Update On How To Compact A Trench

Update On How To Compact A Trench FARM HOME Miscellaneous 27-2-41 Regarding the story in your last issue, "How To Compact A Trench", there's more to this process than meets the eye. I'd like to run up a "red flag" about the method, which involves flooding newly dug trenches with water to settle the soil in them. Water will tend to cause the fluidized soil to fill any voids, but it will not compact it even when the soil dries out. In all cases the soil will bulk up or expand when water is added due to the fact that a thin layer of water forms around each particle of soil. Sand, having a large grain size, will bulk up the least while clay may bulk up as much as 30 percent. There will always be some settlement after a period of time. The optimum moisture content for good compaction is 10 to 15 percent. So adding water may fill the trench in better, but it may actually delay good compaction. When you flood a ditch in heavy clay soil, it can take as long as three years to dry out completely at the bottom. In some conditions, it may work well but it's not a cure-all for all soils and situations. My observations are based on my 36 years as a civil engineer for a major oil company. (Ivan L. Pfalser, RR1, Box 162, Caney, Kan. 67333 ph 620 879-2938)

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