Transnational knowledge exchange on SUDS
case study: permeable pavement
Boogaard F.C.
*+***
, Blanksby J.**, Ven F.*, Chris Jefferies***
* Delft university of Technology. Department of Sanitary Engineering, Faculty of Civil Engineering and
Geosciences, Delft University of Technology, P.O. Box 5048, NL-2600 GA, Delft, the Netherlands
** Pennine Water Group, Department of Civil and Structural Engineering, University of Sheffield, UK
*** Tauw bv, Zekeringstraat 43 g, 1014 BV AMSTERDAM, the Netherlands
**** Urban Water Technology Centre, University of Abertay Dundee DD1 1HG
Email corresponding author: [email protected], [email protected]
KEYWORDS:
Transnational knowledge exchange, innovative SUDS, stormwater quality, maintenance, design, monitoring,
permeable pavement
ABSTRACT
Transnational knowledge exchange is an essential part of raising awareness of the performance of SUDS in
different circumstances or countries. Although the concepts of sustainable urban drainage systems (SUDS) are
widely understood, little attention has been given to how to optimize these systems to improve the hydraulic
benefits and removal efficiency of SUDS to achieve water quality and quantity standards or other aspirations.
Under the flag of the project Skills Integration and New Technologies (SKINT) UK, Norway, Germany and the
Netherlands, experiences in SUDS are being exchanged by international activities such as workshops, fieldtrips,
job rotation etc.
Examples of well constructed SUDS are quite easy to find, but failing SUDS can be more beneficial in illustrating
the consequences of poor design and construction of SUDS. Examples of the impact of poor design and
workmanship on the performance of SUDS include: reduction of the infiltration or storage capacity, reduction of
the discharge capacity and pollution of soil and groundwater. This is illustrated by an on site monitoring
programme and a review of case studies in the Netherlands where permeable pavement was clogged
immediately after construction due to bad design or construction. In general the infiltration rate of these infiltration
facilities can be high after (adequate) construction. In other cases, the infiltration capacity deteriorated over the
years and in some cases has become little different than that of regular pavement. Common failures in the
design, construction and maintenance of SUDS were gathered from several international locations and translated
to the following recommendations.
INTRODUCTION
Transnational knowledge exchange plays an important role in spreading information about and implementing
SUDS around the world, but structured transnational exchange is currently underutilized in this respect. This is
recognized in the project Skills Integration and New Technologies (SKINT) which emphasizes the need for
speaking a multi disciplinary language to integrate the worlds of spatial planning, urban design and water
management. SKINT is encouraging the implementation of innovative technical and sustainable solutions around
the North Sea Region which have already proved to be successful. It is also encouraging their adaptation for
application in circumstances different to those for which they were originally conceived
Several SUDS were tested for their hydraulic behavior and
removal rate as. These included infiltration trenches and
basins, (slow) sand filters, soakaways, ponds, swales,
stormwater wetlands and bioretention, filter strips,
sedimentation basins, (lamella) filters and permeable
pavements. International knowledge exchange in the
laboratory of TU Delft as illustrated in the adjacent picture
has taken place to show several municipalities and water
boards how SUDS function.
Several organizations were interviewed to determine their
lack of knowledge. One of the topics was ‘which criteria do
you use to determine the selection of SUDS’, the most
common criteria were:
1. removal efficiency,
2.
3.
4.
5.
6.
7.
8.
cost (building and maintenance),
required space,
experience maintenance
esthetical
robustness
life cycle analyses
sustainability
International case studies
Examples of well constructed SUDS are quite easy to find, but failing SUDS can be more beneficial in illustrating
the consequences of not designing and constructing SUDS properly. Examples of the impact of poor design and
workmanship on the performance of SUDS include: reduction of the infiltration or storage capacity, reduction of
the discharge capacity and pollution of soil and groundwater.
Examples: SUDS: lamella filter (Netherlands), sedimentation basin (Netherlands), swale (Scotland), pervious
pavement (Scotland). TUD 2011
Reviewing SUDS from different projects in Europe showed that the uncertainties in design can have a large effect
on the performance of the systems. Lack of knowledge about the functions and maintenance of SUDS leads to
diminished performance which can result in flooding or pollution of the environment.
Examples: International educational SUDS: sediment load in stormwater basin, insufficient hydraulic capacity of
swale, clogging of a infiltration system and bad construction of inflow. TUD 2011
In several countries as the UK, Germany, Norway and the Netherlands, experiences in SUDS are being
exchanged. These are described in this paper and particular attention is given to permeable pavement. It’s a
widely used system in Europe and America, but little on site monitoring data has been published and there has
been minimal exchange of experiences and recommendations to increase the lifespan of these facilities under
specific circumstances. An on site monitoring programme was carried out following a review of case studies in the
Netherlands where the permeable pavement was clogged right after construction due to bad design or
construction.
Permeable Pavement
Pervious pavements can be defined as porous pavements or permeable pavements based on the surface type.
Porous pavements can be constructed with pervious paver materials where water can infiltrate through the entire
surface area. Examples of porous pavements are grass surface pavements, gravel surface pavements and
porous (asphalt) pavements.
Permeable pavements
In the Netherlands as in other countries it can be a popular SUD to implement because it uses limited space in
dense urban areas. Most architects or urban planners are not aware of the risks of clogging of the permeable
stones or whole facility. Under specific circumstances, lack of maintenance the infiltration capacity can reduce to
the level of regular pavement in months or years. In most cases the cost of these systems are twice as much of
that of regular pavement. In some designs gullies are not mot included in order to reduce cost, butr in most cases
when clogging occurs this will lead to local flooding.
Methodology of research
The literature review resulted in experiments around the world mainly
in the laboratory or on site experimental set ups (see picture of an
experiment by the University of Abertay). Most of the results had high
infiltration rates, higher than what is determined on site. Since specific
factors are hard to simulate (eg clogging due to atmospheric
deposition and leaves) the main focus of this research was on insitu
monitoring.
The main tool for the on site experiments was the double ring
infiltrometer. The infiltrometer is a device used to measure the rate of
water infiltration into soil or other porous media. Commonly used
infiltrometers are single ring or double ring infiltrometer, and also disc
permeameter.. Since the double ring infiltrometer is the most used
method around the world from a cost effective point of view it is used
for this research to be able to compare international results.
Double ring infiltrometer requires two rings: an inner and outer ring.
The purpose is to create a one dimensional flow of water from the
inner ring. If water is flowing in one-dimension at steady state
condition, the infiltration rate is approximately equal to the hydraulic
conductivity. A second, larger ring is placed around it with the same
waterlevel to prevent horizontal flow of water from the first ring. Water
is supplied with falling head or steady state condition, and a data
logger records the infiltration rate from the inner ring into the
pavement over a given time period.
Infiltrometer – Double ring device (left), introduction permeable pavement with international projectgroup SKINT at
HHNK (water authority in North of Holland, Heerhugowaard)
After a literature review, on site measurements were carried out on 10 locations around the Netherlands. At these
locations the infiltration rate was measured on 3 different surface categories: driving lane, centre of the road and
parking lot. In interviews with manufacturers and municipalities it was stated that the infiltration rate on the driving
lane was bigger because suspended solids would be pushed out of the permeable pavement because of the
pressure of tyres leading to less clogging.
Results
In the next table the results from the literary review and on site monitoring are given. The determined infiltration
rates from permeable pavement can be very low (6 mm/h) or very high (higher than 10.000 mm/h) in different
locations. At the locations different rates where identified for the 3 different categories identified above. No
specific relation was been found to suggest that the infiltration rate of the driving lane is in general higher than at a
parking lot. The speed of cars (mostly 30-50 km/h) can be too low to have the effect of unclogging the facility by
tire pressure which is believed to occur on permeable asphalt roads.
Indication of infiltration rate in time (most permeable pavement should have infiltration rates of >1000 mm/d just
after construction according to manufacturers) TUD 2011
Table of results from different locations (most after 1 or 2 years of construction) TUD 2011
Values
(mm/h)
Several locations (7)
Type of pavement
Different
types
pavement
NL.Lelystad (Ven)
conventional pavement
Infiltrometer
9 ~352
On site
Different
pavements
Infiltrometer
100~10,000
On site
Experiment Location
NL.Utrecht
(boogaard, Rijsdijk)
Germany, TU Kaiserslautern different
locations
of
Method used
Infiltrometer, visual inspection
after rain
0-15
Note
Complaints
municipalities
from
permeable
Articifial rainfall & Infiltrometer
36~670
On site
USA, different locations
Permeable (total 4 types)
Permeable
&
Porous
Pavement
Infiltrometer**
29~40,000
On different sites
NL Urk
Permeable Pavement
Infiltrometer
83~209
On site
NL Edam
Permeable Pavement
Infiltrometer
1019~3081
On site
NL Heerhugowaard
Permeable Pavement
Infiltrometer
2372~9730
On site
NL Heiloo
Permeable Pavement
Infiltrometer
1210~1454
On site
NL Helden
Permeable Pavement
Infiltrometer
47~1120
On site
NL Meijel
Permeable Pavement
Infiltrometer
83~1703
On site
NL Rotterdam
Permeable Pavement
Infiltrometer
32~245
On site
NL Scherpenzeel
Permeable Pavement
Infiltrometer
184~848
On site
NL Schoonhoven
Permeable Pavement
Infiltrometer
155~4417
On site
NL Sliedrecht
Permeable Pavement
Infiltrometer
277~1537
On site
NL Spijkenisse
Permeable Pavement
Infiltrometer
83~342
On site
NL Stamproy
Permeable Pavement
Infiltrometer
104~1076
On site
NL Warmenhuizen
Permeable Pavement
Infiltrometer
227~5292
On site
NL Werkendam
Permeable Pavement
Infiltrometer
76~666
On site
Discussion
The example of permeable pavements illustrates the difficulties that practitioners have in accessing information
on the performance of SUDS. Information on performance and in particular, long term performance is limited and
there is a clear need to pool data. It is possible that the lack of long term data is a direct result of the way that
research projects are realised. This is not a criticism of the quality of the research methodology, but a reflection
on the way that projects are funded and how this leads to the cessation of monitoring after a limited period of
time. One way to overcome this situation is for owners and managers of SUDS to take ownership of the problem
and by working together carry out long term monitoring and pool this information to build up a an effective
knowledge base.
Conclusion and recommendations
An investigation of the functionality of permeable pavements is essential to demonstrate their contribution to the
urban water balance (local water infiltration can decrease the chance of flooding by storage and reduce loads on
the drainage systems and WWTP).
General conclusions can be drawn following a review of a wide range of products and different circumstances in
which permeable pavements have been constructed. In some cases in the Netherlands e permeable pavements
were clogged immediately after construction due to bad design and construction. In those cases, the results of
testing have been excluded, but the problem has been noted.
It can be observed from the on site experimental results that the permeable pavement in the first years after
construction have infiltration capacities to infiltrate storm water in excess of requirements. However, the rates
where lower than expected from manufactures.
In general the infiltration rate of these infiltration facilities is lower after some years of use and in some cases is
little different than that of regular pavement.
Common failures in the design, construction and maintenance of SUDS are gathered from several
international locations and translated to the following recommendations. Some of these guidelines are:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Minimise impermeable areas in the design phase;
Permeable pavement and the storage underneath should be accessible at all times for maintenance;
Proper design and use of SUDS needs adequate communication between the developers, spatial planners,
consultants, architects, engineers and inhabitants
Workmanship not only affects the serviceable life of SUDS, it affects their basic hydraulic performance
Filters can be required to prevent inflow of course particles into the system from connected roofs
Detailed documentation of storm water quality measurements and the performance of SUDS can contribute
to the enhancements of database and guidebooks
Provide controls to regulate and adjust the system after construction when possible
Provide a maintenance guidebook
A structured, means of monitoring (frequently inspecting the system) and sharing knowledge will beneficial to
the SUDS community. This could be informed by monitoring carried out during the commissioning of SUDS
measures prior to adoption of SUDS by municipalities.
More detailed research is advised in order to collect representative data on permeable pavement. The focus
should be on permeable pavements that are in use more than 2 years. We hope that owners and managers of
SUDS take ownership of the problem and by working together carry out long term monitoring and pool this
information to build up a an effective knowledge base.
1
REFERENCES
Boogaard, F Rombout, J. Kluck, J. en Wentink, R. 2007. Storm water treatment facilities. STOWA 2007-20 (In
Dutch)
Boogaard F.C., Blanksby J, de Jong J., Van de Ven, F.H.M, Optimizing and implementation of innovative SUDS
by transnational knowledge exchange, guidelines for the design & construction and operation, NOVATECH 2010
Boogaard F.C., Van de Ven, F.H.M, Palsma B, New guidelines regarding the design, operation and maintenance
of SUDS in the Netherlands, ICUD 11th, 2008
Boogaard/ Guangcheng Study on the infiltration capacity of permeable pavement TUD, 2011.
Davies J.W., Pratt C.J. and Scott M.A., 2002. Laboratory study of permeable pavement systems to support
hydraulic modelling. 9th International Conference on Urban Storm Drainage, Portland, pp13, Sep 2002, citied by
Zhang, 2006.
Dierkes, C., 2008 Pollution retention capability and maintenance of permeable pavements.
Jefferies C, Mullaney J, The performance of block paving with and without geotextile in the sub base enny
SUDSnet Conference 11/12 May 2011
Ven, F. & Dam, F., 1985. Infiltration in the pavement..Lelystad
Rijsdijk M, Boogaard F, NL. 2010 Utrecht On sit monitoring permeable pavement