Commissioning and operation .1 Commissioning

Commissioning includes the filling of the pipeline with gas for the first time and includes all activities that occur after pre-commissioning until the moment when the pipeline is ready for gas transfer.

After pre-commissioning, the pipeline will be filled with dry air. To prevent a mixture of air and dry gas immediately before injection, the pipeline will be filled with nitrogen (an inert gas), which will work as a buffer between the air and the gas.

The pipeline volume is approximately 170,000 m³. Assuming that the pipeline will be completely nitrogen filled to a pressure of 12 bar, the standard nitrogen volume will be approximately 2∙10⁶

Document ID: PL1-RAM-12-Z02-RA-00003-EN 39/433

Nm³. A typical capacity for mobile nitrogen plants is 5,000 Nm³/hr; therefore, assuming that two mobile nitrogen plants will be used, it will take 1-2 weeks to fill the entire Baltic Pipe pipeline to a nitrogen pressure of 12 bar.

When adequate separation has been provided by nitrogen, the natural gas is introduced from one end (Danish compressor station). At the opposite end, the air and nitrogen will be discharged through an air silencer or flare, until gas content/traces are detected (Polish receiving terminal).

The air and nitrogen emissions do not cause any environmental impact, and it will be ensured that the emission facilities are designed to ensure that there also will be no health impacts.

3.10.2 Operation

The expected pipeline life is 50 years. During that period, constant supervision of the gas transfer as well as scheduled and unscheduled checks and works related to maintenance will be carried out.

During the pipeline operation, technical operations will be conducted with the purpose of ensuring the integrity of the pipeline, and in particular maintaining the proper pressure and securing the infrastructure.

These activities will include geophysical surveys to control the integrity of the pipeline and the surrounding seabed. Also, pigs will be used for monitoring the wall thickness and the possible corrosion of the pipeline.

Supervision of the gas transfer will be carried out from the project management centre at a location to be designated at a later stage of the project.

3.11 Decommissioning

The Baltic Pipe offshore pipeline will be constructed based on a design life of 50 years of operation. After this period (and a possible prolongation), the pipeline system will be decommissioned.

Below is an overview of the existing legislation and best practice with respect to decommissioning of offshore pipelines. The actual method of decommissioning will be agreed with the relevant authorities in due time before the decommissioning activities. In addition, an EIA (or equivalent) will be prepared to assess the impact on the environment. It is not possible to detail the method to be used at this time, as it will depend on the legislative regime as well as the technical options available at the time of decommissioning.

3.11.1 International legislation and best practice

The overriding principle of all international regulations and guidance is that decommissioning activities should not result in any harm to other users of the sea or to the environment (IOGP, 2017).

The process of decommissioning is regulated by international, regional and national conventions and legislation in terms of the removal of installations (primarily concerned with safety of navigation and other users of the sea) and disposal of materials (primarily aimed at pollution prevention). The primary conventions are noted below:

• United Nations Convention on the Law of the Sea (UNCLOS), 1982. Article 60 contains provisions on the construction and removal of offshore installations and requires coastal State authorization for any installation or structure intended to remain on the seabed.

Document ID: PL1-RAM-12-Z02-RA-00003-EN 40/433

• London (Dumping) Convention, 1972. The convention (and the subsequent 1996 Protocol) promotes effective control of all sources of marine pollution and provides generic guidance for any wastes that can be dumped at sea. New guidelines, which specified different classes of waste, including platforms and other man-made waste, were adopted in 2000.

• International Convention for the Prevention of Pollution from Ships (MARPOL), 1973, 1978. MARPOL sets the standards and guidelines for the removal of offshore installations worldwide.

• Convention for the Protection of the Marine Environment of the North East Atlantic (OSPAR Convention), 1992, 1998. The OSPAR Convention seeks to prevent and eliminate pollution of the marine environment in the North-East Atlantic from land-based sources, dumping and incineration, and offshore sources. The OSPAR Convention does not include the environment of the Baltic Sea, which is regulated by the HELCOM Commission.

None of the international guidelines provide guidance in relation to pipelines or cables (IOGP, 2017). And no specific guidelines exist for decommissioning in the Baltic Sea.

For the North Sea / North Atlantic, Norway and the UK have developed guidance notes on decommissioning. They mainly concern decommissioning of offshore installations, but they also address decommissioning of pipelines and cables.

The Norwegian requirements regarding decommissioning of pipelines have been expressed in the Norwegian Parliament White Paper No. 47 of 2001 (Norwegian Parliament, 2001). As a general rule, pipelines and cables may be left in place as long as they do not cause obstruction or present a safety risk for bottom fishing, considering the costs of burial, covering or removal of these items. Final decisions on the disposal of infrastructure within Norwegian territory are made by the Norwegian authorities. The following disposal solutions are usually considered:

• Clean and leave in situ;

• Burial/trenching;

• Rock installation;

• Removal.

As a response to the above, Norwegian industry guidelines on environmental impact assessment for offshore decommissioning were developed (DNV, 2001). An overview of the various technical options for decommissioning is provided in DNVGL-RP-N102, 2017.

The UK authorities have issued guidance notes on decommissioning of offshore oil and gas installations and pipelines (BEIS, 2017). As these are most likely the best-developed existing guidelines, they are briefly outlined below.

The general approach to decommissioning of pipelines includes the following:

• All feasible decommissioning options should be considered, and a comparative assessment should be made;

• Any removal or partial removal of the pipeline should be performed in such a way as to cause no significant adverse effects upon the marine environment;

• Any decision that a pipeline may be left in place should be regarded as to the likely

deterioration of the material involved and its present and possible future effect on the marine environment;

• Account should also be taken of other users of the sea, and the future fishing activities in the area.

Document ID: PL1-RAM-12-Z02-RA-00003-EN 41/433

Determination of any potential effect on the marine environment at the time of decommissioning should be based upon scientific evidence. The factors to be considered should include (BEIS, 2017):

• The effect on water quality and geological and hydrographic characteristics;

• The presence of endangered, threatened, or protected species;

• Existing habitat types;

• Local fishery resources;

• The potential for pollution or contamination of the site by residual products from, or deterioration of, the pipeline.

To evaluate the potential environmental impact, it is necessary to evidence the contents of the pipeline and outline the cleaning operations that will be undertaken (BEIS, 2017).

Where it is proposed that a pipeline should be decommissioned in place, either wholly or in part, then the decommissioning programme should be supported by a suitable study which addresses the degree of past and likely future burial/exposure of the pipeline and any potential effect on the marine environment and other uses of the sea. The study should include the survey history of the pipeline with appropriate data to confirm the actual status of the pipeline including the extent and depth of burial, trenching, spanning and exposure. It should also detail levels of fishing activity in the area (BEIS, 2017).

Where rock-dump has been used to protect a pipeline, it is recognised that removal of the pipeline is unlikely to be practicable and it is generally assumed that the rock-dump and the pipeline will remain in place. Where this occurs, it is expected that the rock-dump will remain undisturbed (BEIS, 2017).

3.11.2 Danish legislation and best practice

Generally, the same legislation that is applicable for the construction and operation of offshore pipelines are relevant for the decommissioning phase. This legislation will naturally have been updated when it is time for decommissioning of the Baltic Pipe offshore pipeline.

A group of Danish oil & gas industry companies carried out an exercise for describing future decommissioning of offshore facilities in the Danish sector of the North Sea in 2013

(Fornyelsesfonden, 2013). The study included plans for the decommissioning of three pipelines by insitu decommissioning or by removal to shore for reuse, recycling, or disposal as

appropriate.

The pipelines in the Danish North Sea have a history of stable burial, as demonstrated by survey records. Using a comparative assessment of the technical, safety, environmental, and societal impacts, the study recommended that pipelines be decommissioned by insitu decommissioning, with appropriate remedial work at the pipe ends and crossings by trenching, burying, or cutting out problematic sections where practical. The area would subsequently be subject to a post-decommissioning environmental survey, and the pipelines would remain the responsibility of the operator and be subject to an agreed monitoring programme to ensure that the lines remain free of hazards to other sea users (Fornyelsesfonden, 2013).

According to Section 4(2) of the Danish legal order on certain pipeline installations in the TW and the EEZ³, the Danish Minister for Energy, Utilities and Climate (Energi-, Forsynings- og

3 Danish Legal Order no. 1520 of 15/12/2017 on certain pipeline installations in the TW and EEZ (Bekendtgørelse om visse rørledningsanlæg på søterritoriet og kontinentalsoklen).

Document ID: PL1-RAM-12-Z02-RA-00003-EN 42/433

klimaministeren) can in the permit to establish and operate pipelines, determine how the pipeline decommissioning shall take place.

3.11.3 Environmental impacts of decommissioning

In case the pipeline is left in situ, the potential environmental impacts will, for a number of years, be comparable to some of the impacts caused by the presence of the pipeline during the

operational phase. This includes the continued presence of the pipeline on the seabed, which potentially leads to a “reef effect”, and there can potentially be an impact on commercial

fisheries. Also, there will be a continuation of the release of metal from the sacrificial anodes (see Section 5.2.5).

In addition to the above, there will be a release of mainly iron from the gradual corrosion of the steel pipelines in the marine environment. This release will be slow and is not expected to have any negative impact on the marine environment.

In case the pipeline is fully or partly removed, the potential impacts on the marine environment are expected to be comparable to the impacts of construction of the entire or parts of the offshore pipeline. In addition, there will be a large amount of materials recovered, which will partially cause waste creation, and partially provide resources for recycling (e.g. the pipeline steel).

Document ID: PL1-RAM-12-Z02-RA-00003-EN 43/433