trigger-happy;506752 wrote: i'd spread the sand out in a large rubbermaid or similar container, so that it has the largest surface area possible, then attack it with a hose. Just sit the hose inside the container and let it fill up and overflow. Periodically stir the sand. When the water stops running cloudy when you do that, you should be good to go.
Bear in mind that method doesn't really work for sugar-fine sand. I tried it...the sand particles are so tiny and light that they just wash away along with the dust and the other bad stuff.