Could someone give me an idea if the process and cost to remove and fill in an average size in-ground pool that is concrete...not a liner? Thx for the help

@Chris Ryan

It might be simply cheaper to fill it in with dirt and be done with it.

You have to bust up the concrete so water will go thru , Depending on the size and access  about  $ 4000  to $ 9000 in Maryland

Mathew is correct.  You have to at least put holes in the bottom before you fill in the pool or you'll end up with a marsh in your back yard.  Then it's just the cost of the fill dirt and labor.  Really you should compact the dirt as you go so you don't have a big sink hole.  Do you have any dirt or rocks on the property that can be used for fill?  Depending on the size of the pool it can easily push $9-10k down here in the D.C., Virginia, Maryland area.

We did an infill on a small kidney shaped concrete pool about 30ft long a little over a year ago.  Also had to remove some of the underground plumbing (per inspector request) The initial bid was $7,500, the investor and I agreed on a change order after the plumbing issue came up. The final project cost was $8200.

This was near Ann Arbor Michigan, I would suggest you call the building department and check the requirements for an infill. That way you have a better understanding of what the scope of work will be to avoid surprise. Good Luck!

@Chris Ryan The costs and exact procedures may vary somewhat based on the location as some municipalities require a permit, and have different requirements, to demo/fill a pool. But here's a rough idea of the basic steps involved and what it cost when I did it:

STEPS:

~ Drain the pool

~ Remove pool equipment & cap off water lines

~ Remove/cap off any unused electrical

~ Knock down the edges around the pool and make holes in the bottom of the pool for drainage 

~ Fill pool with "clean fill" material (i.e. soil, gravel, rock, sand, etc)

~ Tamp the fill material as you put it in to compact it and reduce the chance of it settling over time once it's all full

COSTS: (we did the labor ourselves so this is just for the material)

~ $450 to buy a jackhammer to knock down the edges around the pool and also to make the holes in the bottom (we could have rented a jackhammer for cheaper but this way we own one and can use it on future jobs)

~ $1600 for the fill dirt (it was a lot of dirt!)

~ $450 for a bobcat & operator to transfer the dirt from the delivery trucks and into the pool (we were going to just rent the bobcat but found a guy on Craigslist who owned one and was willing to also do the driving of it for about the same price as it would have cost to just rent the bobcat by itself)

~ $100 to rent a tamping rammer to compact the dirt 

So, in total, about $2600. 

Here's a few pics to give you a visual:

Is in-filling a pool less expensive than restoring the pool, or is there another reason for it?  Does it have something to do with lot coverage compliance for an addition?