Do you want to learn how to plan affordable and context-specific sanitation solutions? Be up-to-date on the newest developments in urban sanitation planning and programming? Get to know best practice examples of urban sanitation systems in low- and middle-income countries? If yes, this course is for you! This course provides you with an introduction to integrated sanitation planning, both on a citywide scale and for specific contexts such as informal settlements. You will become familiar with different sanitation planning frameworks as well as different systems and technologies relevant along the sanitation value chain. You will learn why systems’ thinking is crucial for urban environmental sanitation, and how to apply key terminology and important concepts. INSTRUCTION Eawag-Sandec and EPFL jointly offer this course with support from sanitation experts of the World Bank and WHO. LANGUAGES We simultaneously offer this course in English and French. The name of the French course is « Planification & Design des Systèmes et Technologies d’Assainissement ». MOOC SERIES This course is one of four in the series “Sanitation, Water and Solid Waste for Development".
2.9b Conveyance - Condominial Sewerage Systems
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En provenance du cours de École Polytechnique Fédérale de Lausanne
Planning & Design of Sanitation Systems and Technologies
426 notes
École Polytechnique Fédérale de Lausanne
426 notes
À partir de la leçon
Sanitation systems & technologies
After getting to know different sanitation planning frameworks in the first part of this week, you will learn about the key terminology and concepts used in the systems approach to environmental sanitation. We will also explore why systems thinking is crucial for urban environmental sanitation.
Rencontrer les enseignants
Christoph LüthiDr.
Sanitation, Water and Solid Waste for Development / Eawag
Condominial Sewerage Systems
Planning & Design of Sanitation Systems and Technologies Klaus Neder, CAESB
Welcome to this module of the MOOC on condominial sewers
and the approach employed in their design and implementation.
My name is Klaus Neder.
I am an engineer at CAESB,
the Water and Sanitation Utility
of the Federal District in Brasília, Brazil,
where I have led CAESB’s efforts
to roll out condominial sewers
and appropriate wastewater treatment
to the whole of the Federal District
region over the past twenty years.
Nowadays serving about 1.5 million people,
the metropolitan area of Brasilia
is one of the most extensive examples
of the use of the condominial sewers in the world.
In this module, you will learn,
what are condominial sewers
and how do they differ from conventional sewer systems.
What are the advantages of condominial sewers
over conventional sewers
and in which circumstances
are they particularly beneficial.
What are the implications of condominial sewers
for a utility company?
Prior to adopting the condominal sewerage approach in Brasilia,
CAESB found that conventional sewers
were being built but,
households would not connect to them.
It was quite common that less
than 50 percent of the neighborhood
was effectively connecting to the new sewer systems.
Consequently, the large amounts of funds
invested in the trunk sewer infrastructure
and in the wastewater treatment plants
would not realize their expected public health
and environmental benefits.
Some of the major factors for this failure were,
a lack of dialogue between the utility
and the households regarding the sewerage solutions
to be designed and installed.
The high capital costs of conventional sewers
that utilities,
and by extension their customers,
had to cover.
We found that the major reason
that caused users not to connect to sewers included,
a lack of funds in the household to allow them
to make the piped connection to the sewers.
No adequate internal toilet/plumbing
installations in the household.
The local topography, including situations
where internal installations
are located lower than the sewer lines.
An existing solution, such as septic tanks,
already in use.
Where connecting would require
the breaking of floors and walls
or where the wastewater was already connected
to some kind of drainage requiring its separation.
Soon we realized that conventional approaches
to implement sewers are generally rigid
and not flexible or adaptable enough
to take into account the specific requirements
of the target population
and of the local situation,
such as those mentioned.
As a result, it is often difficult
to roll out conventional sewerage systems
to which households actually connect,
especially in informal,
densely populated, unplanned settlements.
When CAESB first introduced condominial sewers in Brasilia,
we adopted an approach
in which we did not expect the client
to come after the sewerage project
but, instead,
through which we would actively pursue the client.
In fact, following the condominial philosophy,
we start our work and our analysis
from the upstream source of the sewage,
this means at the household,
with a focus on each individual household connection,
and then follow a downstream path through the trunk sewers
to the wastewater treatment plant.
Such an approach is in the marked contrast
to conventional sewerage projects
in which the household connection
is the last concern or sometimes
is not a concern at all.
Providing adequate, effective,
and affordable connection to the sewer network
is thus a main objective of condominial sewer.
The following slide will show the key characteristics
of the condominial model, which has been developed
and refined in Brazil, generally,
and in Brasília with CAESB, in particular,
over a number of decades.
The Condominial approach features several key characteristics
that distinguishes it from the implementation
of conventional sewerage interventions.
One key difference is the participatory approach adopted
during the design and implementation
of condominial sewers and, sometimes,
during their operation and maintenance as well.
Households are mobilized
even before engineering designs
are commenced
and are fully encouraged to engage in the design
and the works phases
of the implementation of the local sewers.
The community is a major decision
maker regarding the design
and implementation of the sewer system,
and becomes the owner of the ‘condominial branch’,
which will be described more fully later.
An important factor of condominial sewers
is the reduction in capital costs
that can be achieved when compared to conventional sewers
through the optimization of the condominal network
in regards to branch routing,
pipe extension, pipe depths, pipe diameter,
and the optimized use of inspection boxes.
One outcome of this optimization
is that condominial sewerage
networks can typically be
50 percent of the length of conventional ones.
The condominial approach to implementing sewers provides us
with the tools to depart from conventional thinking
on the design principles of sewers.
It thus allows us to design sewer system
that can be successfully implemented in densely
populated, unplanned,
informal areas, such as in slums.
One of the guiding principles of the condominial approach
is to achieve 100 percent connection rate of households,
whether they are located in rapidly expanding poor
informal settlements or in middle class
or rich areas of the city.
Technical details for the implementation
and maintenance agreement of the condominial branch
are the result of a discussion
and a joint decision of the utility
and the targeted community,
and result after consideration
of all viable solutions.
Households are not forced into certain solutions,
but the technical and other alternatives
are discussed with them
so that an agreed optimal position is reached.
In many cases, however, the local topography
and the elevation of existing household
sanitary installations
are the determining factors
for locating the household
connection and for routing the condominial branch.
The sequence of development
and execution of condominial works
is different from that of the traditional sewerage system.
After the utility has concluded a survey,
a preliminary sewer design is used to define the ‘condominiums’.
These are the units of service
which will be each having a single,
shared condominial branch sewer.
Both the social and the technical teams
of the utility will work
with the Condominium members to define the type
and routing of the condominial branch
that will serve them as well as the terms
that will be applied to the construction
and subsequent operation of the sewer branch.
An essential part of the implementation
of a condominial program is the dialogue
and collaboration of the utility with the Condominium members.
A close relationship between the two parties
is required
to successfully design,
construct and operate the condominial sewerage system.
Since such participatory approaches are relatively new
to traditional sanitation,
CAESB deploys “social teams”
together with their “technical teams”
to facilitate the approach
and to thus help successfully arrive
at the necessary joint agreements
between the utility and the community.
The final engineering design related to the collector networks
are only undertaken after agreement has first been reached
between the utility and the condominiums
on the lay out of the condominial branch.
This process of finalizing
the design of the collector networks
is carried out during the execution of the corresponding sewer
civil works themselves,
we call it in the field "final design".
Let us take a closer look at the possible
layout of a condominial sewerage network
and the different elements made up by it.
As we just heard, a condominium
is a newly formed service unit
with a single, collective connection point.
All households in one condomium
will connect to a shared branch
that discharges into a secondary sewer network.
Instead of service laterals
directly connecting households
to a sewer main under the street,
the condominial system uses one single pipe
that connects to each household in the block.
This is called the “condominial branch”.
There are different types of branches,
depending on their location.
However, irrespectively of whether the branches
are internal or are at the sidewalk,
they are considered the responsibility
of the household,
as a sewer connection would be
under traditional sewerage projects.
The illustration shows how the extension of the pipe network
can be reduced through optimized routing
of the condominial branch.
Together with the shallower depth of the branches,
smaller pipe diameters,
and the use of simple inspection boxes instead of manholes,
capital costs can be consequently
reduced.
Besides the optimized network layout introduced
when using the condominial approach,
there are other design aspects of condominial sewerage
that help optimize the costs of installation.
Pipe diameters in condominial branches are generally minimized.
Hydraulic conditions permit a diameter of 100 milimeters.
Shallower depths of pipes can be used
when sewers are laid in front or in the backyard or under the sidewalks,
thus avoiding traffic-bearing sites
so to get as little as 60 cm,
reducing the amount of excavation required.
In condominial sewerage system,
the number of costly manholes is reduced
and they are replaced by simplified forms
called inspection chambers.
These factors not only reduce the cost of the sewers,
but can also prove beneficial during maintenance and repairs.
When condominial branches are located in household yards
and in sidewalks, access for repair
and maintenance is possible
without the need for the utility
to break up roads and interrupt traffic.
The condominium members jointly agree on the location
of the condominial branch.
If the utility is to maintain the branch,
the sidewalk is the preferred branch location.
However, in informal, densely populated,
unplanned settlements,
or in other circumstances
such as where the sanitary facilities are located
at the back of the house,
the back-of-the-lot branch
is sometimes the only feasible option.
It is in these circumstances
where the condominial approach is especially beneficial,
as it can provide solutions in situations
where conventional sewers would not be feasible.
Costs savings of condominial sewerage systems
usually range between 30
and 40 percent of those of conventional systems.
Furthermore, given that construction costs
of the condominial branches,
which are considered the private part of the sewerage network
and are generally covered by the household,
this arrangement represents a significant reduction
in the financial burden assumed by the utility.
Even though the households are responsible
for the cost of construction of the condominial branch,
in most cases it is executed by the utility.
These construction costs are covered
by the condominium members in the form of a connection fee,
and are in accordance with the agreement
signed by each household and the utility.
A service fee for operation of the condominial sewer
is usually based on the household’s monthly water consumption.
In situations where users opt to maintain
their branch themselves,
they qualify for a reduced service fee.
The condominial approach involves
the targeted households
and their community as a fundamental part
of the sewerage solution
and thus creates ownership among the users,
which is an important factor
in the sustainable operation of the sewers.
The condominial approach is based upon the full participation
of the community in the engineering design
and construction of the local sewerage system.
This requires that the utility
employs social outreach specialists
as well as technical/engineering specialists to work in conjunction
on the design and implementation phases.
This participation throughout the project cycle leads
to high levels of connection by households
to the sewer network,
often reaching 100 percent.
Given the optimization of the local sewer layout,
the smaller sewer diameters,
the shallower depths and the greater distances
between the inspection chambers,
the costs of the condominial sewer
civil works can be reduced by some 30 to 40 percent of the costs
of a corresponding conventional sewerage solution.
The adaptability of the condominial approach
to local conditions enables the provision
of sewerage service
where conventional solutions would not be possible,
for example in informal,
densely populated, unplanned, peri-urban settlements.
However, the condominial approach
can be equally applied
to formally urbanized areas.
In the district of Brazil where CAESB works,
condominial sewers have been successfully implemented
in all types of urban settings,
poor and rich alike.
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