This question has been asked before but only with respect to washing a small container.  We have a friend who runs fruit stands in the summer and we typically get 10 pounds of blueberries at a time from him.  Before freezing or eating, they need to be washed, and I always struggle to find an efficient way to get rid of the squished berries, the stems, the leaves, etc.  I'll post what I do as an answer, but I wonder if there is a better way, or some equipment that would make it easier. 
What I do is use a big plastic bowl.  The bowl is about 18" in diameter at the top and holds about 2 gallons of water.    I fill the bowl about 1/2 to 2/3 full of blueberries and then fill it to the brim with water and leave the water running into it.  As the bowl is filling and when it's full I gently agitate the berries with my hands.   Most of the chaff naturally floats to the top and spills over the edge of the bowl.  As I agitate the berries, I also try to direct any leaves to the edge and pull any berries back from the edge.  I lose a few good berries, but not too many and since I'm dealing with a lot of them I don't worry about it too much.  As I'm agitating the berries, I can feel a lot of the squishy ones and pull them out to look at them and discard if they're too far gone.  When most of the chaff is gone, I dump the berries into a colander and let them drain.  I've tried spinning them in a salad spinner, but for the amount of berries I'm trying to process, I've found that in order to remove any appreciable amount of water I can only put a small amount at a time in the spinner so it takes forever to spin them all.    So I let them drain, and then since I'm usually freezing these berries, I put some paper towels down on a tray and spread out a layer of berries.  When they're spread out I can pick out most of the squished or shriveled ones that I missed earlier, then I pull the paper towels out and freeze them.  I haven't ever looked for one, but I've always wondered if there's such a thing as a colander or sieve or screen with really big holes - i.e. just slightly smaller than a blueberry - that I could just dump the berries into and rinse off all the debris.    One big limitation to this technique is that it bogs down if you're dealing with less than fresh berries.  Picking out all the squished or moldy ones if they've been sitting around too long is problematic. 