Comparison of Spill Frequencies and Amounts at Vapor Recovery and Conventional Service Stations in California

Abstract

Based on a survey conducted in 1989 and 1990 at 21 conventional nozzle and 33 vapor recovery nozzle equipped service stations in California, the California Air Resources Board staff conclude that conventional nozzles in California produce a greater number of quantifiable spills (≥1 ml) and a greater average volume per spill than do vapor recovery equipped nozzles. This conclusion is based on survey results showing conventional nozzles having spills 30.3 percent of the time at four fueling intervals vs 22.3 percent for vapor recovery nozzles, and having an average spill volume of 13.3 ml vs 10.6 ml for vapor recovery nozzles. However, if spillage noted from a conventional nozzle during a very large spill event is subtracted from the total quantified spill volume, the average volume per quantifiable spill for a conventional nozzle would drop to 11.0 ml. This value is very close to the 10.6 ml average volume per quantifiable spill with a vapor recovery nozzle. In addition, conventional nozzles in California produce about 14 percent more drop (<1 ml) spillage than do vapor recovery nozzles. Drop spillage has not been quantified as to the volume of gasoline it represents.