Table of Contents
Page
SANITARY SEWER SERVICES
6.1
INTRODUCTION........................................................................................................................... 6-1
6.2
MATERIALS IN USE .................................................................................................................... 6-1
6.3
DESIGN CRITERIA ...................................................................................................................... 6-1
6.3.1
6.3.2
6.3.3
6.4
INSTALLATION ............................................................................................................................ 6-2
6.4.1
6.4.2
6.5
Insulation .......................................................................................................................... 6-4
Heat Trace........................................................................................................................ 6-5
Bleeding Water to Waste ................................................................................................. 6-5
THAW RECOVERY ...................................................................................................................... 6-5
6.7.1
6.7.2
6.7.3
6.7.4
6.8
Service Saddles ............................................................................................................... 6-2
Service Entry to Main ....................................................................................................... 6-3
FREEZE PROTECTION ............................................................................................................... 6-4
6.6.1
6.6.2
6.6.3
6.7
Depth of Bury ................................................................................................................... 6-2
Basement Services .......................................................................................................... 6-2
MAIN CONNECTION .................................................................................................................... 6-2
6.5.1
6.5.2
6.6
Service Sizing .................................................................................................................. 6-1
Material Selection............................................................................................................. 6-1
Minimum Grades .............................................................................................................. 6-1
Building Sewer Access..................................................................................................... 6-5
Portable Steamers............................................................................................................ 6-5
Portable Hot Water........................................................................................................... 6-5
Heat Trace........................................................................................................................ 6-5
BUILDING/PLUMBING CONNECTION ....................................................................................... 6-6
6.8.1
HDPE Service – Above Grade Building ........................................................................... 6-6
6.9
PIPE BUNDLES – UTILIDOR....................................................................................................... 6-6
6.10
SEWER SERVICE PUMPS .......................................................................................................... 6-7
6.10.1 Pump Use......................................................................................................................... 6-7
6.10.2 Sump ................................................................................................................................ 6-7
6.10.3 High Level Alarm .............................................................................................................. 6-7
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
Apr-04
6.0
SANITARY SEWER SERVICES
6.1
INTRODUCTION
Sanitary sewer services serve to convey sewage from the building to the sewer mains.
See Appendix A for GNWT water and sewer standard drawings.
6.2
MATERIALS IN USE
See Section 2.2.
6.3
DESIGN CRITERIA
Material selection and sizing of sewer services must be done early in the design process.
Recommendation
6.3.1
6.3.2
Service Sizing
Recommended minimum singlefamily service size is 100 mm.
Good practice. 100 mm will service the majority of
single-family homes.
Recommend obtaining a size
direction from building mechanical
engineering designers for large
buildings.
Fixture counts in the building and the National Plumbing
Code of Canada will dictate the service size.
Material Selection
Recommend obtaining municipal
standards prior to material selection.
6.3.3
Rationale
Many municipalities have standards regarding service
material types and only stock repair pipe and fittings for
these types.
Minimum Grades
Recommended minimum grade on a
100 mm sewer service is 2%.
Good practice.
Minimum grade on services over
100 mm should provide a minimum
velocity of 0.75 m/sec when the pipe
is flowing full.
Good practice.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
6-1
Apr-04
6.4
INSTALLATION
Installation of buried sewer service pipes should follow good pipe laying procedures as outlined in
Section 2.6.
Recommendation
6.4.1
Depth of Bury
Recommend a minimum of one
metre bury for underground sewer
services outside the building
footprint.
6.4.2
Generally ensures work on the lot will not damage the
service.
At one metre depth the soil temperature adjacent to the
pipe is much warmer than severe air temperature.
Basement Services
Recommend a minimum depth of
2.45 m at property line if homes with
basements are contemplated.
6.5
Rationale
A 2.45 m depth will generally allow full gravity service
from a home basement.
MAIN CONNECTION
The means of connection to the main will vary, depending on the pipe materials in use.
Recommendation
6.5.1
Rationale
Service Saddles
Recommend use of a service saddle
on all 100 mm services.
Provides a leak-free joint between service line and main.
Photo 6.1 – Typical Sewer Saddle
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
6-2
Apr-04
Recommend use of a 150 mm
service saddle only if the main
sewer is 250 mm or larger.
Pipe wall is weakened if a 150 mm ø opening is cut in a
200 mm diameter (or smaller) pipe wall.
Recommend use of prefabricated
"T" where service size is 200 mm or
greater.
Commercial saddles generally are not available for
services larger than 150 mm.
Recommend opening in main line be
cut using a round coring saw.
Provides the proper round opening.
Photo 6.2 – Typical Service Saw
Square cut or rough free hand cut openings are prone to
leakage and can accumulate paper and debris leading to
blockages.
6.5.2
Service Entry to Main
Recommend connection be at
10:30, 12:00 or 1:30 o’clock position
on the main.
Connecting on the upper portion of the main ensures
there is no backup of sewage in the service when the
main is running near capacity.
Recommend use of a 45° bend on
the service (10:30 or 1:30
connection) or a 90° bend (12:00
connection).
Realigns sewer service to desired grade.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
6-3
Apr-04
Use of a bend adjacent to the main provides a means to
allow some movement of the main relative to the service
without failure of the joint.
Figure 6.1 – Sanitary Service Entry
6.6
FREEZE PROTECTION
Sanitary sewer services generally convey relatively warm sewage (showers, dish washing, laundry,
etc.); however, they are in use on an infrequent basis and may experience no flow for a high
percentage of the day. Blockages due to freezing can occur due to wetting during use and
subsequent freezing or by frost buildup as warm moist air from the mains is drawn towards building
vent stacks and contacts the cold pipe.
Recommendation
6.6.1
Rationale
Insulation
Recommend all above grade sewer
service pipes and all service pipes
within 1.5 m of ground surface be
insulated.
Minimizes freezing.
Recommend design calculations be
undertaken to determine need for
insulation on service pipes with
more than 1.5 m of cover.
Ground temperatures may, at 1.5 m depth or lower, be
such that insulation is not warranted.
Recommend designers determine
the insulation thickness required for
each project.
Insulation is expensive and the best cost/benefit should
be achieved.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
6-4
Apr-04
6.6.2
Heat Trace
Recommend use only where
conditions are such that insulation
alone will not prevent freezing.
6.6.3
Bleeding Water to Waste
Recommend bleeding is not done
unless in an emergency.
6.7
Power costs are high and the majority of sewer services
do not require active freeze protection.
‘Bleeding to waste’ increases water supply costs and
sewage treatment/disposal costs.
THAW RECOVERY
Sewer services can be blocked by freezing.
Recommendation
6.7.1
Building Sewer Access
Recommend each building have a
sewer cleanout or access point that
is accessible and close to the
service exit from the building.
6.7.2
6.7.3
6.7.4
Rationale
Provides a ready access point to insert steam or hot
water thaw devices. Required by National Plumbing
Code of Canada.
Portable Steamers
Recommended for thawing steel,
ductile iron or other non-plastic
services.
Provides relatively quick thawing of a frozen sewer
service.
Recommend local private
contractors or municipal staff have
portable steamers.
Municipal staff or private contractors can respond to
problems in a timely manner.
Portable Hot Water
Recommended for thawing PVC or
HDPE services.
Both PVC and HDPE can be damaged by overheating
with steam during thawing.
Recommend local private
contractors or municipal staff have
portable hot water devices.
Municipal staff or private contractors can respond to
problems in a timely manner.
Heat Trace
Electric heat trace can, if installed,
be utilized to thaw a frozen service.
This can, however, be a lengthy
process.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
Heat trace is generally sized to provide sufficient heat to
prevent freezing. Considerably more heat is required to
thaw a frozen service.
6-5
Apr-04
6.8
BUILDING/PLUMBING CONNECTION
Generally the sewer service is connected outside the building, or beneath the building, using a
coupler suitable for joining the pipe types in use.
Recommendation
6.8.1
Rationale
HDPE Service – Above Grade
Building
Recommend use of connection
detail for above grade buildings
developed by the GNWT, with due
consideration to potential seasonal
frost heave.
The GNWT connection detail is both comprehensive and
proven, but there may be seasonal frost heave on the
vertical riser.
Figure 6.2 – Sewer Service Riser
6.9
PIPE BUNDLES – UTILIDOR
Available heat in the recirculation water system or in the sewer lines can be used to advantage.
See Section 5.10.1.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
6-6
Apr-04
6.10
SEWER SERVICE PUMPS
Sewer service pumps may be required when gravity service from all or a portion of the building is
not possible.
Recommendation
Rationale
6.10.1 Pump Use
Sewage service pumps should only
be considered where gravity service
is not possible.
Pumps and starting devices require maintenance. Most
homeowners are not equipped or prepared to deal with
sewage pumps.
6.10.2 Sump
Sewage service pumps require a
sump.
Pumps cannot run continuously; a sump is required to
collect sewage prior to periodic pumping.
Sumps must be sealed during use.
To prevent sewage gas and odours from entering the
home.
Sumps must have a vent to the
house vent stack.
To allow air to escape as the sump fills and to allow air
to re-enter as the sewage is pumped out of the sump.
6.10.3 High Level Alarm
An audible and visible high level
alarm is recommended.
GOOD ENGINEERING PRACTICE
Sanitary Sewer Services
Alerts the building occupants of a problem before sewer
backup occurs.
6-7
Apr-04