For the purposes of subdivision (a) of Section 6500, only one permit shall be required for a project involving several trenches or excavations. The provisions of Section 6500 shall not apply to the construction of trenches or excavations for the purpose of performing emergency repair work to underground facilities, or the construction of swimming pools, or the construction of “graves” as defined in Section 7014 of the Health and Safety Code or to the construction or final use of excavations or trenches where the construction or final use does not require a person to descend into the excavations or trenches.