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The EGL Pressure Sewer Solution Description of the
Pressure Sewer System
EGL Pressure sewers consist of a network
of pressure pipe, much like a water pipe network and EOne
grinder units, which
are installed serving all the properties throughout the collection
system. Depending on local factors each unit will serve one
residence or several home units or townhouses, or larger
facilities. Upstream from the grinder pumps, gravity house
drains from within the residence are no different from any
other system, except much shorter.
The Street Main Pressure
Network
The polyethylene pressure pipe network is usually
installed in the road reserve. The network is completely
sealed through
the use of electrofusion welding techniques for jointing,
thus eliminating infiltration and inflow.
The Grinder Pump
The EOne grinder pump grind the sewage and
discharge a finely ground slurry into the small-diameter
pressure piping. The
semi-positive displacement pump in the grinder pump station
is the best type of pump for successful parallel operation
of many pumps into a system of common pressure mains. The
pumps do not have a single fixed “operating point”,
but must operate consistently over a wide range of heads
that are continually, and often rapidly, changing. The maximum
desirable pumping head is 45m.
The Grinder Pump Unit
A grinder pump unit consists of a grinder
pump, tank, alarm panel and connecting cable. The gravity
pipework upstream
and the pressure pipework downstream connect to the grinder
pump unit, with electrical connection also required.
System
Operation
In operation, the grinder pump station will handle
sewage and many items that should not, but often do, appear
in domestic
wastewater. For example, plastic, wood, rubber and
light metal objects can be routinely handled without jamming
the grinder or clogging the pump or piping system. Transporting
sewage several thousand metres to a discharge point at a
higher elevation is possible as long as the sum of the static
and friction losses does not exceed the desirable design
limit of 45m.
Target Market Water authorities around Australia are addressing
the backlog of unsewered properties in their areas of operation
to provide
them with sewer service. This septic tank replacement
effort has gained considerable momentum in recent years.
Accordingly, the standard approach for sewering communities
with gravity sewers is increasingly being found to be a
more expensive approach.
In addition to backlog sewerage, developers
are also beginning to recognise the advantages of pressure
sewer for new developments
as well.
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Completed installation |
Where pressure sewer systems are best used
To protect sensitive
environmental areas:
- Areas with significant underlying rock
formations
- Flat sites
- Hilly or difficult terrain including islands
- Sites with high
water table
- Areas remote from existing infrastructure
- Low density housing
areas
- Where avoiding infiltration and inflow is critical
- To avoid
numerous standard pumping stations
| The Basis of Successful
Pressure Sewer Systems |
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It is clear from 30 years of pressure
sewer experience in US, Canada, Sweden, Japan, New Zealand
and Australia that
there are at least five keys to successful pressure sewer
systems. The delivery of EGL Pressure Sewer Division services
is fully aligned with the key success principles described
below:
Quality Community Interface
Pressure sewers have equipment
on every property served. Therefore,
this is potentially very intrusive on customer properties.
Accordingly the appropriate handling of the community aspects
of a pressure sewer project frequently makes the difference
between happy and unhappy customers.
Quality Design
Design is not trivial even though it may appear to
be straight forward. Onsite data collection and documentation
is a critical but little understood aspect of a successful
pressure
sewer project. The design of the onsite component of
the work makes up a significant portion of the design work
and must be completed sensitively and comprehensively. Understanding
pressure sewer design requirements and practices contribute
enormously to the implementation of quality installations.
Quality
Equipment
Reliable pumping equipment is the heart of successful
pressure sewer systems. The reliability of EOne grinder pumps
is well
documented, indicating a low level of corrective and no preventive
maintenance. An average time between service calls
has been established as 6 to 10 years. Independent verification
is available to support this.
Quality Installation
The use of trained installers who are well versed
on the installation process of the EOne Grinder pump station
will
result in a substantial reduction in the number of remedial “callouts” to
the jobsite. Comprehensive startup and commissioning procedures
along with the use of supplier-trained commissioning personnel,
further improve the reliability of the installed equipment.
Quality Service
Trained service personnel (phone, field & shop)
with the tools to do the job right the first time are required
in order to maintain quality service to customers. Service
records must be kept simple but complete to identify service
trends and improve service processes.
Close alignment to these
principles in the provision of services to the sewerage
industry keeps the ongoing maintenance costs
to a minimum.
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