Prof. dr. ir. Timo J. Heimovaara
Advantages of the Amazing
Sub-Surface
Intreerede
1 februari 2013
T
J
Delft
DelftUniversity of Technology
Advantages of the Amazing Sub-Surface
Intreerede
Uitgesproken op vrijdag 1 februari 2013 ter gelegenheid van de aanvaarding van
het ambt van Hoogleraar Geo-Environmental Engineering aan de faculteit Civiele Techniek en Geowetenschappen van de Technische Universiteit Delft
door
Meneer de Rector Magnificus, Leden van iiet College van Bestuur,
Collegae Hoogleraren en andere leden van de universitaire gemeenschap. Zeer gewaardeerde toehoorders,
Dames en heren,... Ladies and gentlemen,
I am honoured that so many of you have found the time to come and listen to my inaugural lecture. The title of this lecture is "Advantages of the Amazing Sub-Surface" and during this lecture I hope to share my fascination with the sub-surface with you. This fascination started at the end of my 2nd year in Wageningen during a field work around the "Zoom", a former cliff coast in the southern part the Netherlands near Bergen op Zoom. During this field work we studied many different soil profiles and I became fascinated by the process of soil formation. The consequence was that when returning to Wageningen I decided to switch from regional soil science to soil chemistry. During my career I developed an appreciation for the adaptive qualities of soils, and in general the sub-surface, which eventually led me to stand in front of you today. During this lecture I will also explain to you how I view the field of "geo-environmental engineering" as many of you have asked me what it is that I do for a living.
Sub-surface Reactivity
Geo-environmental engineering initially developed as a field focused on cleaning up contaminated soils which are a legacy of our industrial past. In the Netherlands geo-environmental engineering really kicked off with the pollution scandal at a new neighbourhood in Lekkerkerk in 1979 [van Grinsven (2010)]. The neighbourhood was built on a chemical waste dump and settlements caused a drinking water pipe to break which led to a soil investigation. The scandal was all over the media and subsequently received a lot of political attention. As a result the polluted soil was removed from beneath the houses within a year in what was one of the fastest Dutch soil remediation projects ever. The visit to the project by queen Beatrix was her first official public appearance after her inauguration, and as a result television footage of this happening went all over the world. This scandal was the trigger that eventually led to the development of the Dutch law on soil protection which was effected in 1987, last year we celebrated it's 25'th anniversary.
In the early 1980s we assumed that the number of sites with soil pollution in the Netherlands would be limited and that all these sites could be remediated to so-called multi-functional conditions, meaning fit for all possible uses. However,
1990s, government, consultants, contractors and academia started developing concepts in which risk, fitness for specific use and spatial context were put central. I was lucky to be part of this effort during my time at IWACO, Royal Haskoning and later at Groundwater Technology B.V.
Before I go on with the Reactive Properties of the Sub Surface I need to introduce a short intermezzo on environmental impact and recovery times. During the 1950s and the 1960s western societies began to realise that environmental pollution was damaging our health and measures were implemented in order to prevent further pollution. The initial focus was on air and water quality and the effort was a big success: it is hard to imagine that in the 1960s the river Rhine was nearly a dead river, many fish species had disappeared. Nowadays even salmon has returned [BBC (2004); Pawlowski et al. (2012)].
io,ooa_, S ioooi E 0) CO E o oc 1 0 0 _ J 10_ M e t e o r s t r i k e I n d u s t r i a l G r o u n d w a t e r p o l l u t i o n e x p l o i t a t i o n U r b a n i z a t i o n s a l i n i z a t i o n M o d e m V o l r a n i r a g r i c u l t u r e F l o o d f^"^^^ A c i d S l a s h a n d b u m r L a n d s l i d e F o r e s t O i l spill ^ A t o m i c b o m b T s u n a m i V L i g h t n i n g I I I i i l| I M I l l j I I I l l l j I I I I I l j — I I I I I lj 1 M I M | — I I M l l | 10^ 1 10 Spatial scaie (km^) ICQ 1000 10,000
Figure 2: The relation between the spatial scale of natural and anthropogenic disasters and their approximate expected time to recovery. Figure taken from Dobson (1997).
Here in Western Europe we have been very successful in improving our air quality, but other parts of the world still suffer from severe air pollution. For example, in January 2013 the air quality in Beijing was so bad that the January 14th edition of the Dutch Newspaper NRC stated "Smoking is healthier than breathing the air in Beijing", see figure 1. However, removing the source of the 5
the risk. Research in to the behaviour of contaminants in the sub-surface also showed that many of these contaminants were naturally degraded, and for some contaminants this was really a big surprise! Natural attenuation of contaminants occurs under many conditions and as a result, many sites posed a smaller risk than we initially thought. Management of soil contamination became a remediation measure in itself, but one that requires a significant amount of time and (sub-surface) space.
The implementation of the Dutch soil policy during the 1990s led to significant innovation in soil remediation technology. Universities, consultants, contractors, and site owners worked together in the NOBIS and SKB research programs. Many of the colleagues I worked with in these programs I now may call my friends.
Figure 3: Soil core from near Almere showing many buried soils.
During these years we started to realise that the subsurface is an ecosystem, abundant with life. As the natural subsurface is very poor in energy sources for life (food), any addition of a substrate that potentially contains energy which is suitable to grow on, will cause the system to adapt in order to benefit from this substrate. It is the life present in the sub-surface which causes the soil pollution to slowly disappear. The pollution is degraded by the living sub-surface! The soil core in figure 3 was sampled near Almere and is a clear example that the
function. I^any of these processes lead to so-called ecosystem services provided by the sub-surface to our present day society [Technische Commissie Bodem (2012)]:
• biomass production, including agriculture and forestry;
• storing, filtering and transforming nutrients, substances and water; • biodiversity pool, such as habitats, species and genes;
• physical and cultural environment for humans and human activities;
• source of raw materials;
• acting as carbon pool;
The concept of ecosystem services for the sub-surface has led to the development of a holistic framework in which all activities and processes in the subsurface can be integrated. Given the fact that the recovery time of the sub-surface to disturbances is very long, we have to be very careful about using the sub-surface for our needs. Figure 5 is from the Dutch foundation SKB illustrating many kinds of sub-surface use. Clearly not all of them are sustainable, some are essential and many activities indicate a possible conflict!
Figure 5: Different types of present day use of the sub-surface
The concept of ecosystem services provides a coherent framework which can be used in order to organize the multiple use of the sub-surface, it enables us to weigh the consequences of certain choices. The sub-surface should be used within the context of sustainability such that current use should not impact the opportunity for future generations to use the sub-surface as they deem necessary. Ecosystem thinking also opens up the opportunity for ecosystem engineering: Can we optimize the properties of the sub-surface for societies benefit? What does this mean for sustainability?
process while maintaining the major benefits. We aim to develop the process in order to strengthen the sub-surface in order to prevent piping in dikes and liquefaction as these issues are important failure mechanisms.
Figure 6: Stromatolites found at Shark Bay Australia
In another project (Biological Corrosion Protection, BioCoPro) we aim to tailor naturally occurring processes in the sub-surface to develop a self-healing protective layer on underground structures such as steel pipes, and sheet pile walls. Corrosion is a huge problem for these constructions. We know that micro-organisms can precipitate solid minerals on and in the neighbourhood of structures. The goal in this project is to understand what these processes are, and specifically develop engineering approaches to control these processes. Our vision is to develop a self growing and self-healing protective layer which is ecologically compatible. Because this type of research is multidisciplinary, we collaborate in this project with researchers from the University of Utrecht and the Netherlands Institute of Ecology in Wageningen.
Other opportunities which we are investigating are concepts where micro-organisms in the sub-surface are used to produce acids which leach valuable minerals from ore deposits. This technique may result in a different way of 11
completely different flow regime etc. We aim to solve these issues by making use of numerical models which we link to smart measurements in a so-called data assimilation approach. These approaches have become feasible because of the ever increasing computing power.
nm |jm mm m
10-9 10-8 lQ-7 IQ-e lQ-5 IQ-A lQ-3 lQ-2 I^Q-l ^QO ^Ql
Molecules Enzymes
Membranes
Figure 7: Bridging a wide range of scale
Although I have been talking about the amazing properties of the sub-surface and the advantages this brings society, I have to acknowledge the fact that Salomon Kroonenberg also mentioned in his valedictory speech: "two major disadvantages of tlie sub-surface are tiiat it is not transparent and it is very difficult to access''. Both these properties make it very difficult to do research in the sub-surface. Therefore we need to develop methods to obtain the required information. Most of the time it is impossible to directly measure the property we are interested in. During my PhD-research I worked on using electromagnetic signals in order to measure the frequency dependent dielectric properties of soils. These properties could then be used to estimate how much water was present in the soil. Currently we are further developing this technique to quantify the disturbance of clay while sampling and the growth of microbial biofilms in unsaturated porous media.
Another example of measurement technology is shown figure 8. The photograph shows a set-up developed by Suze-Anne Korteland for her PhD research. Her goal was to use electrical current to quantify the flow of water and dissolved solutes in the soil column. Together with Kees van Beek, she developed a very fast Electrical Resistivity Tomography (ERT) measurement system which collected a large amount of data which she interpreted with a number of
advanced numerical models. In figure 8c we see an interpretation of the three dimensional results obtained with this measurement system. The graphs with the lines show breakthrough curves of stream lines at different positions within the column. Clearly the flow in the column is not homogeneous and using this analysis Suze-Anne was able to indicate that the velocity in the flow varied throughout the column which is illustrated in the cross-section plots marked with V at different depths z. We aim to use this type of measurement technique to provide insight in the three dimensional processes that occur within the sub-surface and to control the (biological) boundary conditions in geo-environmental eco-engineering solutions.
this we need to accept that we are changing the quality of the sub-surface. Implementing regulations in order to limit these changes to tight bandwidths may prove to be counter productive because the dynamics of the sub-surface are often very different from the dynamics above. There is no such thing as a free iunch and we must be clear about how much quality reduction we want to accept and how long this impact should be allowed to last. In addition, an important issue we need to worry about is what we are going to do about the consequences of the large amount of infrastructure we installed in the ground for many types of different activities: tunnels, foundations, wells for water, oil and gas, heat and cold storage systems, etc. The life expectancy of these systems is in the range of 50 to 100 years. What are we going to do with the infrastructure after the useful life-span? Are we going to leave the installations in place or remove them completely? What are we going to do with the holes we made? Clearly answering these questions requires more input than we, engineering scientists, can provide. Implementation of these novel principles requires a multidisciplinary effort where (geo)engineers need to collaborate with economists, social scientists and regulators to make things acceptable and work. This requires a beta-gamma research program which is driven by stake holders striving for a sustainable use of the subsurface.
Education in the context of the exponentially growing amount of digital information
Although it seems that many scientists working within a university have a different perception, an important task of the university is to educate young people. At the TU Delft these are future engineers and more and more future scientists. The average time a Dutch student stays at the TU Delft in order to obtain a masters degree is 7.2 years [TU Deift (2012)1 which has been so for a very long time. Currently society no longer accepts this situation and we, the academic community, are obliged to change our approach to education in order to have our students graduate faster. The current goal is to have the majority of the students obtain their bachelors degree within 4 years and their masters degree within 6 years.
In order to achieve this goal, a major restructuring of our bachelor programs is under way. We strive to introduce active learning concepts in our education, which is a challenge when you have 300-h students in your class rooms. Luckily we are living in a unique era, information on the topics we want to teach our students is easily available. The amount of information accessible from digital media is doubling every two years leading to an exponential growth in the
The photograph in figure 11 is an image that we will be seeing more and more at the Delft University of Technology as more and more students enrol in our programs. Students come to the lecture and take a seat. Those in front try to be active, those more to the back attend lectures with an idea to interact with their friends and fellow students. Especially in the morning, some students tend to dose of quite easily. I visited a conference on education in January 2013 and one of the one liners that stuck with me was: "The only place where students sleep more than in their own bed is in your lecture room...". Perhaps it is true, I hope to find an alternative approach before I give by valedictory lecture.
Figure 11: Full lecture theatres
Dankwoord
Ik ben aan het eind van mijn oratie gekomen en wil graag een aantal mensen bedanken. Interessant werk, leuke projecten, uitdagend onderzoek, dit kan mijns inziens alleen als je het geluk hebt om met goede mensen samen te werken. Ik heb het geluk gehad om heel veel interessante en leuke mensen als collega tegen te komen. Allereerst wil ik de leiding van de afdeling Geoscience & Engineering en de faculteit Civiele Techniek en Geowetenschappen bedanken voor het vertrouwen dat zij stellen in mij en het inzicht dat geo-environmentai engineering een belangrijke toevoeging is aan het onderzoek en onderwijs binnen de geo-engineering. Ik was in 2007 blij verrast met de mij geboden kans om alsnog een academische draai te geven aan mijn carrière. Ik wil hierbij met name Stefan Luthi en Louis de Quelerij noemen. Ik ben Hans Bruining zeer dankbaar voor de mij gegunde vrijheid om mijn eigen richting te zoeken en de mogelijkheid om in de luwte een groep op te bouwen zodat ik nu hier voor jullie mag staan.
Mijn eerste ervaring met wetenschappelijk onderzoek was tijdens een stage die ik heb gelopen bij het US Salinity Laboratory in Riverside California. Rien van Genuchten had middelen beschikbaar gesteld zodat ik kon komen. Ik kreeg de volledige vrijheid om mijn nieuwsgierigheid te volgen en ik dook op een nieuwe
Wit, maar oolc andere mensen met een verfrissende blik op het probleem van de ondergrond zoals Harry Vermeulen en Sietze Keuning. Deze collega's maar ook alle anderen hebben mij gevormd en in mijn huidige positie profiteer ik nog dagelijks van alle inzichten die ik in deze tijd heb opgedaan.
Veel dank ben ik verschuldigd aan mijn vrienden. Sportvrienden, tennis en hockey, onze wekelijkse uurtjes zijn voor mij prima momenten om tot rust te komen en op een andere manier fanatiek te zijn. Mijn jaarclub, NnO, wij hebben elkaar zien ontwikkelen, lachen elkaar nog regelmatig uit en weten alles weer in het juiste perspectief te brengen. De familie van Duijn is uitermate belangrijk voor mij. Bert en Mei, zoals Bert al zei in zijn oratie in Leiden, onze beslissing nu meer dan 18 jaar geleden om een oppasregeling te starten heeft perfect gewerkt. Naast alle flexibiliteit die we hebben genoten is er de allergrootste bonus: Anna en Julia zijn een deel van mijn gezin geworden!
Mijn moeder neemt een heel speciale plaats in in mijn hart. Niet alleen heeft ze mijn zusje, mijn broer en mij alleen weten op te voeden, ze heeft het fantastisch gedaan. Ik vind het altijd fijn als je bij ons bent.
Tot slot mijn gezin, jullie zorgen ervoor dat het leven een feest is, Sjoukje, Joosje, en Fenneke zoals beloofd: tot slot danken wij Dautse!
Ik heb gezegd!
Advantages of the Amazing Sub-Surface
Intreerede
Uitgesproken op vrijdag 1 februari 2013 ter gelegenheid van de aanvaarding van
het ambt van Hoogleraar Geo-Environmental Engineering aan de faculteit Civiele Techniek en Geowetenschappen van de Technische Universiteit Delft
door
Meneer de Rector Magnificus, Leden van het College van Bestuur,
Collegae Hoogleraren en andere leden van de universitaire gemeenschap. Zeer gewaardeerde toehoorders.
Dames en heren,... Ladies and gentlemen,
I am honoured that so many of you have found the time to come and listen to my inaugural lecture. The title of this lecture is "Advantages of the Amazing Sub-Surface" and during this lecture I hope to share my fascination with the sub-surface with you. This fascination started at the end of my 2nd year in Wageningen during a field work around the "Zoom'; a former cliff coast in the southern part the Netherlands near Bergen op Zoom. During this field work we studied many different soil profiles and I became fascinated by the process of soil formation. The consequence was that when returning to Wageningen I decided to switch from regional soil science to soil chemistry. During my career I developed an appreciation for the adaptive qualities of soils, and in general the sub-surface, which eventually led me to stand in front of you today. During this lecture I will also explain to you how I view the field of "geo-environmental engineering" as many of you have asked me what it is that I do for a living.
Sub-surface Reactivity
Geo-environmental engineering initially developed as a field focused on cleaning up contaminated soils which are a legacy of our industrial past. In the Netherlands geo-environmental engineering really kicked off with the pollution scandal at a new neighbourhood in Lekkerkerk in 1979 [van Grinsven (2010)]. The neighbourhood was built on a chemical waste dump and settlements caused a drinking water pipe to break which led to a soil investigation. The scandal was all over the media and subsequently received a lot of political attention. As a result the polluted soil was removed from beneath the houses within a year in what was one of the fastest Dutch soil remediation projects ever. The visit to the project by queen Beatrix was her first official public appearance after her inauguration, and as a result television footage of this happening went all over the world. This scandal was the trigger that eventually led to the development of the Dutch law on soil protection which was effected in 1987, last year we celebrated it's 25'th anniversary.
In the early 1980s we assumed that the number of sites with soil pollution in the Netherlands would be limited and that all these sites could be remediated to so-called multi-functional conditions, meaning fit for all possible uses. However,
Maskers op in Beijing tegen dikke smog
Beijing is in de greep van een gevaarlijke smog van 'postapocalyptische' afmetingen. Als het even kan zoeken buitenlanders hun heil in Shanghai.
Dooronze correspondent BEIJING. Een dikke, bruingele mist van kolendampen, uitlaatgassen cn woestijnzand bedreigt de gezond-heid van de bewoners van Beijing en 77 andere steden in centraal- cn noordelijk China. Het Bcijingse Ge-meentelijk Milieucentrum zag de luchtvervuiling vanaf vrijdag verer-geren van 320 m iaogram kleine stof-deeltjes per kubieke meternaar raeer d.in 700. Het meetstation op het dak van de Amerikaanse ambassade zag de teller uitslaan naar meer dan 900 microgram per kubieke meter. Dat zijn dc hoogste metingen sinds cr in de hoofdstad apparatuur is geïnstal-leerd om fijns tof tc meten.
De
Wcreldgezondhddsorganisa-• ^ Wcreldgezondhddsorganisa-• Wcreldgezondhddsorganisa-•
vuiUng van dc lucht met microsco-pisch kleine stofdeeltjes een norm van ZS microgram per kubieke me-ter. Deze Ideine stofdeeltjes kunnen diep doordringen in de longen. Ge-schat wordt dat jaarlijks in China als gevolg van de luchtvervuiling.
De vuile mist die wordt veroor-zaakt door explosieve stijgingen van dekolcnconsumptieinelcktrlcitciis-centralcs cn het autobezit in Chiii.i. calyptischc sfeer", aldus een bloggcr. Een andere inwoner stelde vast dat
Het is gezonder om te roken dan om de lucht van Beijing te ademen
„het gezonder is om te roken dan dc lucht van Beijing in icidemcn'.
Gebouwen werden on, door dc luchtvervuiling en op lucht-havens waren grote vcrtrnuingen. Ucwoners bleven binnen. De vervui-ling, die zal aanhouden tot dc wind op wocnsd.-ig draal t, is zo ernstig dat dc autoriteiten gedwongen worden noodmaatregelen tc nemen. Door de publieke druk kunnen zij het pro-bleem niet langer ontkennen, zoals in het nabije verleden werd gedaan. Nieuw Is dat ookde Chinese media uitgebreid cn zeer kritisch aandacht schenken aan het problcan. 'Heal-thy debate over air', kopte de ailna
Daily. Zelfs dc censuur hield zich
ge-deisd: Greenpeace China kreeg ruim dc Eclegenhcid de overheid te bekri-tiseren en tc hcri n neren iun de woor-den van presiwoor-dent Hu Jlntao, die vo-rig jaar zei dat dc ecologische vernie-tiging van China gestopt moet wor-den. Volgens Greenpeace zijn alle
De (kyline van Bc«lng op een normale das (bovcn) cn vandaag. Foto's Reuters
maatregelen die vier j.iar geleden werden bewoners gemaand binnen crogram fijnstof per kubieke meter huizen van Beijing naar Slianghai. werden genomen om dc lucht te zui- te blijven cn maskers cnluchtverve^ rebtief minder alarmerend. Dat Is VolgensMcrcercnHaysclscnenkrij-veren tijdens de Olympische Spelen singsapparatuur aan te schaffen. Zo- ook de reden waarom het personecU- gen expaa vanwege de luchtvervul-teruggcdraald. wel op internet als In winkels vond bureau Mcrccrcn Hays heeft vastge-
llngeDdevoedselkwallteitookhoge-In alle grote steden in noordclUk een run plaats op deze apparaten. llngeDdevoedselkwallteitookhoge-In stcld dat buitenlandse werknemers re vergocdinRcn voor het werken llngeDdevoedselkwallteitookhoge-In China, Beijing en Tlanjln voorop. Shanghai is de situatie met 175 mi- in China als zij de kans krijgen ver- China dan elders In AziU.
Figure 1: Articie from NRC edition 13 January 2013 [Garscliagen (2013)].
as policy was being made, and information was being gathered on the soil quality, it became apparent that the number of contaminated sites was much larger than initially expected. Eventually, in 2005, when the inventory of soil pollution by all industrial and commercial activities in the Netherlands (using historical records for municipalities) was completed, potential contamination of soil and groundwater could have occurred at about 400 000 sites throughout the Netherlands. During the second half of the nineteen eighties and early nineteen nineties it turned out that costs of soil investigation and remediation to meet the criteria of multi-functionality were so high that society was not prepared to pay. As a result spatial development at polluted sites stopped causing a multitude of societal problems. Another approach was needed. During the mid
1990s, government, consultants, contractors and academia started developing concepts in which risk, fitness for specific use and spatial context were put central. I was lucky to be part of this effort during my time at IWACO, Royal Haskoning and later at Groundwater Technology B.V.
Before I go on with the Reactive Properties of the Sub Surface I need to introduce a short intermezzo on environmental impact and recovery times. During the 1950s and the 1960s western societies began to realise that environmental pollution was damaging our health and measures were implemented in order to prevent further pollution. The initial focus was on air and water quality and the effort was a big success: it is hard to imagine that in the 1960s the river Rhine was nearly a dead river, many fish species had disappeared. Nowadays even salmon has returned [BBC (2004); Pawlowski et al. (2012)].
10,OOQ_ 1 0 0 0 _ l 1 0 0 _ J 10-4 S l a s h a n d b u m f- L a n d s l i d e I n d u s t r i a l G r o u n d w a t e r pollution e x p l o i t a t i o n U r b a n i z a t i o n S a l i n i z a t i o n M o d e m a g r i c u l t u r e c , ^ . V o l c a n i c „ F o o d .. A c i d e r u p t i o n . A t o m i c ''^"^ F o r e s t b o m b T s u n a m i O i l spill ^ L i g h t n i n g r T n | I I I I M| I I I M lj I l i I l l j — I I I I I lj—I 1 1 1 i i | — I 1 1 1 i i | 10^ 1 10 Spatial scale (km^) 100 1000 10,000
Figure 2: Tiie relation between the spatial scale of natural and anthropogenic disasters and their approximate expected time to recovery. Figure taken from Dobson (1997).
Here in Western Europe we have been very successful in improving our air quality, but other parts of the world still suffer from severe air pollution. For example, in January 2013 the air quality in Beijing was so bad that the January 14th edition of the Dutch Newspaper NRC stated "Smoking is healthier than breathing the air in Beijing", see figure 1. However, removing the source of the
pollution quickly leads to improvement of the environmental quality because the flow of air and water leads to a quick dispersion of the pollution. As a result the recovery time of these systems is short. We recently experienced this during the Olympic games in Beijing, the air quality recovered quickly as a result of very stringent measures taken by the authorities forcing air polluting activities to temporarily close down.
For soil and groundwater contamination, recovery times are completely different. Figure 2 shows a graph illustrating the recovery time and spatial scales of a number of environmental impacts on soil. The ovals illustrate events with a natural cause, the rectangles are related to human causes. I would like to draw your attention to the right hand side of this graph, here we see that human activities on the sub-surface have consequences on a very large spatial scale which require a very long time to recover from the damage.
A close-by example is the soil contamination in the Dutch and Belgian Kempen region with Zinc and Cadmium. The source of this contamination was the presence of several Zinc smelters where emissions occurred via exhaust fumes and via utilization of the slags from the ovens as road foundations. The result was wide spread soil contamination. Currently a major effort is being carried out to remediate several hot-spots, but it will take the eco-system in this region at least several decades to hundreds of years to recover from the diffuse contamination. Sediment in the river Rhine is another example: although the water quality has significantly improved, the (deeper) sediment is still burdened with the contamination from the past, disturbing this sediment leads to the release of this contamination to the water.
Now we return back to the topic of soil pollution. Remember that the large number of contaminated sites in the Netherlands was too much to handle and a more pragmatic approach was required. This approach was called Risk Based Land Management. The basis of this approach is to quantify the risk associated with the soil contamination and see if this is a problem for the foreseen use of the site. Risks include impact on human health and the environment which we subdivide in the ecosystem and groundwater. If risks are unacceptable immediate remediation is required, if risks are acceptable, then measures are required to prevent further spreading of the contamination. When in the future the use of the site changes, further remediation may take place during redevelopment.
Introducing Risk Based Land Management also stimulated the development of novel in-situ remeditation techniques, which mainly were aimed to reduce
the risk. Research in to the behaviour of contaminants in the sub-surface also showed that many of these contaminants were naturally degraded, and for some contaminants this was really a big surprise! Natural attenuation of contaminants occurs under many conditions and as a result, many sites posed a smaller risk than we initially thought. Management of soil contamination became a remediation measure in itself, but one that requires a significant amount of time and (sub-surface) space.
The implementation of the Dutch soil policy during the 1990s led to significant innovation in soil remediation technology. Universities, consultants, contractors, and site owners worked together in the NOBIS and SKB research programs. Many of the colleagues I worked with in these programs I now may call my friends.
Figure 3: Soil core from near Almere showing many buried soils.
During these years we started to realise that the subsurface is an ecosystem, abundant with life. As the natural subsurface is very poor in energy sources for life (food), any addition of a substrate that potentially contains energy which is suitable to grow on, will cause the system to adapt in order to benefit from this substrate. It is the life present in the sub-surface which causes the soil pollution to slowly disappear. The pollution is degraded by the living sub-surface! The soil core in figure 3 was sampled near Almere and is a clear example that the
surface of the Netherlands is heterogeneous, we find clay layers, layers with fine sand, layers with course sand and peat layers. Some layers show evidence of buried soils. Soils are teeming with life and when these soils get buried, the life present in the soil gets buried as well. Luckily enough, the microbial communities in the sub-surface do not die and disappear, the communities slow down until they are fed with contamination!
The Dutch Soil Protection Policy was finalized around 2005 and is a pragmatic approach based on a standstill approach (prevent new soil pollution from occurring) and the polluter pays principle (the polluter is fully liable for any contamination after 1987). Historical soil pollution should be managed according to the Risk Based Land Management approach where the fit for use principle is implemented. As a consequence, the Dutch market for soil remediation has grown up and become mature which is illustrated by the number of soil remediation projects in 2009 shown in figure 4. In this market there is very limited space for innovation and very limited interest in fundamental research. So why now become a professor in Geo-Environmental Engineering? Who will benefit from the results from our research?
Figure 4: Soii remediation sites in the Netheriands in 2009 [RIVM (2009)].
Ecosystem Services
The natural capacity of the sub-surface to degrade soil and groundwater pollution let us realise that the subsurface is an ecosystem in its own right. Application of ecosystem theory to the subsurface led to the insight that it is the presence of a multitude of inter related processes that allows the system to
function. I^any of these processes lead to so-called ecosystem services provided by the sub-surface to our present day society [Technische Commissie Bodem (2012)]:
• biomass production, including agriculture and forestry;
• storing, filtering and transforming nutrients, substances and water;
• biodiversity pool, such as habitats, species and genes;
• physical and cultural environment for humans and human activities;
• source of raw materials;
• acting as carbon pool;
The concept of ecosystem services for the sub-surface has led to the development of a holistic framework in which all activities and processes in the subsurface can be integrated. Given the fact that the recovery time of the sub-surface to disturbances is very long, we have to be very careful about using the sub-surface for our needs. Figure 5 is from the Dutch foundation SKB illustrating many kinds of sub-surface use. Clearly not all of them are sustainable, some are essential and many activities indicate a possible conflict!
Figure 5: Different types of present day use of the sub-surface
The concept of ecosystem services provides a coherent framework which can be used in order to organize the multiple use of the sub-surface, it enables us to weigh the consequences of certain choices. The sub-surface should be used within the context of sustainability such that current use should not impact the opportunity for future generations to use the sub-surface as they deem necessary. Ecosystem thinking also opens up the opportunity for ecosystem engineering: Can we optimize the properties of the sub-surface for societies benefit? What does this mean for sustainability?
Geo-environmental engineering is now moving away from a field providing end-of-pipe solutions by repairing the damages caused by human activity. In this domain of end-of-pipe solutions, geo-environmental engineering is primarily considered to be a cost and seldom an opportunity. Increased understanding of processes in the sub-surface enables us to develop new means of using the subsurface, providing society with added value, without reducing the quality of the surface in the long run. We have to realise that any use of the sub-surface will change the system, the challenge we face is to find approaches which balance the negatives with the positives while taking sustainability criteria in to account. Geo-environmental engineering is the field that will provide society with these opportunities!
Novel Solutions
One of the privileges of leading a research group at a university is that you have the opportunity to work with excellent and creative colleagues. Leon van Paassen is one of these. An Australian group found a biological process to use micro-organisms to catalyse the precipitation of calcite in porous media in order to strengthen the structure in sands. The photograph in figure 6 shows stromatolites in the Shark Bay on the coast of Australia (wikipedia). Stromatolites are formations of biogenic origin where biofilms trap particles and cement these together using a biological mediated precipitation of calcium carbonate. Leon's PhD-research aimed to develop an engineering concept based on this Australian biogenic calcite precipitation process that can be used in real projects. In 2010 this process was applied in a demonstration project where a horizontal drilling was used to install a gas pipe of the Gas Unie under a rail road and a canal. The project was carried out by Visser & Smit Hanab and Deltares. One of our students was involved in monitoring the biogrout process for his MSc thesis project. At this specific site, the drilling had to be performed in a gravel layer. Horizontal drilling through gravel is virtually impossible, as the grouting fluid required to keep the hole open, can easily flow away through the gravel. Using biogrout to cement the gravel stones together prevents the collapse of the bore hole. Although the project was a success, the process used is not very sustainable, as high amounts of ammonium chloride are produced which have to be removed after the biogrouting process has completed.
Currently four PhD students are working in a project called BioFix where the aim is to develop a next generation biogrout process which is based on utilizing naturally occurring micro-organisms and naturally occurring nutrients and electron-acceptors. The aim is to reduce the environmental impact of the
process while maintaining the major benefits. We aim to develop the process in order to strengthen the sub-surface in order to prevent piping in dikes and liquefaction as these issues are important failure mechanisms.
Figure 6: Stromatolites found at Shark Bay Australia
In another project (Biological Corrosion Protection, BioCoPro) we aim to tailor naturally occurring processes in the sub-surface to develop a self-healing protective layer on underground structures such as steel pipes, and sheet pile walls. Corrosion is a huge problem for these constructions. We know that micro-organisms can precipitate solid minerals on and in the neighbourhood of structures. The goal in this project is to understand what these processes are, and specifically develop engineering approaches to control these processes. Our vision is to develop a self growing and self-healing protective layer which is ecologically compatible. Because this type of research is multidisciplinary, we collaborate in this project with researchers from the University of Utrecht and the Netherlands Institute of Ecology in Wageningen.
Other opportunities which we are investigating are concepts where micro-organisms in the sub-surface are used to produce acids which leach valuable minerals from ore deposits. This technique may result in a different way of
mining. We no longer need to dig a hole in order to extract the ore from the subsurface. In stead we pump the leachate with the valuable minerals using a series of wells. How to do this in an environmentally sound way is of-course a huge challenge.
Finally, our environment is facing many pressures which reduce the environmental quality. Remediation and protection of our environment still require a significant effort in the future. We would like to work on those environmental problems which are specifically related to geo-engineering and which are large scale. Examples are related to mine-waste, landfills, and tailings related to oil extraction from tar sands. Currently three PhD-students and a Post-doc are closely collaborating with Dutch landfill operators and the Dutch government in a STW project where we are developing concepts for stabilising landfill waste bodies in order to achieve a sustainable after-care of these sites. The current regulatory approach to landfill after-care is based on the concept of eternal after-care where every 50 to 60 years the final cover on the landfill needs to be completely replaced. This is a significant burden for future generations. We have found that natural processes occurring within the waste body lead to the reduction of emission levels. If we can reduce the emission potential to a level where emissions no longer are a risk to human health and the environment, a situation may arise where we may stop with the landfill after-care. The research focuses on developing tools with which we can monitor and predict how the emission potential decreases when landfill stabilisation technology is being implemented in existing sanitary landfills.
Research
Ecosystem engineering in the geo-environmental context is a very fruitful research field. Although, approaches we are developing are being applied in practice, much understanding of the details is still lacking. A major challenge of this research field is to bridge the wide range of scales illustrated in figure 7. Much fundamental research is being done at the scale of individual pores in the porous media. Upscaling this knowledge to the application scale (tens of meters) is a real challenge. We are currently working on developing concepts where we try to link local understanding of degradation of organic matter within a landfill to the consequences this degradation has on the emission of landfill gas en landfill leachate at the scale of a complete landfill. We describe the degradation processes at the scale of a laboratory batch reactor (in the order of 1 litre) and want to interpret the results for a landfill of 50 hectares and 15 meters depth. This is a scale difference of 7.5-10^ which leads to several challenges which we have to face such as how to handle heterogeneity, the
completely different flow regime etc. We aim to solve these issues by making use of numerical models which we link to smart measurements in a so-called data assimilation approach. These approaches have become feasible because of the ever increasing computing power.
nm pm mm m
10-9 lQ-8 IQ.6 10-5 IQ-A lQ-3 10-2 ^Q-l
Molecules Enzymes
Membranes
Figure 7: Bridging a wide range of scale
Although I have been talking about the amazing properties of the sub-surface and the advantages this brings society, I have to acknowledge the fact that Salomon Kroonenberg also mentioned in his valedictory speech: "two major disadvantages of the sub-surface are that it is not transparent and it is very difficult to access". Both these properties make it very difficult to do research in the sub-surface. Therefore we need to develop methods to obtain the required information. Most of the time it is impossible to directly measure the property we are interested in. During my PhD-research I worked on using electromagnetic signals in order to measure the frequency dependent dielectric properties of soils. These properties could then be used to estimate how much water was present in the soil. Currently we are further developing this technique to quantify the disturbance of clay while sampling and the growth of microbial biofilms in unsaturated porous media.
Another example of measurement technology is shown figure 8. The photograph shows a set-up developed by Suze-Anne Korteland for her PhD research. Her goal was to use electrical current to quantify the flow of water and dissolved solutes in the soil column. Together with Kees van Beek, she developed a very fast Electrical Resistivity Tomography (ERT) measurement system which collected a large amount of data which she interpreted with a number of
0^,2=0.15 cm a.^, 2=0.15 cm V. 2=0.15 cm a . 2=0.15 cm
-10 -5 0 5 10 -5 0 5 -40 -20 Ó 20 40 -100 -50 0 50 100
(%) (%) (%) (ro) (c) 3D interpretation of solute break through
Figure 8: ERT tank experiment of Suze-Anne Korteland
advanced numerical models. In figure 8c we see an interpretation of the three dimensional results obtained with this measurement system. The graphs with the lines show breakthrough curves of stream lines at different positions within the column. Clearly the flow in the column is not homogeneous and using this analysis Suze-Anne was able to indicate that the velocity in the flow varied throughout the column which is illustrated in the cross-section plots marked with V at different depths z. We aim to use this type of measurement technique to provide insight in the three dimensional processes that occur within the sub-surface and to control the (biological) boundary conditions in geo-environmental eco-engineering solutions.
Figure 9 provides a schematic overview of my vision that in geo-environmental eco-engineering we aim to develop methods where we use naturally occurring processes to modify properties within the sub-surface. Properties which we may change are: mechanical strength, flow characteristics, environmental quality, heat storage capacity, leaching properties, binding capacity and reactivity. Due to the inaccessibility we can only achieve this by forcing the boundary conditions of the system. Forcing can be done by the flow of water and gases in order to control the transport of dissolved components and perhaps even (nano) solids. In some cases attempts have been done to influence the local biological diversity by introducing novel micro-organisms although I believe a better approach is to allow the natural biodiversity to adapt to the new conditions which develop as a result of the applied boundary conditions.
dissolved compounds
water
sub-surface ecosystem
heat solid material
micro-organisms
- mechanical strength - flow characteristics - environmental quality - heat storage capacity - leaching properties - binding capacity - reactivity
Figure 9: Engineering tfie sub-surface properties by controlling boundary conditions
Sustainability is an important issue when we consider that the sub-surface is a sensitive system. Using natural processes in order to change the properties of the sub-surface, automatically ensures ecological compatibility. In general, the idea should be that although we change the system, the general ecosystem services provided by the sub-surface should remain intact. For example, changing the strength by biogrout should not reduce the permeability to such levels that flow can no-longer occur or that micro-organisms can no longer degrade soil and groundwater pollution. Keeping this in mind and defining sustainability in the context of utilizing ecosystem services will always remain a challenge. Using the sub-surface for heat and cold storage in efficient heating and cooling systems, requires us to increase the temperature in the sub-surface. As soon as we allow 16
this we need to accept that we are changing the quality of the sub-surface. Implementing regulations in order to limit these changes to tight bandwidths may prove to be counter productive because the dynamics of the sub-surface are often very different from the dynamics above. There is no such thing as a free iunch and we must be clear about how much quality reduction we want to accept and how long this impact should be allowed to last. In addition, an important issue we need to worry about is what we are going to do about the consequences of the large amount of infrastructure we installed in the ground for many types of different activities: tunnels, foundations, wells for water, oil and gas, heat and cold storage systems, etc. The life expectancy of these systems is in the range of 50 to 100 years. What are we going to do with the infrastructure after the useful life-span? Are we going to leave the installations in place or remove them completely? What are we going to do with the holes we made? Clearly answering these questions requires more input than we, engineering scientists, can provide. Implementation of these novel principles requires a multidisciplinary effort where (geo)engineers need to collaborate with economists, social scientists and regulators to make things acceptable and work. This requires a beta-gamma research program which is driven by stake holders striving for a sustainable use of the subsurface.
Education in the context of the exponentially growing amount of digital information
Although it seems that many scientists working within a university have a different perception, an important task of the university is to educate young people. At the TU Delft these are future engineers and more and more future scientists. The average time a Dutch student stays at the TU Delft in order to obtain a masters degree is 7.2 years [TU Deift (2012)1 which has been so for a very long time. Currently society no longer accepts this situation and we, the academic community, are obliged to change our approach to education in order to have our students graduate faster. The current goal is to have the majority of the students obtain their bachelors degree within 4 years and their masters degree within 6 years.
In order to achieve this goal, a major restructuring of our bachelor programs is under way. We strive to introduce active learning concepts in our education, which is a challenge when you have 300+ students in your class rooms. Luckily we are living in a unique era, information on the topics we want to teach our students is easily available. The amount of information accessible from digital media is doubling every two years leading to an exponential growth in the
digitally available information. Figure 10 illustrates the growth in digitally stored information since the early nineteen eighties, when I started my academic career as a student in Wageningen.
20001 ^ ^ ^ 1
2020 Year
Figure 10: Exponentiai growtti of digitai information in exabytes (10^^ bytes)
Clearly, in the early nineteen eighties mass lectures were an efficient means to transfer state-of-the-art knowledge to large audiences. Nowadays we may question this efficiency as there is so much state-of-the-art information readily available, much more than we ever can address in a lecture. Modern day students are also very apt at acquiring this information, even while we are teaching these classes. I am convinced that we need to change the way we use the lectures. We need to adopt an educational approach where students are challenged to acquire the knowledge we want them to learn from these readily available sources by self-study, alone or in groups. The lectures then should illustrate applications and address the issue how to identify which knowledge is of high quality and which is garbage. Much of the codified information is of questionable quality, even though it has passed "peer review". Our role as educators should be to provide our students with sufficient knowledge, skills and a critical attitude to information so that they will be confident in acquiring the knowledge they require in order to be successful in their future career. I like to think that my students require about 5 to 10 years in order to achieve the level that my generation was able to achieve in 20 years. In other words, I hope that my graduates will be 4 times more efficient than I was. The readily available information is one of the key technologies they can use for this.
The photograph in figure 11 is an image that we will be seeing more and more at the Delft University of Technology as more and more students enrol in our programs. Students come to the lecture and take a seat. Those in front try to be active, those more to the back attend lectures with an idea to interact with their friends and fellow students. Especially in the morning, some students tend to dose of quite easily. I visited a conference on education in January 2013 and one of the one liners that stuck with me was: "The only place where students sleep more than in their own bed is in your lecture room...". Perhaps it is true, I hope to find an alternative approach before I give by valedictory lecture.
Figure 11: Full lecture theatres
Dankwoord
Ik ben aan het eind van mijn oratie gekomen en wil graag een aantal mensen bedanken. Interessant werk, leuke projecten, uitdagend onderzoek, dit kan mijns inziens alleen als je het geluk hebt om met goede mensen samen te werken. Ik heb het geluk gehad om heel veel interessante en leuke mensen als collega tegen te komen. Allereerst wil ik de leiding van de afdeling Geoscience & Engineering en de faculteit Civiele Techniek en Geowetenschappen bedanken voor het vertrouwen dat zij stellen in mij en het inzicht dat geo-environmentai engineering een belangrijke toevoeging is aan het onderzoek en onderwijs binnen de geo-engineering. Ik was in 2007 blij verrast met de mij geboden kans om alsnog een academische draai te geven aan mijn carrière. Ik wil hierbij met name Stefan Luthi en Louis de Quelerij noemen. Ik ben Hans Bruining zeer dankbaar voor de mij gegunde vrijheid om mijn eigen richting te zoeken en de mogelijkheid om in de luwte een groep op te bouwen zodat ik nu hier voor jullie mag staan.
Mijn eerste ervaring met wetenschappelijk onderzoek was tijdens een stage die ik heb gelopen bij het US Salinity Laboratory in Riverside California. Rien van Genuchten had middelen beschikbaar gesteld zodat ik kon komen. Ik kreeg de volledige vrijheid om mijn nieuwsgierigheid te volgen en ik dook op een nieuwe
meet methode voor het meten van watergehalte en elektrische geleidbaarheid in de bodem. Terug in Nederland moest ik mij verantwoorden bij de afdeling bodemnatuurkunde aan de Wageningen universiteit. Waarom kenden ze mij niet terwijl ik een bodemnatuurkunde stage had gedaan. Als genoegdoening vond de afdeling dat ik de capita selecta bodemnatuurkunde moest volgen, wat ik met veel plezier heb gedaan.
In Wageningen studeerde ik af op een onderwerp bij bodemscheikunde, het modelleren van adsorptie aan Goethiet. Ik kreeg wederom zeer veel vrijheid van mijn begeleiders, Tjisse Hiemstra en Willem van Riemsdijk. Blijkbaar was ik overtuigend, want Willem liet mij zijn eigen PC gebruiken, die dingen waren nogal schaars in die tijd. Dit is cruciaal geweest in de ontwikkeling van mijn vaardigheden. De kennis van programmeren die ik heb opgedaan tijdens mijn afstudeeronderzoek is van groot belang geweest voor de start van mijn promotieonderzoek later.
Direct na mijn afstuderen kon ik beginnen aan een onderzoek aan de Universiteit van Amsterdam. Willem Bouten en Koos Verstraten hebben een zeer grote invloed gehad op mijn visie op onderzoek, de koppeling van het wetenschappelijke aan het praktische, "monitoren is meten en modelleren". Ik heb een zeldzaam mooie tijd gehad tijdens mijn promotie onderzoek en het genoegen gesmaakt om precies op het juiste moment aan een onderwerp te werken dat in de belangstelling stond en dit te mogen doen in een goede en inspirerende groep. Nog steeds kom ik mensen tegen die refereren naar de resultaten die we toen hebben geboekt. Ook heb ik veel geleerd van de manier waar Willem en Koos met zijn tweeën een onderzoeksgroep hebben gestuurd, ik hoop daar in mijn groep de vruchten van de kunnen plukken.
In 1996 heb ik besloten om de universiteit te verlaten om mijn blikte verruimen. Ik mocht aan de slag gaan bij IWACO, een milieu advies bureau dat later is overgenomen door Royal Haskoning. Hier heb ik zeer veel geleerd van een groot aantal mensen. Veel van mijn toenmalige collega's en concurrenten reken ik tot mijn vrienden. Een aantal mensen wil ik met name noemen: Stefan Ouboter en Peter Doelman, beiden inmiddels overleden. Stefan heeft mij leren inzien hoe een consultant werkt door samen met mij naar klanten gaan en direct na afloop het verloop van de vergadering door te nemen. Mijn wetenschappelijke benadering was in veel gevallen niet de meest effectieve, luisteren, niet één van mijn sterkste vaardigheden, was iets dat ik toen heb geleerd en waar ik later veel profijt van zou krijgen. Peter was een gepassioneerd mens die een diep geloof had in het leven in de ondergrond. Samen met Bert Satijn introduceerde hij mij in de wereld van NOBIS en SKB. Hier ontmoette ik collega's zoals Han de
Wit, maar ook andere mensen met een verfrissende blik op het probleem van de ondergrond zoals Harry Vermeulen en Sietze Keuning. Deze collega's maar ook alle anderen hebben mij gevormd en in mijn huidige positie profiteer ik nog dagelijks van alle inzichten die ik in deze tijd heb opgedaan.
Veel dank ben ik verschuldigd aan mijn vrienden. Sportvrienden, tennis en hockey, onze wekelijkse uurtjes zijn voor mij prima momenten om tot rust te komen en op een andere manier fanatiek te zijn. Mijn jaarclub, NnO, wij hebben elkaar zien ontwikkelen, lachen elkaar nog regelmatig uit en weten alles weer in het juiste perspectief te brengen. De familie van Duijn is uitermate belangrijk voor mij. Bert en Mei, zoals Bert al zei in zijn oratie in Leiden, onze beslissing nu meer dan 18 jaar geleden om een oppasregeling te starten heeft perfect gewerkt. Naast alle flexibiliteit die we hebben genoten is er de allergrootste bonus: Anna en Julia zijn een deel van mijn gezin geworden!
Mijn moeder neemt een heel speciale plaats in in mijn hart. Niet alleen heeft ze mijn zusje, mijn broer en mij alleen weten op te voeden, ze heeft het fantastisch gedaan. Ik vind het altijd fijn als je bij ons bent.
Tot slot mijn gezin, jullie zorgen ervoor dat het leven een feest is, Sjoukje, Joosje, en Fenneke zoals beloofd: tot slot danken wij Dautse!
Ik heb gezegd!
Bibliography
BBC (2004), BBC - european environmental inequalities case study - rivers: Rhine: Strategies, "http://www.bbc.co.uk/scotland/education/int/geog/ eei/rivers/rhine/strategies".
Dobson, a. R (1997), Hopes for the future: Restoration ecology and conservation biology. Science, 277 (5325), 515-522, doi:10.1126/science.277.5325.515. Garschagen, 0. (2013), Maskers op in Beijing tegen dikke smog,
maandag 14 januari 2013 | NRC Handelsblad | NRC Digitale editie. Pawlowski, S., 1 Jatzek, T. Brauer, K. Hempel, and R. Maisch (2012), 34 years of investigation in the Rhine River at Ludwigshafen,
Germany; trends in Rhine fish populations. Environmental Sciences Europe, 24 (1), 28, doi:10.1186/2190-4715-24-28.
RIVM (2009), Jaarverslag monitoring bodemsanering over 2009; een rapportage van de bevoegde overheden bodemsanering, Tech. rep.. Ruimte en Milieu, Ministerie van Volkshuisvesting en Ruimtelijke Ordening.
Technische Commissie Bodem (2012), Advies beter besluiten met ecosysteemdiensten, Tech. rep.. Technische Commissie Bodem. TU Delft (2012), Delft university of technology:
Sneller studeren - niet makkelijker, "http://tudelft.nl/nl/actueel/laatste-nieuws/ artikel/detail/sneller-studeren-niet-makkelijker".
Van Grinsven, H. (2010), NBV canon van de nederlandse bodemkunde: Lekkerkerk (1979), "http://www.bodems.nl/canon/venster-25.php".
