By: Terry Meier, Geofoam Specialist
There is a saying that when something is extremely inexpensive it is “dirt cheap”.
When using EPS foam as a light weight fill material (Geofoam), it is often replacing dirt, so then how can Geofoam be cost competitive with something as cheap as dirt? Why would EPS Geofoam ever be used to replace dirt when dirt is so “dirt cheap?”
The answer is simple. Just because something is cheap doesn’t necessarily mean that it is always cheap to use.
I was surprised to learn that compacted soil weights as much as 125 pounds per cubic foot. That’s a lot! EPS Geofoam by comparison is 1 to 3 pounds per cubic foot depending on density.
100 to 1 weight ratio. The cube of Geofoam & the bag of dirt weigh the same amount.
Because dirt is so heavy it exerts a great deal of pressure causing numerous problems such as settlement, structural damage, and instability. Measures taken to prevent those problems are often very expensive. Even though EPS Geofoam is more expensive than dirt, in many cases it can actually save money by eliminating these problems associated with using heavier dirt.
Here are a few examples of jobs that saved money by replacing dirt with EPS Geofoam.
At this location on I-15 there are 3 utilities crossing the embankment. If regular fill material (dirt) had been used these utilities would need to be relocated to prevent damage caused by additional weight and differential settlement. The cost of this relocation was estimated at over $5,000,000. By using EPS Geofoam the utilities were left in place saving the cost of relocation.
Provo City Temple
The entire city block surrounding the temple used Geofoam to fill in depths of 3’ to 6’ on the upper level of the garage. Beneath the Geofoam was an underground parking structure and additional rooms extending from the temple. The Geofoam was either covered over with landscaping or paved over to accommodate parking. Geofoam lightened the load on the underground structures so much that the builders could reduce the volume of concrete and rebar required to support the structure. This reduction of building materials resulted in significant cost savings.
The foundation wall on this hospital was over 30 feet tall. Using soil would exert a tremendous amount of lateral pressure on the wall. The wall was designed to be 32 inches thick to support this pressure. By using Geofoam the wall thickness was reduced to 18 inches. This reduction of thickness saved a great deal of money.
These are just of few of the many examples of how dirt isn’t always “cheap” and how using Geofoam instead of dirt can bring about some big dollar savings.