Guidance for Storage Tank Owners

Transitioning to Gasoline Containing Ethanol

This guidance provides Maine's aboveground and underground gasoline storage tank owners with basic information on preparing for the introduction of an ethanol-gasoline blended product to their tank systems. The primary areas of concern are product cleanliness, materials compatibility, and water control . Failure to adequately address these three areas of concern could lead to tank system failure and/or customer dissatisfaction.

Southern New England is receiving 10% ethanol in their fuel supply. These areas with severe air quality pollution are required in the Clean Air Act to use Reformulated Gas (RFG). Since many states, including Maine have banned MTBE, refiners are using ethanol as a replacement for MTBE as an oxygenate in the fuel. Because Maine is not required to use RFG, we continue to receive conventional gasoline without MTBE and without needing ethanol as a fuel oxygenate. However, ethanol blended RFG with 10% ethanol (E10) sold in New Hampshire and Massachusetts is being trucked into Maine for sale at some retail facilities. Handling of ethanol has unique requirements and requires an investment in the fuel storage and delivery infrastructure. To determine if and when an ethanol-blend gasoline will be delivered to your facility, please check with your supplier.

Maine requires gasoline meet a certain Reid Vapor Pressure (RVP) in two separate areas of the State. One area, encompassing seven southern counties, is limited to a RVP of 7.8 psi from May 1 to Sept. 15 of each year, the remaining nine counties has a RVP of 9.0 psi. The federal RFG meets the 7.8 RVP standard in the summertime, however; when E10 is blended with conventional gasoline the RVP exceeds even the 9.0 psi RVP. 40 CFR part 80.27 includes a 1.0 psi waiver for conventional alcohol blended fuels, however Maine does not permit that waiver in Chapter 119 Motor Vehicle Fuel Volatility Limit of the Departments Rules. Therefore, any fuel blended with ethanol must meet the RVP respective requirements in both areas of the State.

Product Cleanliness

The ethanol in an ethanol-blend gasoline acts as a solvent and may dissolve and/or loosen materials such as bottom sludge and some wall coatings on petroleum storage tanks. The loosened materials will be suspended in the gasoline and may cause pump filters and vehicle fuel lines to clog.

To prevent clogging from occurring tank owners should conduct the following two steps prior to receiving the first shipment of an ethanol-blend gasoline:

  • Empty and thoroughly clean the storage tank. If this cannot be done, vacuum as much sludge and debris off the bottom of the tank as possible, using an external pump; and
  • Install pump filters suitable for removing an expected increase in particulate matter. Contact your product supplier to determine the correct type of filter to use. These special pump filters will have to be changed frequently during the first few months of use of an ethanol-blend. If the special pump filters are not used, retail customers may experience clogged automobile fuel line filters and lodge complaints with the station.

Materials Compatibility 

Petroleum storage tank systems designed and installed after 1981 should not experience a compatibility issue due to the introduction of an ethanol-blended gasoline. For those systems installed prior to 1981, the manufacturer should be contacted to determine compatibility.

Many materials, such as zinc-galvanized metals, Buna-N seals, Neoprene seals, urethane rubber elastomers, polyurethane, and alcohol-based pipe dope polymers may not be compatible with the use of an ethanol-blend gasoline. Tank owners should perform the following three steps prior to receiving the first shipment of an ethanol-blend gasoline:

  • Check with your tank, pump, and piping manufacturers to determine if the material of manufacture is compatible with an ethanol-blend gasoline;
  • If your tank has been lined, check with the lining company to determine if the lining material and/or adhesive is compatible with an ethanol-blend gasoline; and
  • If the interior of your tank has been repaired check to make sure the area of repair will not deteriorate upon the introduction of an ethanol-blend gasoline.  

Water Control

Control of water in the tank system is essential with an ethanol-blend gasoline due to ethanol's affinity for water. An excess of water in the tank may cause the ethanol to partition itself out of the gasoline and into the water. The water level in the tank must be checked prior to the introduction of an ethanol-blend gasoline and frequently there after. If water is present in the tank, it should be removed prior to the introduction of an ethanol-blend gasoline. Further, it must be determined how the water entered the system. If the investigation indicates water intrusion is a problem, the cause of the intrusion must be eliminated prior to the introduction of an ethanol blend gasoline.

To measure water in an ethanol-blend gasoline a special water finding paste applied to the gauging stick is required. Ask your supplier for a paste designed to detect water in an ethanol-blend gasoline. Check the directions to determine what each resulting color means, i.e., water is present or has phase separation.

Install alcohol absorbing filters on the dispensers. These water sensitive filters will attempt to absorb water that is present. If the filter's capacity is exceeded the filter will slow the flow of gasoline to a very low rate or stop it entirely. The filter will then have to be changed.

Disclaimer:

This guidance document is intended to provide the gasoline storage tank facility owner with basic information to prepare for the introduction of an ethanol-blend gasoline. The facility owner is encouraged to contact their distributor for more specific instructions. The Maine Department of Environmental Protection does not assume any liability for failure or damage to any gasoline storage tank system associated with the preparation to receive an ethanol-blend gasoline, and encourages the facility owner to consult with his/her distributor for the propoer instructions. 4-7-08