The Part Catalog
Once you know what parts you require, you need to investigate the part catalog to make sure these parts (or a reasonable approximation) are available.
The part catalog is a collection of two domains that contain two catalogs each. Structures are considered one domain, and Pipes are the second. The Structures domain consists of a Metric Structures catalog and a US Imperial Structures catalog; the Pipes domain consists of a Metric Pipes catalog and a US Imperial Pipes catalog.
Although you can access the parts from the catalogs while creating your parts lists in Civil 3D, you can’t examine or explore the catalogs easily while in the Civil 3D interface. It’s useful to understand where these catalogs reside and how they work.