Synthesis
Novatech 2001
1. PHYSICAL PHENOMENA
1.1 Pollution sources
In town, pollution origins are extremely diversified; the role of the roofs
must be taken into account when a heavy metal study is made during the analysis.
2.2 Chemical and biological phenomena
They have a very important part in the transfer of pollutants overland as
well as in the drainage network. The result can be positive (quite fast biodegradation
of surface hydrocarbons, biodegradation of the organic matter inside the drainage
system). The result can also be negative (synthesis of compounds different
from the ones that have been introduced and that are potentially more toxic).
2. METROLOGY
2.1 Lack of data
More data is needed and the current ones are very imprecise. That point constitute
an obstacle for the improvement of knowledge. The evaluation of associated
uncertainties is essential.
2.3 Data basis
Nevertheless, researchers are developing data basis available on Internet
in order to share information (in particular data basis on the alternative
technologies achievements).
3. DEVICES
3.1 Innovative technologies
Many new technologies are becoming mature and thanks to a better knowledge,
the innovative technologies processes are improving (storm water decontamination,
infiltration techniques, house detention devices),
3.2 Open questions
Nevertheless, there are still open questions, in particular concerning the
maintenance and sustainability of the devices. Financing the maintenance is
often difficult. In a lot of countries, it is much easier to find funds to
build than to maintain.
Some new problems appeared and are becoming serious, in particular the one
related to the responsibility towards the risk of accident in the devices
that are opened to the public. Real time control of the devices seems to have
found a second wind (examples of Quebec or Barcelona) thanks to an important
potential efficiency. The main problem now is the limitation of pollutants
overflows. The efficiency can be improved mainly for small rainfalls. In that
case, the obstacles related to the weather forecast difficulties are less
insuperable. The problems of the data quality and the possibility of their
real time verification are crucial aspects.
4. THE PARTICULAR CASE OF THE DEVELOPING COUNTRIES
In the developing countries, the situations, very different the ones from
the others, implicate to look for solutions adapted to each of those particularities.
The two main words that participate in the achievement of those solutions
are " local culture " and " participatory schemes ". Technical
problems come after.
5. THE NEED TO CHANGE STRATEGY
This aspect was mainly the central point of the discussions. The problem is
not to improve the drainage devices but it is to change strategy in urban
storm water management. This topic can be divided in three points:
5.1 Decision making
The current limit of the integrated approaches appears to be extremely linked
to the fact that the problems of decisions are not well defined. Looking for
performance indicators that would be common to everybody is not that easy
: for example, how can the relation be made between the overflows and the
receiving water?
There is a wide difficulty in integrating technical aspects to institutional
and social aspects. This is particularly complicated when the objectives of
the devices are numerous.
Finally, it is difficult to clearly define the objectives; it introduces an
essential and widely debated question:
5.2 How can citizens be involved?
As an attempt of response, the following was suggested :
5.2.1 It is necessary to have a long term vision which consequently brings
the matter of participation, education and adaptation of the organisations.
5.3 Economical aspects
Few conferences directly pointed out this topic which, nevertheless, constituted
a central aspect in the discussions. Besides the classical questions on costs
evaluation, two strong ideas have been pointed out :
5.3.1 The design of devices with multiple uses facilitate the financing of
the investment and the functioning.
5.3.2 What is the economical value of water?
Synthesis
Novatech 1998
NOVATECH 1998 was the third conference
in the series of Novatech conferences on InnovativeTechnologies in Urban Storm
Drainage. It was organised by GRAIE (Groupe de Recherche Rhone-Alpes sur les
Infrastructures et l'Eau) and co-sponsored by 11 French and international
agencies led by Eurydice 92 and Le Grand Lyon. The conference attracted about
340 participants from 24 countries.
This third NOVATECH conference has been the largest and best-attended ever,
and confirmed the steadily growing prestige of this conference series. The
conference program comprised more than 130 papers, which focused on innovative
methods of sewerage and drainage analysis, stormwater management, and CSO
control and treatment. All the presented papers were included in the conference
proceedings, which are available from GRAIE. To provide for a
wider circulation of selected conference materials, the conference organisers,
in collaboration with IAWQ, have arranged for publication of a special issue
of the IAWQ journal Water Science and Technology (WS&T) on this conference.
To meet the page restriction of the WS&T issue, the conference organisers
engaged the NOVATECH Scientific Committee, led by Professor M. Desbordes,
in a rigorous selection of the papers for this special issue. The result of
this process is the compilation of papers that follows. The goal of this special
issue is to provide a representative cross-section of the innovative approaches
discussed at the conference. By focusing on a smaller number of papers, it
was possible to allocate more space to individual authors, so that they could
further expand their original conference presentations and enhance them on
the basis of paper discussions at the conference. Some brief observations
on the subjects covered at the conference follow.
The issues of sustainable development keep attracting attention, particularly
in connection with urban wet-weather flows. Some concepts discussed at the
conference went as far as proposing a zero emission goal for urban areas,
with respect to pollutants and other materials. In some aspects, the City
of Tokyo (Japan) is making great strides towards
reaching this goal. Other papers focused on mathematical modelling of water
quality constituent balances, as a first step in sustainability planning (The
Netherlands), or emphasised the aesthetic features of stormwater management
in urban area, but without discussing ecological implications (USA). With
respect to funding stormwater management,
the user pay approach, through public stormwater utilities, was recommended
(USA).
A fair number of papers dealt with an extended characterisation of wet-weather
pollution, addressing not just the chemical composition, but also treatability.
In this process, much attention focused on settleability, which is evaluated
through various laboratory or in-situ procedures. Some standardisation would
be desirable, not just for comparing the methods but also when interpreting
result of various treatment processes. High-tech innovations in this
field include the use of in-situ laser particle size analysers (Canada), UV
spectrophotometry (France), and image processing enhanced by neural network
modelling (Denmark).
Further advances in wet-weather flow modelling were reported, either by developing
new models or by refining/modifying the existing ones. With respect to CSOs,
there were calls for simplified approaches to modelling based on stochastic
models (Belgium, The Netherlands). In CSO treatment, further refinement of
various processes has been continuing. Several papers addressed operation
of hydrodynamic separators, using laboratory observations or computer simulations
(UK, Belgium, Germany). The understanding of operation and performance of
these devices has been further advanced. Other CSO treatment processes reported
on included settling with chemical aids, air flotation-sand filtration-UV
disinfection; physico-chemical precipitation/ flocculation-chemical oxidation;
skimming by
control booms; screening by self-cleaning brush screens; and, removal of debris
by CSO litter separators (Canada, France, Germany). In-depth studies of CSO
tank maintenance (flushing) were reported, using a CFD model to study flow
patterns in these tanks (Belgium, Germany).
Stormwater management is practised extensively in many countries; besides
ponds and swales/ditches, which are popular in North America, many papers
focused on infiltration facilities, and particularly infiltration trenches
and their long-term performance (Denmark). A recent addition to this class
of practices can be described as a grassy swale
overlaying an exfiltration trench (Germany). The benefits on biofiltration
(i.e. runoff passing through a vegetative strip) were also assessed and found
effective in runoff quality enhancement. A series of papers dealt with porous
pavements, with or without underground storage (vault reservoirs, either filled
with stones, or created by honeycomb-type concrete or plastic structures).
Such measures are widely studied and used in France. New hydraulic
structures for controlling peak outflows from stormwater networks were developed
in Australia.
Finally, a number of papers dealt with impacts of wet-weather on operation
of sewage treatment plants. The preferred approach to dealing with these problems
consists in proper plant operation, using real-time control supported by various
commercially available programs.
In closing, we can look forward to the fourth NOVATECH in Lyon, France, in
2001. Program committee's emphasis on papers dealing with innovative solutions
and actual data make these conferences most worthwhile of attending. For participants
from outside of Europe, these conferences represent an ideal forum for learning
about the latest research on wet-weatherpollution conducted in Europe. Organisation
of scientific conferences is a most difficult task requiring tireless efforts
of many contributors. With respect to NOVATECH 1998, the whole organising
team deserves thanks for a job well done. To recognise the main leaders of
these efforts, special thanks are extended to Prof. Michel Desbordes, Université
de Montpellier, President of the Scientific Committee, M. Bruno Polga, Deputy
President of the Grand Lyon , President of the Organising Committee, and the
driving force of these events, Prof. Bernard Chocat, INSA, and Dr. Elodie
Brelot, GRAIE.
Jiri Marsalek
Secretary of the IAHR/IAWQ
Joint Committee on
Urban Storm Drainage
Synthesis
Novatech 1995
Three years ago, there were 180 participants
and 55 papers at NOVATECH 92. Everybody thought it was a successful manifestation.
This year, we have welcome 250 participants and nearly 80 papers for NOVATECH
95. This conference is becoming a successful manifestation and a regular appointment.
I would like to thank here all the persons and organisms which contributed
to the great quality of this conference, regarded to the form as to the contents.
The excellent work of the members of the scientific committee should specially
acknowledged ; by their rigorous selection, they insure the quality of the
presentations and, moreover, of the papers published in this special issue
of Water Science and Technology. I think that, due to more and more constraints,
the "all water to sewer" system is called into question and the
natural water cycle has to be reintroduced in urbanised areas, especially
by the way of innovative technologies.
Overall, NOVATECH 95 showed that sustainable development and management of
our urban water resources demands the use of innovative and integrative techniques
to satisfactorily address the complex and interdisciplinary problems posed
by urban drainage systems. The conference also made it clear that international
exchanges are the best way to promote the setting-up of such approaches, and
I enjoy that NOVATECH constitute an opportunity for it.
The papers presented in the framework NOVATECH 95 dealt with new proposals
in the field of urban storm drainage, essentially from the following three
perspectives :
- new technologies in urban storm drainage : storage and in situ infiltration
facilities, as well as techniques for the treatment and control of wet weather
pollution ;
- - new approaches to urban water management, and new criteria taken into
account in the study of urban storm drainage : many papers were concerned
with forging links between water management as a whole (both the anthropogenic
and natural cycle components) and land use planning ;
- - analysis and prediction of the operation of the various facilities and
of the urban water cycle components the development of modelling tools (physical
as well as mathematical) and real-time control methods. We have organised
the selected papers in eight subjects.
1- Integrated management of urban rivers in the framework of drainage
strategies in built-up areas
This theme is given particular importance by B. Ellis and G. Geldof, and is
an underlying theme in several other presentations. The central question here
is to determine how to reconstitute the connection between the man-made part
of the water cycle, which is represented by the sewerage system, and the more
or less natural part, which deals with the hydrographic network.
2- Definition of new criteria and decision-making methods in the choice
of urban storm drainage strategies
Decision-making in the selection of urban storm drainage strategies is the
subject of three presentations, dealing with the following main issues :
- research on decision management criteria (J. Argue, Y. Azzout)
- - relations between planning decision and their consequences for the water
cycle
- - classical methods which have been tried and tested in other domains, e.g.
quality assessment (E. Alfakih), expert systems (Y. Azzout, J. Argue).
3- Runoff water infiltration
Infiltration facilities for surface runoff seem to warrant further research,
and particularly in semi-arid climatic zones, where they could enhance usable
water reserves, at least for irrigation purposes during dry periods (J.R.
Argue, S. Watanabe).
4- Porous pavements with reservoir structure
These techniques are becoming important, especially in France and in some
north European countries. All the studies presented confirm the capability
of these techniques to reduce peak flows and total volumes of runoff, as well
as concentrations and total masses of pollutants, even without specific pollution
control structure (J.D. Balades, V. Colandini, C.J. Pratt, M. Dakhlaoui, C.
Steninark).
5- Control and treatment of urban wet-weather effluents before discharge
The control and treatment of urban wet-weather effluents came across as one
of the high points of the conference. It is particularly widely studied in
Europe, essentially due to changes in government regulations. Several possibilities
are explored:
- the use of storage basins for settling purposes (D.I. Nicholas, D.I. Phillips,
P. Bourgogne)
- the use of vortex separators (M. Hilbner) ;
- the reduction of pollution at source (J. Sansalone)
- specific treatment processes ( C. Delporte, C. Bemard, T.H.F. Wong) : lamellar
separators, flocculation and wetlands;
- a suggestion is put forward for reducing pollution resulting from combined
sewer overflows (H.C. Preul), by storing waste water when rain is imminent;
- a paper (N. Belhadj) emphasises the importance of sewer infiltration resulting
from rain events.
6- Institutional difficulties in implementing new techniques and the
necessity of integrating them into urban planning
Several case studies, carried out on different continents, reveal a large
degree of similarity of the problems of integrating new wet-weather water
management techniques into urban planning (G. O'loughlin, I.T. Clifforde).
7- Development of new tools for data collection and studies
An initial series of papers presents a new generation of softwares for modelling
urban wet weather discharges (D. Blanc, R.I. Segarra). The principal improvements
have to do with ergonomics and userfriendliness.
The paper of A.G. Bamett deals with modelling of inundations during extreme
storms. In terms of methodology, the most significant point is the large number
of studies carried out on the use of chronological series of observed rain
events as inputs for models, associated with a statistical analysis of the
results (C. Roux, J. Raso, A. Saget). As to the design of storage facilities,
P. Bourgogne presents a study carried out in a physical-scale model, to represent
phenomenon which are difficult to be mathematically modelled.
Finally, a paper (G. Ruban) discusses a monitoring technique. The on-line
methodology proposed constitutes a considerable improvement over existing
sampling techniques.
8- Real-time management
Although real-time management was not a central theme of the conference, an
interesting cases is brought up in the paper of M. Jorgensen.
Conclusions
There are two specific conclusions which merit particular attention, and which
will be subjects of reflection in the future. The primary concern of NOVATECH
is that of applying new technologies to urban storm drainage. This leads to
the question: What do we call "new" ? The conference showed that
many new technologies have in fact nothing new about them, except the fact
that they are not highly developed, and. thus, de facts, are innovative by
comparison with conventional techniques. Many have been in use for several
decades, and some have been known for many centuries. In many cases, scientists
and engineers have acquired knowledge and skills which are adequate from the
technical point of view ; so, the obstacle to using these innovations is not
technical, but financial, social, political, etc.. If the use of these techniques
is to be generalised, the technicians will need, above all, to put their viewpoint
across to the public, and especially to the politicians and planners. The
second question, which arises from the first, is that of the utility of these
new concepts for our society. What kind of economic activity are they likely
to generate ? What services are they likely to produce ? If these questions
are of significance for the industrialised countries, they seem to be even
more relevant in developing countries, where, moreover, the new technologies
could particularly well answer the needs and problems which are to be found
there.
To provide reasoned responses to these questions would probably constitute
a powerful motor for better urban water management. These questions, which
came to the fore during NOVATECH 95, will no doubt be taken up in greater
detail during NOVATECH 98, in Lyon in 1998.
Synthesis of conferences