DEC Fuel Oil Storage Tank Tightness Test We will perform a Horner EZY 3 Tank Tightness Test as follows: Product levels in tank are measuredTesting equipment is installedSupply and return lines are closed as close to the tank as possibleVent and fill lines are pluggedTest is performed and completedTesting equipment and plugs are removed, and valves are restored to original positionsLastly, a copy of the test report will be sent to NYC Department of Environmental Conservation.