I purchased a new construction home that was built in 1999. Last summer I
had a dump truck full of mulch bury itself to its axles in my front yard.
Now that the snow has melted my back yard (cleared one-acre lot) is riddled
with so many sink holes that I am afraid to let my 2 year old daughter walk in
the yard. I talked to my neighbor and he said that instead of hauling the trees
off the lot they were buried, leaves and all, in 3 or 4 large 20 foot deep
holes

You need a lawyer. The buried trees will take many years to rot & settle, & you
need to make the contractor dig them up. Also, your house may be built over an
underground stream. Get an attorney, fast.

Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)