Landscaping is a very big part of ADOT projects. The topsoil, top two feet of soil, must meet certain specifications to ensure plants will thrive. This classic blog shows you how soil is tested for, among other things, calcium carbonate:
Science of Transportation: Calcium Carbonate testingPlants won’t grow if they’re rooted in the wrong soil – no matter how green your thumbs are.Before you start asking why ADOT, a department responsible for building and maintaining state highways, would put time and money toward soil and plants, let us just say that landscaping serves a very practical role beyond making things look prettier.
We’re not going to focus on every single test in this blog post . Today, we just want to explain how topsoil is tested forAs you can see in the video above, ADOT’s Materials Chemistry Lab starts with a gram of soil. Now, a Sodium Hydroxide Solution is measured into that solution until it turns to a pinkish color. The amount of Sodium Hydroxide Solution necessary for that reaction to take place is recorded and used in an equation that shows the percentage of Calcium Carbonate in that soil sample.In order for topsoil to pass for use on an ADOT project, six samples can’t average more than 8 percent Calcium Carbonate.
“It can bind the soil particles together so tightly that water can’t penetrate,” said ADOT’s Chief Landscape Architect LeRoy Brady. “If the percentage of Calcium Carbonate is too high, you’re not going to get infiltration of what little rainfall we get.”If a topsoil source does not meet specifications, ADOT can reject it and require that the contractor use another source. In some cases, ADOT can require that a contractor treat the soil to fix the problem.