common apocalypse book methods to get fuel out of underground takes is:
a: hose to bottom of tank attached to pump & generator. Noisy.
b: rag and golf ball or similar stopper attached at far end of hose tied to string or wire that goes through hose. Hose is lowered as far in as it can be, and then string is pulled, squeegeeing the fuel through the hose and into whatever container you have at top. Then repeat.
For something like b to be done, garden hoses, or similar long hoses should probably be implemented.
c: There is probably some way you could set up a one-way valve or something near the top end of the hose, and then bike pump, or similar manually operated pump, without filling the pump up with fuel. Especially if the container was made to be air tight, and the underground tank was left to be open air, allowing the vacuum from pulling air from above ground container to pull fuel from underground tank. Though I am worried the weight/vacuum pressure might not be enough in that situation. Similar to hold up 10 gallons of fuel with your lungs alone.