Underground piping Flashcards
Trenching Safety
• Before you dig or disturb the ground, find out
what is buried below the surface.
• Call Alberta One – Call at least 2 days in
advance
• Alberta One-Call may not have all the utilities
• When it comes to trenching, it is important
that you are thorough in your investigation in
order to protect yourself and your co-workers.
Trenching Safety
• An employer must stabilize the soil by:
• shoring
• cutting back
• stabilize the soil using an artificial soil
stabilization technique, including freezing soil by
artificial means or grouting if the process used is:
• Designed by a professional
Methods of Protection
• If >5’ deep and the worker is within the height of the
wall from the edge, the employer must:
• Cut back the walls of the excavation to reduce the height
of the remaining vertical walls, if any, to no more than 5’
(1.5 m) for “hard and compact soil” and “likely to crack
or crumble soil”
• Install temporary protective structures, or
• Using a combination of the methods
• Unless cutting through solid rock
Methods of Protection
• If the soil is classified as “hard and compact soil”, the
walls are sloped to within 5’ (1.5 m) of the bottom of the
excavation at an angle of not less than 30 degrees
measured from the vertical
• Alternately a bench system can be used
Methods of Protection
• If “likely to crack or crumble soil” the walls are Sloped
to within 5’ at an angle of not less than 45 degrees
measured from the vertical
Methods of Protection
• If “soft, sandy or loose soil” the walls are sloped from
the bottom of the excavation at an angle of not less than
45 degrees measured from the vertical.
Methods of Protection
- Shoring and trench boxes
* Build from the top down
Other rules
• Loose materials must be kept from the sides
• Spoil piles must be kept at an angle of 45 and 3’ away
from the excavation
• If the trench is >5’ deep must have safe entrance and
exit within 26’ and safe access to the entrance/exit
• Part 32 OH&S addresses Excavating and Tunneling
Engineer
> 3 meter deep trench engineer required
Approved joint connections
• Grooved connections are acceptable
• rolled, cut or cast to grooves that are compatible with
couplings being used.
• Copper shall be
• brazed or pressure fittings as specified by NFPA standards.
• Plastic connections
• fusion welding; which melts the plastic together
• solvent welding which uses a glue to mix polymers of fittings
and pipe together
thrust forces
- Due to the thrust forces, the pipes must be restrained
- Thrust blocks are used at all
- change of directions
- tee’s
- plugs
- Dead ends
Piping options
ductile iron, concrete, plastic, brass, copper, and stainless steel.
connecting into building
underground pipe cannot extend into the building more than 24 inches
review from water supplies
- How far into the building? 10’
- Pipe joints under foundations? no
- How far below foundations? 12”
- Exception? sleeved
- If piping is in a building
- Conditions of joints within a building? restraint
- Are trenches allowed? Yes, accessible, non-combustible,
drainage - Valves? Where it enters the trench
- How far can it come up through the slab? 6.1.4.1 24” max
Underground Flushing
• The minimum rate of flow shall be not less than one of
the following:
1. Hydraulically calculated water demand rate of the
system, including any hose requirements.
2. Flow necessary to provide a velocity of 10 ft. / sec.
(3.1 m/sec.) in accordance with NFPA 13.
3. Maximum flow rate available to the system under fire
conditions.
