45.2.1 Removal or Abandon in Place

Removal of an abandoned pipeline may cost as much as current installation costs. It can also disrupt full land productivity for as much as 5 years, and in some cases, result in soil admixing, which has the potential to affect soil quality. However, there are instances where removal is necessary such as: the right-of-way is required for another pipeline, or utility, future land use dictates it, a proposed development requires subsurface excavation or the pipeline owner wants to remove any liability. If the pipeline is small enough, it may be removed relatively easily by pulling it from the ground or from beneath waterways. Precautions must be taken to not disturb sensitive ecosystems, or if necessary, the pipeline is left in place at sensitive ecosystems with suitable safeguards such as pipeline cleaning, filling with inert material or inert gas, and then plugging the pipe [1].

Cathodic protection will be disconnected from any pipe abandoned in place. Since there will be no other measures to protect the structural integrity of the pipe there is a potential for abandonment in place to create issues in the future. Common landowner concerns are that

1. the presence of the pipe could interfere with future development plans;
   
2. the pipe could become exposed or interfere with farming, including the need for One-Call locates;
   
3. the pipe could interfere with drainage by becoming a conduit;
   
4. the pipe could collapse and cause damage to land, infrastructure, or farm equipment; and
   
5. the liability for residual contamination or pipeline removal costs in the future may not be funded.

As a result of these concerns, early engagement with potentially affected parties and persons with right-of-way agreements is encouraged to provide information and discuss how concerns will be managed during the abandonment process and in the future.

45.2.2 Consultation

Typically, a regulator will want an application for approval to abandon a pipeline. The application should include an abandonment plan. A plan must be tailored to the specifics of the project and comply with current regulatory requirements. It is also necessary that the plan be broad in scope and encompasses postabandonment responsibilities in the form of right-of-way monitoring and remediation of problems associated with the abandonment. The application should identify if landowners, aboriginal groups, occupants, land managers, lessees, municipal agencies, upstream and downstream users, and other persons potentially affected were sufficiently notified and consulted. This consultation would include:

• details on what areas require soil and groundwater remediation or cleanup;
  
• discussion about what portions of the pipeline or aboveground facilities must be removed;
  
• information about what land reclamation will be provided;
  
• whether or not the correct land use is being accommodated; and
  
• how potential issues will be mitigated.

The degree of engagement should be as great as possible to develop the abandonment plan as well as to finalize an application for abandonment. There may be third-party interest in reusing the pipeline, access road, or associated facilities such as a pump station where a jurisdiction permits that.

An abandonment plan is the best means to reduce the risk to public safety, property, the pipeline owner, and the environment to an acceptable level. Section 45.2.3 provides an example of an outline for a plan.

45.2.3 Abandonment Plan Outline

The following outline is provided from the National Energy Board Guide Regulating Pipeline Abandonment [2].

1. Background
   
   
   
   1. General description of the pipeline and facilities, including history and product
      
   2. Proposed abandonment process, including timelines
   
   
2. Location map (right-of-way, pipe, stations, valves, storage, and so on)
   
3. Detailed description of facilities to be abandoned
   
   
   
   1. Pipeline composition, diameter, thickness, coatings, and so on
      
   2. Adjacent pipeline facilities (corridor)
      
   3. Facility components on company-owned land
      
   4. Land use along the route (e.g., agricultural, urban, parkland)
      
   5. Natural features (e.g., water bodies, wetlands, native prairie, rare vegetation, species at risk)
      
   6. Landowners and land administration agencies
   
   
4. History of ruptures, leaks, and other construction occurrences
   
   
   
   1. Location of incidents and former contamination sites
      
   2. Environmental Site Assessment results at locations where contamination could have occurred
      
   3. Status of contamination remediation
   
   
5. Abandonment procedure
   
   
   
   1. Facilities to be left in place
      
      
      
      1. Locations and justification
         
      2. Mitigation measures
         
         
         
         1. Cleaning (procedure and standards)
            
         2. Filling or plugging
            
         3. Removal of unnecessary surface equipment
            
         4. Identification of the location of facilities
            
         5. Estimation of risk and risk reduction plans
            
            
            
            1. Contamination removal or management
               
            2. Soil subsidence
               
            3. Corrosion effects
               
            4. Pipe collapse
               
            5. Soil erosion effects
               
            6. Water conduit
               
            7. Water crossings
               
            8. Transportation and utility crossings
         
         
      3. Access
         
      4. Records
      
      
   2. Facilities to be removed
      
      
      
      1. Locations and justification
         
      2. Cleaning and removal procedure
      
      
   3. Recycling and reuse plans
      
   4. Reclamation procedure
      
      
      
      1. Restoration of Facility sites and access roads
         
      2. Right-of-way reclaimed to a state comparable with the surrounding environment
         
      3. Reestablishment of habitat to a native state for sensitive plant species and communities
   
   
6. Consultation for developing the plan
   
   
   
   1. Guiding principles and goals for the consultation program
      
   2. Design of the consultation program
      
   3. Reporting on the results of the consultation
   
   
7. Performance measures
   
   
   
   1. Maintenance period
      
   2. Monitoring procedure
      
   3. Measures of success
   
   
8. Statement of responsibility for any facilities left in place
   
9. Abandonment costs
   
   
   
   1. Initial
      
   2. Ongoing
      
   3. Sources of abandonment funding

The document created with this table of contents can be subject to ongoing revisions throughout the life of the pipeline. More information will be available on pipeline abandonment based on research and more certainty will evolve for abandonment plans as the pipeline nears the end of its useful life.

45.3.1 Contamination Remediation

When a pipeline spill occurs, the resulting contamination is expected to be cleaned up immediately to the most stringent environmental standards required by the regulators to prevent harm to the public and the environment. However, there may be residual contamination in groundwater and soil that is difficult to remove in the short term. The resulting remediation process must meet the most stringent standards and is to be conducted within a schedule agreed on with the regulators.

The schedule for remediating contamination on sites owned by the pipeline company, such as at a pump station or tank farm, may be over the course of several years or at the abandonment stage if the regulator is satisfied with the application for that schedule. In the interim, contamination must be contained on-site and monitored in accordance with all regulatory requirements. For a pipeline to be considered fully abandoned, all contaminated soil and groundwater must be remediated such that it meets required criteria. The regulator may provide a document to acknowledge the remediation but future changes in land use or discovery of undetected contamination may mean the site will require further work.

45.3.2 Pipeline Cleaning

Cleaning a pipeline during the abandonment process is essential, no matter whether the pipe will be left in place, removed for disposal, or removed for reuse. Each of these end conditions has regulatory cleanliness requirements to safeguard the environment and any persons coming in contact with the pipe. The pipe may corrode at some point and the contaminant life may exceed the pipeline so the environment may be put at risk if a high degree of cleanliness is not achieved. Further research on the degree of cleanliness required in varying environments will occur over time.

Pipelines of unknown conditions present special challenges. If they have been dormant for some time, they may have compromised integrity, which would not stand up to traditional pig runs. In these cases, workers’ safety aspects need to be considered when using compressed gases for pushing pigs. In addition, releases to the environment can occur if the line fails during cleaning. Where the pipe condition is unknown, vacuum trucks and coiled tubing units should be used first to remove as much fluids as possible before running cleaning pigs or performing a freshwater flush. Freshwater displacement may be used until returns are clean and may be followed by a progressive pigging program. Before running pigs a safe pigging pressure using any gases needs to be established. In some cases, clean fresh water for pushing pigs may have to be utilized. The effectiveness of any cleaning procedure will vary with the pipeline based on size, product carried, and location.

The following general cleaning procedure [3] is recommended for dry natural gas pipelines and medium-duty (relatively wax-free with an occasional scraping operation) oil pipelines.

45.3.3 Removal of Facilities and Apparatus

A buried pipeline that has been abandoned in place should be capped and plugged and be physically separated from any in-service piping. It also should have all related surface equipment that is not part of another pipeline removed to pipeline depth. Examples of such equipment could include pipeline risers, liner vent piping, casing vents, underground valve vaults or valve extenders, inspection bell holes, and cathodic protection equipment such as cathodic protection rectifiers, test posts, or anode wiring.

Abandoned aboveground pipe and all related surface equipment should be removed. This would include all mechanical and electrical equipment, buildings, associated piping, supports, and foundations. Aboveground storage tanks or pressure vessels must be emptied of liquids, purged, and safeguarded against trespassing until removal for disposal or reuse at a different site. If being removed for disposal, then checks need to be performed that all hazardous residue has been effectively removed and meets regulatory disposal requirements. Caution needs to be exercised when moving or handling insulated equipment as asbestos may be present, and proper containment or removal may be required.

It is also recommended that any underground structures such as underground vaults, closed-top pits, or storage tanks be removed. For those that are to remain, the walls and floor should be cleaned of contamination and the walls removed to an appropriate depth as determined in the abandonment plan. The insides of the structure can then be filled with clean soil. The abandonment of underground tanks should be conducted as specified in standards such as API 1604 Closure of Underground Storage Tanks. Checks for leaks on buried tanks should be performed as soil remediation may be required. There have been many instances of tank leaks that have occurred that were never detected while the tank was in service.

In addition to removal of infrastructure, final reclamation of a company owned or leased property should include removal of gravel, decompaction of soil and removal of unneeded access roads. Additional restoration considerations are identified in Section 45.3.6.

45.3.4 Water Bodies

Water bodies such as rivers, streams, lakes, and wetlands pose special problems for abandonment. Pipelines are often installed to cross a water body by

1. horizontal directional drilling below the bed of the water body (rarely done prior to 1990s);
   
2. a wet crossing that includes trenching in the bed of the water body;
   
3. a wet crossing where the pipeline is held in place on the bed of the water body with concrete saddle weights; or
   
4. suspended aerial crossing.

There are potential risks if a pipeline is left in place in these situations. One is that the pipeline is perforated and it becomes a conduit for contamination into the water body from external sources. The converse might also occur where a perforated pipeline siphons water from the water body accidentally. Another risk is that the pipeline becomes exposed so it poses a navigation risk or collects debris, which may affect river flow. In all cases, exposed pipes near or in a water body are likely to be viewed negatively by the public.

Cleaning the pipeline as described in Section 45.3.2 requires additional precautions at water crossings, whether the pipe is removed or left in place. The collection of cleaning fluids must be conducted with great care. If the pipe is to be removed then all regulatory requirements for constructing a pipeline crossing would apply to provide maximum environmental protection to wildlife, fisheries, and riparian vegetation. If the pipe is to remain in place, then consideration should be given to filling the pipe with an inert material and plugging and capping it to prevent a conduit effect. For a pipeline laid on the bed of a water body, it is recommended the pipe be removed, otherwise there is a risk of the weighting not being appropriate for an empty pipeline to prevent buoyancy issues, and drilling holes in the pipe may introduce contaminants to the water body where the cleaning process either did not meet cleanliness criteria or where criteria were not available [4].

Furthermore, as the pipe degrades large pieces may break away from anchors and be carried downstream with the water current. Exposure of the abandoned pipeline at the shore of the water body or the pipeline floating in the water crossing is a long-term potential issue. It should both be monitored and mitigated as needed or that section of pipeline is removed if it is susceptible to erosion.

Aerial crossings should also be removed as the suspension support structure will deteriorate over time allowing the abandoned pipeline to fall below.

45.3.5 Transportation and Utility Crossings

Transportation and utility crossings require consideration to maintain the structural integrity of that infrastructure. In the abandonment planning stage, the owners of these crossings must identify their requirements if not already dictated by crossing agreements. The need to prevent disruption in service and subsidence may mean that the pipeline is filled in place with concrete or if there is a utility way such as a tunnel or pipe casing, then the transfer of ownership of the remaining conduit once the pipe is removed from it may be agreed to. Otherwise, a further abandonment strategy for the opening below the road, railway, or utility is required.

45.3.6 Right-of-Way Restoration

Abandonment may require the removal of portions of a pipeline and equipment from a right-of-way on private or public land. In addition, there will be excavations to clean the pipe and install plugs and caps. As a result, the land surface must be restored or reclaimed at these locations to a state comparable to the surrounding environment unless otherwise directed by the regulators. This also means that agricultural soil is reclaimed, so soil productivity is restored usually within 5 years. Vegetation must be planted and sustained to demonstrate productivity. In noncultivated areas, it may be necessary to restore the right-of-way to its original state by planting native species. Caution needs to be exercised and future checks done to make sure noxious weeds and foreign vegetation are not accidentally introduced into the right-of-way by equipment brought in. The degree of restoration of a right-of-way will depend on the regulator’s requirements and any agreements arrived at in consultation with landowners. In addition, any pipeline apparatus must be removed to a depth that will not interfere with farming equipment.

All surface and subsurface apparatus (including signage) along the route of a pipeline that is to be abandoned through removal also be removed as part of the abandonment process. Conversely, if the pipeline is to remain in place, signage must be maintained to inform persons conducting ground disturbance of necessary contact information to obtain assistance when working in the vicinity of existing pipelines.

Where contamination remediation is ongoing either on- or off-site, the abandonment and associated restoration must be held in abeyance until all standards for groundwater and soil are met.

45.4.1 Ground Subsidence

Any underground construction can lead to voids being left in the soil structure. The natural settling or subsidence process, often aided by water percolation, leads to depressions on the land surface. These depressions can cause impediments to traffic, water ponding or channeling, and possibly erosion and poor crop production. In most cases where a pipeline has been in operation and the pipe is not removed, the soil structure is stable and further subsidence will not immediately occur. If subsidence occurs, filling in the depression is necessary with the appropriate soil, which is usually topsoil. Subsidence may also occur where pipe deterioration occurs. This is addressed in Section 45.4.2.

45.4.2 Pipe Deterioration and Collapse

Given that the steel components of a pipeline are subject to corrosion where the coating deteriorates, it is a common assumption that the pipeline will perforate and eventually collapse. However, there are many factors affecting corrosion and there are many factors affecting soil collapse.

Corrosion will normally occur on the outside of the pipe because the interior is protected from the outside environment by plugs and caps. In the case of production pipelines, it is possible that some internal corrosion may occur as the process of purging may leave minor amounts of water or other contaminants inside the pipeline. This corrosion would not be expected to continue beyond a short period of time. The rate of external corrosion will depend on the presence of moisture and the soil properties, and the rate at which any external coatings deteriorate. As external coatings are generally polymeric in nature, they can exist for an extended time before eventually breaking down. This may occur locally at first but eventually could be expected to be widespread. However, in the process of coatings deteriorating, the resulting perforations would be random and not concentrated enough to cause complete failure of the pipeline structure over any significant length.

An eventual perforation could then introduce moisture to the interior of the pipeline, where corrosion could occur primarily on the bottom of the pipe [4].

Given the slow corrosion rate and the ability of a pipe to maintain strength even with holes, it is possible that a pipeline will not have a structural failure for centuries [5]. At that time, the soil in the vicinity of the pipeline may mitigate any surface depression. The soil surrounding a pipeline provides support to the pipeline for lateral movement. However, as a pipeline deteriorates, it is likely that soil would gradually fill in the pipeline as it decomposed [4]. The result might be a gradual surface depression that would only be evident on large-diameter pipes. If the soil above a pipeline has more stable properties, such as those exhibited by clay, then it could also sustain larger vertical loads and resist collapse, but eventually a form of surface subsidence would occur over time.

These assumptions are yet to be proven but research should occur to determine the factors that could shed more information on predicting the effects of pipeline deterioration.

45.4.3 Pipe Exposure

Soil removal can occur in a number of ways to expose a pipeline. Soil may be removed by mechanical means if human activity is not controlled. It may also occur due to a geotechnical or hydrotechnical event [4]. However, it most often occurs due to erosion by water or wind. The most susceptible sites to erosion are those where slopes or fine soils are present. Pipeline trenches themselves can preferentially erode in the presence of moving surface or subsurface water, as the unconsolidated materials surrounding the backfilled pipeline can be more easily eroded than adjacent undisturbed soils. It is sometimes necessary to install water breaking devices in the trench to inhibit the movement of groundwater through the looser materials, though this is usually done at the time of initial construction.

Pipelines abandoned adjacent to watercourses can be exposed through flood events or bank movement. Where an abandoned pipeline is susceptible to this then removing the pipe is recommended. Otherwise, removal in the future will likely become necessary for aesthetic, access, and public safety reasons.

45.4.4 Water Conduit Effect

When pipeline abandonment in place occurs, eventual corrosion may allow water to enter the pipe. If the source is of significant volume such as from a water table or surface runoff then a serious problem can be created downslope where the water may exit the pipe and cause erosion, vegetation damage, sink holes, or otherwise affect property. Conversely, artificial drainage can disrupt natural runoff conditions that can affect ecosystems and interrupt water supplies for persons relying on them.

This water conduit effect can be prevented with the installation of caps and pipe plugs at the time of abandonment. The plugs should be long enough to prevent corrosion. Consideration also needs to be given to the location of such plugs as the pipe wall adjacent to the plug will eventually corrode away again allowing water to enter. The plugs should adhere to the pipe, be impermeable and nonshrinking, and able to resist deterioration. Examples of suitable materials are concrete grout or polyurethane foam. The use of impermeable earthen plugs may also be a viable option.

Plugs should be installed downstream of any water bodies or known high-water conditions. Plugs should also be installed upstream of water bodies and environmentally sensitive areas to prevent contamination or introduction of sediment. Guidelines for locating plugs are presented in Table 45.1.

45.4.5 Slope Stability

Pipelines should be left in place on unstable slopes as the pipe may provide support to the slope and remediation is difficult. In most cases, vehicle traffic on slopes can cause loss of cover so it should be discouraged where possible and mitigated if access is an ongoing need. If the pipeline is removed on a slope, then remediation with fast-growing vegetation is recommended and frequent monitoring over a few years is necessary.

In anticipation of the pipeline caps or plugs failing, there will need to be mitigation against water conduit effects on a slope. If recapping the pipe is not possible or the risk to slope failure through possible pipe water transport, then the pipeline should be forced to exit at a location where energy dissipation can occur to prevent erosion and where release of sediment is acceptable.

45.5.1 Monitoring and Maintenance

If a pipeline is left in place, then signage should be maintained to inform affected persons of its location to prevent damage to excavating or farming equipment. Contact information for the owner and One-Call information is often required. In areas that maintain a One-Call center, the pipeline should remain on the database. The pipeline right-of-way should also be examined on a frequency to be determined to check for general issues that require maintenance such as subsidence, pipe exposure, erosion, and weed growth.

45.5.2 Land Use Changes

When a land use change is contemplated, an abandoned in-place pipeline may need to be removed to accommodate development such as a road or housing development. This is not always necessary and the pros and cons of doing so need to be carefully considered between the pipeline owner and the project developer. Different jurisdictions may treat the costs of removal of the pipe in different ways. In some, costs of removal would be the responsibility of the owner of the pipeline unless the landowner had agreed to assume responsibility at some time. In others, a shared cost approach may be used depending on when the pipeline was originally constructed and on the circumstances of the proposed development. Regulatory jurisdictions may also provide processes to mediate or dictate the allocation of costs; this will need to be investigated thoroughly in each specific jurisdiction.

45.5.3 Liability

In some jurisdictions, an abandoned pipeline remains the responsibility of the owner until it is removed from the right-of-way (e.g., Alberta Canada [6, 7]). In other jurisdictions, liability is not clear once abandonment is approved, because the regulatory authority may apply only to the transportation of a product. Certainly, most North American environmental regulatory jurisdictions have a “polluter pay” principle where any residual contamination is the responsibility of the entity that caused the pollution.

Liability may be further complicated by existing land use agreements that may have included conditions respecting liability. Further conflicts may exist if original land use agreements have been nullified and easements are taken off the land title. As a result, it is recommended that a company abandoning a pipeline assume it has ongoing liability, and therefore continues to maintain a right to access the abandoned pipeline for monitoring and maintenance.

45.5.4 Financial Resources

A large corporation that abandons a pipeline must have funds to not only conduct the physical abandonment but also to mitigate postabandonment issues where a responsibility is identified. A smaller entity will also be required to demonstrate sufficient funds to conduct the physical abandonment but once that occurs often it either transfers ownership, with regulatory approval, or assumes the pipeline has no further need for financial resources. As previously noted, there are ongoing monitoring and maintenance needs at a minimum. For all companies it is recommended that there be an ongoing budgetary allocation for monitoring, maintenance, and contingencies. An alternative is a security fund that is in trust with a third party for the care of the pipeline if the entity ceases to exist.