How to Build a Salt Dome
Salt domes are common fixtures in locations with cold winter climates. Named after the mounds of salt that form in nature, salt domes are storage units for the salt a community uses to keep its roads clear in the colder months. While many cities have very large salt domes, individuals may wish for smaller ones to use on private property, especially in more rural areas. Salt dome construction follows simple patterns that hold up well in blustery climates. Does this Spark an idea?
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Things You'll Need
- Measuring tape
- Wooden stakes, at least 9
- Shovel
- Rubble
- 50-pound polypropylene bags
- Loose material for bag fill
- Tamper
- Barbed wire, 4-point
- Twine
- Ladder
- Cement-based plaster
- Latex roof paint
Instructions
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1
Decide on the site for your salt dome. Ideally it will be flat and clear of debris. It should also be in a spot that drains easily and is somewhat protected from the elements. Ensure that the space the dome will occupy is as clean and level as possible.
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2
Plot the base of your dome using the tape measure and wooden stakes. Begin by marking the center of the interior with a stake, and measuring out the radius (4-feet or more is typical) from the center in an 8-prong pattern. Mark each of the eight points with wooden stakes.
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3
Dig a 1-foot deep trench around the outside of the wooden stakes. This will be for the foundation and should be about as wide as the bags you plan to use for the wall. Be sure to leave a gap in the trench for the salt dome entrance.
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4
Fill the trench with rubble, leaving just enough room for the first layer (course) of filled bags. The rubble you use can be inexpensive items like gravel, urbanite (broken concrete) or stones.
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Fill your bags with a material of your choice. If you can't use loose soil from your property, consider an alternative like crushed volcano rock, which is lightweight and insulating. The amount of filed bags you will need is dependent on how large you plan to make your dome. Double bag enough bags for the first course that will be in the foundation, just atop the rubble.
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Lay the first course of double bagged soil or other material on top of the rubble, filling the trench. Make sure that each bag is closed tightly and pushed right against the previous bag. Tamp down the bags with the tamper, and continue to tamp each new course.
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Place two rows of barbed wire on top of the first course, each about 4 inches in from either edge of the bags. Continue to place the barbed wire above each new layer. This helps to lock the bags in place and prevent slippage.
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Under each successive course (beginning right on top of the first, double bagged course), lay a piece of twine under each bag so that it hangs about 1 foot over the interior and exterior of the wall. These will be tied to the twine two courses up, reinforcing the wall.
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Lay each new course inset just slightly (about 1/2 inch or less) from the course below it, making sure that each layer is well in place. The best way to ensure this is with the barbed wire, tying the pieces of twine to the twine two courses above it and staggering the bags in a brick-type pattern, with the bag centers placed over bag ends of the course below. Close each bag tightly and push it snugly against the next in the course.
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10
Use the ladder to complete the upper levels of the dome, which should come together naturally as you inset each new course.
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Coat the entire dome, inside and out, with a cement based plaster. Allow the plaster to dry completely, and paint the exterior with a latex roof paint for waterproofing.
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Tips & Warnings
If the soil around your trench is loose, place wire mesh on either trench wall before laying the rubble.
If you plan to install a door, jog the trench inward on either side of the break for the entrance, and build inset walls to support the door.
When considering the size of your dome, know that a dome with a 40-foot diameter and an 8-foot high wall can hold about 630 tons of salt. Consider these measurements when figuring out your building material needs.
Have at least one other person helping you, especially as you get to the higher levels of the dome. Working with slanting walls can be challenging and dangerous, and caution is necessary.
References
Resources
- Photo Credit Jupiterimages/Photos.com/Getty Images
