Fuel management is more than processing fuel usage by vehicles. It's more important than ever to track what's not been used by your fleet. In the last few years, there's been increasing enforcement on accounting for the fuel dispensed by underground storage tanks (UST).

The law states that producers must account for all dispersals of the fuel deposited into USTs. Many factors can cause a shortfall.

You could have an accounting problem. Employees may be putting fuel into equipment, often service vehicles and pickup trucks, but not recording their actions. You could have a theft problem or a vendor who has short-delivered. But the worst situation is you could have a problem with leaking USTs.

Older steel tanks and their underground piping systems often develop leaks due primarily to rust. Just as common as the loss of fuel is the infiltration of water.

Diesel is a living fuel, meaning that its chemical composition is constantly changing. The fuel starts oxidizing and forming sludge as soon as it leaves the refinery and comes in contact with air.

Inside tanks, the oxidation process is reinforced as humidity condenses and provides oxygen to feed airborne bacteria and fungi. These anaerobic bacteria feed on hydrocarbons (fuel), form living colonies, and secrete acids as their waste. This waste can clog filters and obstruct fuel-metering equipment, especially today's high-performance engines' precision fuel systems.

Knowing this risk, the Petroleum Equipment Institute is developing guidelines for UST inspection. It recently posted “Recommended Practices for the Inspection and Maintenance of UST Systems” on its Web site at www.pei.org/RP900.

But UST maintenance is more than leak detection. Experts suggest fuel system management involves treating fuel with chemicals appropriate for operating climate and conditions. Today's new fuels, ultra-low-sulfur diesel and bio-diesel are especially prone to gelling or thickening in cold weather.

This may be the year you consider winter additives to prevent diesel gelling and prevent ice in fuel lines. It should be a part of the periodic UST treatment, including considering biocides to retard organic growth in tanks. Year-round fuel treatment plans improve fuel lubricity, detergency, and stability.

Read the related article, "Keeping an Eye on Fueling".