I'm looking for a professional-context appropriate synonym for the word "a lot", but with the additional expression of "each contributes only a little"
For example,
To fill up that vat you'd need a crapload of tennis balls.
Here "crapload" implies that each individual tennis ball is actually worthless on it's own. Where the vat is big, "crapload" serves to color the sentence.
Unfortunately "crapload" is unprofessional. "A lot" is just colorless. Suggestions?