A2Z Environmental Group

Exposing the top of the UST

A2Z was contracted by International Steel Group to clean a three million gallon #6 fuel oil tank. The tank needed to be gas-free in order to expedite needed repairs that included welding and burning. The tank contained 200 thousand gallons of #6 fuel oil that had to be transferred before cleaning. The job was contracted for a fixed price to be completed in eight weeks. If the job took longer, A2Z had to absorb the additional cost. If the job finished early, there would be a bonus paid.

Number six oil is very dense oil that doesn‟t flow very well. A six man crew containing operators and technicians arrived to transfer the oil using vacuum trucks and vacuum trailers on site. The transfer operation was completed in two weeks.

Once the bulk of the #6 fuel oil was vacated, there was a thick residue of #6 fuel oil stuck to the walls and floor of the tank. This residue was too thick to pump. Number two oil was used to cut, or dilute the #6 fuel oil. It was sprayed and worked with squeegees very methodically in order to cut the oil for re-moval. Two five man crews worked around the clock, on 12 hour shifts to expedite the removal of the oil. It took two weeks to remove enough oil to allow surface cleaning of the tank.

During the washing stage, a 3500 PSI hot water pressure washer was used to clean the tank. The complete floor and 8" of the walls needed to be clean enough to pass a gas-free test. The oxygen level must be 20.9 or higher and the LEL (Lower Explosive Limit) read less than 10%. To achieve this level hot water was used to wash off the oil. The two five man crews worked around the clock washing and removing the rinsate. The rinsate was taken to an oil recycling com-pany on the grounds of International Steel Group for recycling. No disposal left the site.

A Marine Chemist was brought in to inspect the tank five weeks after the job started. A certificate was given as the tank passed inspection on the first test. The job was com-pleted three weeks early.