Alberta Transporation Springbank Off-Streem Reservoir Project
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Alberta Transportation Springbank Off-stream Reservoir Project Response to AEP Supplemental Information Request 3 dated November 4, 2020 December 2020 ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 Table of Contents 1 ACRONYMS .......................................................................................................................... 1 2 GENERAL ............................................................................................................................... 2 2.1 Hydrogeology ....................................................................................................................2 Question 1 ......................................................................................................................2 2.2 Aquatics ...........................................................................................................................14 Question 2 ....................................................................................................................14 2.3 Vegetation .......................................................................................................................28 Question 3 ....................................................................................................................28 LIST OF TABLES Table 1-1 Fish Distribution and Movement of the Elbow River Fish Community at Biologically Significant Periods (Updated from Alberta Transportation’s Response to Round 2 NRCB Question 19) ...........................17 Table 1-2 Estimates of Relative Abundance and Population Size for Elbow River (adapted from Alberta Transportation’s response to Round 2 NRCB Question 19 with New Information from August 2020 Fieldwork) .......21 LIST OF FIGURES Figure 1-1 Simulated Net Change in Head for the PPX1/EEX1 Sensitivity Scenario 1 at Timestep 650 with Conservative Loading Applied (revised from Round 2 AEP, IR42, Appendix 42-1, Figure E1.1) ....................... 5 Figure 1-2 Potentiometric Surface of the Conservative Loading Simulation using Conservative Hydraulic Conductivity (x10) minus Bedrock Surface showing Confined Bedrock Aquifer Areas (revised from Round 2 AEP IR 47, Figure 47-2) ............................................................................................... 6 Figure 1-3 Potentiometric Surface of the Conservative Loading Simulation and Conservative (x10) Hydraulic Conductivity minus Topographic Surface (revised from Round 2 AEP IR47, Figure 47-3) ..................................... 7 Figure 1-4 Simulated Net Change in Head for the PPX0/EEX0 Scenario with Increased (10x) Hydraulic Conductivity (revised from Round 2 AEP IR48, Figure 48-1) ................................................................................................ 8 Figure 1-5 Simulated Net Change in Head for the PPX0/EEX0 Scenario with Increased (10x) Hydraulic Conductivity Compared to Original (1x) Hydraulic Conductivity ...................................................................................... 9 i ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 LIST OF APPENDICES APPENDIX 2-1 FISH POPULATION ASSESSMENT ii ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 1 Acronyms December 2020 1 ACRONYMS The following acronyms are used in this Supplemental Information Request. AEP Alberta Environment and Parks BSP Biologically Sensitive Period EIA Environmental Impact Assessment FWMS Fisheries and Wildlife Management Information System IR Information Request LAA local assessment area NRCB Natural Resources Conservation Board TDR technical data report TOR Terms of Reference 1 ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 2 General December 2020 2 GENERAL 2.1 HYDROGEOLOGY Question 1 Supplemental Information Request 2, SIR 55, Page 268 - 270 Alberta Transportation states: c. As stated in the response to a., there is confidence in the conductivity values used for the initial conditions in the numerical model and the calibrated hydraulic conductivity values. However, the model sensitivity analysis presented in the TDR Update, Attachment E does examine the hypothetical effect of increasing the permeability of both the till and bedrock layers within the model. The hydraulic conductivity values for these units were increased by a factor of 1,000 (well beyond the expected range of natural variability of these geologic materials). The sensitivity analysis results suggest that the model simulations are most affected by parameterization of hydraulic conductivity values, and the higher conductivity values lead to further propagation of effects and, in turn, a larger area of effects. However, even when increasing the hydraulic conductivity values of the low conductivity units, the modelled effects remain within the LAA and north of Elbow River. The above sensitivity analysis used different boundary conditions compared with the Supplemental Information Request 2, SIR 47 and 48. In the TDR Update, Attachment E - the boundary conditions along the diversion channel were wrong according to the statements in Supplemental Information Request 2, SIR 48; and the boundary conditions on top of the reservoir area didn’t apply the loading head. As a result the sensitivity analysis results need to be updated. a. Using the models explained in Figure 47-2, 47-3 and 48-1, update the conductivities so they are similar to those in the TDR Update, Attachment E. Complete the sensitivity analysis. b. Provide maps similar Figure 47-2, 47-3 and 48-1 for a hydraulic conductivity of 10-5. c. Analyze the difference of the drawdown cone along the diversion channel. Explain the findings. d. What percentage of the seepage has changed to the diversion channel? 2 ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 2 General December 2020 e. Analyze the difference of the potential artesian area to the east and south-east of the off- stream dam. Explain the results. f. Does the potential impacted area remain within the LAA? Explain. g. What is the contingency monitoring and mitigation plan for a hydraulic conductivity of 10-5 should it occur? Explain. Response a. The model sensitivity Scenario 1 presented in the Hydrogeology Technical Data Report (TDR) Update (see Alberta Transportation’s response to Round 1 Alberta Environment and Parks [AEP] information request [IR] 42, Appendix IR42-1), Attachment E considered an increase in hydraulic conductivity by a factor of 1,000 in the low conductivity till and bedrock layers. The same sensitivity scenario has been rerun for the purpose of this response using the updated version of the numerical model shown in Round 2 AEP Question 47 and Question 48, which includes the application of the conservative loading effect whereby the hydraulic head pressure in the reservoir has been applied directly to the bedrock layer. The results of increasing the conductivity by a factor of 1,000 and applying the conservative loading effect are presented in Figure 1-1. Figure 1-1 is an updated version of Figure E.1-1 (presented in Attachment E of the TDR Update), and it depicts the net change in head between PPX1 (the design flood with the Project) and EEX1 (the design flood without the Project). The updated sensitivity scenario results in increased lateral extent of the hydraulic head change around the reservoir. Hydraulic head increases are observed up to 800 m from the reservoir in the northeast and southwest directions. Increases are also observed up to 800 m to the southeast toward Elbow River. These updated sensitivity scenario effects are limited to the local assessment area (LAA) and do not extend beyond the edge of the fluvial deposits or beyond Elbow River. The model simulations for this sensitivity analysis show that the model is sensitive to the application of the conservative loading effect. However, the modelled effects remain within the LAA and north of Elbow River. Note that this simulation is meant as a theoretical exercise (i.e., increasing the hydraulic conductivity by a factor of 1,000 in the low conductivity till and bedrock layers is well above values derived from the field measurements) to explore the model sensitivity; it is not considered to be representative of potential subsurface conditions, based on the hydrostratigraphic framework for the Project. 3 ALBERTA TRANSPORTATION SPRINGBANK OFF-STREAM RESERVOIR PROJECT RESPONSE TO AEP SUPPLEMENTAL INFORMATION REQUEST DATED NOVEMBER 4, 2020 2 General December 2020 b. Updated versions of Round 2 AEP Question 47, Figures 47-2 and 47-3 are attached as Figures 1-2 and 1-3 and an updated version of Round 2 AEP Question 48, Figure 48-1 is attached as Figure 1-4. Figures 1-2 and 1-3 use the latest iteration of the model with the corrected nodes along the diversion channel and the conservative loading heads applied for the PPX1 simulation (the design flood scenario with the Project). This simulation incorporates an increase in the hydraulic conductivity by a factor of 10, for example, from 10-6 to 10-5 m/s for the upper bedrock, as requested in this IR. As was the case in the response to Round 2 AEP Question 47, the model was also run in steady state mode to represent the most conservative