Document ID: EPA-HQ-UST-2011-0301-0184
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-11-18T05:00Z

Scenario 1
Multiple bulk above ground storage tanks directly supplying fuel to the hydrant piping, which fuels the aircraft.
   * Proposed definition does not regulate any part of this system UNLESS 10% or more of the volume of the "airport hydrant fuel distribution system" is below ground.  
   * The "system" comprises of the group of storage tanks directly connected to the hydrant piping.  Under this scenario, the group of tanks is the bulk ASTs.

Scenario 2
Multiple bulk above ground storage tanks that directly supplies fuel to a group of intermediary underground storage tanks, which directly feeds the hydrant piping to fuel the aircraft.
   * Proposed definition defines the "airport hydrant fuel distribution system" as the group of storage tanks directly connected to the hydrant piping and the hydrant piping.  Under this scenario, the group of tanks is the USTs.
   * The bulk ASTs are not considered to be part of the "airport hydrant fuel distribution system" under this scenario.  

Scenario 3
Multiple bulk above ground storage tanks that directly supply fuel to an intermediary underground storage tank, which directly feeds the hydrant piping to fuel the aircraft.
   * Proposed definition defines the "airport hydrant fuel distribution system" as the group of storage tanks directly connected to the hydrant piping and the hydrant piping.  Under this scenario, the group of tanks is the single UST.
   * The bulk ASTs are not considered to be part of the "airport hydrant fuel distribution system" under this scenario.

Scenario 4
Bulk underground storage tank feeds multiple intermediary USTs, which directly feeds the hydrant piping system.
   * Proposed definition defines the "airport hydrant fuel distribution system" as the group of storage tanks directly connected to the hydrant piping and the hydrant piping.  Under this scenario, the group of tanks is the smaller USTs that directly feed the hydrant piping.
   * The bulk UST is not considered to be part of the "airport hydrant fuel distribution system" under this scenario.  However, the bulk UST would be regulated as a field constructed underground storage tank or as a traditional UST.

Scenario 5
This scenario contains two distinct "airport hydrant fuel distribution systems" and a bulk above ground storage tank farm.
   * Each set of storage tanks directly connected to hydrant piping that fuels aircraft is a distinct "airport hydrant fuel distribution system."
   * The ASTs in the tank farm are not regulated by the proposed definition.
   * The proposed definition regulates the intermediary UST directly connected to an airport hydrant piping run and this hydrant piping run.
   * The proposed definition regulates the intermediary ASTs and the hydrant piping run that they are directly connected to ONLY if 10% or more of the volume of these ASTs and this hydrant piping run are below the ground.