Underground Propane Tanks

Q: What are the plusses and minuses of underground LP tanks versus above-ground tanks?
— Mario Steele, via e-mail  

A: Most people install an underground propane tank for aesthetic reasons – they don’t want the tank to detract from their nicely landscaped yard and/or beautiful cabin. And while the number of underground tank owners is rising, there are more factors to weigh with an underground tank than with an above-ground model.

The first factor to consider is tank location, and usually your LP gas company will help with this. Water table level and drainage are key here; if the housing dome of the tank fills with water, all the regulators, valves, gauging devices, fittings and the tank itself will corrode or malfunction. Also, you’ll want your tank somewhere where it won’t be driven over. It’s possible to have tanks under driveways with preventative barriers in place, but it’s best to avoid the situation entirely.

Other main considerations for an underground tank are cost, maintenance and serviceability, says Gary W. Maul, who has worked in the LP gas and related industries for 34 years.

Underground tanks cost more – both to install and maintain. The extent of these costs depends on your dealer and his/her labor rates. The tank itself runs several hundred dollars more, as it’s coated externally to protect it from the underground environment.

Then there are installation costs (which are higher because of excavation) and purchase and installation of a cathodic protection device.

“Cathodic what?” you ask. The cathodic protection system further prevents tank corrosion and is a backup to the external protective coating on the tank. Tank corrosion occurs because the steel surface of the tank – which sends out and receives DC currents – creates an electrochemical reaction with the soil. Only when these currents flow out of the tank does deterioration occur.

A cathodic system applies DC current from an outside source, making the tank a cathode – which prevents corrosion.

In order to ensure the system is working properly, there are different regulations on how often cathodic systems must be tested. In Colorado, Maul says, tests must be conducted every three years.

Comparatively, maintaining an above ground tank is simple: leaks and other tank problems are generally easy to spot.

One final consideration: If you live in the snowbelt, you’ll most likely have to uncover the lid of your underground tank when you need it filled during winter. The lid will be marked with some type of indicator, but removing the snow is usually the owner’s responsibility.

Although there are more factors involved in having an underground tank, if they’re installed and maintained properly, you shouldn’t have any problems – out of sight, out of mind. If you don’t like the look of an above ground tank, but aren’t sold on an underground tank either, look for places on your lot that would easily hide or at least partially camouflage it.