So, after 2 seasons have come and gone, I figure it might be helpful for me to post an update for others doing the same route of seasonal install on top of grass. Here are some of the details of my journey and what I have experienced and learned.
Year #1 (2013)
Using a water level, I measured to verify level ground and cut the grass a short as possible. In the 1st picture below, the dirt patch is covering a sprinkler location and you can see a vary faint green spray paint circle that helped with planning and placement.
I put down 2 tarps, then 1/2" sheets of PolyISO foam, followed by a tarp on top. I placed plywood squares under the feet.
Installation went well. I used the cart portion of an old BBQ I was tossing out to make a table for the filter pump equipment. I strongly recommend something like this as it keeps things cleaner and allows easy access to the controls without bending down.
After the season was over and while packing up, I found lots of grubs (beetle larvae) under the pool. Up to this point I thought beetles were kinda cool and then it hit me like a ton of bricks why I had been having a gopher occurrence. Gophers dine on the grubs, so the pesticides came out and no more grubs, no more gophers.
Year #2 (2014)
Slight changes for this year. Instead of 2 tarps + foam + 1 tarp, I used 1 less tarp. I'm not having any problem with aggressive grass growing into any plastic tarp or vinyl. I reused the same foam from last year, although it was a little beat up and difficult to deal with. 2 seasons was the max I could get 1/2" foam to last - it got trashed. I did not use anything extra under the feet. They went directly onto the tarp or the foam and were perfectly fine for me. I did have a couple of pin holes in the liner upon set up, or what seemed like pin holes. I could only find one. I put a piece of scotch tape on the outside while I located a patch kit. To my surprise, the stupid scotch tape trick lasted all season and I never opened the patch kit. hahaha, and a total surprise to me! Other areas that were wet and suspected of having a pin hole dried up. Maybe there never actually was a hole or maybe final water pressure sealed something up? I don't know, but all good.
I am very happy with the pool and with seasonal setup on grass. The grass definitely gets killed, but I can get it back green and healthy in 1-2 months without any major work or touching the dirt at all. Every year I am able to get all the parts (except the ladder) broken down into their original packing and into the original box. For off season preservation, all rubber seals get a coating of silicone grease and all the plastic clips and spring connectors get a spritz of silicone spray lube. I rinse (especially since I run a saltwater pool) and thoroughly dry all parts. The liner gets some talcum power before storage. I built this platform on wheels to help move it around easily.
Obviously different regions could have different variables, but here is what I've learned for MY pool, MY ground, and MY environment:
Always spray pesticide down before putting the pool up.
The liner does need some kind of thicker flooring to prevent sharp dirt and rocks from poking up. 1/2 foam is a bit fragile to expect lots of repeated use. Thick foam would cost a pretty penny and be a pain for me to store off season. I want to now look into the artificial grass idea to replace the need for foam. (BTW, placing on concrete is sooo much easier prep and cleanup)
I do not need any pavers and anything special under the feet.
I am a fan of keeping equipment off of the ground so I really like the table/rack for the filter pump. I also made and really enjoy an accessory rack which can be seem here:
http://www.troublefreepool.com/thre...l-(I-Should-Patent-This!)?p=740793#post740793
Hopefully my experiences will help others plan their seasonal set up on grass and storage for many years of reliable use.
I set up my pool in early June and take down in October.
Happy off season and I'll be back into the swimming pool game later!