Jo, check out a new material for building underground drainage systems called RainStore3 manufactured by Invisible Structures, Inc. of Aurora, Colorado.
As to the specific design of the system for your yard, it is not possible to determine the configuration of the system without the benefit of a site visit. I highly recommend that you contact an engineer familiar with drainage technology in your area. Provide the engineer with the information about the Invisible Structures products, if he or she is not familiar with it, from the web site with the following address.
invisiblestructures.com
JWA