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

What is Soil Permeability?

Soil permeability is the rate of flow of water through soil layers. Information obtained from permeability tests are used in geotechnical site investigations. Geotechnical and civil engineers as well as hydrogeologists and environmental scientists use this information for various projects. It is important to understand the hydrologic characteristics of the soil for flood management practices, embankments, and dam designs. Any material having continuous voids (porosity) is referred to as ‘permeable’, e.g., gravels are highly permeable, whereas stiff clay is least permeable.

Importance of Soil Permeability Testing

BHM Geotechnical offers several geotechnical services in Sydney including soil permeability testing. Here is why this is important:

  • This is essential for various applications like when building an on-site detention tank or bioretention system. It is crucial to understand permeability of the soil to ensure an appropriate design. The amount of seepage depends a great deal on the granular soil skeleton. 
  • It is essential for engineers and agriculturists to study the fluid flow through the soil mass when working with soil.
  • The level of soil permeability affects the supply of air, moisture, and nutrition from the roots.
  • Water seepage is a common issue that has to be dealt with in excavation sites. Measure of soil permeability can help provide vital information for a construction site.
  • It is vital to ensure the stability of earthen structures like retaining walls, dams, etc.
  • Good management is critical to mitigate the effects of natural disasters like floods as well as effluent infiltration.

How We Measure Soil Permeability?

Soil permeability can be affected by several factors such as, soil type, texture, particle size, moisture, porosity and more. A geotech in Sydney can perform soil permeability tests to determine the permeability coefficient which assesses drainage characteristics, rate of consolidation, and rate of settlement of soil bed. This is important information for construction project managers, agriculturalists, and many other professionals. It can be measured using several techniques. Listed here are two main techniques:

Constant Head Test: Soil samples must be collected for laboratory testing. This method involves water flowing through a column of cylindrical soil sample under the constant pressure difference, the test is carried out in a permeameter. This is necessary to determine the rate of flow of the water. This method is useful to determine the permeability of granular soils such as sand, gravel, and several types of clay soils containing little or no silt.

Falling Head Test: This test is used to determine the permeability of fine-grained soils with low permeability such as silts and clays. This method involves water flowing through a soil sample that is connected to a standpipe, the volume of the water that passes through is then measured. The test is carried out in a falling head permeability cell.

Benefits of Contacting BHM Geotechnical for your Project

The relation between soil and water affects its permeability in many ways. Some of the common issues faced with soil during agriculture, construction, etc. include:

  • Soil moisture
  • Soil texture
  • Soil structure
  • Soil porosity

BHM Geotechnical was specially established to deal with the industry demands in this field and ensures the best geotechnical consultants in Sydney. This is an engineering, geotechnical and environmental firm which provides cost-effective assessments and technical analysis. We have a talented workforce using optimal techniques to provide accurate reports. BHM Geotechnical believes in pushing the limits and facing the challenges that come our way with continuous improvements and developing new and more efficient techniques.