Which standards cover the installation requirements for underground piping?

The correct choice identifies NFPA 13 and NFPA 24 as the relevant standards for the installation requirements of underground piping.

NFPA 13 is the standard for the installation of sprinkler systems, which outlines general requirements for various components, including underground piping. It provides guidelines that help ensure that the installation meets safety and performance standards, contributing to the effectiveness of the overall water-based fire protection system.

NFPA 24 specifically addresses the installation of private fire service mains and their appurtenances. These guidelines detail the requirements for the design and installation of underground piping used for fire protection purposes, ensuring proper installation techniques, material specifications, and testing procedures to maintain system integrity and reliability.

Together, these standards establish comprehensive protocols for the effective installation and maintenance of underground fire protection piping, making them the appropriate references for the question at hand.