Originally Posted by boarddad
OK, seriously, get a lawyer and do it now. It sounds like you and your neighbors have the makings of a class-action lawsuit. The lawyer will be able to tell you what documentation you need, what expert witnesses you need to hire (i.e. another Civil Engineer), etc. But first he'll fire off a tersely worded letter that could solve all your problems. Phone calls and e-mails will get you nowhere, letters from you will help, but a letter from an lawyer theatening to drag their asses into court will have the contractor fixing the problem this afternoon. It's not as expensive as you might think, and if the contractor doesn't fix it you'll need (you guessed it) a lawyer anyway. Besides that, if you think your contractor or developer doesn't already have legal representation you're being naive.
BTW, I'm an engineer, not a lawyer. I've just seen firsthand how horribly awry this can go.