In reply to Dave Garbutt.

The Significance article goes into a lot more details about the federal standards. You can look them up online. Briefly, for a city of about 100,000, the MDEQ should have collected at least 100 samples from the "worst cases." The MDEQ did not know where the worst cases were, so they used voluntary sampling. They still only got 71 samples, which left them with less statistical power than is recommended. Because time was a factor, they analyzed the data they had, rather than try to collect more.