Safety, Tools, and Job-Site Practices
Site hazards
- Excavations: a protective system is required at 5 ft depth; a competent person inspects daily; spoil and materials stay at least 2 ft back from the edge; a ladder is provided within 25 ft of travel.
- Confined spaces: permit-required spaces such as vaults, pits, and large tanks need atmospheric testing before entry, an attendant, and rescue provisions.
- Hot work: soldering, brazing, and grinding require a fire watch, clear combustibles, and shielding. Many District buildings require a hot work permit.
- Older buildings: assume asbestos pipe insulation and lead paint and follow disturbance rules before cutting.
- Silica and dust: use water suppression or dust collection when cutting concrete or masonry.
Testing and protecting the system
- Rough-in testing: drainage and vent systems are tested with a 10 ft head of water, or an approved air test at the pressure and duration stated in the code; water distribution is tested at or above working pressure.
- Cap and plug every open pipe; debris left in a new main is a callback.
- After shutdowns and repairs, flush and disinfect potable water lines before returning them to service, especially where older service lines are present.
- Lock out and tag equipment, and verify a gas valve is closed before breaking a line.
Worked example
A crew replaces a cast iron stack in an occupied apartment building. Sequence: permit and notice to tenants; temporary water if service is interrupted; ventilation and containment for dust; hot work permit and fire watch for cutting or soldering; eye, hand, and respiratory protection; protection of potable lines with flushing on completion; and a pressure test of the new stack before the wall is closed.
Traps that cost marks
Entering an unshored trench for a quick look; skipping the hot work permit; leaving open pipe ends where debris enters; and failing to test or flush before the water is turned back on.