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Specifications to Install an Underground Propane Tank

Propane is a popular gas used to meet the energy needs in millions of households. In residences, propane tanks are installed either above or below ground. Underground tanks are convenient as they occupy less space. The specifications for installing an underground propane tank are entirely different from what is required for one above ground, particularly with relation to the design and fitting locations of the tank.

  1. Underground Systems

    • Underground propane tank systems are placed into three categories. The partially exposed underground system contains part of the tank uncovered and above the surface with the other part underground. In mounded underground systems the part above the surface is covered with a noncombustible material such as earth or perlite. The entire tank is installed below the surface in fully underground systems. Only tanks developed specifically for underground installation are used.

    Choosing a Location

    • Installing an underground tank in areas experiencing vehicular traffic is not recommended and installation under a driveway is illegal. If unavoidable, appropriate measures should be taken to prevent damage such as concrete slab coverings. If rocks are present at the installation site it should be covered in a bed of sand approximately 6 inches thick. High groundwater level areas should also be avoided, but as a precautionary measure tanks should be securely fastened and frequently filled to prevent flotation.

    Connecting and Use

    • The relief valve capacity needed for fully underground and mounded systems is up to 30 percent less than above-ground tanks, yet partially exposed systems require the same capacity as tanks installed above ground. In tanks with over 2000 gallon water capacity, the discharge from these relief valves is piped approximately 7 feet above the surface of the tank. All underground tank connections are stored in a housing dome.

    Protection

    • Protective measures for underground tanks are also specific given their unique storage conditions. For example, the electrolytic effect of earth and water will cause damage to metal objects. Hence an anode bag is installed with the tank, which absorbs electric currents that would have otherwise targeted the tank. Tanks are also covered with sand or rock-free earth as an additional protective coating to ensure damage is avoided.

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