General Order 128
Section III
Requirements for Supply Systems
32.3
Materials and Strength
The materials, design and construction of
manholes, handholes, subsurface equipment enclosures, and other underground
boxes shall be such as to provide sufficient strength to sustain, with a
suitable margin of safety, the loads which may reasonably be imposed on them.
Manholes, handholes, and subsurface equipment
enclosures in street areas which are subject to vehicular traffic shall be
constructed to withstand H-20-44 highway loading as designated by the American
Association of State Highway Officials. Floors of manholes shall meet the
requirements of Public Utilities Code, Sec. 8054. (Also see Appendix B, Fig. 9,
and Appendix D.)