The party has found the Vault of Dragons from the Waterdeep: Dragon Heist module. They've managed to play two of the BBEGs against each other and have neutralized the 'enemy' factor of the module, have also managed to fly under the radar of Waterdeep's authorities, and they want to keep all of that sweet, sweet gold for themselves.
However, the access to the Vault in their version of WD:DH is down a 150' ladder, under a hidden trap door in the back of an abandoned building. They now own the building, but are wondering how to move all the gold out. For plot reasons, they can't nickle and dime it out slowly (because I am evil and didn't want to give half a million gold to a 5th level party, but also wanted to reward their superb creativity by letting them keep it all!) ...as soon as any of the gold leaves the Vault, a magical alarm will alert the authorities who will then form a large troop and come to recover the gold. This gives them barely an hour to move the whole thing, or risk losing it all.
They've been debating this for a while, have gone on several more adventures, have gained a few more levels, and are now ready to tackle the challenge of how to get 10,000 pounds of gold up and out of a two foot square hole that's 150 feet deep.
Their current plan is to use the wizard's Fabricate spell to create a ten foot diameter shaft with stairs along the sides that spiral down to the Vault doors. They've already calculated the volume of stone to be removed (70 castings!), how the raw stone will be turned into bricks, loaded into a wagon and dumped outside the city, and how to keep all of this low key enough that no one will suspect what they're really up to.
The crux of the plan is the fast removal of the gold from the Vault. They plan to have the wizard use Floating Disk to move 500 pounds per trip up the stairs, the rogue use their Bag of Holding to move 500 pounds per trip, and the goliath can carry 600 pounds per trip. That means 6 trips of about 5 minutes per trip, leaving the party about half an hour to escape Waterdeep with their wagon load of gold.
Is there a better/faster way to do this? How might a character transport hundreds of thousands of gold inconspicuously?, while similar, is more concerned with general moving of massive amounts of gold, and none of the answers to that question would work for this case.
The party has access to all spells of 5th level and below. They do not have another Bag of Holding nor do they have a Portable Hole, and the purchase of a powerful magic item isn't going to be allowed. Single use items like scrolls or potions would be considered as the party may be able to afford them. They do have several thousand gold of their own, and would be willing to hire someone in case a certain class/ability would work.
How can a party move 10,000 pounds of gold?