Question
I recently removed 4 large pine trees from my yard.  I had the stumps ground up and what is left behind is a mess of woodchips.  I can get alot of them cleaned up, but not all of them.  Is it okay for me to simply leave a lot of the chips in the ground, cover it with dirt, and then sod over it?  Or do I need to remove as many of the chips as humanly possible?  Thanks for your help and I look forwad to hearing from you.

Answer
I see a recurring nightmare in your future, sir.  There you are, tossing and turning, the same bad dream, the Return of the Monster Pinetrees.

There you stand, you pay the Tree Company for their services, you stand with Pinetree Shavings -- the official state tree of Arkansas, Alabama and Idaho, pulverized into dust and coarse mulch awaiting disposal.  You go to sleep, and you wake up in 25 years and THERE THEY ARE.  Pinetrees, everywhere.

Don't get me wrong.  Removing '4 large pine trees' was probably the best thing you could have done for your landscape.  But if you don't remove a tree PERFECTLY, you will be living with the results for the REST OF YOUR LIFE.

Really!

Not just pines.  All trees.  Maples, Oaks, Spruces, Sycamores, Dogwoods.  Trees.

Deep removal of the entire trunk below the soil including all the roots is the ONLY way to stop a trunk from
rotting for the next 100 years under your lawn.  Bacteria in charge of decomposing the wood cellulose suck all Nitrogen from the soil, leaving NOTHING for your grass, causing wide, ugly, dead circles where the tree used to be.  

The problem with removing trees and trying to grow Grass is that there is still this huge root system and sometimes stumps, branches and ground wood underground.

Even if these are way down deep under the soil surface, several FEET from the Grass, the wood is buried.  Try sodding, and weeks later, the Grass is brown again.

Hard to believe, but completely grinding up the stumps is not enough.

Tree roots are thick and woody, too.  Anything left will rot slowly, consuming Nitrogen by the ton, for decades to come.

Your only answer is to remove every trace of tree at least 12 inches below the soil -- roots, stumps, any wood.  Drill several large holes in any remaining stump, fill with Nitrogen fertilizer, and water to accelerate final decomposition of these problem Pines.

If you can't do that, hire someone else to get some heavy duty equipment and yank all the roots out.  They'll tear up your lawn, but you'll have a clean slate to work with.  NEVER let them "incorporate" the wood chips or sawdust into your soil -- you will be wrecking the soil structure with the Lignin and it won't decompose.  Pay whatever they want to have remnant tree roots ground or yanked as deep as they can get.  And ignore the grass damage.  The grass is nothing here -- you can easily plant new grass seed.  Find a great pro and expect to pay for what you get.