What is an Infiltration Test?

To understand how to measure the infiltration rate of soil and the importance of conducting that type of testing, we must first discuss soil infiltration itself. Soil infiltration (often called by design engineers as permeability or hydraulic conductivity) is the speed at which water moves through different types of soil, typically measured in inches per hour. However, when conducting field tests it is ideal to learn how to measure the infiltration rate of the soil in the number of minutes it takes for each inch of water to permeate. Our team will discuss the importance of a proper infiltration test, infiltration testing methods, and more below.

Why are Soil Infiltration Tests Important?

Conducting an infiltration test is a crucial step in early planning on any job, whether it be a commercial, residential, or public project. Proper infiltration testing can provide insight into the subsurface conditions at a site, and can help guide your planning of stormwater mitigation. Understanding how the soil on your site will react to a sudden deluge of water is crucial for building a safe structure that will withstand storm damage. Soil infiltration testing should be done at various locations across a site to get a sense of how the entire area will react to a downpour. Factors such as soil compaction have tremendous implications for building construction and maintenance, and are thus a central focus for geotechnical analysis.

Infiltration Testing Methods

With the importance of infiltration testing solidified, you may be wondering how to measure the infiltration rate of soil. In order to measure infiltration, onsite tests must be conducted, though it’s important to note that different jurisdictions have different codes and thus will accept different types of infiltration tests.

Two common infiltration testing methods are “Single ring, falling head” and “double-ring” infiltrometer tests.

Single-Ring, Falling Head Test:

One of our most favored methods, a single-ring, falling head test is a measurement of long it takes for a unit depth of clear water to infiltrate the soil. Before this test can be conducted, soil suitability must be determined by way of limiting zones and water level data.

Double-ring infiltrometer Test:

A double-ring infiltrometer test measures the vertical movement of water through the bottom of the test area. A double-ring infiltrometer is made up of two concentric rings that are driven uniformly into the ground and filled with water. The drop in the volume of the water level in the center ring is used to calculate the infiltration rate. The downside to this method is that it’s difficult to perform and tends to be less accurate than a single ring test.

Team Up With Central Geotechnical Services

If you have an upcoming project, consult with our team here at Central Geotechnical Services for expert guidance. Our work has taken us to very diverse regions, and we have vast experience mitigating all types of site risks. Connect with us today to discuss the goals of your next build, we’d be happy to hear about the job and find a way to help!