General Order 128
Section III
Requirements for Supply Systems
31 Duct Systems
Open trenching, tunneling, boring, jacking, plowing, and submersion
in water, either singly or in combination, are among the recognized methods
of installing duct systems.
31.1 Definition
31.2 Maintenance and Ispection
31.3 Construction
31.4 Clearance and Depths
31.5 Risers and Other Above-ground Terminations
31.6 Sealings Service Laterals