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��'�'ITA�4A7'H7-�913C�[lJEI4'" �din�YYfp Cwpry Other possible leak scenarios include a leak developing in the siphon bar, developing in the fuel supply line to the fuel island dispensers, or fuel siphoning out of the tank through the fuel supply line. Safeguards for each of these modes is described below. The siphon bar is a 2" diameter pipe that runs from near the bottom of one tank, up and over to the other tank, and down to near the bottom of the other tank. For the siphon to work, it must be full of fuel. If it develops a leak, air will enter the siphon bar and break the siphon. Only a small quantity spill would be expected from this scenario. If a leak developed in the fuel supply line, product might siphon out from the tank into the curb/bermed area. However,the fuel supply pump is equipped with an anti-siphon solenoid valve. As discussed on the Petroleum Equipment Institute website (https://www.pei.org/wiki/antisiphon-valve): On systems where the piping connections come out of the top of an AST it consists of a small normally open solenoid valve which is installed in the highest point in the pipe run. It is de-energized (open) when the pump is not running. Loss of prime back into the tank is prevented by installing a check valve in the suction riser pipe coming up out of the tank. When the pump is turned on,the solenoid is energized, and it closes. Normal pump suction draws fuel up out of the tank, and down to the pump.When the pump is shut off the solenoid (siphon breaker) opens again. If there is a leak, or a valve in the pump or downstream of the pump is accidentally left open, or of a pump seal fails, fuel will flow out of the system, but with the siphon breaker introducing air into the piping as fuel flows out, only the amount of fuel held in the pipe will spill out. None will be drawn out of the tank by siphon, because the siphon breaker has introduced air into the suction line and broken the continuous siphon effect. Oil-filled Operational Equipment Oil-filled operational equipment at this facility, (i.e., electrical transformers), does not have passive secondary containment. Active containment measures are used to prevent a release from reaching navigable waters. A Spill Control Equipment supplies drum is located near each of the three transformers. The typical failure mode, and the most likely quantity of oil that would be discharged from a leaking transformer are as follows: • A spill from maintenance of the transformer dielectric fluid • A release due to a hole in the dielectric fluid reservoir or cooling fins • The release rate is not expected to be greater than 6 gpm, except in the instance of a transformer fire. This rate is estimated by calculating the flow rate through a 1/2" diameter hole (puncture) with 4 ft of head (full transformer). The release rate would decrease as the height of the dielectric fluid dropped. Secondary Containment Calculations Page 2 of 5 Appendix L