Structures within Parts Catalog

[Aquaserpent]

Does anyone know where we can acquire a set of standard structure sizes, for example:
Ditch Bottom Inlets from 2’- 0” x 3’ 1” to 3’- 0” x 6’ - 7”,
Manholes circular from 3’- 0” Dia. to 8’- 0” Dia.,
Manhole rectangular from 3’ – 0” x 3’ – 0” to 14” – 6” x 9’- 6”,
Curb Inlets from 3’ – 6” x 9 – 0”
Etc…

I have looked at the Part Builder and without knowing what each variable stands for I could make a real mess.

[rpwband]

I used the standard manhole that was set up in civil 3d. When I added it to the parts list I specified its inside dia and made sure the wall thickness was correct and it draws it correctly. Not sure if this is the best way, but it was easier than part builder.