Heating oil spilled during overfilling may contaminate the surrounding soils. This problem, if caught quickly, may involve only minor cleanup. Leaks from underground storage tanks result from defects in tank material, improper fittings, improper installation, damage during installation, corrosion or mechanical failure of the pipes and fittings or tanks which are improperly abandoned or removed. Older tanks, especially those constructed of bare steel and those tanks located in highly corrosive areas, are more susceptible to leakage problems. All tanks, regulated or unregulated, must comply with local building, fire and zoning ordinances.
Proper construction reduces owner liability and the threat to ground and surface waters.
Materials used for underground tanks should be corrosion proof, such as fiberglass reinforced plastic or steel wrapped with polyethylene, especially in sensitive ground water areas. Also, steel tanks can be purchased with corrosion protection for the tank and piping. Double-walled tanks and piping can provide added protection at a higher cost. Protective equipment, including spill and overfill prevention devices and daily or continuous discharge monitoring systems, is also recommended. Older tanks, especially those over 20 years in age, should be replaced if they are not corrosion protected or at least tested for leakage.