Underground Storage Tanks in Idaho
An underground storage tank (UST) is defined as one or any combination of tanks and connective underground pipes used to contain regulated substances with 10% or more volume (including underground pipes) beneath ground surface. This does not include, among other things, tanks for storing heating oil for consumption on the premises or septic tanks.
USTs store petroleum products or certain other hazardous liquids that can harm the environment and human health if released into the environment. USTs are subject to Idaho rules and federal regulations. Idaho has about 3,500 regulated USTs; there are about 561,000 nationwide.
What is a regulated UST?
While many types of storage tanks may be buried, the term underground storage tank refers specifically to certain types of regulated tanks. These tanks store either petroleum products (e.g., gasoline, diesel, kerosene, or jet fuel) or certain hazardous substances.
Certain types of tanks specifically exempt from the rules include the following:
- Farm and residential tanks with capacities of 1,100 gallons or less of motor fuel used for noncommercial purposes
- Tanks storing heating oil for on-site consumption
- Tanks on or above the floor of underground areas, such as basements
- Septic tanks and systems for collecting stormwater and wastewater
- Emergency spill and overfill tanks that are immediately emptied after use
Regulated tanks are subject to a Tank Fee of up to $100 for each tank or tank compartment.
Learn if your property contains an UST
If you own or plan to buy or sell property that may contain an UST (even one that is no longer in use), it is important to find out if an UST exists or existed on the property. The question of contamination from a leaking UST (past or present) may come up in a property transaction. Any past or newly discovered contamination must be disclosed to a potential buyer and reported to DEQ to determine if remedial action is required.
A visit to the property may or may not uncover evidence of abandoned USTs. In many cases, there are no aboveground indicators of an UST. USTs are commonly found at gasoline stations, convenience stores, bus terminals, railroad yards, airfields, and auto dealerships; however, USTs are routinely found in unusual places such as schools, auto repair shops, farms, homes, factories, and retail facilities.
DEQ maintains a database of active and closed UST sites across the state. Regardless of whether DEQ has a record of an UST on a property of interest, you may wish to investigate as a normal course of due diligence. If you are considering buying or selling a property, you may wish to hire a contractor to conduct an environmental site assessment. Lenders often require site assessments for loans on certain types of properties.
Are residential/home heating oil tanks regulated?
No regulations or rules address heating oil tanks on residential property unless a leak has been confirmed. DEQ does not regulate residential heating oil tanks or maintain an associated database.
Although a residential heating oil tank may not be regulated for operation and maintenance purposes, if a release is found or occurs, the current property owner is responsible for the cleanup under state cleanup rules.
A leaking underground residential heating oil tank—or even an empty one—can cause problems, as outlined below.
- The property owner can be held liable for damage caused by contamination from the tank system.
- Leaks can contaminate soil on the property and neighboring properties.
- Leaks can contaminate ground water and possibly the residence’s well water.
- Cave-ins can occur when tank walls collapse due to corrosion.
- Most lending institutions and buyers require closure of unused heating oil tanks before finalizing a residential sale.
If your heating oil tank is still in use, watch for signs that it may be leaking, such as your furnace using more fuel than usual (consider other possible reasons as well, such as unusual weather or furnace malfunction). You may also wish to actively check for leaks.
For more information on closing a residential heating oil tank and checking for leaks, see Real Estate Professionals and Underground Storage Tanks or contact your DEQ regional office.