How to Identify the Different Kinds of Fill Dirt

17 February 2016
 Categories: , Blog


Avid DIY homeowners may wish to determine the composition of fill dirt before using it during a home improvement project (such as improving the grade of the yard so that drainage improves). This article discusses a simple method that you can use to determine which kind of fill dirt will be suitable for your project.

The Shake Test

Get a clear glass jar and put water into it so that only a third of the jar is empty. Add a teaspoon of dish soap into that water in the jar. Add a sample of the fill dirt that you would like to buy. Keep adding more dirt until only about an inch of space is left within the jar. Screw the lid of the jar tightly. Shake the jar vigorously for about a minute, and then place it on a table so that the constituents of the sample can settle. The sand in the fill dirt will descend to the bottom immediately. Any silt in the sample will form a layer above the sand a few minutes later. The clay content of the sample will take the longest time to settle. For example, it may take more than a day for it to settle. Leave the jar until the water is clear once again. Examine how thick each of the layers is in order to know what kind of fill dirt that particular lot is. It may be one of the two kinds below.

Clay-Dominated Fill Dirt

Clay soil forms the topmost layer once the sample in the jar settles. If clay forms the thickest layer, then the fill dirt is predominantly made of clay soil. Such fill dirt will not allow water to drain through it easily. It will also be difficult for plant roots to penetrate it. Consequently, such fill dirt should not be used in an area where you want to grow plants, unless you will add a thick layer of topsoil onto that fill dirt. This type of fill dirt is very good if you want to form a solid base for a garden structure (such as a patio).

Sand-Dominated Fill Dirt

Your sample will be sand-dominated if the sand at the bottom of the jar forms the thickest layer in the sample tested. Such fill dirt is very good for areas where plants will be grown because it allows water to drain through it. Plant roots can also easily penetrate it. It is also very good if you would like to improve the drainage of a section of your property by raising its grade.

The test above is basic and does not give you information about other important matters (such as the presence of hazardous materials). It is therefore better for you to purchase clean fill dirt that has been certified to be free from any hazardous substances. The other advantages of clean fill are that the large clods will have been broken and all the organic debris will have been removed so that the leveled part of your home does not develop depressions later on.

For assistance, talk to a professional like Eastern Plant Hire.