Coordinated watercourse assessment streamlines pipeline development

April 4, 2011
It is beneficial in the early stages of a pipeline project, particularly one involving multiple water crossings, to have a multidisciplinary team conduct an initial field assessment instead of relying on multiple teams of subject-matter specialists.

Steve Jasper
WorleyParsons
Calgary

Raymond Doering
Enbridge Northern Gateway Pipeline
Calgary

Jason D. Harris
Triton Environmental Consultants Ltd.
Terrace, BC

It is beneficial in the early stages of a pipeline project, particularly one involving multiple water crossings, to have a multidisciplinary team conduct an initial field assessment instead of relying on multiple teams of subject-matter specialists. The single-team strategy encourages a collaborative approach in which many factors can be identified and discussed on site.

Watercourse crossings pose potentially major environmental and technical problems for pipeline projects.1 Factors related to these problems include, but are not limited to fish and fish habitat, access to the crossing location, geotechnical and hydrological issues, integrity of the installation, and cost and maintenance issues. Some factors, at least initially, seem to conflict, creating difficulties with respect to the risk and benefit evaluations of various crossing options to determine each crossing's most appropriate location, method, and timing of construction.

Evaluating a watercourse crossing typically involves various specialists gathering field data to provide their assessments independently. For example, fisheries biologists will often assess fish and fish habitat characteristics of a section of the watercourse without benefit of knowing exactly where the crossing is and what method and timing of construction is preferred. Engineers, on the other hand, may be concerned with valley slope stability and pipeline integrity issues, while construction specialists focus on access, cost, and the timing of construction.

This article provides an example of such a multidisciplinary team, the strategic watercourse assessment team (SWAT), assembled for a major pipeline project proposed for Western Canada.

Background

The Enbridge Northern Gateway Project (Fig. 1) includes a 36-in. OD, 1,172-km oil pipeline extending from Bruderheim, Alta., to Kitimat, BC, and a 20-in. OD condensate pipeline running the opposite direction. In the three major drainages in Alberta, the pipeline route crosses the Central Parkland, Lower Foothills, and Dry and Central Mixedwood natural subregions.

In British Columbia, the pipeline route crosses the Sub-Boreal Spruce, Engelmann Spruce-Subalpine Fir, Boreal White and Black Spruce, Alpine Tundra, Coastal Western Hemlock, Mountain Hemlock, and Interior Cedar Hemlock zones of the biogeoclimatic ecosystem classification.

Fisheries resources in Canada, including protection and management of fish and fish habitat, are regulated by the Fisheries Act and administered by Fisheries and Oceans Canada (DFO). This project considers five relevant sections of the Fisheries Act (Sections 21(3), 22(2), 22(3), 32, 35(1) and Section 36(3). Fish species found along the pipeline route include 27 sportfish species, eight coarse fish species, and 23 forage fish. Sixteen of these species are common to Pacific (Fraser, Skeena, Kitimat, Douglas Channel) and Arctic (North Saskatchewan, Athabasca, Peace AB and BC) drainages.

Methods

The project identified more than 750 watercourses intersected by the proposed pipeline right-of-way (ROW). Over 200 watercourse crossings, or sites, were prioritized for SWAT assessments based on the following factors:

• Fish species present (e.g., important game fish and-or species of conservation concern) and fish spawning, rearing, and overwintering habitat (based on preliminary research, baseline studies, and discussion with regulatory agencies).

• Geomorphologic features (channel morphology, confinement, coupling, etc.).

• Hydrologic features (stage, discharge, velocity, etc.).

• Disturbance indicators (eroding banks, abandoned channels, etc.).

• Constructability issues (accessibility to channel, floodplain, staging areas, etc.).

The SWAT prepared a list of candidate sites for each field season and gave each site a unique ID number identifying the intersection of the most current pipeline route alignment with the watercourse. SWAT management then provided the site ID location to field crews as GPS coordinates, along with biophysical and fisheries data, hydrology, and geotechnical information and construction spread timing if available. Maps (1:20,000 and 1:5,000 scale) developed for each site showed the current pipeline route alignment, together with access roads and trails. Maps preparation used light detection and ranging (LiDAR) imagery, if available.

Two members of the multidisciplinary sensitive watercourse assessment team examine a potential water crossing along Enbridge's Northern Gateway Pipeline route (Fig. 2).

The SWAT (Fig. 2) consisted of a fisheries biologist, a pipeline watercourse construction specialist, and other technical support personnel. Field team member selection drew from specific technical expertise and experience with biophysical and fish habitat assessments, pipeline watercourse crossing methods, and pipeline access and installation at watercourses. For most sites this meant a field crew size of at least three persons.

At each site SWAT first assessed the current location of the crossing based on environmental and constructability issues. Fish habitat (in particular, spawning areas), stream morphology, access down the valley slopes and construction staging areas were some of the important factors considered. In many cases, the best location with respect to minimum risk to fish and fish habitat, was not the best location from a construction perspective. In those cases, SWAT members would collectively determine the best location (i.e., least risk for environmental effects and high probability of construction success) based on professional judgment.

This sometimes led to the most feasible (construction-wise), low risk (environmental-wise) crossings, determined by SWAT, lying various distances (upstream or downstream) from the mapped centerline. Deviations greater than 100 m prompted generation of a new site number. Each preferred crossing location deviating from the initial location by more than 20 m was identified for possible update to the current route alignment.

In most cases, engineering determined the preliminary crossing method, construction spread, and season. Timing (season) also considered least-risk periods (LRP) established by DFO and provincial authorities (e.g., British Columbia Ministry of Environment) for important fish species and life-history requirements. Previous field baseline and desktop studies determined fish species composition at each crossing.

The SWAT reviewed preliminary crossing methods and timing, making recommendations as to whether either should be changed. In many cases it identified an alternate method or timing as a possibility or conversely, ruled it out as not feasible. For example, stream morphology or unsuitable bed substrate may render a particular isolation method unusable, or environmentally unsuitable, due to high fishery values, such as spawning areas. In this case an alternative, trenchless method may move to the fore and the assessment continued with that in mind.

The presence of multiple important fish species (e.g., salmon and trout) that spawn in different seasons often constrained in-stream construction timing, reducing it to a single month or even shorter duration. Further, river discharge rates during the reduced construction window can be greater than during other seasons, making construction more difficult and increasing the potential for environmental risk.

Identifying the preferred location and reviewing the preferred method and timing allowed completion of a biophysical and construction field assessment. The SWAT assessment included, where possible, the following items:

• Crossing identification, preferred crossing coordinates.

• Access, approach to crossing location.

• Site crossing sketch showing rough gradients.

• Reconnaissance fish, fish habitat assessment following British Columbia Resources Inventory Committee guidelines.2

• Constructability assessment, potential issues.

• Site-specific mitigative measures.

• Site-specific compensation, reclamation measures.

• Photo documentation of crossing location.

• Conceptual site plan sketch showing preferred crossing method and specific mitigations.

• Contingency crossing method.

Results

Assessments took place from 2006 to 2009, during which the route corridor and centerline changed several times. At many watercourses more than one assessment took place where the crossing alignment changed from one year to another. Several route revisions identified a total of 227 priority watercourses for the project, with 271 SWAT site assessments completed.

Teams would assess an average of about two sites/field day, with the time needed to access the crossing location often being the deciding factor. Teams could only use vehicles on existing roads and trails up to a point, after which access needed to continue on foot. This limited the number of sites assessed in one day but had the advantage of exposing such access issues as deactivated forestry roads or accessibility concerns down valley slopes. Helicopter access allowed more assessments in 1 day but was constrained by cost and the limitation on the number of passengers and thus the size of the field crew. Once at a crossing location the SWAT assessment was typically completed in 1-2 hr.

Following field data collection, the team examined the information at each site for errors, omissions, and discrepancies, editing field-site cards if necessary and clarifying or redrawing site sketches as required. Scanning the sketches into a portable document format (PDF) allowed for electronic storage along with digital photos of each crossing.

A purpose-built Microsoft Access database coordinated input, display, and report of all SWAT data. A typical SWAT site report generated from the database is 6 pages long and consists of locational (GPS) data, a biophysical assessment (fish habitat description, channel morphology, bank substrates, etc.), a constructability and mitigation assessment, two photo pages, and a site crossing-plan sketch.

Relocating watercourse crossings to avoid sensitive fish habitat features and improve constructability is important in reducing the effects of construction. One or more of the following factors typically guided a recommendation for relocation:

• Avoidance of high-value fish habitat (spawning areas, deep runs and pools, large woody debris, limiting habitat features, etc.).

• Relocation to a nonfish bearing section of the watercourse.

• Improved probability of construction success (less cross-cutting of approach slope, perpendicular alignment, reduced approach gradient, avoidance of bedrock, narrower crossing widths, better staging areas, etc.).

• Avoidance of flooded or ponded areas.

• Avoidance of bank erosion, slumping, and slope failures.

• Incorporation of previously disturbed areas such as cutblocks, access roads, and trails.

• Minimizing riparian disturbance, loss.

Of the 271 sites assessed SWAT recommended relocating 109 crossings (40% of the total, see accompanying table).

Minor shifts (<20 m) were accepted; however shifts >20 m were documented and referred to the project's pipeline route committee for possible relocation and revision to the route alignment.

The well-vegetated riparian areas, undercut banks, channel meandering, and high habitat complexity of this location gave it a high fishery value and led the SWAT team to seek an alternate crossing location (Fig. 3).

Fig. 3 shows an example of a site recommended for relocation. SWAT determined this initial crossing site included high fisheries values such as well-vegetated riparian areas, undercut banks, channel meandering, and high habitat complexity. Fig. 4 shows the SWAT-preferred location, 350 m downstream, with potentially less riparian impact, a straighter channel, and good construction access on both sides.

Using an integrated SWAT team allowed determination of a more suitable crossing just 350 m downstream as part of the same route examination, reducing the man-hours required in pipeline routing (Fig. 4).

In addition to the measures detailed in environmental protection plans, the SWAT provides site-specific details regarding possible mitigation measures to reduce the potential effects of construction, including:

• Erosion, sediment controls.

• Water disposal locations, recommendations.

• Restoration (e.g., riparian revegetation areas) options.

• Enhancement opportunities (e.g., groundwater-fed backchannels, nonfunctioning culverts, and other potential fish migration barriers).

• Alternate or contingency crossing method, timing of construction.

• Conceptual site-plan sketch with specific mitigation measures highlighted.

Design plans will incorporate these specific measures into all sensitive watercourse crossings for review during permitting.

At some sites the SWAT also recommended specific fish habitat compensation measures, including these measures as required into detailed compensation plans developed as part of watercourse crossing regulatory applications.

Finally, a photo record of the preferred crossing location provided input both during consultation with the regulatory, aboriginal, and local communities, and for developing detailed watercourse crossing drawings.

Discussion

The SWAT approach provides an iterative process between the client and regulatory review group for relocating crossings, revising crossing techniques, and modifying mitigation measures. The approach streamlines the assessment, review, and decision-making processes, thereby reducing time required by all parties.

Most decisions on the most appropriate pipeline-crossing method, timing, and location of sensitive watercourses are complex. In many cases the decision is finalized during detailed project design. Before that, the SWAT provides an efficient, high-level evaluation of the proposed crossing location, possible crossing methods, and construction timings, focusing additional field investigations and ongoing detailed discussions.

One of the SWAT's strengths is including on site discussions encompassing different disciplines so that conflicting issues are identified and consensus achieved. This is much more difficult to accomplish via multiple field assessments, each focusing on a particular discipline and conducted independently.

A recommendation to move a crossing's location based on environmental considerations is one important objective of the SWAT assessment. Of the sensitive sites assessed, 40% were not at the optimal crossing locations. The pipeline operator subsequently adopted many of the recommendations for relocation as part of the route evolution process.

Another important objective for a SWAT assessment is evaluating the possible crossing methods and timings of construction. More than one option is feasible for many of the sites, however, and on the balance of environmental and construction factors, one method and timing often stand out as the preferred option. Biophysical, fish habitat, construction, and site access information allows the SWAT to provide a high-level evaluation of possible methods and recommendations as to a preferred crossing method and timing of construction to carry forward to the detailed design phase of the project.

Watercourse crossings are a major element in the environmental assessment of pipeline projects. Because of this, regulatory agencies expect to see documented evidence, during the route evolution process, that a project is taking steps to reduce environmental risk. DFO refers to this as "Relocating and-or Redesign."3 The SWAT program fits into the project's strategy of assessing the potential risk to fish and fish habitat at pipeline watercourse crossings and taking steps to reduce that risk. Careful selection of the crossing location and method and timing of construction, as well as providing site-specific mitigative measures, reduces the risk to fish and fish habitat.

Considerations

SWAT works best for small to medium-sized watercourses, i.e., 10 to 100 m in width. Watercourses smaller than 10 m generally do not warrant the expense of SWAT. In these cases, if there are no significant engineering or constructability issues, key parameters including fish and fish habitat and expected flow rate at the time of construction can determine crossing location. Watercourses wider than 100 m are difficult to assess in a couple of hours and usually have complex technical issues demanding effort beyond which SWAT can typically provide.

The success of the SWAT is to a large degree a function of the training and experience of the individual team members. For example, the fisheries biologist needs to be well trained in biophysical and fish habitat assessments but must also have a good practical knowledge of pipeline installations at watercourses. Conversely, construction and other technical specialists have to have appreciation of the issues of fish habitat.

All team members must be prepared to work as a team to identify issues, mitigative measures, and construction options. The team must also be aware of permitting and regulatory processes relating to construction at or around watercourses. Experience shows the best personnel to be those who have been "on-the-ground" during pipeline installations, for example as environmental inspectors or part of construction teams.

On large pipeline projects different companies often supply the environmental, engineering, and other technical personnel. Scopes of work are sometimes rigidly defined for each company. The SWAT process, however, requires a high level of coordination and collaboration between different disciplines, making it important the value of SWAT be identified earlier in project planning so discipline silos don't interfere with the multidisciplinary SWAT process.

References

1. Canadian Association of Petroleum Producers, "Pipeline Associated Watercourse Crossings," 3rd edition, Canadian Energy Pipeline Association and Canadian Gas Association, 2005. https://www.neb-one.gc.ca/clf-nsi/rsftyndthnvrnmnt/nvrnmnt/lfcclpprch/pplnwtrcrssngs2005-eng.pdf.

2. Resources Inventory Committee of British Columbia, "Reconnaissance (1:20,000) Fish and Fish Habitat Inventory: Standards and Procedures," Version 1.1, 1998. http://www.ilmb.gov.bc.ca/risc/pubs/aquatic/fishform/fishform.pdf.

3. Department of Fisheries and Oceans Canada, "Policy for the Management of Fish Habitat," 1986. http://www.dfo-mpo.gc.ca/oceans-habitat/habitat/policies-politique/operating-operation/fhm-policy/index_e.asp.

The authors

Steve Jasper ([email protected]) is a consultant to WorleyParsons Canada, the lead engineering company for the Enbridge Northern Gateway Project. He has more than 35 years' environmental experience including 20 years in pipeline planning, permitting, and assessments. He is a registered professional biologist and a member of the Association of Professional Biologists of British Columbia. Jasper earned a biological science degree (1970) from the University of British Columbia.
Raymond Doering ([email protected]) is the engineering manager for the Enbridge Northern Gateway Project. He has more than 20 years' experience in pipeline design, permitting, and construction. Doering is a registered professional engineer and a member of the Association of Professional Engineers, Geologists, and Geophysicists of Alberta. Doering graduated in mechanical engineering (1986) from the University of Alberta.
Jason Harris ([email protected]) is the senior watercourse crossing consultant for the Enbridge Northern Gateway Project. He is also vice-president and senior fisheries biologist for Triton Environmental Consultants Ltd. Harris is a registered professional biologist and a member of the Association of Professional Biologists of British Columbia.

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