Site C Clean Energy Project Topic Specific Sessions: Presentation by Natural Resources Canada

Transcription

1 Site C Clean Energy Project Topic Specific Sessions: Presentation by Natural Resources Canada Fort St. John, British Columbia January 13, 2014

2 Outline 1. Context for NRCan s Participation in the Joint Review Panel Process and Results of Technical Review of Acid Rock Drainage Metal Leaching (Jessica Coulson, Team Leader) 2. Seismic Hazards (Dr. John Cassidy, Research Scientist) 3. Terrain Hazards (Dr. Peter Bobrowsky, Research Scientist) 2

3 Context for NRCan s Participation in the Joint Review Panel Process NRCan is participating as a federal authority: providing specialist and expert information and knowledge within the meaning of s.20 of the Canadian Environmental Assessment Act, 2012 NRCan s Technical Review (CEAR #1818): Acid Rock Drainage Metal Leaching Seismic Hazards Surficial Geology and Terrain Hazards Fluvial Geomorphology Hydrogeology and Groundwater Methyl Mercury Forestry 3

4 Results of NRCan s Review: Acid Rock Drainage Metal Leaching (ARD-ML) ARD-ML is a result of natural weathering of sulphide-bearing rock Released metals originate from the oxidizing sulphides or enhanced leaching of associated minerals when acidic conditions are reached Environmental impact of ARD-ML depends on its extent, degree of neutralization, dilution and/or attenuation 4

5 Results of NRCan s Review: ARD-ML (cont.) Given the abundance of disturbed rocks with high ARD- ML potential and short lag time to onset of acid generation, and non-acid generating overburdens with elevated selenium content, ARD-ML prevention and mitigation could pose challenges The preliminary nature of the geochemical characterization data acquired as presented in the EIS (more detailed test work is on-going) and the lack of geochemistry-supported water quality modeling presents a degree of uncertainty 5

6 Recommendations to the Panel: ARD-ML Prior to construction, conduct a thorough water quality modeling study supported with pertinent geochemical data to inform development of an effective ARD and ML management plan Involvement of responsible regulators in developing and finalizing the ARD-ML management plan Development of a water quality monitoring plan in consultation with responsible regulators for both construction and operations phases, including detection and tracking of possible groundwater plumes 6

7 Natural Resources Canada s Overview Presentation and Technical Review Related to Seismic Hazards Site C Clean Energy Project January 13, 2014 Dr. John Cassidy

8 Presentation Outline 1. NRCan s role in relation to earthquakes 2. What is an earthquake? 3. Where are earthquakes most likely to occur and why? 4. Canada s Seismograph Network monitoring earthquakes 5. Earthquakes in Western Canada 6. NRCan s Review of Seismic Hazard Assessment for Site C 7. Conclusions 8

9 Role of Natural Resources Canada Natural Resources Canada (NRCan) is the Government of Canada s principal earth sciences agency NRCan is responsible for the provision of information on the actual or probable occurrence and intensity of earthquakes, which is accomplished by: Recording and locating earthquakes in Canada and adjacent seas Providing rapid information on significant earthquakes to the public, the media, emergency response, etc. Maintaining the Canadian National Earthquake Catalogue Providing national seismic hazard assessments Conducting research into earthquake hazards to improve codes and standards 9

10 Earthquake = Sudden movement on a fault plane causing seismic vibrations The larger the area on which there is movement (rupture) the larger the magnitude of the earthquake 10

11 Where are earthquakes most likely to occur? Plate Boundaries SITE-C

12 Where do most earthquakes occur? Plate Boundaries

13 Size of an Earthquake Magnitude (M) as magnitude increases, the strength of ground shaking, duration, and area impacted increases very quickly. Ground shaking: Increases by 10 times for every magnitude unit Energy released: Increases by 32 times for every magnitude unit Duration of shaking: Increases from a few seconds (M4) to several minutes (M9)

14 Canadian National Seismograph Network M ~ 1.5 Seismic Monitoring History M ~ 2.5 M ~7 : 1898 M ~6 : 1920 M ~5.3 : 1940 M ~ 3.3 : 1965

15 Earthquake Effects Earthquakes smaller than M2½ generally not felt M4+, shaking can be felt over distances of km Near the epicentre, M5 is the minimum magnitude to make light items fall, M5½ can cause some damage to masonry Natural Earthquakes global average: M 5-6: 1319 / year M 2-3: 150 / hour

16 Canadian National Earthquake Catalogue Authoritative inventory of earthquake information (location, magnitude, depth, etc.) Based on historical and instrumentation records NRCan s seismograph network can detect all earthquakes greater than Magnitude 3 anywhere in Canada Near some populated areas, the denser station network allows for the detection of earthquakes as small as M 1 NRCan currently locates about 5000 earthquakes a year, almost all of which are too small or too remote to be felt 16

17 Tectonics of Canada M Earthquakes in Canada Cassidy et al., 2010 Site C Distance from plate boundary ~900 km Earthquakes discussed in Cassidy et al.,

18 Cassidy et al., 2010 M Earthquakes in Canada Site C Distance from Site-C: km km 18

19 2010 Earthquake Hazard Map for BC/AB Largest events 2001 Mw km NE Dawson Creek Items knocked over. (70 km from Fort St. John) 1986 Mw km NE Prince George minor damage (old chimney s) near epicentre. (230 km from Site-C) 19

20 Seismic Review Reservoir Triggered Seismicity (Reservoir Filling) Filling of reservoirs in some cases triggers seismicity (RTS). Globally, larger reservoirs are more likely to trigger more significant earthquakes. The largest ever confirmed (ICOLD, 2011) was a 1967 M 6.3 event (103 m Konya Dam, India). For <60 m reservoir depth, the probability of induced (RTS) seismicity is extremely low. In BC, there is no history of significant reservoir triggered seismicity at the nearby WAC Bennett dam (183 m) or the Peace Canyon dam (50 m). 20

21 Induced Seismicity Oil and Gas Activities Swarms of small earthquakes have been associated with hydrocarbon production near Fort St. John. The largest earthquake was M 4.3. A detailed study showed a correlation of seismicity with high-pressure water injection into oil fields (Horner et al., 1994). Lowering the injection pressure significantly reduced the number of small earthquakes. 21

22 Induced Seismicity Hydraulic Fracturing Hydraulic fracturing is associated with very small (M< 3.8) earthquakes (BCOGC, 2013). Most induced events are associated with highpressure injection of waste-water into deep injection wells. Only a very small fraction of waste-water injection wells are associated with induced seismicity that can be felt. 22

23 Results of NRCan s Review: Seismicity Key issues: Seismic hazards in the area and the codes/standards that will be utilized; Potential impacts of induced seismicity (reservoirtriggered seismicity, injection wells, fracking, etc.) and mitigation measures; Possible effects of seiches; On-going seismic monitoring of the dam site (during operation of the dam); and Lessons learned on dam impacts from large recent earthquakes. 23

24 Results of NRCan s Review: Seismicity Review Approach and Scope: NRCan reviewed the documents to verify whether the EIS appropriately described and assessed the seismic hazards in the project area, impacts of induced seismicity, seismic monitoring of the dam site, possible effects of seiches. In addition NRCan compared the information and earthquake models and hazard results to those prepared by NRCan. 24

25 Results of NRCan s Review: Seismicity Seismic hazards in the area: This is a region of low seismic hazard (NRCan/NBCC) and it has been accurately characterised by the Proponent. The Proponent s seismic hazard model incorporates past, present, and likely future earthquakes. Active faults are important for design. The Proponent has examined LiDAR data and surficial sediments and found no evidence for active faults. Codes/standards that will be utilized: The highest level of dam design (Canadian Dam Association, 2007) will be used for critical structures. 25

26 Results of NRCan s Review: Seismicity Potential impacts of induced seismicity (reservoirtriggered seismicity, injection wells, fracking, etc.) and mitigation measures: The largest induced earthquakes in this region are accounted for in the design by the Proponent. Possible effects of seiches: Likely, and previously observed (Little and Scott, 2004) seiches ( sloshing of water ) in the region are <1 m. Proposed freeboard (available extra vertical height before overtopping) is 7.6 m. 26

27 Results of NRCan s Review: Seismicity Summary of the on-going seismic monitoring of the dam site (during operation of the dam): Seismic monitoring (strong-motion) proposed. Summary of lessons learned on dam impacts from large recent earthquakes: It has been documented that well-compacted earthfill dams perform well in earthquakes. Potential liquefaction is an important factor in the design of earthfill dams and the proponent has taken this into consideration. 27

28 Results of NRCan s Review: Seismicity Conclusions: The Proponent plans to use the highest dam classification (CDA 2007 guidelines) that will provide the highest safety standard for earthquake design. The Proponent has conducted a thorough seismic hazard assessment and has adequately addressed questions on all types of potential induced seismicity, seiches, monitoring, mitigation, and dam safety issues. NRCan is satisfied with the information provided by the Proponent. 28

29 Thank You 29

30 Natural Resources Canada s Overview Presentation and Technical Review Related to Terrain Hazards Site C Clean Energy Project January 13, 2014 Dr. Peter Bobrowsky

31 Presentation Outline Geological Survey of Canada - role we play in relation to terrain hazards / landslides. What is a landslide? Common landslides in the Peace River area, BC. Valleys and landslides. What causes landslides? Landslide studies. Landslide monitoring. Landslide stabilization and mitigation. Living with landslides. 31

32 Presentation Outline For the Site C evaluation: Terrain hazards analysis - background Review the approach for landslides / terrain hazards study by Proponent What did we look at? Why did we look at it & why is it important? What did we find? Conclusions 32

33 NRCan - Role in Terrain Stability - Natural Resources Canada (NRCan) through the Geological Survey of Canada (GSC) serves the needs of the government and the good of the public in issues related to slope instability at the federal level. - Several geoscientists and engineers at the GSC focus on landslide issues of relevance to public safety. 33

34 What is a landslide? Terrain Stability A landslide is a downslope movement (under the influence of gravity) of rock, soil, or both and may sometimes include other debris (e.g., trees). The general term landslide can be used for all types of mass movements. They can be small or large, slow or rapid, on land or under water, etc. 34

35 Schematic of a typical landslide 35

36 Terrain Stability Landslide types and classification: There are various types of classifications available and widely used by landslide professionals. Most of the classification systems rely on some combination of the following parameters: state of activity, rate of movement, type of material, and mode of movement. Examples of landslides common to NE BC: Rockfalls - Rotational landslides - Translational landslides - Topples - Debris flows - Earth flows 36

37 Terrain Stability Rockfall 37

38 Terrain Stability Topple Topple 38

39 Terrain Stability Rotational Landslide 39

40 Terrain Stability Translational Landslide 40

41 Debris Flow Terrain Stability 41

42 Terrain Stability Earth Flow 42

43 Valleys and Landslides Valleys are products of erosion. All valleys evolve through time. V-shaped valleys reflect early stages of river erosion. U-shaped valleys represent glaciated environments. Gentle sloped valleys are indicative of more mature terrains. Besides the valley geometry and geomorphology, the valley materials (type of vegetation, soil, rock), the climate and human activities are some of the other factors that may influence the type, extent and frequency of landslides that could occur. All valleys around the globe are the result of different types of erosion (including landslides).

44 Classic V-Shaped Valley 44

45 Glaciated U-Shaped Valley 45

46 Meandering River Valley, Peace River, BC 46

47 Terrain Stability What causes a landslide: There are two primary categories of causes of landslides: natural and human-caused. Natural causes include those triggered by water, seismic activity and/or volcanic activity. Human causes include triggering activities such as removing vegetation, loading the top of slopes, oversteepening slopes, excessive irrigation, etc. 47

48 Landslide Studies Involves a progressive and logical process based on acceptable standards, protocols and best practices including the following: assessing the history of landslides (types, location and frequency), characterizing the underlying materials (nature of soil and rocks), evaluating the slope conditions (angles, vegetation), determining factors that may influence the slope conditions (precipitation, erosion, fires, etc.), modeling and analyzing the data, generating interpretations and where necessary providing solutions for monitoring and mitigation measures. Typical output that may be produced during such studies: inventory map, susceptibility map, risk map. 48

49 Terrain Stability Depending on the extent for potential instability, individual slopes can be monitored for signs of movement or where necessary measures can be adopted (mitigation) to reduce or eliminate the threat for further movement of the slope (stabilization). Landslide Monitoring Examples of monitoring that has been used or can be used by the Proponent: field observations, air photographs, satellite imagery (InSAR interferometric synthetic aperture radar), LiDAR (light detection and ranging), differential GPS stations, robotic total station targets, crack gauges, strain gauges, tilt sensors, settlement gauges, extensometers, piezometers, inclinometers, temperature probes, seismographs, etc. 49

50 Monitoring 50

51 Terrain Stability Landslide Stabilization and Mitigation Examples from around the world include: excavation (benches), strengthening slopes (rock-fill buttresses, check dams), drainage techniques (ditches and drains, retaining walls, gabions), vegetation (mulch, seeds, planting), catch ditches, curtains (cable, mesh, fencing), rock sheds, scaling and trimming, reinforcement (shotcrete, gunite, anchors, bolts), etc. 51

52 Stabilization and Mitigation 52

53 Stabilization and Mitigation 53

54 Living with Landslides Living with landslides 54

55 Living with Landslides Debris flow scars in Los Angeles, USA 55

56 Results of NRCan s Review: Terrain Hazards Review Approach and Scope: NRCan reviewed the documents to verify whether the EIS appropriately described and assessed the terrain hazards in the project area. NRCan performed its own research for the area which involved a desk top study compiling and assessing existing research completed during the past few decades. Some of the authors of these original studies were contacted and the situation regarding slope instability in the Peace Region was discussed. 56

57 Results of NRCan s Review: Terrain Hazards Conclusions: The Proponent compiled and collected all relevant literature regarding the geology, geomorphology and terrain hazards in the study area. An inventory (and map) of landslides in the region was prepared. Field data (e.g., samples, drill holes) were appropriately collected from surficial and bedrock units in the study area. Air photographs, LiDAR and ground observations were utilized to prepare a terrain classification map. Current practice for terrain hazard classification was adopted in the development of a terrain stability map ( susceptibility ). 57

58 Results of NRCan s Review: Terrain Hazards Conclusions (cont.): Study specific models for shoreline erosion were developed, applied and used by the Proponent. Study specific models for landslide generated waves (seiches) in the reservoir were developed by the Proponent. Slope stability analysis was applied in the generation of the various impact lines. Slope stability line and landslide generated wave impact line are conservative and may exceed minimum required standards. 58

59 Results of NRCan s Review: Terrain Hazards Conclusions (cont.): NRCan is satisfied that the proponent followed and adopted current standards and best practices used in Canadian/international slope stability studies and in some situations the standards were exceeded by the Proponent. NRCan is satisfied with the information provided by the Proponent. 59

60 Thank you for your attention 60