Mining activities in a coastal zone: Effects and remedial measures in the Netherlands

(1)

8th INTERNATIONAL CONFERENCE ON COASTAL AND PORT ENGINEERING IN DEVELOPING COUNTRIES

COPEDEC 2012, IIT Madras, Chennai, INDIA. 20-24 Feb. 2012

Mining activities in a coastal zone

Effects and remedial measures in the Netherlands

K. d'Angremond1 and J.P. van de Water2

Abstract: In July, 1959, the presence of gas in the subsoil of the Province of Groningen in the ex-treme NE part of the Netherlands was confirmed. Subsequently, it became clear that the mining of the gas would result in considerable subsidence and a disruption of the drainage system of an area adjacent to the North Sea, and situated already partly below sea level.

To prevent damage on land, extensive remedial measures were designed and carried out. The cost of the remedial measures was compensated under a special agreement between the stakeholders and the mining company. In this way lengthy and costly court procedures could be avoided.

In 1994, new gas reserves were found under the Wadden Sea, a part of the North Sea that is shielded by a long row of barrier islands along the Dutch, German and Danish coast. The Wadden Sea is a Wetland Area according to the Ramsar Wetland Convention and a protected nature conser-vation area under European legislation. It took about 10 years to get these reserves nevertheless into production due to political discussions and court proceedings filed by NGO’s and others.

Based on scientific studies and the outcome of an advice from independent experts in 2004, all par-ties involved were willing to find a way out of the deadlock situation. Eventually, agreement was reached between the mining company, the national and local Government and the NGO’s. The aim of the agreement was to ensure that gas production could not lead to deterioration of the ecological qualities of the Wadden Sea. Also financial means were provided to support improvements to the quality of the area.

By listening to each other, and focussing on a positive outcome for all parties involved, here again, further lengthy and costly court procedures could be avoided. In 2007 gas production from locations under the Wadden Sea has commenced.

Keywords: mining, coastal zone management, subsidence, water management, damage com-pensation, nature conservation, protection of habitats.

INTRODUCTION

In July, 1959, the presence of gas in the subsoil of the Province of Groningen in the extreme NE part of the Netherlands was confirmed (See Figure 1). The company that made the successful boring was Nederlandse Aardolie Maatschappij (NAM), a joint venture of Shell and ExxonMobil. The find proved

1 Emeritus Professor of Coastal Engineering, Delft University of Technology, Delft, the Netherlands, Email::k.dangremond@xs4all.nl.

2 Senior Legal Counsel , Nederlandse Aardolie Maatschappij BV, Assen, The Netherlands, Email: pie-ter.vandewater@shell.com .

(2)

Proceedings of COPEDEC 2012, 20-24 February 2012 Mining activities in a coastal zone; Effects and remedial measures in the Netherlands

later to be the largest onshore gas field of mainland Europe (> 3000 billion cubic meter of natural gas). The reservoir was situated at a depth of about 3 km in a sand stone layer. Political and com-mercial discussions delayed the exploitation for 4 years. But even in 1963 (granting year of the pro-duction licence), the actual propro-duction of gas had to wait until a pipeline network for delivery throughout the country and further into Europe would be completed. That took roughly another 5 years.

Fig. 1. Map of the Netherlands with Groningen Province in the far North-East (from Wikipedia) It was not before 1971, that it became clear that the production of large quantities of gas would result in considerable subsidence. This would have a serious effect on the water management in the sensitive coastal zone in the Province of Groningen. At that time, a subsidence of about 1 m was expected in the centre of the gas field, while the diameter of the subsiding area would be in the or-der of 40 to 50 km. This would not result in directly visible effects because of the very gentle slopes, but the subsidence could have serious effects on the protection against flooding during storms surges, the drainage of the area and shipping facilities. Figure 2 shows the extent of the area where subsidence is expected. The maximum subsidence is estimated for 2070 at the end of the gas pro-duction and amounts according to the latest calculations to about 0.5m.

Eventually in 1983, NAM entered into an agreement with the Province of Groningen, the latter act-ing also on behalf of local water boards and the Port of Delfzijl/Eemshaven, now Gronact-ingen Sea-ports. The company agreed to monitor the subsidence and to compensate damage. Other private parties could (and still can) become participants in the agreement.

Adjacent to above mentioned Groningen gas field, new substantial gas discoveries were made in 1994. The extent of the new fields is shown in Figure 3. These discoveries were under the Wadden Sea a part of the North Sea that is shielded by a long row of barrier islands along the Dutch, German and Danish coast. The Wadden Sea is a Wetland Area according to the Ramsar Wetland Convention. The European Union designated the Wadden Sea as Special Area of Conservation (SAC) and as Spe-cial protection Area (SPA). SpeSpe-cial Areas of Conservation (SACs) are strictly protected sites desig-nated under the EC Habitats Directive. Article 3 of the Habitats Directive requires

(3)

Mining activities in a coastal zone; Effects and remedial measures in the Netherlands

Fig. 2. Present prognosis for subsidence in Groningen gas field in 2070 (courtesy NAM) the establishment of a European network of important high-quality conservation sites that will make a significant contribution to conserving the 189 habitat types and 788 species identified in Annexes I and II of the Directive (as amended). The listed habitat types and species are those considered to be most in need of conservation at a European level. Special Protection Areas (SPAs) are strictly pro-tected sites classified in accordance with Article 4 of the EC Birds Directive, which came into force in April 1979. They are classified for rare and vulnerable birds (as listed on Annex I of the Directive), and for regularly occurring migratory species.

Fig. 3. Wadden Sea gas fields

Initial debates about this new gas production between the government, NGO's and the mining com-pany ended up in court in 1998. The outcome of these proceedings was unsatisfactory for all parties: uncertainties about the effects of the gas extraction prevented a final judgement, which meant that the mining activities were suspended anyway. Subsequent studies and a recommendation by inde-pendent experts in 2004 eventually resulted in an agreement between the mining company, the government and the majority of the NGO’s. In order to prevent damage due to subsidence from gas

(4)

Mining activities in a coastal zone; Effects and remedial measures in the Netherlands

production under the Wadden Sea, the annual gas extraction should be limited in such a way that the natural sedimentation in the Wadden Sea could compensate the subsidence bowl including the effect of sea level rise. A Wadden fund of € 800 million would be made available by the government in order to enable improvement measures for the benefit of the Wadden area as a whole.

DESCRIPTION OF THE AREA Geography

Groningen Gas Field

The present landscape in the Province of Groningen is rather flat, roughly from 1 m below to 1 m above MSL. The tidal range is about 3 m, so that drainage takes place partly by gravity through sluices during LW and partly by pumps when the tidal level is too high for gravity discharge. The whole coastline is protected by a high sea dike that protects the land against flooding during storm surges that can reach a level of more than 6 m above MSL.

The upper 10 m of the soil is consisting of recently deposited (and thus soft) layers of clay and peat on top of a well compacted Pleistocene sand layer. The main source of income for the local popula-tion was agriculture (on the very fertile clay grounds) and agro- industrial activities. To facilitate the agricultural output, the ground water level is generally kept 0.5 to 1 m below the land surface. The area concerned is divided into a large number of separate polders. In each polder a different water level is maintained that depends on the local ground level and the land use. In between the polders, there is an extensive network of canals that are used to convey the run-off to the main pumping stations and sluices close to the sea. These medium sized canals were used in the past as well for transport of agricultural products, and more recently they serve also pleasure navigation. The area had one port at the city of Delfzijl that had a function for coaster traffic in the North Sea and the Baltic. The port is connected to the inland navigational system of the Netherlands via a ma-jor canal that intersects the Province and gives access to the ports of Amsterdam and Rotterdam. More recently, the Port of Delfzijl expanded its activities with a deepwater port, Eemshaven. Around Delfzijl there is some waterborne industry like shipbuilding. For a proper understanding, one must realize that the port area is located outside the sea dike. It has been filled to such level that inunda-tion may take place, be it not too frequently.

Centrally located in the Province is the capital city, also named Groningen, with a population of about 190 000. Major buildings and most of the infrastructure are supported by a pile foundation that rests on the stable Pleistocene sand layer. Many smaller buildings and farms have a more sim-ple foundation, directly on the layer of soft, compressible clay. This type of foundation is quite sensi-tive for changes in the ground water level as this may cause compaction and uneven settlement of the clay and thus lead to cracks in the structures.

Wadden Sea Fields

The Wadden Sea is a part of the North Sea, between the mainland and several barrier islands in the northern part of the Netherlands (Figure 3). There is a diurnal tide with a tidal range of about 3 m. During LW, large parts are drying and form salt marshes and tidal flats.

The Wadden Sea is an area with a high organic production of benthic and plankton which is food for (amongst others) migratory birds (Figure 4). The Wadden Sea is part of an international system for several species of migrating birds and a nursery ground for fish in the North Sea. It is designated as a Nature World Heritage Site and a well-known recreation area. The area is protected under European and Dutch legislation. Sea level rise (and subsidence because of gas production) could lead to

(5)

ing of the Wadden Sea and loss of the tidal flats that are essential as feeding and resting ground for the migratory birds. Comprehensive morphological calculations have demonstrated, however, that the influx of sediments through the inlets between the barrier islands is sufficient to compensate a combination of an expected sea level rise and a moderate progress of subsidence due to gas extrac-tion.

Stakeholders

In the area that is affected by subsidence, a large number of stakeholders is active. In the public sec-tor, the national government is involved through Rijkswaterstaat, the agency that has the overall responsibility for protection against flooding by the North Sea. Rijkswaterstaat is also involved in construction and maintenance of the major navigation routes. Other stakeholders in the public sec-tor are the Province of Groningen, the local water boards, municipalities, the Port Authority of

Fig.4. Impression of the Wadden Sea Ecosystem

Delfzijl/Eemshaven (Groningen Seaports) and several NGO’s which take care of the nature interests. The Province is primarily responsible for the smaller inland navigation routes and it supervises the local water boards. The local water boards are taking care of the quantitative and qualitative water management. After some mergers between those boards, at present three water boards are in-volved. Several municipalities have an interest in subsidence because of their own role in the (sur-face and waste) water management and infrastructure in the urban areas. The Port of Delfzijl/Eemshaven is a landlord-type of organization and as such responsible for the quay walls and harbour areas that are mainly located outside the sea dikes that protect the hinterland.

In the private sector, the variety of stakeholders is even larger. Here, we see private farmers, asso-ciations of farmers, land owners of nature reserves, professional and hobby fishermen, industries, marina's and water sport associations, port operators, shipyards, house owners and just inhabitants. LEGAL FRAMEWORK FOR COMPENSATION

According to the Dutch Mining Law, any mining company is liable under the Civil Code for the dam-age caused by its mining activities. In normal circumstances, this requires a legal procedure to estab-lish the causal relation between damage and mining activity and the amount of the damage. A court procedure under civil law is costly, it may take a long time and it requires a lot of manpower input, both from the complainant and the defendant. The cost and time factors count heavily since such claim cases are also open for appeal. Another disadvantage of the formal legal framework is the fact

(6)

that it is difficult to claim and assess damage that will gradually develop in the future. These were all good reasons for the major stakeholders to see whether an alternative method for compensation of the damage would be feasible that could also deal with preventive measures.

Following intense negotiations, by an agreement of 1983, NAM committed itself to pay for all dam-ages and remedial measures to a maximum of Dfl 650 million at the price level of April 1980. (Equivalent is about € 295 million). This sum is corrected annually for inflation. Under the agree-ment, a Committee is installed that decides on any claims submitted. NAM guarantees prompt pay-ment of all claims approved by the Committee. The Committee consists of six members and six stand-ins, half of them appointed by the Province of Groningen and half by NAM. Most members of the Committee are independent engineers and lawyers. The Committee decides in unanimity and the decision is binding, without any appeal. Claimants that participate in the agreement accept that there is no appeal possible against the decision of the Committee, and there is no access to the normal legal system. The Committee follows the claims from the first design stage to completion. Although the original signatories represented the public sector, the agreement is open to private parties as well. By joining the agreement, they lose access to the regular legal system (including the right of appeal), but they are sure that their claims are considered relatively quickly by an independ-ent group of experts. It is evidindepend-ent that the agreemindepend-ent does not supersede the currindepend-ent legislations. As such, any private complainant has the right to present his case to court and circumvent the agree-ment between NAM and the other stakeholders So far, nobody has exercised this right, which is an indication of the general satisfaction about the working of the agreement and the executive Com-mittee.

At the same time that the agreement between NAM and the Groningen Province was signed, a simi-lar agreement was made between NAM and Rijkswaterstaat. Claims under this agreement are treated by the same Committee. This agreement will not be considered in this paper as it is much smaller and more specific than the agreement with the Province.

DAMAGE BY SUBSIDENCE

As indicated in the introduction, the area affected by subsidence due to the extraction of gas from the Groningen field has roughly a circular shape with a diameter of 40 to 50 km. According to the present insight, the maximum subsidence in the heart of the area will be eventually in the order of 0.5m. This subsidence will bring the sophisticated drainage system in disarray. In the absence of any measures, the water table in the centre would remain the same, thus reducing the freeboard signifi-cantly. This would cause serious damage to the agricultural sector. Lowering the water table artifi-cially by 0.5 m would save agriculture in the heart of the subsidence area, but it would cause drought damage along the periphery, and more seriously, the lowering of the water table in the periphery would cause serious additional settlements in the layers of soft clay and peat. As a consequence it would inflict serious damage to many structures and buildings that do not have a pile foundation. It will be clear that the subsidence and potential countermeasures result in relative changes of the land level in relation to the surface water level and ground water level. In this way, a lot of secon-dary effects must be expected. A distinction is made for damage caused by a relative rise and a rela-tive fall of the water levels in relation to the land level.

x In case of a relative rise of the water level the main detrimental effects are:

o reduced freeboard of dikes (both sea dikes and dikes along inland waterways) o reduced passage under bridges

(7)

o difficult access to farmland with heavy equipment o reduced agricultural output for certain crop o working length of slipways being reduced.

x In case of a relative lowering of the water level the main effects are: o reduced depth for navigation

o inhibited discharge towards the sea o discharge sluices becoming less effective o pumping stations requiring a greater head o reduced agricultural output due to drought o difficult vessel access in marinas

o damage to foundations due to compaction of clay and peat layers o slipways loosing access

Another way to classify the damage is according to the nature of the stakeholders involved. Damage to the infrastructure is suffered by a limited number of public bodies (Central Government, Provin-cial Government, Municipalities and Water Boards) that all have in-house technical and legal exper-tise. Damage to houses, other private buildings, shipyards and farmland touches a large number of widely scattered stakeholders that in general lack sufficient technical or legal background.

For this reason, it was considered a good option to try and modify the drainage infrastructure in such a way that the damage for the private stakeholders would be prevented or minimized. A closer study demonstrated that most small scale damage cases could be prevented when the relative rise or fall of the water level would be within plus and minus 10 to 15 cm. This would almost eliminate the risk of damage to foundations and it would also prevent wet or drought damage to agricultural land. This resulted in the decision to adapt the water management infrastructure.

REMEDIAL MEASURES

For this reason, a master plan was designed for the drainage system that could prevent most of the negative effects sketched above. The master plan consisted essentially of a division of the subsi-dence area into compartments (slices) with an adapted water level in such way that the relative changes of the inland water and ground water levels in each compartment would be limited be-tween plus and minus 0.1m (See Fig. 5).

Slice 1

Minimum Subsidence 0.4m Maximum subsidence 0.6 m Water level change -0.5 m Slice 2

Minimum Subsidence 0.2 m Maximum subsidence 0.4 m Water level change -0.3 m Slice 1

Minimum Subsidence 0 Maximum subsidence 0.2 m Water level change -0.1 m

Barrier, consisting of dams, weirs, locks and pumping station

(8)

Figure 5. Schematic view of compartments in subsidence area

This would lead to negligible effects on agricultural production and on the foundation of structures and buildings. For this purpose, a complete network of pumping stations, navigation locks, weirs and dams had to be designed. Execution of all these works takes place gradually, along with the progress of the subsidence under the responsibility of the water boards. Since 2010, the first and second slices are in operation after the completion of the lock and pump complex near Abelstok.

Figure 6 shows the recently completed pumping station and lock complex at Abelstok that com-pleted the ring around the second slice. This pumping station has a capacity of 10m3/sec and a head of about 0.3 m. The lock complex has special facilities for the passage of canoes and -in wintertime- for skaters.

Additionally, the crest level of dikes and the head of existing pumping stations were increased. Bridges were (and still are) either replaced or jacked up. At Delfzijl, a new quay wall and port areas were constructed. In the few places where infrastructural measures could not prevent damage com-pletely, a compensation for damage is paid. Figure 7 shows a large new pumping station discharging into sea near Delfzijl, with a capacity of 45m3/sec at a head of about 4.5 m. Figure 8 shows the new harbour area at Delfzijl.

Fig. 6. Lock and pumping complex near Abelstok

(courtesy Noorderzijlvest and Henk Breedland Vliegerluchtfotografie)

At this point, it must be added that not all new facilities were financed for 100% under the subsi-dence agreement. The close relation between the claimants and the Committee facilitated the com-bination of projects with a different purpose and/or the joint execution of projects that would oth-erwise have been built soon after each other. In this way, money could be saved to the benefit of both, the claimants and the defendant. It resulted in a partial payment of the cost through the Committee. In other cases, the new structures replaced existing facilities that were close to the end of their life time. In those cases, a reduction "new for old" was applied.

(9)

Fig. 7. Pumping Station "Rozema" near Delfzijl (courtesy Hunze en Aa's)

Fig. 8. Aerial view of Port of Delfzijl with new harbour area on left hand side (courtesy Groningen Seaports)

MONITORING

For a proper assessment of potential future damage, timing of preventive measures and a proper design of structures that takes into account the expected future subsidence, regular monitoring is essential. For this reason, NAM is under contractual and statutory obligations to perform regular surveys. In addition to these surveys, every 5 years, an updated prediction is made of the subsidence and its development as a function of time. An example of such prediction is shown in Figure 2. The surveys by NAM are subject to approval by State Supervision of Mines (the national mining in-spectorate), and are discussed by the Committee in relation to the design of the drainage system. Originally, the surveys consisted mainly of the traditional levelling of benchmarks. This is gradually replaced by remote sensing techniques that provide equally reliable results. It remains difficult, however, to make a reliable distinction between autonomous settlement of the soft upper layers and the subsidence of the firm Pleistocene layer as caused by the extraction of gas. This is especially the case with benchmarks connected to buildings with a questionable foundation.

SPECIAL CASE: DAMAGE TO THE ENVIRONMENT Legal Framework with Respect to the Wadden Sea

The damage occurring on land under the Groningen gas field as discussed above can be expressed in monetary values. Claimants can be compensated by paying an adequate compensation. Essentially this is governed by civil law. Nature values have no owner and damage cannot easily be expressed in money; damage to natural values can thus not be compensated in terms of a sum of money paid to a claimant. This means that any damage to the environment must be treated under public law. The legal framework for compensation of affected environmental values is mainly based on Euro-pean rules and regulations (e.g. Habitat and bird directives) which are implemented into the Dutch legislation. (The Nature Protection Act). Any plan or a project for or in a SAC/SPA designated area shall not be approved or permitted by the competent authority unless the owner of the project has proven the plan or project won’t have a significant impact on the values to protect. At first one should prevent damage to the protected nature values by taking mitigating measures. If preventing deterioration is not possible the plan or project only can be executed if the project is of national interest and before the project will be executed, nature compensation measures in the vicinity shall

(10)

be carried out as a substitute for lost nature... For gas production in the Wadden Sea, the above mentioned framework has been taken into account when permits were granted in 2006.

Damage by Subsidence due to Gas Production In the Wadden Sea and Remedial Measures

When the subsidence velocity due to gas extraction combined with sea level rise and natural subsi-dence cannot be compensated by natural sedimentation, the tidal flats will be inundated perma-nently and loose much of their ecological value. At the same time, it must be realized that there is also a limit to the annual sedimentation. If this is too high, benthic organisms are literally buried alive. This fact eliminates the possibility to nourish the tidal flats artificially by dumping sand.

Comprehensive morphological and ecological calculations have shown that the ecological system can cope with an average maximum rise of the relative water level of about 6 mm per year. The natural morphological processes are able to supply that quantity of sediment and the ecological processes are that robust that they can survive that rate of change. This boundary value of 6 mm relative rise of sea level per annum must cover both, the sea level rise due to climate change and the subsidence due to the extraction of gas. It is estimated that the annual sea level rise will increase from about 2.6 mm per annum at present to about 5.5 mm per annum around 2040. This creates room to allow for additional subsidence by gas extraction in the coming 30 years as shown in Figure 9. The rate of the gas production must be tuned in such a way that the total change will not exceed the limit of 6 mm per year. This way of producing gas is called: “production with the hand on the tap”.

Fig. 9. Room for Relative Sea Level Rise in the Wadden Sea

The sediment that flows into the Wadden Sea through the tidal inlets between the barrier islands originates from the outer beaches of these barrier islands. It is evident that the increased influx of sediment due to gas extraction leads to increased beach erosion. In order to maintain the natural coastline along the seaward side of the barrier islands, sand nourishment is carried out on a regular basis by the Central Government (Rijkswaterstaat).

Measurements and Monitoring

The subsidence is measured with a wide range of different survey methods including remote sens-ing. Models are used to predict subsidence as a function of the actual gas extraction... Periodically

Year

Relativ e Se a Level R ise in m m p er Annu m

(11)

these predictions are actualised taking into account the outcome of the actual measurements. If the actualised subsidence prediction shows the available room for subsidence might be exceeded in the near future, the gas production can and will be adjusted.

In addition to this technological monitoring, also monitoring of species (birds/macro benthos) and geomorphology (sedimentation measurements, measurement of area drying shoals etc.) takes place. The outcome of the monitoring is compared to reference areas and trends elsewhere in the Wadden Sea.

Every year the mining company is compelled to report the outcome of the measurements and moni-toring to stakeholders (i.e. NGO's) and the authorities in charge. If the outcome is not accepted the gas production must be adjusted or can even be stopped.

THE AGREEMENTS IN HINDSIGHT Subsidence Agreement Groningen

Advantage of the system is that lengthy and costly legal procedures are avoided. Never in its exis-tence, the Committee failed to reach a unanimous decision and, consequently, there has never been a need for calling in a supervisory board that exists in the background. Claimants are in general satis-fied with the decisions of the Committee. In the mean time, similar arrangements have been made for damage due to gas extraction in the Province of Friesland.

After its first meeting in March 1984, the Committee met more than 140 times in plenary and ap-proved expenses to an amount of over € 125 million at the 1980 price level. In this way, an amount of roughly € 170 million (price level 1980) is still available for future works. At the present price level this equals about € 360 million.

In this way, more than 200 claims, amounting to € 125 million (price level 1980) have passed the Committee. Out of this total, about 38% has been spent on the construction or adaptation of pump-ing stations and locks, about 30% on port facilities, about 12% on inland waterways and their banks, about 10% on exploitation of new facilities and all kinds of research, and 10% on claims by private parties like industrial enterprises, farmers and house owners.

At the time the agreement was negotiated, subsidence was considered the only potential cause of damage. At that time earthquakes were not foreseen. In the mean time, it has become clear that relatively weak quakes are also generated by the gas extraction, their strength remaining below force 4 on the Richter scale. Damage due to earthquakes (if any) is, however, not covered by the agreement.

A large remaining task for the committee is the assessment of the net present value of the running cost and depreciation of the new facilities. Eventually, these costs will also be reimbursed by NAM. Major issues in this respect are the interest rate that is used to capitalize running cost, the life time of facilities and their components and the annual cost of maintenance and repair.

Gas Extraction under the Wadden Sea so far

Gas extraction under the Wadden Sea runs now for several years under the granted permit condi-tions. Although the observation period is relatively short, the outcome of the yearly measurements and monitoring shows no signs of negative impacts on the Wadden Sea. In 2013 a comprehensive evaluation of all measured and monitored parameters is foreseen.

The Wadden fund amounted originally to € 800 million. This amount will be spent in 20 years time. Periodically projects can be nominated for a financial contribution out of this fund. One of the first

(12)

measures to improve the ecological conditions financed from this fund was a buy-out of the cockle fisheries. The fishermen are compensated for giving up their fishing rights in the Wadden Sea result-ing in an increase in available food for birds. The actually remainresult-ing resources of the fund are about € 500 million.

So far, the agreement with all stakeholders and the permit conditions for gas extraction under the Wadden Sea work to the satisfaction of all concerned.

CONCLUSIONS

Gas extraction in the Province of Groningen has caused and still is causing a significant impact on the water management of the area. The subsidence due to the gas extraction is relatively small in abso-lute numbers (up to 0.5 or 0.6 m), but because of the flat conditions and the low elevation close to the sea, it creates a considerable disruption. The magnitude of the damage is limited due to reme-dial measures that reduce the relative changes between land level and local water level after subsi-dence.

The main stakeholders have entered into an agreement that avoids costly and time consuming legal procedures. Damages are reimbursed on the basis of the judgement of a jointly created independent committee. This set-up has worked satisfactorily for over 25 years.

Gas extraction in an ecologically sensitive area like the Wadden Sea is possible without causing a negative impact on the environment under strict and site specific conditions. A sophisticated moni-toring and measurement system (early warning system) secures that the values to be protected will not be affected by subsidence due to gas extraction.

By listening to each other, and focussing on a positive outcome for all stakeholders like the admini-stration, local and national politicians, NGO’s and the gas mining company, further lengthy and costly court procedures could be avoided and the ecological qualities of the area could be improved by financial support from the Wadden fund.

ACKNOWLEDGEMENTS

This paper could be written thanks to the permission of Nederlandse Aardolie Maatschappij NAM. Assistance by the permanent secretariat of the Committee (Commissie Bodemdaling) and permis-sion of the water boards "Noorderzijlvest" and "Hunze en Aa's" and of "Groningen Seaports" to ac-quire and use pictures are gratefully acknowledged.

REFERENCES

Schenk, J. 2009. Groningen-Gasveld Vijftig Jaar (in Dutch), Uitgeverij Boom, Amsterdam, The Nether-lands, ISBN 978 90 8506 763 4

Commissie Bodemdaling door Aardgaswinning Groningen, 1984-date. Annual Report (in Dutch) Commissie Bodemdaling door Aardgaswinning Groningen, website: www.commissiebodemdaling.nl