Improving Petroleum Products Storage

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Improving Petroleum Products Storage

Storage Tank Location • Tank Design and Installation • Monitoring • Tank Closure

The most important aspect of your liquid petroleum storage tank location is how close it is to your drinking water well. The Arkansas Water Well Construction Code does not specify a distance that storage tanks should be from a well. However, you should attempt to keep storage tanks and fuel-filling areas at least 100 feet from any well.

Even though diesel fuel and fuel oil are more dense than gasoline and move more slowly through the soil, they can eventually reach groundwater. How quickly the petroleum product reaches groundwater will depend upon the soil permeability. The more porous the soil (sands and gravels, for example), the faster the rate of downward movement to groundwater. You may choose to locate a new tank more than 100 feet away from your well, to provide reasonable assurance that subsurface flow or seepage of contaminated groundwater will not reach your well. If possible, the tank should also be located downslope from the well.

New storage tank location

Along with maintaining adequate distance from your drinking water well, choose a location for a new tank based on the following considerations:

Soil characteristics Highly corrosive clays, wet soils, and acid (low pH) soils can speed up the rate of corrosion of underground metal tanks and piping.
Soil stability Consider the soil's ability to support both underground and aboveground tanks. For special tank locations, such as hillsides, be sure to properly anchor and hold tanks in place. Be sure that pipes cannot twist or break if the tank is bumped or disturbed.
Current and previous land use Sites that contain abandoned pipes and tanks or waste materials can cause special underground installation problems. Any metal already in the ground will increase corrosion rates for the new underground tank.
Traffic Determine whether the location of the tank will block movement of farm vehicles during refueling or cause special problems if any work needs to be done on the tank. Protect piping from collisions with farm and fuel vehicles.
Depth to groundwater Low-lying areas or areas with a shallow water table are poor locations for underground storage tanks. An aboveground tank should be considered for these areas.

2. Tank design and installation

Whenever you install a fuel storage tank, carefully follow the manufacturer's recommended practices. Proper installation will minimize the leaking potential of the tank or the piping connected to it. Even scratches in a metal tank caused by careless installation can increase corrosion and tank deterioration.

Underground tanks

All underground storage tanks of 110 gallons or more must be registered with the Arkansas Department of Environmental Quality (ADEQ), 501-682-0999. Residential and farm underground storage tanks of less than 110 gallons are not federally regulated.

All new underground petroleum storage tanks and related piping must be constructed of nonmetallic materials, such as fiberglass, or have corrosion protection. Methods of corrosion protection include interior liners and "sacrificial anodes." New installations must also have spill and overfill protection. Existing installations (> 110 gallons) must have spill and overfill protection by December 22, 1998. Spill protection generally consists of a catch basin. Overfill protection is an overfill warning or prevention such as an automatic shutoff or buzzer. Spill and overfill protection can help prevent groundwater pollution. Contact the ADEQ for more information on underground storage tank requirements and recommendations.

Aboveground tanks

Aboveground farm tanks have been exempted from registration requirements with the ADEQ (501-682-0999). Residential and farm aboveground storage tanks are regulated by the Spill Prevention Control and Countermeasure Plans (SPCC). Check with State Fire Marshall.

To decrease pollution potential, construct a dike and pad (secondary containment) under storage tanks so spills and leaks can be contained. The State Fire Marshall (501-618-8624) is responsible for regulating aboveground storage tanks and can be contacted for more information on aboveground storage tank requirements and recommendations.

3. Monitoring

Regulations for new underground tanks require that all tanks have a method of detecting leaks. Select the tank location carefully to ensure ease of installation and reliability of leak-detection methods. Test the tank periodically for leaks, and measure the tank inventory on a monthly (or more frequent) basis to help detect leaks before major problems develop.

Since cleanup of gasoline leaks is always costly and often not totally effective, it is important to consistently monitor underground tanks containing petroleum products. If you already have a petroleum storage tank on your farm, be especially aware of the age of your tank as well as the need to establish a leak-detection program. Since most tanks used on farmsteads are bare steel, tank corrosion or piping problems will cause leaks sooner or later. If your tank is more than 20 years old, make a special effort to determine whether leaks exist.

Even when a tank has been tested and proven tight, existing regulations and good practice require that you have a method for regularly detecting leaks.

You should install such internal or external monitoring methods as groundwater monitoring wells, vapor monitoring, automatic tank gauging, or other approved methods.

Measuring tank inventories is an inexpensive and easy way to help detect leaks. Leakage is apparent when there is any unexplained decrease in the fuel level. Inventory measurement will not detect very small leaks, but it will at least provide a warning that further checking may be necessary.

The closer the tank is to the farmstead's drinking water well, the more important it is to ensure that an adequate leak-detection system is in place.

Leaks and spills

If you find a leak or spill which exceeds 25 gallons from any underground storage tank, state law requires that you notify the ADEQ within 24 hours (501-682-0999). Leaks and spills from aboveground storage tanks that are not contained in a confinement area should also be reported to the ADEQ. You should take whatever actions are safe and necessary to correct the problem and prevent fire and explosion hazards and follow any further instructions obtained when you report the spill.

The ADEQ administers the Petroleum Storage Tank Trust Fund, which can reimburse tank owners for a substantial percentage of costs incurred in cleaning up a problem for federally regulated tanks. Residential and farm underground fuel tanks with less than 110 gallons capacity and aboveground fuel tanks with less than 1320 gallons capacity are not federally regulated and are, therefore, not eligible for this assistance. For more information about the fund, contact the ADEQ at 501-682-0999.

4. Tank closure

Tanks no longer in use can cause problems for owners and operators many years later. They may continue to corrode and, if they still contain gas or oil, they can be a safety hazard and a threat to groundwater. Try to determine the location of any unused underground tanks on your property and whether they still hold product or have holes. These tanks should be pulled from the ground and disposed of in a landfill or at a scrap dealer. State law requires that only certified installers can legally pull a tank. Always notify your local fire department at least one month before you have a tank pulled, to ensure that precautions are taken to prevent an explosion or other problem. Deaths have occurred due to improper closure.

If you are concerned that your unused underground tank has been leaking, consult an environmental engineer or an ADEQ inspector (501-682-0999) to determine if further investigation is warranted. If there is groundwater pollution in your area, your neighbors may suspect the tank as its cause. You should document steps you take to legally close your tank so that you are protected from legal action in the event of groundwater problems.

Unused aboveground tanks that leak should be emptied, marked as not to be used, and protected from being refilled by covering fill ports. Abandoned tanks should be taken to an approved disposal site or stored on farm in a manner that water will not enter the tank.

Even though your storage tank may not be subject to the specific regulations mentioned, it is recommended that you consider implementing as many of the safety and water protection actions as possible.

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