How many of Detroit's demo'd home lots are full of rocks, clay, cement?

This story has been revised to correct an editing change. The prior version said demolition costs had increased from $10,000 to $20,000 under Mayor Mike Duggan. It now says the amount of the increase under the Duggan administration is unclear.

For the past year, Charlie LeDuff has taken on Mayor Mike Duggan, his demolitions, and the dirt drama. Costs are up and the feds want answers. Duggan says the high costs is the dirt - but, for once, the dirt is hard to find.

The cost of tearing down a home in Detroit has jumped under Duggan, although the exact amount of the increase is unclear. In October, the mayor said the reason for the increase is the dirt and the cost of transporting it.”

LeDuff hasn't stopped digging - and he found something hard: rock and clay.

That's right, when contractors tear down a home, they have to fill in the hole where the home once stood. The top soil is supposed to be 3 feet of clean dirt. But under that is crappy bits of brick and concrete.

When Ding was doing the demos, there was no dirt drama. Back then, the city was required to fill the whole hole with clean, expensive, dirt. No concrete, no clay - no crappy dirt. When the city went broke and the emergency manager and new mayor took over, that all changed.

The law stated that as long as the top three feet was clean, it could be filled. It was supposed to save a lot of money but it somehow didn't.

Duggan blames the dirt.

Now he's got a full blown federal investigation.

It's unclear if the city, under Duggan, ever followed the three feet of clean fill law. Then it gets weird.

Mike's top lawyer - Melvin Hollowell - is asking the city council to change it to a new "six inches" of dirt law. Not only that, he wants to make it retroactive. That means he wants to go back in time and change the law to "avoid any unintended  consequences."

(How many people in the county jail would dream of a retroactive law to avoid any unintended consequences?)

We reached out to mayor Duggan and his demo experts. They wouldn't speak to us and when our cameras showed up - they ran for the hills.

So we went back to the scene of a home that the Detroit Building Authority showed us. Brian Farkas showed up at a demo site last fall - a site that he picked - and showed off the lot as a model of their demolition awesomeness.

What did Charlie find? Rocks.

He also went to the mayor's 10,000th home that was demo'd six weeks ago. Duggan touted it as progress. What did Charlie find there? "A real moonscape"

That home cost $23,930 to demolish.

You might not be able to grow pumpkins in the mayor's lots kids. You might not be able to play football on them either. Don't worry about it! There's always a bunch of big rocks you can throw at each other!