Figure 1. Map of British Columbia, Canada, Showing the Location of the Pennask Creek Area.
MDAG.com Internet Case Study 27
Highway 97C Road-Cut Environmental Prosecution Near Pennask Creek
by K.A. Morin and N.M. Hutt
© 2007 Kevin A. Morin and Nora M. Hutt
Important Note: This geochemical case study involves a criminal environmental prosecution under the Canadian Fisheries Act, to which the British Columbia Ministry of Transportation (MoT) pleaded guilty to two of ten charges. This case study is not a legal opinion, but is simply our perspective on the available geochemical information from the prosecution.
Abstract
In the late 1980's, Highway 97C (the Coquihalla Connector) was built in southern British Columbia, Canada. A relatively small amount of rock was excavated near Unnamed Tributary, which drained into fish-bearing Pennask Creek and Pennask Lake. This activity produced “rock cuts” on the north and south sides of the highway, which eventually released acid rock drainage (ARD) and elevated metal leaching (ML) into Unnamed Tributary.
As an analog to current road-corridor assessments for ML-ARD, preconstruction information such as test pits, visual observations, and local water chemistry were reviewed for warning signs that significant ML-ARD would arise. No such signs were found. Thus, general preconstruction information, perhaps including shallow, weathered samples, may not successfully characterize the ML-ARD potential of deeper rock.
Prosecution documents contended that the British Columbia Ministry of Transportation should have been aware of, and concerned about, ML-ARD from the highway in the late 1980's. This was based on the Halifax International Airport and a conference paper published in 1990's for the Appalachian area of the United States. However, these arguments appear weak, because they did not reflect current practice for highways in the 1980's or even the early 2000's.
1. Introduction
The Pennask Creek Watershed is located to the south of Pennask Lake in British Columbia, Canada (Figures 1 to 3). Pennask Creek is the main drainage course in the watershed, originating radially around Pennask Mountain to the south and draining generally north into the southwest corner of the lake. The lake is also fed by other surrounding watersheds, so Pennask Creek is not its sole source. Pennask Creek and Lake include a fish hatchery and fish habitat, which is protected under Canada’s Fisheries Act.
Approximately 1.2 km east-northeast of the crossing of Highway 97C over Pennask Creek, the highway crosses “Unnamed Tributary” (also known as “Highway Creek”). Unnamed Tributary flows north-northwest until it enters Pennask Creek approximately 1.3 km (straight-line distance) north of the highway. The rock cuts on the north and south sides of the highway (Figures 4 and 5), just to the east of Unnamed Tributary, are now known as sources of acid rock drainage (ARD) with accompanying elevated metal leaching (ML). They are labelled here the north and south “ARD rock cuts”.
Fisheries and Oceans Canada, Environment Canada, and the British Columbia Ministry of Environment participated in field investigations at and below the ARD rock cuts. Ten charges under Canada’s Fisheries Act were laid against MoT as the result of these investigations. In 2005, MoT pleaded guilty to two of the ten criminal charges, and the remaining eight were dismissed.
Our focus in this case study lies in whether there were any geochemical clues that ML-ARD might arise from the ARD rock cuts, based on information collected prior to highway construction. This represents an analog to current road-corridor assessments in British Columbia. We were also interested in prosecution arguments that MoT should have been aware of ML-ARD potential for highways at that time.
2. Prior to Highway Construction
In the absence of ARD-specific tests (see Section 3), sometimes there are visual clues that ARD is occurring, or could arise in the future. Such clues are currently in use in British Columbia for ARD assessments of road corridors prior to construction. Primary clues are (1) acidic pH values in water accompanied by elevated sulphate concentrations, (2) the occurrence of acid-generating sulphide minerals in exposed rock, and/or (3) significant metal staining, often rusty red-brown to orange in colour, along outcrops or watercourses.
Data from Hardy Associates (1986) showed that water pH values near the proposed ARD rock cuts were among the highest values reported in the area, at 6.7 to 6.8, whereas pH values fell to 6 and lower several kilometers to the east. Thus, there was no evidence of acidic pH and ARD around Unnamed Tributary and the proposed rock cuts before highway construction.
Additionally, no sulphide minerals or coatings were reported near the proposed rock cuts. Many visual observations were available before highway construction, based on observed seepages and test pits. For example, “major seepage encountered at 1.9 m in sand till”, “Test Pits 35 and 35, both located in small gullies in the Section 843 to 847 area, showed minor seepage at depth”, and “Test Pit 30, downhill Station 863 showed seepage at 2.5 m in sand till.” Close to the future ARD rock cuts,
“Because of the relatively high water tables in this section, some spot drainage may be required in the cuts to the right of the control line. Also, because of the wide range in weathering of the rocks encountered in this section, some local ravelling of cutslopes may occur. Some local shotcrete application may be required.”
None of these observations mentioned sulphide minerals, or metal coatings and stains, in or around the seepages and water.
Other surface observations in this area included,
“Outcrop [of the east end of the future ARD rock cuts] exposed in ditch on tote road. Rock consists of slate and quartzite, heavily bedded, blocky (50 to 100 mm spacing). Rock is strong, but slate weathers to clay materials. Rock is overlain by 1 m of till”
From a test pit,
“metamorphics, slates, moderately weathered, mod. strong, shattered, joint spacings 0.02 to 0.1 m, weathered (clayey seams 0.2 m wide on foliation. Sample taken from completely weathered clayey silt), vertical zone. No water encountered.”
Thus, a substantial amount of surface and subsurface work was done on water, soil, and rock in and around the future ARD rock cuts. In all cases, there were no reports of acidic pH, ARD, sulphide minerals, or metal coatings and stains. Therefore, there were no advance indications that ARD would arise after the rock was cut.
However, the ARD rock cuts were not drilled or cored in advance, and no ARD-specific tests like acid-base accounts (ABA) were made. So, it is not clear if ARD-specific tests, at least on shallow, weathered samples, would have correctly characterized the deeper ARD potential. In any case, part of the prosecution involved arguments that MoT should have conducted such ARD-specific work, as explained in the next section.
3. Reasonable Expectations at the Time
As explained in the previous section, there were no geochemical clues or observations that would have indicated that ARD might arise from the ARD rock cuts near Unnamed Tributary. However, ARD-specific tests were not made on the rock, so it is not clear if this would have helped.
The prosecution argued that the MoT should have been aware of ARD potential “as an issue relative to highway construction in North America” in the late 1980's. Thus, the contention was MoT should have assessed the potential using ARD static tests like acid-base accounting and kinetic tests like humidity cells (e.g., Morin and Hutt, 1997 and 2001; Morin et al., 2003).
Although not purely geochemical, we find this intriguing. Thus, we have looked at the prosecution arguments and the state of ARD knowledge for highways in the late 1980's. One general observation is that ARD at that time would have been referred to commonly as Acid Mine Drainage (AMD). This would be an obvious reason to ignore AMD on a highway which was not a minesite.
The prosecution’s arguments for prior awareness, as put forward by SRK Consulting (2004), focussed on two sources. The first is the Halifax International Airport, which has experienced ARD from its runways for about 20 years (Section 3.1). The second argument is a paper by Byerly (1990), based on documents for the U.S. Department of Transportation (Section 3.2). This paper discussed findings from the southern Appalachian Mountains, such as found in the U.S. State of Virginia.
3.1 Halifax Airport
In a conference paper (Hicks, 2003), the Halifax International Airport (HIA) Authority in Nova Scotia explained that ARD had been a problem at the airport for decades. After 20 years of remediation attempts and $20 million of mitigation, the airport had finally installed a $7-million high-density-sludge lime-based water-treatment plant. This was the only option that consistently met compliance goals.
SRK Consulting (2004) pointed out that the Ministry of Transportation should have been aware of the implications for ARD based on HIA. However, SRK Consulting did not clarify why a provincial transportation ministry would have consulted with a federal aviation organization to learn about ARD from runways. Additionally, the Meguma slates in Nova Scotia that generate the ARD (see http://www.dal.ca/~enviro/ard/welcome.html) were not the same rock unit as encountered near Unnamed Tributary. Furthermore, since 1989 when Highway 97C was built, Nova Scotia continues to have problems with ARD from the Meguma slates. Thus, it is not clear why SRK Consulting used HIA to hold the British Columbia Ministry of Transportation to a higher standard than the Province of Nova Scotia, in which HIA is located. This is confusing to us.
The earliest government transportation-related document for HIA on the website for the Meguma slates was from 1989 (Transport Canada, 1989). Therefore, even if the B.C. Ministry of Transportation were diligently reading Transport Canada documents (not related to highways but to airports in Nova Scotia), they would have been made aware of the ARD issue only in 1989 as Highway 97C was being built.
Therefore, this argument that MoT should have been aware of highway ARD, based on the Halifax International Airport, appears weak.
3.2 Byerly (1990)
SRK Consulting (2004) provided a quotation from Byerly (1990):
“It is important that construction engineers consider all rock materials suspect relative to the potential for acid production and consult all available geologic information pertinent to rock compositions in any areas under consideration.”
SRK Consulting indicated the Ministry of Transportation should have been aware of the potential for ARD from road construction based on this paper and the quotation. However, that paper contained few specific recommendations, but many general points, like all outcrops should be mapped and all core should be sampled. Case studies and details in Byerly (1990) on how to predict and control ARD were actually limited, with greater emphasis on controlling ARD after it started. As a result, Byerly (1990) would probably not have been sufficient to inform MoT on how to identify the potential for ARD, but would provide some ideas on how to control it once identified. For example, the use of limestone to control ARD was discussed, which MoT actually used after ARD started.
Daniels and Orndorff (2003) discussed ARD from highways in the State of Virginia, which includes part of the Appalachian Mountains that Byerly (1990) addressed. Obviously, Virginia was not following Byerly (1990):
“While such [ARD] problems historically had been considered isolated occurrences, over the past decade [1993-2003] the Virginia Department of Transportation (VDOT) began to recognise these sites as manifestations of the same underlying cause. While huge sums of monies have been spent on these combined problems in worldwide mining environments over the years, none of the acid materials evaluation and mitigation criteria from mining environments have been applied to the construction and road planning and design process in Virginia.”
If the State of Virginia was ignoring the recommendations of Byerly (1990) through the 1990's, why would the British Columbia MoT be expected to follow them earlier in the 1980's?
Additionally, in Pennsylvania which also contains part of the Appalachians that Byerly (1990) discussed, a U.S. Geological Survey report (Hammarstrom et al., 2005) specifically referenced Byerly (1990). However, it explained the large amount of ARD-releasing material was unexpected during construction along Interstate Highway 99 in 2003. So, in 2003 at a nearby location, Byerly (1990) did not prevent ARD due to unexpected conditions.
Therefore, it would seem that MoT had no reason to suspect the potential for ARD from the proposed rock cuts prior to highway construction, based on Byerly (1990). He was apparently not even listened to in the Appalachian region of his work.
4. Conclusion
The two relatively small rock cuts on Highway 97C (the Coquihalla Connector) release ARD and elevated metals, which led to an environmental prosecution against the British Columbia Ministry of Transportation. As an analog to current road-corridor assessments for ML-ARD, preconstruction information such as test pits, visual observations, and local water chemistry were reviewed for warning signs that ML-ARD would arise. No such signs were found. Thus, general preconstruction information, perhaps including shallow, weathered samples, may not successfully characterize the ML-ARD potential of deeper rock.
Prosecution documents contended that the British Columbia Ministry of Transportation should have been aware of, and concerned about, ML-ARD from the highway in the late 1980's. This was based on the Halifax International Airport and a conference paper published in 1990's for the Appalachian area of the United States. However, these arguments appear weak, because they did not reflect current practice for highways in the 1980's or even the early 2000's.
5. References
Byerly, D.Q. 1990. Guidelines for handling excavated acid-producing material. IN: J.W. Gadsby, J.A. Malick, and S.J. Day, eds., Acid Mine Drainage - Designing for Closure, Geological Association of Canada/Mineralogical Association of Canada Conference, Vancouver, British Columbia, May 16-18, p. 109-129.
Daniels, W.L., and Z.W. Orndorff. 2003. Acid rock drainage from highway and construction activities in Virginia, USA. IN: T. Farrell and G. Taylor, eds., Proceedings from the Sixth International Conference on Acid Rock Drainage, July 14-17, Cairns, Australia, p. 479-487. The Australian Institute of Mining and Metallurgy.
Hammarstrom, J.M., K. Brady, and C.A. Cravotta III. 2005. Acid-rock drainage at Skytop, Centre County, Pennsylvania, 2004. U.S. Geological Survey Open-File Report 2005-1148. 45 p.
Hardy Associates (1978) Ltd. 1986. Report on Geotechnical Conditions - Coquihalla Highway Okanagan Connector Km 81-93 Powerline to Brenda Mines. Report dated October 1986, Boxes 92.9163.0008 and 92.9163.015.
Hicks, S.A. 2003. Acidic Airport Drainage, 20 Years and $20 Million Worth of Experience. IN: T. Farrell and G. Taylor, eds., Proceedings from the Sixth International Conference on Acid Rock Drainage, July 14-17, Cairns, Australia, p. 489-493. The Australian Institute of Mining and Metallurgy.
Morin, K.A., and N.M. Hutt. 2003. Pennask Creek Area of Highway 97C - Assessment and Prediction of Acid Rock Drainage (ARD) and Metal Leaching (ML), and Best Options for Control. Report for the Ministry of Transportation, dated January 25, 2003.
Morin, K.A., and N.M. Hutt. 2001. Environmental Geochemistry of Minesite Drainage: Practical Theory and Case Studies (Digital Edition). MDAG Publishing (www.mdag.com), Surrey, British Columbia. ISBN 0-9682039-1-4.
Morin, K.A., and N.M. Hutt. 1997. Environmental Geochemistry of Minesite Drainage: Practical Theory and Case Studies. MDAG Publishing (www.mdag.com), Surrey, British Columbia. ISBN 0-9682039-0-6.
Morin, K.A., N.M. Hutt, T.S. Coulter, and W.M. Tekano. 2003. Case study of non-mining prediction and control of acid rock drainage - the Vancouver Island Highway Project. IN: T. Farrell and G. Taylor, eds., Proceedings from the Sixth International Conference on Acid Rock Drainage, July 14-17, Cairns, Australia, p. 495-501. The Australian Institute of Mining and Metallurgy.
SRK Consulting. 2004. Opinion on Road Cut ARD, Highway Creek, Highway 97C. Report for Environment Canada, dated November 2004.
Transport Canada. 1989. Requirements for development on mineralized slate, Halifax International Airport.
© 2007 Kevin A. Morin and Nora M. Hutt
For more case studies, see Environmental Geochemistry of Minesite
Drainage: Practical Theory and Case Studies.
Created by K.Morin