Man, you really went to a lot of work! It should work, if you positioned your trench to catch most of the water. “Trap rock” must be a local term–I never heard of it in Pennsylvania nor Virginia. You can certainly use crushed stone, or bank run gravel–two or three inch stone should work fine. Two inch is easier to handle and move around. Be sure it is washed stone, so the fines don’t start filling in your system. And don’t get mixed sizes (modified gravel mix) which are designed to pack down–you WANT to have the voids afforded by similar sized pieces.
Just put enough stone on the bottom of your trench to keep the pipe out of the mud. How much you cover the pipe is up to you. You need enough void to carry the volume of water as it penetrates the pipe. If you have a 12″ wide trench, you can barely cover the pipe with gravel and it will carry a lot of water–then tar paper or plastic, the excavated dirt, and new concrete. If you want, fill it to the bottom of the concrete with stone and skip the dirt, but I doubt you need 8″ of stone.
As a precaution against having your system fill up with dirt, line the trench with geotextile cloth (availiable from you local perf-pipe dealer) before putting in the pipe and gravel. Wrap it up over the top of the gravel and cover with dirt and or concrete.
No sense in punching holes in your sump unless you are surrounding it with gravel to catch additional water where the sump is located. It sounds like you are moving the water to your sump pail, so just let it fill the pail and pump it out.
[Edited by CallMeChaz on 12 April 2001]