EPA Draft Internal Deliberative

**DO NOT QUOTE OR CITE** Key : Not regulated as an “airport hydrant fuel distribution system” Regulated as an “airport hydrant fuel distribution system” Regulated UST but not as an “airport hydrant fuel distribution system” Only regulated as an “airport hydrant fuel distribution system” if 10% or more is below the ground Scenario 1 Multiple b ulk above ground storage tank s directly suppl yi ng fuel to the h yd rant piping, which fuels the aircraft.  Proposed definition does not regulate an y part of this sy stem UNLESS 10% or more of the volume of the “airport hy drant fuel distribution sy stem ” is below ground.  The “s ys tem” comprises of the group of storage tanks directly connected to the hy drant piping

. Under this scenario, the group of tanks is the bulk ASTs.

Scenario 2 Mu ltiple bulk above ground storage tank s that directly supplies fuel to a group of intermediary underground storage tanks , which directly feeds the hy drant piping to fuel the aircraft.  Proposed definition defines the “airport hy drant fuel distribution sy stem ” as the group of storage tanks directly connected to the hy drant piping and the hy drant piping. Under this scenario, the group of tanks is the USTs.  The bulk ASTs are not considered to be part of the “airport hy drant fuel distribution sy stem” under this scenario.EPA Draft Internal Deliberative

**DO NOT QUOTE OR CITE** Key : Not regulated as an “airport hydrant fuel distribution system” Regulated as an “airport hydrant fuel distribution system” Regulated UST but not as an “airport hydrant fuel distribution system” Only regulated as an “airport hydrant fuel distribution system” if 10% or more is below the ground Scenario 3 Multiple b ulk above ground storage tank s that directly suppl y fuel to an intermediary underground storage tank, which directly feeds the hy drant piping to fuel the aircraft.  Proposed definition defines the “airport hy drant fuel distribution sy stem” as the group of storage tanks directly connected to the hy drant piping and the hy drant piping. Under this scenario, the group of tanks is the single UST.  The bulk ASTs are not considered to be part of the “airpo rt hy drant fuel distribution sy stem” under this scenario.

Scenario 4 Bulk underground storage tank feeds multiple intermediary USTs, which directl y feeds the h ydrant piping s ys tem.  Proposed definition defines the “airport hy drant fuel dis tribution sy stem” as the group of storage tanks directly connected to the hy drant piping and the hy drant piping. Under this scenario, the group of tanks is the smaller USTs that directly feed th e hy drant piping.  The bulk UST is not considered to be part o f the “airport h ydrant fuel distribution sy stem” under this scenario. However, the bulk UST would be regulated as a field constructed underground storage tank or as a traditional UST.EPA Draft Internal Deliberative

**DO NOT QUOTE OR CITE** Key : Not regulated as an “airport hydrant fuel distribution system” Regulated as an “airport hydrant fuel distribution system” Regulated UST but not as an “airport hydrant fuel distribution system” Only regulated as an “airport hydrant fuel distribution system” if 10% or more is below the ground Scenario 5 This scenario contains two distinct “airport hy drant fuel distribution sy stems” and a bulk above ground storage tank farm.  Each set of storage tanks directly connected to hy drant piping that fuels aircraft is a distinct “airport hy drant fuel distribution sy stem.”  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 hy drant piping run and this hy drant pipi ng run.  The proposed definition regulates the intermediary ASTs and the hy drant piping run that they are directly

connected to ONLY if 10% or more of the volume of these ASTs and this hy drant piping run are below the ground.