Are there different ways to decommission a heating oil tank? For Oregon homes, Yes!
Both ‘in place’ and ‘by removal’ options exist.
In-place vs decom by removal
Previous to around 2007 most tank decoms were via removal. Removal of the tank was common. When soil samples showed oil contamination then the soil under the tank would be removed. To replace the volume of soil taken away use of sand, clean fill dirt, crushed concrete, or gravel was common. The Oregon DEQ assessed the data they had collected and issued new guidelines governing the amount of contamination allowed to stay in the ground.
This means less removals, which means less tractor marks and unsightly holes in yards. And easier for everyone if the tank is under Grandma’s prize rose bushes. Or uphill, in the backyard, or inaccessible corner of the property.
If a tank has leaked the Oregon DEQ will allow up to 65 cubic yards of contaminated soil at up to 10,000 PPM (1% by weight). This is a large volume of soil, but the presence of groundwater or high contamination can swiftly meet it. Once exceeded the DEQ will require soil removal and possibly air sampling to give a certification.
If there is no access to the tank or a danger from accessing it you can pay extra to have a ‘triple rinse’. This is much less effective than a traditional decommission at cleaning the tank but meets the DEQ’s requirements. Pumping the tank full of a concrete sully is the last step.
For homes in Washington there is a strict limit, and any contamination over this limit requires removal of the tank and contaminated soil.