That would depend on the foundation's type and use. For example a foundation for a building is going to have a different spec than a foundation for a transformer.
Professional and Structural Engineer (ME, NH)
American Concrete Industries
Are you looking for the method statement for the precaster to fabricate the foundations/manholes or for the installation of the precast pieces?
If it's the fabrication then you'll want ASTM C478 for the manholes. For the pipe support foundations I'd simply call out the ACI 318, 304, 308, and 309 specifications.
Beyond that you'll need the loads to be designed for (or the method you want the precaster to calculate the loads) and any other conditions you want considered. Don't get too deep into it because I've seen many specifications over specify the design and fabrication requirements (typically calling out excessive thickness, reinforcement, or concrete cover) so anything you don't specifically need leave up to the precaster.
Professional and Structural Engineer (ME, NH)
American Concrete Industries