If the .1-meter drawdown specification from the EPA is not really valid should any rule of thumb be used for the amount of acceptable drawdown or does the science say that you only need to pay attention to drawdown stabilization?

The science really does tell us that the only thing we need to watch for is a stabilized pumping water level. It’s a bit of a carrot and stick approach: the stick would say limit it to some arbitrary amount; the carrot would say the quicker you get to a stabilized water level the more rapidly you are going to get indicative parameter stabilization. There really isn’t any rule of thumb. I have heard of people using a slightly higher flow rate initially in order to get the amount of drawdown that they expect, and as they get close to that drawdown they back off on the pumping rate and let the well stabilize at that point. Then they continue to pump for a few minutes until there is indicative parameter stabilization and collect samples.