material. It is generally denoted by the letter ‘K’ and has units of velocity like meters per sec or meters per day. BHM are able to undertake permeability tests or infiltration testing across greater Sydney.

One of the vital aspects of hydraulic conductivity is that it will range from 10-2 m/s (for very open gravels and cobbles) to 10-11 m/s in natural soils and rocks. It is a significantly wider range than most other geotechnical characteristics like shear strength or compressibility would suggest.

It’s also essential to understand that the way a fluid (such as water) travels through soil or rock mass is determined by both the soil/rock properties and the qualities of the permeating fluid. This means that if a given soil or rock is permeated by different fluids, such as water or hydrocarbons, it will react differently (oil). That is why the term hydraulic conductivity is beneficial because it is obvious that it refers to water flow.

The issue with the term ‘permeability,’ which is widely used in geotechnical and is commonly misunderstood by many industries (such as the oil and gas industry) to mean ‘intrinsic permeability,’ which is independent of the permeating fluid – intrinsic permeability has SI units of m2, though it is commonly described in Darcys (where 1 Darcy = 1 x 10-12 m2) – and is a significantly different parameter to hydraulic conductivity.

Why is hydraulic conductivity important to engineers?

Even though hydraulic conductivity is a fascinating theoretical subject, why should practicing geotechnical engineers be concerned about it?

It is a clear answer that it is a peculiar aspect in measuring the requirement for groundwater control and dewatering.