I am replying to this (very old) thread since my blog has had a number of hits from my last message in the last week. If folks are still reading, then info is needed. Please forgive me resurrecting such an old thread.
1. We DIYed the retaining wall and ended up installing just over 100 linear feet of interlocking stone retaining wall. This required trenching and placement of 8" of 'A-gravel', one course of stone below grade, and 1-2 courses of stone above grade. We used a faux wood, concrete capstone to finish the wall. In the course of replacing the retaining wall, we discovered that the pool plumbing was buried about a foot below grade (we are in Canada with a hard frost) and so we replumbed the pool from the jets to the pump using tigerflex hose set inside Big-O drainage tile for protection. This portion of the project was very long and time consuming.
2. Once the wall was complete we turned our attention to the pool and deck. The liner actually failed when we tried to open the pool, and so we went whole hog and replaced everything. A rented concrete saw scored the concrete deck, and a sledge and mattock broke up the deck. I started off DIYing concrete removal, and removed 3 sides of the deck before I realized I was running out of time. Since we had a 2 week vacation scheduled, I hired in contractors to place new coping, pour an 8" concrete strip to hold the coping in place, and to place pavers for a new deck. In the process, it was realized that not only had the hydraulics of the soils destroyed th eold deck/pool, but that chipmunks had undermined the deck and excavated the downhill side of the pool. The contractors used a jackhammer to break up the remaining deck and used it as fill on top of the sand in order to deter rodents at their tunneling level.
3. With the coping complete and landscaping in place, the pool contractor placed a new liner and we replanted gardens surrounding the pool. We are very happy with th eend product and so far have no issues. Except that our new stairs keep floating up - but I think I even have that solved now. A little while ago I posted a before/after on our blog, I would suggest that whatever traffic is going from here to the blog look at that post rather than hitting the blog's frontpage:
http://www.frosthaus.blogspot.ca/search/label/Pool
Even with the DIY element, this project came in at over $25,000 (in Canada 2013) for the new deck, coping, liner, retaining wall and plumbing. It was a very long project, and took most of the summer working evenings and weekends. The retaining wall was the most time consuming piece.
Thanks for checking out the blog - if you need help, I am more than willing to share our experience, post here or leave comments, I check both.