dirk kassenaar earthfx watertech 2016 presentation v1

Project Title

Assessing Cumulative Effects of SAGD Operations in the Mackay WatershedDirk Kassenaar, E.J. Wexler, P.J. Thompson, M. TakedaEarthfx Inc.

Watertech 2016April 7, 2015

Review of Cumulative Impacts MacKay River WatershedIntroductionIn-situ Steam Assisted Gravity Drainage (SAGD) oil sand operations require a source of fresh water for steam injection.

Groundwater supply wells, generally drawing from aquifers above the oil production zone, are a preferred source. 2- Introduction

From MEG Energy Corp.

Review of Cumulative Impacts MacKay River WatershedStudy ObjectivesIn 2014, Earthfx Inc. was hired by the Cumulative Environmental Management Association (CEMA) to answer the following question:Is there enough water in the Mackay watershed to sustain a responsible level of development

Cumulative effects analysis requires the integrated assessment of:Multiple anthropogenic stresses: Numerous spatially distributed SW and GW diversions Land use change (land clearing, drill pads, roads, etc.) Intersecting effects on surface and groundwater systems: Changes in groundwater levels (drawdowns) in all aquifer systems Changes to frequency, duration and severity of low flow conditions

3- Introduction

Review of Cumulative Impacts MacKay River WatershedStudy AreaMacKay River Watershed is located immediately north-west of Fort McMurrray, ABIncludes Syncrude Mine site and numerous SAGD operations

Watershed Area: 5,600 km2Model Area: 7,900 km2

4- Summary of Model Development

Ells RiverAthabasca RiverLegendLakeNamurLakeAthabasca RiverMacKay River

Review of Cumulative Impacts MacKay River WatershedStudy ApproachStep 1: Integrated Model Development and CalibrationModel Development: Compile Geology, Hydrogeology, Climate, Hydrology, HydraulicsModel Calibration: Build and pre-calibrate the SW and GW submodelsComplete the fully integrated model calibration: Full reconciliation of entire hydrologic cycle water budget

Step 2: Sustainability AssessmentDefine Assessment Criteria and Climate PeriodDefine aquifer drawdown and streamflow impact sustainability thresholdsSelect a representative surrogate climate assessment period (25 years)Simulate Pre-development (Baseline), Current and Full Build conditions over the climate periodCompare, on a daily basis, Current and Full-build conditions against BaselineEvaluate GW drawdowns and streamflow changes against Assessment Criteria

5- Introduction

Review of Cumulative Impacts MacKay River WatershedModelling approach6- Modelling Approach

Review of Cumulative Impacts MacKay River WatershedReview of Cumulative Impacts MacKay River Watershed

Review of Cumulative Impacts MacKay River WatershedIntegrated Modelling Approach: AdvantagesStudy Approach: Fully integrated surface water and groundwater modelBetter representation of:Groundwater recharge and Dunnian GW feedbackStreamflow and induced leakageSW/GW storageCumulative effects of all SW and GW diversionsFlux inputs and calibration targetsMeasured precipitation as inputCalibration to total streamflow and measured GW levels7- Modelling Approach

Review of Cumulative Impacts MacKay River WatershedSelected Model: USGS GSFLOWUSGS integrated GW/SW modelBased on MODFLOW-NWT and PRMS (Precipitation-Runoff Modelling System)Open-source, proven and very well documentedFully-distributed: Cell-based representationExcellent balance of hydrology, hydraulics and GW

8- Modelling Approach

Review of Cumulative Impacts MacKay River WatershedSummary of Mackay model development9- Summary of Model Development


Review of Cumulative Impacts MacKay River Watershed

Study Area FeaturesTopography (600 m of relief)Birch MountainsThickwood Hills Incised river and stream networkMacKay River main channelDover and Dunkirk TributariesAthabasca River: South and eastern boundaryLegend and Namur LakesPlus over 100 other lakes in study areaExtensive muskeg and wetlandsBedrock Channel Aquifers Key GW supply source for multiple projectsAnthropogenic StressesSyncrude MineSW and GW Diversions

10- Summary of Model DevelopmentMacKay River ValleyAthabasca River ValleyBirch Mountains

Thickwood Hills

Bedrock Channels

AMBI, 2013)

Review of Cumulative Impacts MacKay River WatershedGSFLOW: Multi-ResolutionGSFLOW is unique in that the resolution of the model can be adjusted to match key features11

Climate inputs( 2.5 km cells)Surface Hydrology/Soil Zone( 200x200 m cells)Sub-surface Hydrogeologic Layers( 13 layers of 400x400 m cells)Stream NetworkLinear 1-D Channel segments(4000 km of streams represented, independent of grid resolution)- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedModel GridFully distributed model: Every cell has unique propertiesGW grid: 400 m by 400 m cellsSelected to match assessment averaging criteria (impact at 150 m from a well) but avoid focus on specific water users.Can be refined for future studiesSW Grid: 200x200 m cellsImproved representation of overland flow, wetlands, interflow and soil zone processes and propertiesStream routing:All streams and rivers simulated


400x400 m GW grid

Review of Cumulative Impacts MacKay River WatershedGeologic Setting13- Summary of Model Development

Surficial GeologyBedrock GeologyPredominantly tills and glaciolacustrine depositsSubcrop of units that dip to the southwest

Review of Cumulative Impacts MacKay River WatershedGeologic Information14- Summary of Model Development

Primary sources for geologic borehole data:25,000 - Alberta Geological Survey255 - Atlas (Western Canada Sedimentary Basin)Limited geologic data in Birch Mountains and central portion of study area

Review of Cumulative Impacts MacKay River WatershedConceptual Stratigraphic Model


After AGS Source: Andriashek and Atkinson, 2007

Empress Channel Sands:Key water supply aquifer

Review of Cumulative Impacts MacKay River WatershedHydrostrat. Layers16- Summary of Model Development19 layer strat. model used to produce 17 layer hydrostrat. model.Some units of similar hydraulic properties were combined.McMurray Basal Sands added as separate aquifer unit.Model does not extend below Prairie Fm. AquicludeAssumed minimal communication due to low vertical K of unit.Simulating higher salinities (>50,000 mg/L TDS) would require density dependent groundwater flow.

Review of Cumulative Impacts MacKay River WatershedGW Level Data803 wells with water level dataWell assigned to hydrostrat. units based on screened intervals.Limited long term temporal monitoring data (GOWN)



17

Groundwater Submodel Calibration18- Summary of Model Development

Steady-state submodel calibration.Better calibration in aquifers where data more plentiful.

Review of Cumulative Impacts MacKay River WatershedHydrologic Submodel Development (PRMS)Based on the USGS Precipitation-Runoff Modeling System (PRMS) code

Fully distributed implementation

200m x 200m cells (196,832 unique cell HRUs)19- Summary of Model Development

In each unique cell:

Review of Cumulative Impacts MacKay River WatershedClimate InputsPrecipitation and temperature interpolated on a daily basis over a 2.5km x 2.5km gridInverse distance squared weighting25 year daily climate time series input for each grid cell


Review of Cumulative Impacts MacKay River WatershedVegetative Cover Classes26 wetland and vegetative cover classes17 types of wetlandsModel parameters assigned by class:Seasonal Cover densityVegetation indicesSoil zone propertiesOverland flow and shallow interflow parameters



21

Overland FlowOverland flow and interflow simulated with a topographically defined cascade network200x200m cell representation22- Summary of Model Development


Lateral Flow Processes23- Summary of Model Development

PRMSSoil ZoneMODFLOWLayer 1MODFLOWLayer 2

3D DarcyGW Flow(MODFLOW)1D Darcy Interflow (PRMS)

Head DependantSaturation Dependant

Mannings Runoff

(PRMS)

Review of Cumulative Impacts MacKay River WatershedDunnian Flow Processes: SW/GW Feedback24- Summary of Model DevelopmentGroundwater feedback dominates in discharge areas, wetlands and shallow aquifersGW feedback in up to 60% of the watershedComplex transient runoff and rejected rechargeOccurs when the water table is at or near surfaceSpatially controlled: Tends to occur in stream valley areasSeasonally controlled: Tends to occur in spring when WT is highGW discharge to the soil zone can become interflow or overland flowOverland flow can re-infiltrate downslope: 3D recharge

UnsaturatedzoneGround-water flow

StreamStreamGravity drainageRechargeWater tableWater tableGround-water flow

Review of Cumulative Impacts MacKay River WatershedFrozen GroundNew frozen ground module developed for this studyGSFLOW is Open Source!Based on a modified form of the Stefan EquationDerived by the U.S. Army Corps of EngineersModel code follows Emerson (1994)


Review of Cumulative Impacts MacKay River WatershedFrozen Ground ResponseFrozen soil dynamics affect both surface and subsurface processes:SW Runoff and Recharge: Enhanced runoff during spring freshet, no winter recharge GW Discharge: Significantly reduced winter discharge to streams and wetlands26- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedModel Calibration and ValidationCalibrated then verified against over 38 year periodA range of hydroclimatic conditions simulated27- Summary of Model Development

ValidationCalibration

Review of Cumulative Impacts MacKay River WatershedModel Calibration and ValidationHydrologic submodel and the final integrated model were calibrated against streamflow observations at 6 Water Survey (EC) and RAMP stations

Historical observations at discontinued stations were an important source of insight28- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedModel Calibration and ValidationGood match to streamflow observations at study area gauges

Daily Nash-Sutcliffe 0.65

Monthly Nash-Sutcliffe 0.75

Good match to validation period: Model has adequate predictive power29- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedDistributed Results30- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedDistributed Results (GSFLOW)31- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedGSFLOW GW/SW Outputs32- Summary of Model Development

AprilMay

Review of Cumulative Impacts MacKay River WatershedGW/SW AnimationAnimation shows spring melt and changes in GW levels and streamflow33- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedGSFLOW OutputsSpring change in water levels and streamflow 34- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedGSFLOW OutputsSpring change in water levels and streamflow 35- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedGSFLOW GW/SW Water BudgetsSignificant inter-annual and seasonal storage effects.36- Summary of Model Development

Review of Cumulative Impacts MacKay River WatershedModel Development ConclusionsThe Mackay GSFLOW model represents the complex transient surface and subsurface process and their interaction and feedback

Extensive submodel development and integrated model calibration was undertaken to all available data

Key aspect of the integrated model calibration:Directly measured flux input: Precipitation Directly observed calibration targets: Total measured streamflow and GW headsOverall water budget must balance no water is gained or lost


Review of Cumulative Impacts MacKay River WatershedAssessment scenarios: Criteria and Results38- Assessment Scenarios


Review of Cumulative Impacts MacKay River WatershedDiversion ScenariosBaseline: No pumping

Current Conditions:4 Operations including 11 pumped wells.

Full-Build Conditions:14 Operations including 42 pumped wells.

39- Assessment Scenarios

CurrentOperationsCurrentOperationsCurrentOperations

Review of Cumulative Impacts MacKay River WatershedLand Use ChangeProcessing facilities and well padsAssumed to be 100m by 100m gravel pads spaced 500m on centerReduced ET, due to the loss of vegetation, increased runoff

Full Build Scenario: Drill pads are estimated to cover 6% of the planned project areas; Roads, pipelines, and facilities cover another 4%.

40- Recommendations for Phase 3

Review of Cumulative Impacts MacKay River WatershedAssessment Climate Period25 year period includes a range of hydroclimatic conditionsIncludes both wet years (1997) and drought years (1998-1999, 2009 and 2011). 5 year spin-up period before start of assessment41

Surrogate Climate Period- Assessment Scenarios

Review of Cumulative Impacts MacKay River WatershedGW Sustainability Assessment CriteriaIn summary, it was agreed that the sustainable drawdown is 50% of the available drawdown in a confined aquifer.Threshold selection based on the Alberta Environment Water Conservation and Allocation Guideline for Oilfield Injection (AENV, 2006) For unconfined aquifers, 66% of the average saturated thickness was used. Available drawdown based on average water level determined by 20 year baseline simulation.

Assessment Process: all three scenarios run using the same climate inputsOnly difference is diversions and land use changeDaily outputs for every model cell and stream reach saved for comparison Drawdown calculationAlberta Desktop Assessment If, under Current or Full-build development conditions, drawdowns exceeded this threshold on any particular day in a 20 year assessment simulation, the cumulative diversion was considered locally unsustainable.


Review of Cumulative Impacts MacKay River WatershedOverburden Impacts43- Assessment Scenarios

Overburden Aquifers

Layer 1 DrawdownsPercent of Total Available Drawdown

Review of Cumulative Impacts MacKay River WatershedChannel Aquifers44- Assessment Scenarios

Empress Formation AquiferLayer 4 DrawdownsPercent of Total Available Drawdown

Review of Cumulative Impacts MacKay River WatershedConfined Aquifers45- Assessment Scenarios

Viking/Pelican AquiferLayer 5 DrawdownsPercent of Total Available Drawdown

Review of Cumulative Impacts MacKay River WatershedDeep Aquifers46- Assessment Scenarios

Grand Rapids AquiferLayer 8 DrawdownsPercent of Total Available Drawdown

Review of Cumulative Impacts MacKay River WatershedGW Sustainability AssessmentCumulative GW drawdowns are significant, in particular in the lower highly confined aquifer units Offset by the fact that lower units have much greater available drawdown

On a watershed scale, GW drawdowns appear to broadly stabilize within the 20 year period, suggesting sustainable water use

Localized zones where drawdown exceed 50% of total available drawdown


Review of Cumulative Impacts MacKay River WatershedSW Sustainability Assessment CriteriaAlberta Desktop Method: Simulated frequency-duration relationship is calculated for every reach under baseline conditionsThe discharge that is exceeded 80% of the time is the ecosystem baseflow (EBF) component. ADM Criteria 1: No surface water diversions are allowed below the 80% EBF thresholdNo diversion allowed when flow is below the lowest flows that occur up to 20% of the time.

ADM Criteria 2: Above the 80% EBF threshold, up to 15% of the available flow can be diverted.

20 year Baseline simulation used to determine weekly EBF threshold in every stream reach48- Assessment Scenarios

Review of Cumulative Impacts MacKay River WatershedSW Sustainability Assessment CriteriaFrequency-duration relationship calculated in the watercourse in a natural state. EBF Weekly Threshold for Mackay River at Fort McKay:


Review of Cumulative Impacts MacKay River WatershedSW Sustainability AssessmentThreshold for Mackay River at Fort McKay shownADM Criteria 1 - fails for select days, as shown in redADM Criteria 2 - never more than 15% divertedNumerous other stream locations also assessed


Review of Cumulative Impacts MacKay River WatershedLocal SW EffectsWhile the overall watershed passes the ADM criteria at the Mackay outfall point, local streams fail the 15% ADM criteriai.e. GW diversions locally induce leakage that exceeds 15% of the EBF (ecological baseflow)51- Assessment Scenarios

Review of Cumulative Impacts MacKay River WatershedSustainability Assessment ConclusionsIn summary, the analysis indicates that projected water use in the study area is broadly sustainable, from both a groundwater and surface water aspect, on a watershed scale.

This conclusion is supported by two findings:Results indicate that drawdowns do not, on a watershed scale, appear to grow over time Accumulated streamflow losses do not exceed the 15% ADM threshold along the main channel of the Mackay and Dover Rivers.

The results do indicate, however, that under the full build scenario, cumulative groundwater diversions appeared to create unsustainable local impacts, as measured by both the groundwater drawdown and ADM thresholds.52- Assessment Scenarios

Review of Cumulative Impacts MacKay River WatershedWater Budget Comparisons53- Assessment Scenarios

Pre-development shows how wet and dry years replenish and deplete storage (royal blue)Full build scenario shows greater fluctuations in storage

Review of Cumulative Impacts MacKay River WatershedWater Budget ComparisonsWinter pumping depletes storage, replenished by April recharge. 54- Assessment Scenarios

Full-Build Conditions

Baseline Conditions

Review of Cumulative Impacts MacKay River WatershedOther InsightsWinter pumping under frozen ground conditions depletes shallow aquifer storage Baseflow discharge in May is reduced by 50% due to freshet replenishment of shallow aquifer storage. Understanding seasonal and inter-annual storage is essential 55- Assessment Scenarios

Average Monthly GW Discharge to Streams

Review of Cumulative Impacts MacKay River WatershedOverall Conclusions56- Recommendations for Phase 3Detailed, fully integrated SW/GW modelling can provide significant insight into both cumulative effects and watershed function.

Numerous applications Local impact assessment, water budgeting, climate change, drought assessment, eco-hydrology and water management.
