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Building with Nature Guideline > BwN Approach > Steps and phases > Operation and maintenance 

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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. Operation and maintenance 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 approachTraditional 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.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 ).


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

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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. Operation and maintenance 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. One example is .


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.

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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. 

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