Download Integrated stormwater management as a long term

NOVATECH 2013
Integrated stormwater management as a long term
strategy for preservation of building environment
La gestion intégrée des eaux pluviales comme stratégie
à long terme pour la préservation du patrimoine bâti
L. Nie1, O. P. Skallebakke2, A. Campisano3 and J. Marsalek4
1 Department of SINTEF Building and Infrastructure, Forskningsveien 3B, 0314
Oslo, Norway. [email protected]
2 Unit for Technical Operation, Fredrikstad Municipality. Postboks 1405, 1602
Fredrikstad, Norway. [email protected]
3 Department of Civil and Environmental Engineering, University of Catania,
Viale A. Doria 6, 95125 Catania, [email protected]
4 National Water Research Institute, Environment Canada. 867 Lakeshore
road, Burlington, Canada. ON L7R 4A6. [email protected]
RÉSUMÉ
La gestion des eaux pluviales est un enjeu majeur, qui affecte tant la durabilité que la qualité des
bâtiments. Les caractéristiques des eaux pluviales dépendent de plusieurs facteurs, notamment : le
climat, la topographie, la densité des constructions, la population, les types d'occupation des sols, et
le plan d'urbanisme municipal. La rapide urbanisation, parallèlement à des planifications inappropriées
concernant l'utilisation des sols, ont mené aujourd'hui à des conséquences négatives telles qu'une
augmentation du risque d’inondation (et des dommages associés), augmentation de la pollution et des
émissions de gaz à effet de serre. L'observation de ces problèmes et des défis associés incitent à
trouver de nouvelles solutions durables et intégrées. Le présent article, plutôt que de décrire dans le
détail une méthodologie et ses résultats, présente un exemple d'une stratégie de gestion intégrée des
eaux pluviales. L'expérience menée dans la ville de Fredrikstad en Norvège y est décrite pour montrer
comment la gestion des eaux pluviales est prise en compte dans le développement urbain, depuis la
simple unité de bâtiment, jusqu'à des échelles plus larges (locales et municipales). Le plan municipal
de gestion des eaux pluviales, associé à la législation en vigueur, les instructions techniques, et
l'expérience pratique, permet de formuler une base de recommandations pour la gestion intégrée des
eaux pluviales comme stratégie à long terme en vue de la préservation du patrimoine bâti.
ABSTRACT
Stormwater management is a key factor that affects the sustainability and quality of life of the built
environment; meanwhile the characteristics of stormwater is influenced and reshaped by the climate,
topography, density of buildings, population, types of land use, and municipal planning. Due to rapid
urbanization and inappropriate planning of land use development, the interactions between these
different factors have resulted in negative consequences, such as increased risk of flooding and
resulting damage, pollution, and Green House Gas (GHG) emissions. The observed problems and
emerging challenges call for sustainable and integrated solutions. This paper rather than presenting
deeply a research methodology and associating results, demonstrates an approach of integrate
stormwater management strategy. It uses the experience in the city of Fredrikstad in Norway,
illustrates how stormwater management is implemented during urban planning and building
development process, from a single building unit to local and municipal scales. A municipal strategic
stormwater management framework plan together with legal Acts and technical guidelines, and
practical experience formulates a basis of recommendations for integrated stormwater management
as a long term strategy for sustainable urban planning.
KEYWORDS
Climate, Ecosystem, Infrastructure, Stormwater management, Sustainability, Urban planning
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1
INTRODUCTION
Stormwater in urban areas was traditionally managed by designed sewer systems for the prevention of
the collection of excess water on urban surfaces and the reduction of risk to people, health, property,
society and the natural and built environment. However, the existing sewer systems in European
central cities were designed 50 – 100 years ago. They are aging and require rehabilitation or upsizing.
As observed globally, climate change has caused more frequent extreme climate events, such as
more intense precipitation period in one region or long drought period in another region, as well as
extremes in temperature. Moreover, urbanization has caused more people are moving to urban areas
that requires development of previously lightly or undeveloped land, replacing pervious with
impervious surfaces. Consequently vegetation areas are thereby replaced by impervious building
roofs, roads and parking places, resulting in increasing of urban runoff. This development also results
in an urban island effect, with deterioration of the sustainable building environment due to large energy
consumption, increased CO2 emission to the environment, and a decrease in biodiversity, and
damage to ecosystems.
Because of the challenges described above, stormwater management has evolved over time from a
focus on water quantity or flood control, to water quality (pollution) control, and more recently to
include recreation, aesthetic and water reuse aspects (Walesh, 1989; Wang, 2012). Therefore
Sustainable Urban Drainage Systems (also called Best Management Practice (BMPs) or Blue-Green
(BG) solutions) have been accepted globally as measures to adapt to or counter changes in the
climate and the effects of urbanization. They have been applied in many countries, e.g. EPA
Stormwater water management program. One can find all types of information in a range of manuals
of stormwater retrofit and BMP, regulations, guidelines and case studies, and municipal and industrial
information.
Literature shows the benefits of the adoption of various stormwater management approaches in Italy.
Stormwater detention tanks with various design configurations (online and outline) and operating
conditions have been integrated to the sewer system all along the peninsula which has demonstrated
good performance with respect to environmental pollution (Todeschini et al., 2012). Also BMP
techniques mainly based on the use of vegetated roofs on the top of public buildings in urban areas
have been setup and tested in northern and central Italy showing to be able to mitigate storm water
runoff generation in terms of runoff volume reduction, peak attenuation and increase of concentration
time (Fioretti et al., 2010). Other emerging techniques based on the use of rainwater harvesting tanks
have been recently tested by Campisano and Modica (2012), pointing out the possibility to use such
techniques as tools to improve the sustainability of drainage systems by mitigating the generation of
storm water runoff at the source and to limit the demand of potable water in houses. EU project
prepared demonstrates the adaptation of SUDS in different countries and a case study of RWH in
Turkey (Aldea et al., 2012)
According to the feedbacks gathered from the participating cities being investigated in the project
PREPARED, most of the cities have experienced problems related to aging such as sewer
obstructions, cracks or collapse, and insufficient drainage capacity. SUDS have been applied
extensively in the cities of Aahus of Denmark, Lyon of France and Barcelona of Spain (Aldea et al,
2012), but are not common in other other participating cities. In Norway some pilot projects applying
stormwater management BG solutions have been performed in the newly developed areas (Lindheim,
2009; Tekna, 2012). A pilot research project testing infiltration basin in Sandli, Bergen has been
reported by Thorolfsson et al. (1997) with some success. Some retention basins have been also
established in the Oslo region in order to reduce the heavy metal pollution from main roads to the
rivers (Åstebøl and Hvitved Jacobsen, 2006). However, practice is not common in existing building
areas. Municipalities plan to disconnect surface stormwater inflow from private building areas to the
public sewer systems (in fact some municipalities like Fredriksatd have already implemented it), which
will require building owners to retain or infiltrate stormwater in private areas by grass land, rain garden
or permeable or semi-permeable surface or private roads, or to construct infiltration trenches and
basins, or use green roofs, etc. Although plenty of information and international experience is available
for implementation of SUDS, it is unknown whether local areas have the potentials to accommodate
the surface water by detention and infiltration measures. Solutions have to be found according to the
local conditions.
This paper presents an integrated approach that brings together legislation, municipal strategies for
urban planning, technical guidelines for stormwater management from the scale of an individual
building unit to the neighborhood, and from local areas (subcatchments or catchments) to the
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NOVATECH 2013
municipal level, taking into account climate change and urbanization impacts on stormwater quantity
and quality and ecological issues and the interdependency of critical infrastructure networks. The
approach is demonstrated in a case study in Fredrikstad of Norway.
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INTEGRATED STORMWATER MANAGEMENT APPROACH
2.1
Important issues to be considered
2.1.1
Stormwater runoff
Stormwater is water generated from precipitation during rain and snowmelt events. Stormwater
runoff is water flowing over land or impervious surfaces that does not percolate into the ground. As
the runoff flows over the surfaces (such as paved streets, parking lots, and building rooftops) it also
accumulates debris, chemical particles, sediment or other pollutants that could adversely affect water
quality if the runoff is discharged without treatment. Inappropriate stormwater collection and disposal
may cause urban flooding and pollution to the recipients and urban natural environment.The primary
method to control possible negative consequences caused by stormwater is the use of Low Impact
Development measures (LIDs, also called SUDSs or BMPs) during urban planning
process.Stormwater management.
2.1.2
Objectives of urban stormwater management
Primary objectives of urban stormwater are defined as follows:

Protection of life and lessening the risk on public health and safety

Reducing the risk of floods and monetary damage to private and public properties

Minimizing the disruption on community affairs and indirect consequences

Protecting the quality of surface and ground water resources

Enhancing the quality of life in urban areas

Managing the water in the contexts of physical, chemical, bio-ecological and sustainable
perspectives.
2.1.3
Integration of stormwater management with other types of urban infrastructure
Important urban infrastructure usually includes the utility systems that supply public services, such as
electricity, water supply and drainage systems, heating and gas supply systems, transportation,
telecommunication; and the systems that provide for welfare and social and economic service such as
hospitals, financial centres, as well as systems for safety and emergency services such as fire
stations, police stations, flood warning and forecasting systems and associating buildings (Gordon and
Dion, 2008; Lhomme et al., 2012). In the contexts of stormwater management in the built environment,
the urban sewer system (also called minor system) and the road system (also called major system)
and electric power system are the most relevant. A failure in one system (or its components) may
cause a chain of failures in other systems, e.g. the electric power distribution system may be cut
during flooding or storm surge because of strong wind and heavy precipitation, which may cause
failure to operate the pumping stations of the drainage system or failure to lift the gates of the
spillways. Similarly inundation of the pumping station may cut off the electric supply systems, causing
further flooding and related consequences. In order to make the city more resilient in the face of
various natural disasters or system failures the linkages between different infrastructure network
systems should be considered during city planning.
2.2
Integrated stormwater management approach
Given the above-mentioned considerations, a comprehensive stormwater management and their
interaction with buildings, important infrastructures and other influence factors are illustrated in Figure
1. In order to ensure appropriate implementation of the framework at difference levels and scales
during the urban development process, a holistic approach is introduced in Figure 2.
This paper uses the city of Fredrikstad as an example, illustrates how the stormwater is handled in the
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municipality from strategy to urban planning and how various measures are implemented in practice.
Roads
Buildings
Urban drainage systems
Integrated stormwater
management
Climate
Social economy
Lakes, rivers and streams
Open surface
Figure 1. Integration of stormwater management with important infrastructure and other important factors
Water course Act
Legislation at national level
Pollution control Act
Integrated stormwater management
Planning and Building Act Water resources and land use planning
Regulation and planning at municipal level level
Regulation on flood and pollution control
Harmony of building development and landscape
Non‐structural measures
Dams and flood ways ( e.g. rivers or streams)
Rehabilitation of minor and major drainage systems
SUDS measures at municipal, local and individual levels
Implementation of Blue‐green solutions
Control of stormwater runoff quality and CSOs Restoration of urban bio‐ecological systems
Figure 2. A holistic approach for integrated stormwater management in different levels in Norway
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NOVATECH 2013
3
3.1
CASE STUDY
Fredrikstad
Fredrikstad is situated in the South of Norway. It has population of over 75 000 and total area of 289
km2. The largest river in Norway – Glomma passes by the city before its tributary merges to the sea
while the main branch goes to the Øster River. Thus, the city has contact with sea and in the right side
of river Glomma. The soil is dominated by bedrock and clay in the city areas. The groundwater level is
very shallow, which can be 1-2 m below the surface. The potential for infiltration of stormwater is low in
the city area.
The mean monthly temperature varies from -3.1 oC in January to 16.7 oC in July. Total annual
precipitation is 825 mm in average. Intense precipitation in very short time periods (10-15 min) have
been observed in recent years (Skallebakke, 2011) and projections of the future climate scenarios
indicate that the city will be exposed to more frequent heavy rain events and sea level rise and storm
surges (Hanssen-Bauer, et al., 2009).
Before 1978 there was no technical guideline for sewer design in Norway. The stormwater drainage
system in the urban areas has been developed based on a principle that leads the stormwater as
quickly as possible to the underground sewer systems and discharges it to the nearest receiving
waters. From 1978 to 1998 the sewers were designed based on a guideline mandated by the National
Pollution Control Authority (SFT, 1978), according to design rains with return periods of 1 in 10 to 15
years. Since 1998, the design standard of EN 754 was adopted as a national standard for design
outdoor urban drainage systems in Norway (NS-EN 752, 1998).
About 20% of water and wastewater (including stormwater) systems (WWS) in Fredrikstad was
developed before 1940, for which no written information is available. According to the statistics of the
municipality (FM, 2010), from 1940 to 1979 the WWS was developed steadily with an increase of less
than 10% in each decade. The development of the water and wastewater infrastructure after 1980
increased at double the rate of previous decades. About 40% of sewers carry combined flow.
Climate change and recent quick urbanization have caused significant increase of surface stormwater,
subsequently more inflow was discharged to the sewer system than it was designed to be, which have
caused waterlogging in local areas, basement flooding and pollution in the recipients.
These challenges call for sustainable stormwater management both in the existing and new
developing areas, taking into account of the water quantity, quality and ecological and environmental
aspects.
3.2
Assessment of climate change impacts on urban drainage systems
After the severe flood event in 2002 (65 mm rain in six hours, the return period of the event is
estimated more than 100 years) caused more than 250 house basements flooded and total economic
damage of about 17 million Norwegian crowns (equivalent to 2.1 million EURO (Lindholm et al, 2006),
several other flooding events occurred in in 2006, 2007, 2008 and 2009 in the city. The IntensityDuration-Frequency (IDF) has been an important factor indicating the change of climate. Figure 4
presented the changes of IDF curve calculated according to the historical events (control period) and
according to the projected scenarios (2071-2100) (Nilsen, 2013). A stantistics showing that the intense
storm event in 2008 has a higher intensity than the values for 100 years' flooding (Skallebakke, 2012).
Climate change impacts on the sewer system in Veumdalen catchment of Fredrikstad have been
continually studied since 2002 (e.g. Røysted and Lindholm, 2006; Tøndel, 2007; Nie et al., 2009;
Myking, 2012). These studies provided some assessment results of the potential consequences with
regard to the given climate scenarios, mainly increase of precipitation intensities and change of air
temperature. The main consequences are waterlogging in local areas and flooding of house
basements and resulting erosion and contamination problems.
3.3
Integrating stormwater
development process
management
in
the
municipal
building
Since large economic damages have been caused in buildings and private properties in the building
basements, as well as the project scenarios of climate change, stormwater management has been an
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important issues in the overall municipal urban development planning. In 2007 Fredrikstad
municipality worked out a comprehensive stormwater management plan as a municipal strategy.
Operation
Implementation of measures
Final plan
Obligated announcement and evaluation
Preliminary plan
Land use classification
Municipality Plan
According to the national Planning and Building Act (DM, 2008), the municipality introduces standard
process to control and supervise building development process from planning to implementation (or
construction) and operation stage (Fig.3). This ensures the efficient implementation of the legislation
and municipal strategies regarding land use, stormwater management, flood and pollution control.
Advices, approval and control from technical units
Figure 3. Progress plan for building application and implementation
3.4
Stormwater management and sustainable solutions
In order to support municipalities and building owners to handle stormwater safely and sustainably,
technical guidelines of stormwater management have been made in water, building and transportation
sectors (Lindholm et al., 2008; Statens Vegvesen, 2011; Hafskjold,L.S. 2012). Based on the legal
Acts and the sectoral guideline for stormwater management, large municipalities have made their own
regulation plan and technical guideline and norms for stormwater management and promotion of
various SUDS solutions (Oslo VAV, 2011).
These guidelines recommend municipalities to take into account stormwater management in
municipality’s plan for development, such as (1) the municipality should plan for storm runoff that
cannot be drained by the underground sewers, to be handled on surface; (2) applying sustainable
urban drainage solutions (SUDS) such as infiltration, retention and detention solutions and green
infrastructure. The SUDS should be incorporated into all levels at the municipalities’ area planning; (3)
the stormwater cannot be handled by stormwater measures will be conveyed in open floodways (major
drainage systems) without causing significant damages. The return period of design rains for the
analysis of safe open flood ways should be 100 years; (4) polluted storm runoff should be treated
before to be discharged to receiving water bodies.
In combination the technical guidelines with the practical situations in Fredrikstad, several stormwater
control measures have been implemented in the municipality.
3.4.1
Disconnection of roof stormwater
In order to diminish the risk of basement flooding and overflow from public sewers, stormwater from
3000 building roofs have been disconnected from public sewers. For single house with garden, they
lead the roof water to the garden for infiltration (although it can be difficult in wet seasons, and low
infiltration potential because of the hard bedrock and clay, and high ground water levels). Each
building owner has received subsidy from the municipality about 400-500 NOK for the implementation
of a single measure (Figure).
3.4.2
Pipe detention
In the existing building areas without gardens, the owners are recommended to use large pipe (D=12m) as a detention but with small outlet in order to control the discharge to the trunk sewers.
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NOVATECH 2013
3.4.3
Domestic rainwater harvesting
Because of the geological and soil condition, as well as high groundwater level in Fredrikstad, the
potential for infiltration of stormwater is low, especially in wet seasons. In order to control the
stormwater discharge to the terrain from building roofs and other impervious surface, the authors
examined the potential benefits of applying domestic rain water harvesting (DRWH) techniques based
on the retention and reuse of the collected rain water from the rooftop. Preliminary simulations for the
present climate condition during control period (1961-1990) and scenario periods (scenario IS92A for
period 2013-2042; scenario A2 for period 2071-2100) have been specifically run. For scenario A2, the
simulation results indicate that for given stormwater reuse demand in the house (d=0.2, 0.5, 1.0 and
2.0), the overflow discharge to urban surface can be reduced up to 25%, 55%, 90% and 100%
depending on the DRWH system hydraulic characteristics and size (for frequency level fi =0.75). The
methodology for the analysis of the benefits of the DRWH systems is introduced by Campisano and
Modica (2012). The DRWH model and a testing case carried out in Oslo, Norway were presented in
another paper (Campisano, et al, 2013). Simulation results based on a similar approach obtained in
Fredrikstad are presented in Figure 4. Based on the simulation results, the authors suggest the
municipality investigate potential to use Domestic Rain Water Harvesting (DRWH) tanks or ponds as a
retention option to reduce the surface runoff and discharges to the sewer systems.
Figure 4. Overflow discharge (Ov) values as function of reuse factor (d) and retention factor (Sm)
(where f is the exceedance frequency) for scenario A2 (2071-2100)
3.4.4
Re-open the closed rivers
During 50-60 years, some rivers are closed and replaced by culverts or underground tunnels. Because
of the effects of climate change and urbanization, the importance of having free water surface in the
urban neighbourhood and restoration of natural floodways have been realized in more recent years. It
is vital for restoration of the natural biological and ecological environment and consideration of
aesthetic and recreative use of urban landscape, and also for flood control. Green, nourishment
aquatic vegetation and infiltration areas will be important for the purification of polluted storm water
and reduce surface runoff. In the future, the municipality will give priority to the following principles for
stormwater management:
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
Stormwater systems should preferably be open rather than closed systems. Where appropriate,
consideration will be given to open existing stream that was closed some decades ago.
Reopening Veum stream is such an on-going project.

In built-up areas, storm water to the greatest extent should be possibly dealt with at the source
through retention and infiltration, e.g. green roof, rain beds or rain gardens.
Upon renewal of surface water systems and existing infrastructures, solutions that make the water
visible and establish free surface water self-treatment basins or tanks (from urban areas and main
roads, etc.) and measures that replace impervious road shoulders by permeable materials should be
given priority.
4
DISCUSSIONS AND RECOMMENDATIONS
Integrated stormwater management has proven vital to the restoration of sustainable urban
landscapes and preservation of a sustainable built environment, in particular to adapt to the impacts of
urbanization and climate change. This paper also indicates that it is important to take into account the
interaction of stormwater management with buildings and the other urban infrastructure networks like
electricity, roads and buildings.
Several adaptive SUDS measures applied in practice in Fredrikstad are introduced in this paper. Reopening of the closed river and stream sections, disconnecting roof water and using large pipes as an
option for detention are popular measures in Fredrikstad and other municipalities in Norway.
Because of sufficient fresh water resources, reuse of stormwater and DRWH are not common practice
in Norway. However concerning on the potentials for stormwater detention in building areas, and
reduction of inflow to public sewer systems, the use of Rain Water Harvesting (DRWH) tanks or ponds
as a retention option should be further investigated, e.g. use DRWH in combination with rain beds and
rain garden are recommended to be investigated in the near future.
Norway is a country situated the most north in the world. It has both continental and maritime climate,
i.e. heavy rain in very short time in summer or autumn, sometimes in winter, long rain period in
autumn, rain and snowmelt in early or late spring, which complicates the application of SUDS
solutions. The pilot studies show that most measures perform well; special care has to be taken for
long and cold winter seasons during planning, construction, operation and maintenance stages.
ACKNOWLEDGEMENT
This paper presents the result from the project BIVUAC- Building and Infrastructure Vulnerability and
Adaptive Capacity to Climate Change (07.2010-06.2013). Authors thank the financial support by the
Research Council of Norway through the research program NORKLIMA.
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