World Soil Day

Today is World Soil Day! Soil is critical to infrastructure engineering and foundational to effective and long-lasting designBelow are three ways soil impacts engineering:

1. Understanding Soil Sets the Stage for Smart Engineering Decisions

Leaning Tower of Pisa, Italy

There are many important engineering decisions that go into developing safe buildings, bridges, and other structures (known as the infrastructure of a community). One of these is determining the best soil to build on. Ideal soil for infrastructure has the following properties:

  • balanced chemistry and neutral pH, so that building materials are not corroded;
  • stability throughout wetting and drying cycles, so that expanding soil does not crack roads or foundations;
  • strength under pressure, so that the weight of the building does not cause it to sink into the ground; and,
  • ability to capture precipitation, so that runoff and erosion do not damage structures.

There are some well-known examples in history where inadequate soil properties resulted in structural failures. One of the most famous being the Leaning Tower of Pisa. Soft ground and shifting soil had destabilized the tower’s foundations, causing it to begin leaning by the time builders got to the third story. The land underneath which seemed stable during the dry season became unstable during the wet season and sank unevenly.

2. Understanding Soil Protects Resources During Infrastructure Development

Soil test pit to help characterize hydrology onsite

Soil can be used to help provide the history of water movement in an area, like wetlands. By examining the features of the soil (texture, color, organic matter) that are tied to natural processes, environmental engineers can effectively complete wetland delineation, allowing wetlands to be measured and protected during the construction process. Each project site is unique and it is important to understand site-specific soil information not only for design purposes, but to help protect special resource areas as well.

3. Properly Managed Soil is Critical Infrastructure

Healthy soil is flood control infrastructure. Filled with organic matter it acts like a sponge, soaking up heavy rains and melted snow, buffering farms and communities downstream against a surge of runoff. Healthy soil is also drinking water infrastructure. It filters polluted runoff before it enters our lakes, rivers, and streams.

Local and federal government has spent billions of dollars to protect residents and ensure a healthy water supply to millions of US residents. Yet investing in simple soil management practices that proactively minimize runoff and keep pollution and excess nutrients out of our water supply can be a more cost effective way to reduce the strain on flood control infrastructure and water treatment plants.

“Essentially, all life depends upon the soil… There can be no life without soil and no soil without life; they have evolved together.”

Charles E. Kellogg, USDA Yearbook of Agriculture, 1938