Underground Heating Oil Tank Removal
Almost all houses existing before the mid 1960s used heating oil which was stored in either an underground or above ground storage tank (UST or AST). Being underground, a buried heating oil storage tank is typically out of sight and out of mind for many homeowners. Often, the current homeowner may not even know that an oil tank exists on the property. It is a common practice to remove the unsightly fill and vent pipes once the tank is no longer in use just to improve the landscaping.
Most residential USTs are from about 250 to 1,000 gallons in capacity. On average, an underground tank will develop corrosion holes and begin to leak after about 20 to 30 years of use.
Once they begin to leak, as oil leaves the tank, water typically enters. Being denser than the heating oil, the water accumulates on the bottom of the tank. Once the water reaches the opening of the copper supply line suspended about 4 inches off the bottom of the tank, water is drawn to the furnace and fouls the heating system.
At this point, the homeowner calls the heating oil supplier and complains that the furnace is not working. The home owner is then presented with the options of replacing the leaking tank with another buried tank or changing to an above ground tank. In the past, this usually meant leaving the leaking underground tank in the ground. If natural gas is available, most homeowners take this opportunity to convert to the natural gas system.
Although a home heating oil storage tank is not typically regulated by the State of NC, the surrounding soils and groundwater are regulated. If significant leakage has occurred, immediate abatement of the release associated with proper cleanup and assessment is required by the State. In most cases, this requires removal of the oil tank and excavation of contaminated soils. This can be expensive costing on average around $10,000. Fortunately, the State offers financial assistance through a Trust Fund which reimburses much of the cost and is available to most homeowners.
Occasionally, underground oil tank removal is impossible because of where the tank is located or other site factors. If the soils are contaminated the State may approve abandoning the tank in-place. In these cases environmental assessment is required before the State will allow closure of the incident and the Trust Fund will reimburse much of the cost of the environmental assessment for most homeowners. See the tank abandonment page for more information on Cedar Rock's recommended method of tank abandonment.
Underground oil tank removal typically involves access to the UST location with a backhoe. The average size pit for the excavation and removal of the oil tank and contaminated soils (~50 tons) is about a 10 foot cube. Once the excavation is completed, the pit is backfilled and tamped to grade, and the impacted yard is regraded, reseeded, and strawed. This process requires about one day to complete.
Cedar Rock can usually perform a site inspection to locate an underground oil tanks and whether or not it has leaked within 24 hours of request. Scheduling the removal of an underground oil tank and contaminated soils requires a weeks notice. A clearance letter from the State indicating that no further action is required is usually obtained within about one month from the date of excavation.
THE PRESENCE OF MANY USTS ARE UNKNOWN TO THE CURRENT HOMEOWNER.
- Buyers should have an inspection for the presence of a heating oil tank and associated soil contamination for any house built before mid 1960s.
- Request an inspection as soon as a contract to purchase is drawn.
- Include an escape clause in the offer to purchase in case contaminated soil is confirmed.