Swimming Pool Information
Building a Swimming Pool vs. Your Soil
Do you know what kind of soil you have? It could effect the ease (or lack thereof) of digging a backyard swimming pool. Once you've chosen a site for your swimming pool, it's a good idea to take a core sample of the ground and have an expert analyze it. (Your pool contractor should be familiar with the process and can help you find a soils engineer, then make suggestions based on the findings.)
Types of soil:
Bedrock is what you hope you don't have. Because you can't dig through rock, you may need to use dynamite to blast the hole for a swimming pool. This can be a very costly process and will most certainly increase the usual estimate for an in-ground swimming pool.
Although not as difficult to work with as bedrock, clay soil can also be troublesome. It is made up of small packed particles that expand when they get wet. This puts pressure on the shell of the pool, so you may need to strengthen your pool with extra steel rebar or concrete.
Sandy soil is pretty easy to dig as it consists of large particles. Unfortunately, the hole tends to fall in on itself as you dig (just like at the beach), so the diggers will probably have to use wooden supports to prop up the walls or else spray them with concrete as the dig progresses.
This is the best kind of soil (what you hope you have) for swimming pools as it is easy to excavate and provides good drainage.
Sunset's Swimming Pools and Spas