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Engineers
The SBS™ system is appropriate for new
development and re-servicing older communities. The system
comprises of a piping network for transmission of sewage fluids,
and on-site interceptor tanks attached to the buildings that
provide for an early separation of sewage solids and the liquid
portion of sewage. The piping
system is a one-piece network of conduits that collect the sewage
liquids and directs the effluent to a suitable receiver. The
piping is comprised of butt fused (welded) high density polyethylene
(HDPE) that directs the system fluids from the outlet of the interceptor
(clarifiers) tanks to the receiving system. The receiver
is normally a sewage pumping station that is attached to a sewage
treatment plant. The on-site individual clarifiers act to
separate the solids and liquids, and in doing so, affect the removal
of solids in the collection mains, as well as reducing the impact
of the sewage on downstream receiving infrastructure.
Functionality
The SBS™ collection
system is a high performance technology that simplifies the process
of sewage transmission and management. The
early separation of solids and liquids results in simplifying
the design, the maintenance, the operation, and ultimately, the
replacement of the collection system (at the end of its design-life). The
clarifier removes solids from the sewage and retains the solids
by design for a minimum of 7 years. The mains are smaller
than historic mains and are designed on the basis of hydraulic
equations that are used for transmission lines, and not related
to over-sizing due to maintenance requirements (associated with
historic sewers). The mains collect and direct the liquids
for further treatment, with the treatment normally comprising
of secondary and tertiary technologies. The solids reside
in the clarifiers for an extended period of time, allowing natural
digestion of the sewage sludge (~ 50% less net volume), and reducing
the impact of sewage sludge on the environment. Maintenance
is simplified to 7 year cycles of flushing the mains, tied to
the clean-out cycle for the system tanks. SBS™ is
a modern technology that creates efficiency in the age old process
of moving sewage from homes and businesses to ultimate treatment
and discharge.
System Venting
System venting
is tied to two separate issues. The tanks
require venting for the removal of system odors and to assist in
the movement of sewage from the home to the tank. Secondly,
the mains require venting in order to allow displacement to take
place between the air and the fluids in the main system. Strategic
designed venting is introduced to the main system at key points
in order to avoid hydraulic lock as the peak flows enter and move
through the system. Earth vents are also provided to avoid
odor at points in the system where turbulent flow will occur. These
may be characterized by areas with steep main gradients, or at
pumping stations where the inlet is exposed to the air.
The household
or building plumbing that is constructed under current codes is
sufficient to provide for the tank venting. A design
analysis is provided to place main venting in suitable locations
to allow for the requirements of the transmission of the liquids
to the receiving infrastructure, and to address any odor control
that may be required.
Tanks – Function and Quality
The
clarifier tanks function to intercept solids from the sewage streams. The
tank functions as a natural digester for sewage sludge and affects
a significant reduction in sludge accumulation, lowering the cost
and frequency of sludge handling/management for the community and
municipality. The tanks act as flow
surge suppressors and function to lower system peaking factors
and allow the use of much smaller laterals and collection mains,
pumping stations, and transmission systems. The tanks are
sealed to prevent the introduction of groundwater into the collection
system.
The clarifier tanks are constructed in a single
cast for structural integrity. Once constructed and at design
strength, the tanks are subjected to a comprehensive vacuum test
in order to verify strength and water tightness. Additional
wall thickness and higher strength concrete is used in order
to withstand the vacuum testing and provide a more competent
vessel when compared to standard tankage designs. The inlet
and outlet fittings are installed and embedded at the factors,
as is the connecting mechanism between the first and second chambers
of the tank. Three
distinct hatches have been designed to allow access to the first
and second chamber and permit the inspection of the connecting
mechanism between the two compartments. An access maintenance
hole is designed to be installed over the access hatch that is
provided for the sludge chamber. The access is extended by
adjustable rings and a PVC surface hatch to the surface of the
ground. This becomes the maintenance hole access that is
used for sludge removal on the design cycle for the system.
The
standard 3,600 litre residential clarifier tank is designed for
a typical sludge retention volume of twelve years for a 3.4 person
family. The same tank will service a 2 person family
for up to 17 years. With the application of a significant
factor of safety, the recommended clean-out cycle is reduced to
7 years between clean-out for these tanks. The parameters
of sewage volume retention and clean-out cycles become part
of the design process, but the current standards/approach that
are used by Clearford Industries Inc. provide for a very efficient
and optimized operational system for the system owners.
Installation
The SBS™ installation
methodology is superior in three aspects: less time, less disruption,
and the Ministry of Transportation has no issue with horizontal
drilling in highway corridors. Past comparable projects indicated
that construction time was cut in half by the use of trenchless
technology. Daily production rates for sewer mains can be up to
4 times higher with horizontal boring. Our experience has been
that historic sewer systems require many road-closures and community
inconvenience, whereas horizontal drilling is efficient, contained
to a much smaller area, requires much smaller equipment and less
manpower, and generates little disruption to the community.
Learn
more about the SBS™ system
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