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Release Detection for Retail Fuel Systems <br /> <br />EPA and state regulations require all new fuel systems to have double-walled tanks and piping with <br />interstitial monitoring (active monitoring of the space between the tank or piping walls). Monitoring <br />requirements are met with liquid sensors designed to detect a leak into the interstitial space within 30 <br />days. Operators must verify the functionality of all sensors annually. <br /> <br />Tanks <br />Release detection systems for double-walled underground storage tanks have either a liquid-filled or a <br />dry interstitial space. Buc-ee’s utilizes a dry interstitial system with a liquid sensor mounted, within the <br />double wall space, at the lowest point beneath each tank. Any liquids which enter the interstitial space, <br />either due to a breach in the outer wall (groundwater) or a breach in the inner wall (fuel), will be <br />detected by the sensor and result in both an audible alarm and an immediate email communication to <br />the Buc-ee’s fuel/environmental team. <br /> <br />Piping <br />Typically, interstitial sensors for piping are installed within the tank-top <br />equipment sump near the point at which the product piping terminates into <br />the tank. The secondary product pipe opens into the sump, and any product <br />releases from the primary pipe into the interstitial space will flow to the sump <br />and be detected. In addition to interstitial monitoring, all pressurized piping <br />must also have a system which tests the integrity of the piping following every <br />dispensing episode to ensure no leaks greater than 3.0 gallons per hour exist. <br />Historically, most releases from fueling systems occur from pressurized piping. For this reason, Buc-ee’s <br />exceeds the requirements for piping release detection by utilizing discriminating liquid sensors (can <br />distinguish between fuel and water) in every sump connected to each product pipe, not just the tank top <br />sump. The fuel control system is programmed to immediately cut power to any fuel motors which pump <br />fuel through that sump when a sensor detects fuel. The location of sensors in every sump allows for <br />much faster detection of any leaks from the primary piping, and the immediate shutdown feature <br />significantly reduces the chances of a significant release due to a catastrophic failure, especially if that <br />failure occurs while the system is in use. <br /> <br />1058