Chapter 3
Problem 2: Hydro-Compactable Soil
Some Soil Sinks
Throughout time, soil has been deposited at the foot of the
Rocky Mountains by wind, water, and weather. This loose,
low density soil made of sand and loess (wind blown sedi-
ment) is especially apparent in areas where the wind blows
consistently. These types of soil are hydro-compactable,
meaning that as water enters the soil, they become more
dense.
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Soil Changes with Weather
Sandy soils like this will compact, sometimes as much as 20% when
water is added. Normally, this doesn't appear to be a problem
because the sun tends to dry out the top layers of soil. Problems
can begin when water enters the soil on a regular basis, or in large
amounts, then returns to dry, and back again. This causes large
shifts in the height and compaction of the soil, resulting in structural
issues.