Operation and maintenance

The application of Building with Nature Design is extended as far as the Operation and Maintenance Phase. Considering maintenance aspects early on in the design process may optimize the design and reduce lifecycle cost significantly. But also Operation and Maintenance an BwN approach may lead to forms of adaptive management and development that will generate additional environmental and cost benefits.

Apart from decommissioning, the operation and maintenance phase may be considered the last phase of a project. Still it covers most of the project lifecycle. are long-lasting activities that may be adapted to changing socio-economic needs and environmental trends. This conforms to the notion that the implementation of a BwN project is just the beginning of a long-term development.

BwN approach
The BwN approach incorporates the possibility of incremental adaptation to changes in system dynamics, environmental conditions or operation practices. Objectives and functioning are not fixed indefinitely, but leave room to seize new opportunities. Building with Nature does not aim at fixing habitats of a preset number of individuals of a certain species, but rather respects natural system dynamics.
Traditional approach
Operation & Maintenance are about keeping the structure of the facility in its original state and functioning as intended. Often traditional approaches lead to regular, more or less identical interventions with little attention for possible adaptive management or incremental development. Such interventions are often more expensive than an incremental approach and they usually have greater environmental impact.


Typical characteristics of the O&M-phase of a BwN-type project are:

  • A constant drive to improve design, functioning and management of the project. For example by:
    • – Improving its functioning. Example: adding a self-maintaining shallow foreshore in front of a dike, i.e. a vegetated foreshore which reduces wave action and traps sediment.
    • Improving its management. based on improved system understanding, observation of its evolution and assessing what form of management works best.
    • Adding (ecological) functions and value. Example: creating additional aquatic habitats within harbour basins to improve their ecological functioning; eco-structures are essentially add-ons, rather than being part of the original design. Example: equipping the exposed slope of a flood defence with a Rich Revetment, a habitat-enriching micro-topography with tidal pools and rough semi-open substrates which also help to reduce wave run-up. Also the construction of habitat enhancing structures, serving as attractive dive-areas, on top of a functionally required strengthening of a dike foreshore, is a good example of how functionality can be combined with eco-development.
  • Experimentation that seeks innovation and improved performance. Example: by testing a bandwidth in different management regimes, one will see what regime it to be preferred.
  • Dealing with uncertainties via adaptive management, aiming to stimulate observed positive developments and to mitigate negative ones.
  • Dedicated forms of monitoring directed at improved understanding and adaptation. Many environmental effects will only become manifest after some time. These slow processes call for specific kinds of monitoring that will help to an adaptive approach: based on observations one gathers more insight into the system’s functioning and decides on how to proceed.
  • Interaction with stakeholders and public, by keeping them informed, but possibly also by involving them in maintenance activities (for example, see River Cleanup).

This chapter provides guidance on BwN operation and maintenance approaches. Where appropriate, useful methods and tools are suggested.


Discussions, negotiation and decision making will be necessary with respect to:

  • The balance between investments in project implementation and in Operation and Maintenance.
  • How uncertainties and related risks will be handled and allocated between different parties and laid down in contracts and commitments.
  • The interaction needed between different parties that are responsible for the management of different parts of a project.
  • The discussion on how new potentials may be fulfilled and major changes in management can be taken.

Operation and maintenance needs to be carefully balanced with design and construction. It requires debate between those responsible for design and construction and those that play a role in the use, operation and management of a project. This debate, which involves different stakeholder groups, will often be about the allocation of costs, since designs bringing less lifecycle costs may be more costly to construct. It is also a debate between a fixed design with well-defined objectives and reasonable certain behavior and benefits, and a more flexible design which may bring larger, but also less certain benefits. This can easily lead to friction between parties, especially when O&M is funded from a different source than construction. Therefore, this debate needs to be carefully managed and supported with adequate information. Life cycle costing will help to make the cost issues more explicit. Expectation management will help to come to agreements that contain the necessary “if-then-else” decision procedures, and also to effectively inform stakeholders on what to expect.

Since a BwN project works with natural processes and incorporates nature into the design, it is not possible to fully predict its future evolution. For O&M this means monitoring and adaptive management, for the design it means taking into account a realistic range of possible developments and enabling adaptive management in the O&M-phase. This bandwidth makes decision-making more complex and communication more diffuse. This bandwidth and related risks needs to be made clear so explicit decisions can be taken.

Dynamic development is considered as the natural state of mind; so one does not need to jump to taking hasty and corrective measures as soon as a development differs from what has been predicted.

It is important to consider the potential for adaptive management strategies, also in previous planning and design phases, as it will influence decisions and related operation and maintenance risks. Adaptive management, with associated monitoring and decision making procedures, should be seen as an intrinsic part of the design, similar to the constructive design components.

Clearly, ownership, tasks and responsibilities with respect to operation and maintenance need to be defined. In the light of modern contract forms (e.g. Design – Build – Finance – Maintain), this raises the question how design, construction and operation and maintenance will be contracted. Appropriate incentives in the contract are important in order to achieve BwN-goals.

Operation and maintenance may be in the hands of more than one party. In the case of a flood defence system consisting of a dike and a shallow foreshore, for instance, maintenance of the dike can be the responsibility of a water or levee board, whereas the foreshore is managed by an NGO. In such cases, it takes clear and binding appointments between those parties for the system to keep on functioning. Otherwise, it may happen that in the assessment of the flood defence system the foreshore is simply ignored and the dike is needlessly strengthened. Or, like in the case of New Orleans, the foreshore is not managed for flood defence and sooner or later disaster strikes.

Step 1) Understand the system

Our understanding of the system increases with every phase. For the Operation and Maintenance phase important additional system knowledge relates to:

  • Effect evaluation. The project has been implemented on the basis of projections – often model-based – of expected effects. Formal procedures may require that these effects be monitored to scout for the need for management interventions. This post-construction monitoring has the in-built opportunity to test earlier predictions, to verify the models used and to improve our understanding of the system’s functioning. This requires dedicated forms of monitoring, beyond the mere observation of primary effects. One needs to monitor complete intervention-effect chains, focusing also on biotic and abiotic processes, not only on protected species or whether the project fulfills it primary function such as coastal protection. Moreover, time has to be allotted to process, analyse and interpret the monitoring data,. Experience shows that this needs to be thought out, organised, budgeted and contracted before construction starts.
  • Learning by doing. This is a key element to adaptive management, enabling to optimise the project’s operation and management and or even improve its functioning. offer opportunities to enhance our knowledge of the natural system, technical performance and socio-economic benefits. Experimenting and monitoring are crucial in this respect. Experiments may concern system management as such, but also the use of the area for new functions, e.g. new forms of recreation. Natural processes are monitored by measurements, but the socio-economic perception and use will require observation and interviewing.
  • Added value creation. Previous phases may have identified additional functionalities and potential user benefits, that need to be addressed in, the O&M-phase. Often public works create opportunities for business development, but entrepreneurs are needed to fulfill them. Moreover, new opportunities may emerge in this phase. This requires flexibility and an open eye for win-win situations, for instance by committing users to contribute to the system’s maintenance. An example is one of the many beach-cleanup initiatives.

Step 2) Identify realistic BwN alternatives

Different alternative strategies for operation and maintenance will have been considered in the previous phases in order to seek an optimum between construction and operation and management. Alternative options may relate to:

  • Contract conditions. These are critical if project implementation and subsequent operation and maintenance are strongly related, as in most BwN-type projects. Examples are coastal engineering projects and river training and flood protection projects that need maintenance because of morphological developments. Maintenance costs may depend strongly on the design. This may be a reason to contract design, implementation and maintenance in combination (Design/Build/Maintain contracts). In some cases this may even include the project’s financing (DBFM-contracts).
  • Optimisation . Most infrastructural projects involve a trade-off between construction costs and the costs and benefits of operation and maintenance. In that case, it is important to explicitly define the optimisation domain: are construction and O&M optimised, or separately? One example is the decision to replace a conventional hard sea defence for the extension of the Port of Rotterdam by a . For BwN-type projects, we strongly recommend a lifecycle costing approach
  • Risk management. Less costly and less robust designs may involve higher risks in operation and maintenance. On should distinguish between risks concerning vital project components, failure of which means failure of the project’s functioning, and those for less vital components, failure of which only leads to a need for additional maintenance. More information on risk management can be found in
  • Built-in learning. Most projects are not designed for learning and improving, but are rather considered as one-time implementation jobs. Yet, much can be gained, not only in terms of knowledge but also in terms of reduced management costs and increased benefits, if there is room for experimentation or pilot-testing in the design. Especially where lack of knowledge and experience appears to eliminate more cost-effective alternatives a priori, experiments should be included. In the Operation and Maintenance phase such experiments need to be monitored and evaluated and there has to be room for appropriate adjustments in management. .
  • Built-in incremental improvement. Hard designs often don’t have the flexibility to apply improvements after construction, whereas soft designs do. Also laws and regulations and consequently also licenses may obstruct adjustments and improvements..

The choices discussed above will ultimately lead to a specific operation and maintenance strategy with implications for design, risk management, contracting, etc.

Step 3) Evaluate and select alternatives

Once a project has been implemented, there are various reasons to monitor and evaluate its performance, such as

  • Operation. Monitoring may show a need to change or optimize operation practice. Environmental developments, socio-economic needs, shifts in maintenance costs may require a change in operation.
  • Maintenance. The need to change maintenance may relate to available new management tools but also trends in factors that govern maintenance. A new shoreline may become more robust in time because of the establishment of vegetation, so maintenance can be reduced. A sand bank may shift exposing a shore to larger waves, hence more maintenance is needed to withstand undesired erosion.
  • Compliance. Regular post-construction evaluations will show whether the project complies with licensing requirements, and if further mitigating or compensating measures are needed.
  • Science. Also a scientific ambition may be included. In this case more than in- and output parameters need to be studied. Focus will be on fundamental system processes that determine the response of a system.
  • Innovation. A project may serve as a forerunner for similar projects elsewhere. If so, a number of key cause-effect relationships need monitoring and evaluation. Comparing input and output parameters may be sufficient in this case.
  • Feedback on Functioning. The project design was based on expectations of how it would function after implementation. A BwN-type project is often innovative and evolves with time) Its performance needs to be assessed from time to time. Communication. Stakeholders and the public are interested in how the project performs. This requires monitoring those aspects that proved to be critical to the public in previous phases.

Clearly, project evaluation, adaptive management and adequate maintenance are only possible on the basis of a dedicated monitoring programme. Another necessary condition, however, is a clear assessment framework preferably based on f the decision and design framework developed in the first project phases. Increased understanding of the (eco) system enables optimising the monitoring system.

Step 4) Elaborate selected alternatives

It may be clear from the foregoing, that adaptive management is the preferred management strategy during the implementation of the O&M phase of BwN-type projects. This means learning by doing, a continuous cyclic process in which management and monitoring are tested, evaluated and improved. Experimentation is inherent to his approach and must lead to new insights and further experiments, hence continuous improvement. This already applies if the environment is, but becomes even more important in a changing environment.

Adaptive management can be defined as a structured, iterative process of robust decision making in the face of uncertainty, with the aim to reduce uncertainty over time via system monitoring. In this way, decision making simultaneously maximises one or more management objectives and, either passively or actively, accrues information needed to improve future management.’ and ’The challenge in using the adaptive management approach lies in finding the correct balance between gaining knowledge to improve management in the future and achieving the best short – term outcome based on current knowledge (Allan & Stankey, 2009).’

From this definition several important aspects emerge:

  • An iterative process. The cycle testing – monitoring – interpreting – evaluating – learning – optimizing is fundamental to adaptive management. In order to enable this learning and optimization cycle, room for variation should explicitly be built into design and management practice.
    Examples relate to species population management (e.g. fish quota setting), water level management in nature areas, or grazing strategies in such areas (# cattle per ha). Also periodic shoreline nourishments with amounts tuned to the observed rate of coastal retreat can be seen as a form of adaptive management.
  • To reduce uncertainty over time via system monitoring. Monitoring will help to reduce some uncertainties, but it will not for others. There is a category of uncertainties that are inherent to the system and cannot be reduced by further research. Therefore it is important to distinguish between uncertainties that can be reduced and ones that cannot.
  • To maximize on management objectives. Enabling to achieve management objectives is the prime objective of post-construction monitoring and evaluation. Yet, in BwN-type projects other objectives will also play a role and monitoring should help to achieve them. This means that the monitoring and evaluation program should serve primary as well as secondary goals.
  • To accrue information. Information should be taken in a broad sense, i.e. including interpreted data, model results, and generic and site-specific knowledge. This information can be taken as it comes, but a more effective approach is to set up the monitoring and evaluation program in such a way, that it generates as much relevant information as possible. Especially for innovative projects, this may also experimenting. If so, policies, rules and regulations should enable this.
  • Long-term vs. short-term outcome. This is a dilemma in every project with components that evolve at a large time scale, like BwN-projects. It is important to solve short-term problems the project to survive, but knowledge generation to make it sustainable in the long run is needed, as well. Therefore, one has to find ways to spend due attention and effort to both. There shall always some room for experiments despite budget constraints or legal and other implications. It is therefore important that the experiments and variation and monitoring are based on well-founded knowledge and carefully planned and designed experiments that may enhance knowledge or allow for optimized management. Experiments should test management options that are realistic considering costs, effects and acceptance by stakeholder groups.
  • Monitoring is very important and should focus on learning by doing, both in terms of what and how to monitor (working on basis of a decent plan) and of how to respond to monitoring outcome.
  • Adaptive management involves knowledge and appropriate decision making that enable the translation of learning into adaptation, involving relevant stakeholders. Depending upon the scope of a new adaptation informal or more formal decision making procedures may be needed.

Many BWN projects have great need and potential for adaptive management. Many of these projects take place in dynamic environments and work with soft solutions that trigger uncertain natural developments. Also innovative concepts are proposed that in combination with incremental development give opportunities for testing and improving. Adaptive management is a form of handling uncertainties, making uncertainties identified during the design phase more acceptable to decision makers. Often uncertainties may offer implicit changes of improvements that would not have been possible in a traditional approach. An essential element of the design is incremental development.

In the literature a distinction is made between passive (learning by observing) and active (learning by testing) adaptive management. Some consider reactive management (manage only when required) the basic mode of management. Active adaptive management has the greatest potential of improvement, of the project performance as well as of the management practice, itself.

People involved in nature conservation projects have created a framework, the Adaptive Management Cycle, that is widely used (see Open Standards for the Practice of Conservation) and can also be followed in the case of BwN projects.

Other guidance can be found from online sources such as :

Step 5) Next phases

In many cases at the end of a lifetime dismantling or decommissioning of the structure is foreseen. In relation to sustainable development it is more logic to look for an extended or new life: either as parts or as full structure, either for the same function or for a revised functionality. This ‘next phase’ description give guidance on how adaptive development, during the Operation&Maintenance phase can be used to prepare for such new life.

As society evolves ever faster, infrastructural projects with a lifecycle of typically 50 years or more are not likely to keep on serving exactly the same function throughout their lifetime. Instead, new functionalities will emerge and adaptability to these new functions becomes a project quality. In industrial building, this trend has already advanced further, but hydraulic engineering infrastructures are bound to follow. Building with nature projects, seem to be especially fit to meet this requirement.

The drive for adaptive development will follow from monitoring of both the functionality of the facility compared to possibly changed functional requirements, and of the facility’s environmental values. If an extended life is technically and legally possible, social acceptance might relatively easy develop.

The need and potential for adaptation may include:

  • Expansion of existing functions. Built-in flexibility is already needed to maintain the initial functionality, but it may also be used for a further incremental development of a project. As an example soft flood defences, but also nature development projects that use dredged material require continuous maintenance but may also be extended over the years.
  • Adding new functions or replacing old ones. Ideally, the potential to include new functions and remove old ones should already have been identified in the design phase of the project. It may have the form of creating conditions in advance, or of not excluding certain possibilities.
  • Creating room for experiments and new forms of management. Experiments and subsequent changes in design and management require flexibility in the design but also in contracts and permits. Legally this may be possible as long as potential changes enhance environmental benefits.

Once it comes to dismantling a project, this has to be done in a sustainable way. This is especially relevant to hard structures, such as foundations of offshore wind parks and installations. Sustainable decommissioning of natural project components may focus on limiting the need for future maintenance, so on self-reliance.

Often there are opportunities to improve and to develop a project based on learning by doing approach. This option is open to projects that have sufficient inbuilt flexibility that allows larger alterations and adaptations not only in management but also in design and ideally also in its performance. The key drivers are uncertainties over future scenarios in external factors or required and desired performance, which is identified during the incremental development. Major conditions for success are:

  • Keep options open: give room for inclusion of unscheduled or unexpected opportunities. For example if promising (management) alternatives need first to be tested, the design should keep the option open for alternative forms of management. If further extension may be needed, the required room to do so should be kept available. Keeping options open is also a matter of expectation management, in which also stakeholders should be involved. One should note that most stakeholders prefer fixed agreements instead of if-than statements. The latter form only attractive proposals if there is a net potential gain. Regarding nature development it is not advisable to focus on pre-set deadlines and quantitative objectives especially in dynamic environments and developments. This is especially important in Natura 2000 areas, where there is strong focus on maintaining existing natural values. Flexibility and opportunities can be found where improvement is deemed necessary in order to achieve the Natura 2000 objectives. Objectives should although not be coupled and dependent upon specific succession stages of a project intended to be a long-term dynamic development.
  • No regret: do not build or invest in projects of which success depends on only one type of management or benefit, regardless of future conditions. A (natural) water retention that is not needed for buffering a peak flow can be designed so that it can always be used for recreation.
  • Built in flexibility: anticipate future enhancements, up scaling or strengthening or additional functions.
  • Increase adaptive capacity: always try to reduce related operation & maintenance costs. Work on built-in flexibility with respect to alternative uses and ways of operation & maintenance. Especially nature management should preferably be limited to coaxing successions by limited steering of conditioning factors, such as hydrology. Often nature management consists of intense forms of management such as the repeated cutting and removal of pioneering tree species in wetlands. It is better to have the built in option to steer by means of water level management or opt for natural grazing.

Similar to adaptive management also adaptive development requires monitoring, learning by doing and appropriate decision making structures. The emphasis in monitoring shifts however also to external variables and trends and to aspects that define adaptive capacity development. The goal is to develop in such a way that every subsequent step is in fact more effective, more efficient or environmentally, economically or socially more beneficial.