It is essential that pipeline regulators considering risk-based remediation plans understand early the nature and complexity of the risk assessment to be performed as part of abandonment and whether or not this approach is conducive to unconditional closure of a site.
In Canada, such understanding is particularly important when an application for abandonment pursuant to the National Energy Board (NEB) Act is being considered, as the Board’s jurisdiction terminates as soon as a pipeline is legally abandoned. If the risk-based remediation plan is considered a mitigation measure pursuant to Section 20 of the CEA Act, then the NEB still has a responsibility to ensure that it is implemented.
Parts 1 and 2 of this series provided an overview of the NEB’s regulatory requirements and responsibilities with respect to pipeline abandonment and a detailed examination of the Yukon Pipeline Ltd. (YPL) abandonment and remediation in terms of the pipe and pumping stations.
This concluding article looks at abandonment and remediation of the pipeline’s tank farm and discusses the practical lessons that can be drawn from the YPL abandonment.
Tank farm
The upper tank farm (UTF) sits on a well-drained sand and gravel bluff above the Whitehorse Airport, which in turn lies above downtown Whitehorse. Surrounding land use consists of a highway and airport to the east, primarily commercial use to the northeast and southeast, and primarily residential land use (or probable future residential land use) to the north, south, and west.
The site is relatively level, but beyond the property lines the ground slopes steeply away to the east and southeast. The water table is about 21-34 m below grade and appears to flow principally to the northeast, toward Baxter’s Gulch where groundwater seeps from the ground and forms a stream flowing east toward the Yukon River valley.
Facilities on the 56-hectare site included a pump and meter house, an office, a laboratory, storage sheds, barrel storage, an oil change pit, a spill trailer, truck loading and unloading racks and manifold, underground and above- ground yard piping, booster pumps, valves, a gravel pit, and a former pump station.
Storage tanks included twenty-four 1,600 cu m earthen bermed, bolted construction, fixed-roof aboveground storage tanks (ASTs), as well as a 22,700-l. steel underground storage tank connected to drains below the truck loading racks, a septic tank and a heating fuel AST associated with the office, and a 4,500-l. engine fuel AST associated with the former pump station.
The site is forested aside from areas cleared for facilities, tanks, and roads (Fig. 1).1-4
Abandonment, mitigation
YPL planned to clean and remove yard piping at the UTF in the same manner used for the main pipeline. Tank cleaning and removal were to mirror methods used at the Carcross pump station. YPL attempted to preserve the natural habitat at the UTF.1
Assessment approach
At the UTF, YPL combined its Phase I environmental site assessment (ESA) with its limited initial Phase II ESA. After identifying 11 areas of potential environmental concern (APEC) at the UTF, YPL drilled five boreholes to obtain preliminary soil and groundwater data. Following removal of the ASTs and other facilities at the UTF, YPL conducted a more detailed Phase II ESA, including extensive soil vapor surveys and test-hole excavations focusing on the APECs, including each AST. YPL also drilled an additional 13 on and offsite boreholes.
YPL compared soils in the upper 3 m with Yukon Contaminated Site Regulations (CSR) and Canadian Council of Ministers of the Environment (CCME) criteria for residential land use, and screened soils more than 3 m deep against CSR and CCME industrial land use criteria. It compared groundwater samples with CSR and CCME freshwater aquatic life (FAL) criteria.
YPL identified phase-separated liquid hydrocarbons in monitoring well BH96-01 about 33 m below grade. A preliminary risk assessment determined that the site did not pose a risk to human health (of a trespasser) or the environment in its current state, but would require remediation to accommodate future development. YPL chose to involve a developer in hopes that remediation could be planned to meet both pipeline abandonment and future development needs.2 4
Remediation approach
YPL elected to develop site specific remediation standards (SSRSs) for soils deeper than 3 m.5 It excavated shallow soils exceeding CSR residential criteria and a few deeper hot spots and segregated them into granular material for beneficial reuse and fine material requiring offsite bioremediation and disposal.6-8
YPL then planned for deeper soils exceeding the SSRSs to be subjected to in place soil vapor extraction and bioventing. The residential subdivision proposal laid out the neighborhood so that deeper soils requiring ongoing remediation would lie below cul de sacs or green spaces.5
The SSRS calculations showed that hydrocarbon-saturated soils could be left in place so long as phase-separated liquid hydrocarbons were not present and houses were offset 15-30 m from contaminated areas (depending on the type of basement construction).9 Subsequent soil vapor monitoring, however, demonstrated that the dilution factors used in the SSRS calculations overestimated the actual dilution.10 11
Instead of lowering the SSRSs to values that would protect human health and the environment without imposing further conditions (possibly necessitating further soil remediation), YPL left the SSRSs for soil as is and introduced new SSRSs for vapors in conjunction with monitoring requirements and engineering controls for the proposed new homes.11
YPL has not performed remediation activity for soils deeper than 3 m other than the removal of hot spots in conjunction with excavation of shallower soils. To date, NEB has not granted formal approval to either soil or vapor SSRSs.
YPL’s remediation plan called for routine liquid hydrocarbon recovery and groundwater sampling to continue until phase-separated liquid hydrocarbons were no longer detected and on site and off site groundwater met site-specific groundwater standards (SSGSs) and CSR FAL criteria, respectively, for a period of 2 years.5 Assuming natural attenuation of dissolved hydrocarbons was occurring and that all groundwater from the site would flow into Baxter’s Gulch, YPL back-calculated SSGS for use on site such that concentrations would attenuate to below CSR FAL criteria by the time the groundwater reached Baxter’s Gulch.12 Biostimulation and biosparging would accomplish groundwater remediation, if required.5
In February 2003, following introduction of a new version of the CSR in August 2002, YPL proposed to change the criteria it would use to determine the success of its groundwater remediation program. Instead of applying the SSGSs, YPL proposed to conduct a risk-assessment to determine whether existing hydrocarbon concentrations in groundwater would adversely affect identified human and ecological receptors.13 14
The Board approved YPL’s request to amend its remediation plan but directed YPL to submit its formal Human Health and Ecological Risk Assessment and amended remediation plan for approval before implementing any changes.15 The submitted risk assessment is a topic of ongoing technical debate between YPL and other interested parties and has not been approved to date.16 17
YPL resumed groundwater monitoring at the UTF in June 2005, following a 3-year hiatus, and liquid hydrocarbons (0.57 m thick) were detected on the groundwater table in BH96-01 for the first time since late 2000. Although subsequent monitoring events have detected no liquid hydrocarbons, the discovery raised questions with respect to understanding and delineation of the liquid hydrocarbon plume or plumes and reset the clock with respect to YPL’s monitoring commitments for site closure.18
Issues, concerns
The UTF’s visibility within Whitehorse, potential real estate value (due to its central location and thick overburden), and potential for residential redevelopment have exposed it to ongoing public interest and stakeholder scrutiny.
The UTF abandonment presents many technical logistical, and regulatory challenges. Technical challenges revolve around adequate characterization and understanding of this site to support the risk-based decisions contemplated.
Subsurface vapor migration, delineation of impacted soils at depth, characterization of the groundwater flow regime, demonstration of natural attenuation, and identification and delineation of liquid hydrocarbon plumes remain topics of discussion and debate between the NEB, YPL, and others.
Underlying these topics of discussion is the deeper question of what level of detail is sufficient for YPL and regulators to feel confident in their decisions with respect to protection of human health and the environment, particularly considering the potential for single-family residential redevelopment.
Logistical difficulties include the large size of the site, the large depth to groundwater and contamination at the groundwater table, the large number of discrete sources of contamination within the overall site, and the cost and limitations of drilling technology available to characterize the site.
Regulatory issues include the question of how to conclude a remediation plan approved under and regulated by a pipeline regulator, where the original contemplation of risk-based approaches and site-specific numerical standards has developed into risk-management specifications for future residential development. These are areas outside the scope of the NEB’s jurisdiction that could presumably only be implemented after leave-to-abandon comes into force.
The changing understanding of the site, changing regulatory environment over the course of the project, and the company’s changing approach to remediating or risk-managing the site have complicated remediation. The limited characterization of the site at the time of the abandonment hearing made it difficult to foresee some of the issues and difficulties that would arise in the remediation of this site, as well as the time required to accomplish successful remediation. Changing regulations and standards added further twists.
The Yukon CSR, in draft during the hearing, came into force later in 1996 and were revised in 2002. CCME Canada-Wide Standards for Petroleum Hydrocarbons (PHC) in Soil were endorsed in 2001. As federal standards for bulk PHC had not previously been available, the emphasis of the YPL remediation shifted from meeting federal and territorial standards to meeting just the CSR standards. As a result, participants did not apply the CCME standards for PHC even after their introduction.
In response to these changes in the regulatory environment and understanding of the site, in YPL’s remediation approach shifted, resulting in some unforeseen jurisdictional issues and resource demands for increasingly complex technical analysis.
Although YPL’s remediation plan follows the spirit of the Yukon CSR, it has been evaluated and approved pursuant to the NEB and CEA Acts. In order to facilitate input from regulatory and non-regulatory participants as YPL progressed from preliminary investigation at the time of the abandonment hearing to development and implementation of a remediation plan and site closure, the NEB required YPL to “provide information to and consider the comments of persons who indicate to YPL that they wish to be consulted.”19
The YPL properties, however, have not been designated “contaminated sites” or issued permits for “risk-based restoration” by the YTG pursuant to the Yukon Environment Act or CSR. A disconnect therefore exists between the federal regulatory approval of the remediation plan and the territorial regulatory tools that could be applied to the long-term risk management of the sites.
Lessons
It has been more than 10 years since the NEB wrote the YPL abandonment order and it has yet to come into force. The physical abandonment of YPL’s facilities was relatively straightforward and didn’t involve many of the potential environmental effects that might need to be addressed for the abandonment of a larger diameter underground pipeline. Soil and groundwater contamination issues such as those encountered on this project, however, are seldom quick or inexpensive to address and may involve many unknown variables for which it is hard to plan.
It is important that the abandonment process, including NEB decision and conditions, incorporate appropriate adaptability to address the variables and temporal changes encountered in a multi-year environmental remediation project.
In the past year, NEB has worked to revitalize lines of communication among itself, YPL, and other stakeholders in order to move toward successful, safe, and environmentally sound abandonment of this site. In review of this file, measures emerge that would make future large-scale abandonment processes more efficient and effective, particularly if considered early in the proceedings. These measures pertain primarily to matters of risk assessment, risk management, and jurisdiction.
As summarized by YPL in hearing documents, in order for an adverse health or environmental effect to occur, three components must be present: a hazardous chemical concentration, a receptor, and an exposure pathway.1 Assessment and management of these components can effectively and efficiently address environmental risk associated with contaminated sites but can also be problematic.
Risk-assessment principles underlie many Canadian provincial, federal, and territorial regulations, standards, and guidelines for contaminated sites. Generic soil and groundwater criteria are typically based on conservative default inputs into risk-based environmental models. The regulations, standards, or guidelines also typically contain mechanisms for tweaking generic criteria through input of site-specific parameters, or for implementing full-blown risk assessment or risk management.
The more complex the adjustment, the better the understanding of the site required, the more long-term control over the site required, and the more important full participation becomes. Characterization of the site must be sufficient to support the risk-based decisions being made.
In response to its responsibilities under the CEA Act, NEB can delay leave-to-abandon from coming into force until environmental mitigation measures have been implemented. This might be counterproductive, however, when proponents seek to implement appropriate long-term risk management measures while redeveloping former pipeline property after leave-to-abandon is in force.
Completion of as much of the site characterization and risk-assessment work before applying to abandon the facilities would enable more informed decisions with respect to potential issues, impediments, and costs. In particular, the scope of the risk assessment and timeframe of the risk-management measures being proposed should be well understood.
Options available to NEB might then include limiting the scope of risk assessment and management to measures it can ensure are implemented before formal abandonment, or working with other applicable regulatory agencies to ensure risk assessment and management measures are implemented within their regulatory frameworks and under their regulatory oversight (pursuant to paragraph 20(1.1)(b) of the CEA Act).
The latter option would depend on the jurisdictional boundaries and regulatory framework of the agencies involved and would require establishment of appropriate regulatory roles and responsibilities early in the abandonment process; requiring further analysis with respect to legal and logistical issues.
Operators and regulators alike should consider the following lessons from the YPL case when approaching future abandonments, particularly when contaminated site risk assessment and management is contemplated:
- Companies should complete as much as possible of the site characterization and risk-assessment work before applying to abandon the facilities.
- Site characterization must be sufficient to support the risk-based decisions being made.
- Roles and responsibilities of involved regulators should be determined early in the abandonment process.
- Companies and involved regulators should identify as early as possible the nature and complexity of any proposed risk assessment and management and evaluate whether the approach is conducive to unconditional site closure.
- The regulator may need to limit the scope of acceptable risk assessment and management to measures it can ensure are implemented before formal abandonment, or work with other regulators to ensure risk assessment and management measures can be implemented within their regulatory frameworks and under their regulatory oversight.
- The abandonment process, including regulatory decisions and conditions, should incorporate appropriate adaptability to address changing circumstances over the course of an abandonment project.
References
- NEB, “National Energy Board Order No. MH-3-96, White Pass Transportation Ltd. Yukon Pipeline Abandonment, Hearing held at Whitehorse, Yukon, Aug. 20, 1996, Volume 1,” https://www.neb-one.gc.ca/ll-eng/livelink.exe/fetch/2000/90464/90552/92272/92808/92809/MH-3-96_Volume_01.pdf?nodeid=92811&vernum=0, and referenced exhibits, August 1996.
- Golder Associates Ltd., “Status Report on Environmental Site Assessment of the White Pass Petroleum Products Pipeline and Associated Infrastructure,” July 1996.
- Golder Associates Ltd., “Yukon Pipelines Ltd. NEB Order MO-7-96,” September 2005.
- Golder Associates Ltd., “Report on Environmental Assessment, Yukon Pipelines Ltd., Whitehorse Upper Tank Farm, Whitehorse, Yukon,” February 1998.
- EBA Engineering Consultants Ltd., “Plan of Restoration, Yukon Pipelines Ltd., Whitehorse Upper Tank Farm, Whitehorse, Yukon,” January 1999.
- EBA Engineering Consultants Ltd., “Results of Quality Control Monitoring during Granular Production, YPL Upper Tank Farm, Whitehorse, Yukon,” August 1999.
- EBA Engineering Consultants Ltd., “Data Summary of Excavation Program, Former YPL Upper Tank Farm, Whitehorse, Yukon,” May 2000.
- EBA Engineering Consultants Ltd., “Analytical Results for Additional Excavation Work, Upper Tank Farm, Whitehorse, Yukon,” June 2002
- Golder Associates Ltd., “Report on Development of Site-Specific Remediation Standards for the Soil at the Former Yukon Pipelines Ltd. Upper Tank Farm, Whitehorse, Yukon,” December 1999.
- EBA Engineering Consultants Ltd., “Winter, 2000 Soil Vapour Test Results, Former YPL Upper Tank Farm, Whitehorse, Yukon,” April 2000.
- Golder Associates Ltd., “Addendum Report on Development of Site-Specific Remediation Standards for the Soil at the Former Yukon Pipelines Ltd. Upper Tank Farm, Whitehorse, Yukon,” September 2001.
- EBA Engineering Consultants Ltd., “Site-Specific Groundwater Standards, Upper Tank Farm, Whitehorse, Yukon,” December 1999.
- Golder Associates Ltd., “Workplan to Modify Section 3.6 of the Plan of Restoration to Conduct a Human Health and Ecological Risk Assessment for Dissolved Phase Hydrocarbons in Groundwater, Yukon Pipelines Ltd., Upper Tank Farm, Whitehorse Yukon,” February 2003.
- Fraser Milner Casgrain, “Yukon Pipelines Ltd., Board Order MO-7-96, Leave to Abandon Whitehorse Upper Tank Farm, Pipeline Right-of-Way and Carcross Pump Station,” February 2003.
- NEB, “Yukon Pipelines Ltd. (YPL), Board Order MO-7-96-Plan of Restoration (POR),” July 2003.
- Golder Associates Ltd., “Human Health and Ecological Risk Assessment for Groundwater, Yukon Pipelines Ltd., Upper Tank Farm, Whitehorse Yukon,” July 2003.
- Golder Associates Ltd., “Baxter’s Gulch Risk Assessment,” February 2004.
- Golder Associates Ltd., “Addendum to Golder’s Sept. 7, 2005, Letter, Yukon Pipelines Ltd., National Energy Board Order MO-7,” March 2006.
- NEB, “Reasons for Decision, Yukon Pipelines Ltd. MH-3-96, Facilities Abandonment,” https://www.neb-one.gc.ca/ll-eng/livelink.exe/fetch/2000/90464/90552/92272/92808/92810/1996-09-01_Reasons_for_Decision_MH-3-96.pdf?nodeid=92817&vernum=0, September 1996.