Section 11.3 of Appendix D to 40 CFR Part 80, titled "Tap Sampling," states that where tap sampling is conducted, "[t]he tank should be equipped with at least three sampling taps... extending at least three feet inside the tank shell." The tap extension into the storage tank is commonly called a "stinger." Section 11.1 of Appendix D provides for the use of alternative procedures (such as sampling from taps without "stingers"), however, "if a mutually satisfactory agreement has been reached by the party involved and EPA and such agreement has been put in writing and signed by authorized officials."

EPA has learned that where storage tanks with floating roofs have tap samples, the taps do not have tap "stingers" because they would interfere with the floating roof. EPA also understands that most gasoline storage tanks have floating roofs. Moreover, EPA believes that tap "stingers" do not significantly improve the quality of samples collected, because most gasoline stratification manifests as horizontal strata in the gasoline being stored. As a result, EPA will not require parties to obtain agreement in advance to use sampling taps without "stingers," provided that the storage tank has a floating roof that would interfere with the tap "stingers," and the tank does not allow other types of sampling (e.g., a gauge tube).

In addition, any party that certifies RFG or conventional gasoline using samples collected from a tap sampler must be able to demonstrate the gasoline in the storage tank was homogeneous. Several methods of establishing tank homogeneity have been described in other guidance. See, Sampling and Testing question 1 from the January 23, 1995 Question and Answer document. (10/31/95)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)