Residential heating oil tank (UHOT)
A home heating oil tank that is 10 percent or more underground is an "unregulated heating oil tank system" under NJDEP rules. If one leaks, the owner must report it to DEP right away and clean it up under state rules.
New Jersey example
Made-up example: a buyer's inspection turns up an old buried oil tank behind a house in Teaneck, and soil tests show it leaked. The owner must call DEP's hotline, 1-877-WARNDEP (1-877-927-6337), right away. DEP certifies the contractors who close these tanks, and a state fund offers financial help for eligible cleanups.
Official source
This is a plain-English summary. Rules and dollar amounts change, so check the official source or a professional before you file or sign anything.