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Joe Riddell, M.Sc., P.Geol. Dylan King, P.Geol. WaterTech 2014
Banff Alberta, April 11, 2014
Improved Analysis & Stakeholder Engagement using 3-D Conceptual Site Models
Agenda
1 Overview & CSM Development
2 Examples of CSM Development and Outcomes
3 Conclusions and Questions
Overview & Development of Conceptual Site Models (CSM)
1
CSM – What is it? Compilation of existing site information • Previously collected geological, geotechnical,
hydrogeological, and analytical data for soil/groundwater
• Compiled into a 3D Geomodel of the site • Geological structure, hydrogeologic regime and
key physical processes are characterized
Tells the story of what we know • Presents our current understanding of site
conditions, including contaminant distribution
CSM – Why build a CSM? Allows multiple hypotheses to be evaluated • Data gaps can be systematically filled • Added value and cost savings • Powerful data synthesis tool • Helpful in stakeholder communication with
client/regulators for approvals or scope changes • Very useful for long-term sites and monitoring Valuable reconnaissance for field staff • Field staff starts with salient geological features
and an understanding of the setting • Drilling prognoses • Iterative, on-the-fly improvements to CSM can be
made during drilling program
CSM Development & Challenges Data Normalization • Difficult to normalize data from different sources • Different data types • Incomplete data sets (i.e., lacking well attributes) Requires Experienced Analyst • Earth scientist with understanding of sedimentary
processes, stratigraphic correlations & hydrogeological processes
• Requires advanced supporting software tools
CSM Development Workflow
Data Gathering
CSM Development
Field Program Numerical Model
Statement of problem and objectives
Data Formatting
Interpretation
Data Gap Analysis
• More efficient iteration (on-the-fly)
• File management • Use of other geo-
spatial platforms
Data Compilation and Normalization
Un-normalized Data: Iterative CSM Development Challenges with existing site information • 3-D geological software still needs to be guided • Several technologists logging core • Heterogeneity • Data gaps Skilled operator required • Pre-interpretation • Start simple cross sections > • Normalize data to a consistent CSM (hydrostrat) • Implement CSM in 3-D geological modeling
software
CSM Development and Outcomes
2
Example 1 - Desktop Studies Hydrogeological Issues in Residential Development
• Foothills Subdivision • Water ingression into homes • Previous Geotechnical Study
(during dry period): • Water table configuration • Wetland area & shallow
groundwater issues such as local discharge areas (springs)
• Geology promotes interflow • Toe-slope position & large catchment • Mapped glacial melt water channels • Temporal variability & monitoring • Easily determined during planning
12x
Example 2 – Production Well Installation and Optimization • Concrete Plant • No municipal water supply • Preliminary model (AWWID) • Horseshoe Canyon Fm. • Possible buried channel
deposits • Possible productive bedrock
intervals • Preliminary model with
public water well data • Identification of potential
drilling targets, static WLs, surrounding pump intake and screened interval analysis
• Ongoing model updates during drilling
• Successful production well installation and stakeholder engagement
Example 3 – Use of CSM for hydrocarbon delineation • Capitol Region site
with HC impacts Bring readily available information into model: • Site topography • 72 Borehole logs • Digital air photo of site • Limited data from
AESRD & AGS (raster, vector & even tabular mapping data)
• Minor analytical soil and GW Data from historical reports
Un-normalized Data • Verbatim initial
plotting of the data in a 3D environment
• Plots all observed lithologies on site
• Geologist then works through each record to normalize lithologs with a unified model of site conditions
• Records are re-interpreted On-the-fly iterative process
Generation of Geological volumes • User specifies:
• Stratigraphic rules • Hydrostratigraphic
framework
• Model generates bounding surfaces and volumes of normalized layers in the CSM
• Build water table surface based on monitoring data
Data Gap Program • a) Based initially on soil
vapour screening to produce a conservative contaminated soil volume
• b) View proposed boreholes within context of geology, hydrostratigraphy, and estimate of contaminated Soil volume to accurately delineate a more accurate, refined volume for remediation scoping
a)
b)
Example 4- Solution Mining Project EA Proposed development includes infrastructure, production and injection wells, brine pond and tailings management area (TMA)
Assessment objectives were to
1. Increase understanding
2. Evaluate risk
3. Mitigate risk
Development of a 3D Conceptual Site Model was chosen as an efficient way to synthesize the data to understand groundwater quantity and quality and to evaluate and mitigate potential interactions
Hydrogeology • Base of model is a thick
marine shale aquitard at 100-200 m BGL
• Empress group preglacial or glacial sand and gravel in a large buried channel
• Overlain by a series of glacial drift formations consisting of layered sand aquifers and till aquitards
• Five till units containing six mapped sand and gravel aquifers
Period Stratigraphy Lithology
Group Formation Unit or Member
QUA
TERN
ARY
Sask
ato
on
Surficial Stratified Deposits
Aluvium Silt, Sand, Gravel Clay, Silt, Sand
Silt, Sand, Gravel Clay, Silt, Sand
Haultain Silt, Sand, Gravel Clay, Silt, Sand
Silt, Sand, Gravel Clay, Silt, Sand
Battleford Till
Gravel, Sand, Silt, Clay
Floral
Upper Till
Riddell (Middle) Gravel, Sand
Lower
Till
Gravel, Sand, Silt, Clay
Till
Suth
erla
nd
Warman Till
Gravel, Sand, Silt, Clay
Dundum
Upper Till
Gravel, Sand, Silt, Clay
Lower
Till
Gravel, Sand, Silt, Clay
Till
Mennon Upper
Till
Gravel, Sand, Silt, Clay
Lower Till
Emp
ress
Upper Gravel, Sand, Silt, Clay (Proglacial)
Lower Chert and Quartzite Sand on Gravel
(Preglacial) C
RETA
CEO
US
Mon
tana
Pierre
Odanah Member sand and silt
"Lower" Odanah Member
silt and clay
Millwood Member
silt and clay
Pembina Member
silt and clay
Gammon Member
silt and clay
Hydrogeological Data
Data gathering, review and synthesis. 186 - water well records with e-logs to determine lithologies but additional information to make picks was not available (Carbonate content, preconsolidation pressure)
8 - regional groundwater studies
9 - Shallow groundwater wells in the TMA
• Similar initial steps • Development is
cumbersome and time consuming
• No reinterpretation on the fly • Many iterations of the
process
Traditional CSM Development
grid surfaces individually
grid math to create isopachs
cut cross sections and fence diagrams for pseudo 3D analysis
grid potentiometric surfaces and iso-concentration contours
create blanking files
Development in 3D Software Environment
• Stratigraphic picks form collar table for import into the model
• Create first cut at surface generation
Development in 3D Software Environment
• Dynamic visualization to identify gross anomalies
• Identify discrepancies between model and regional studies,
• Reinterpret e-log as necessary
Development in 3D Software Environment • Add additional e-log interpretation to fill gaps and reinterpret
on-the-fly • Make manual adjustments to surfaces based on depositional
interpretation and stratigraphic principles until satisfied with model
• Add aquifer parameters, hydrochemical & potentiometric data
Numerical Model • Export of 3D CSM directly to
FEFLOW or MODFLOW
• Detail groundwater flow and simulate contaminant transport scenarios
• Collaboration and communication between project hydrogeologist and modeler
• Design meaningful monitoring and mitigation
Project Mitigation based on CSM and Numerical Model • Monitoring network design – appropriate spacing depths
and coverage • Perimeter ditch design around TMA – design depth • Slurry Cutoff Wall Design – appropriate depth based on
contaminant transport modeling predictions
Example 5 – Coal Mining Project EA • Proposed development includes two open pit areas, waste
rock disposal area in a mountainous environment with complex structural geology
• CSM forms framework for the baseline assessment of groundwater flow patterns, quantity and quality
• Numerical model to evaluate interactions between the project, groundwater and surface water resources
• CSM used to develop effective monitoring and mitigation measures to limit potential impact
Project Background • Limited sub-surface data
• Coal exploration picks (x’s)
• Stantec boreholes (green) and hydraulic testing
• Large domain required for EA (limit BC effects)
• Scanned and geo-referenced structural and bedrock geology Maps
• Drift thickness data
• LIDAR of mine site & DEM
• Mine progression plan
• Literature
Geological Interpretation Fenced lines along structural axes to extrapolate the geology of a boss layer (important aquifer)
Assumes hydrostratigraphic column with constant unit thickness
Fencing & proposed Boreholes
• Use high density data and work away from “known” geology to generate key hydrostraitgraphic layer
• Fence lines positioned along fold axes, and polylines used to infer geology using structural data, and ~ 200 proposed BHs were added
• Marked boreholes with the elevation where polyline crosses proposed BHs to get structural geological elevation picks (approx. 200) Regional Anticline
Regional Syncline
Regional Anticline
Building Hydrostratigraphy • Gridded picks to generate surfaces outside of 3-D environment • Build depositional surfaces with hydrostratigraphic column & True Vertical
Thickness offset calculations • Grid math to add the vertical offset to boss layer (Blue) elevation • Erosional deposits specified based on drift thickness and surface
mapping of till and alluvium/colluvium
Final Geomodel for Export to FEFLOW • Aquifers in yellow, aquitards in brown, and surficial deposits • Challenging computation with large, high resolution domain • Send ready–made FEFLOW grid to modeling team for baseline
assessment • Change topography as mine life cycle progresses to evaluate mine pit
inflows and potential impacts
Conclusions 3
Summary In some capacity, our role as a consultant parallels that of a 1st year Earth Science Professor… • Block models and cut-away views are the only way to
communicate the subsurface complexity to lay-people (stakeholder communication)
• Allows rapid visualization, efficient workflow to generate figures & accurate cross sections
Summary Project benefits include: • Iterative and real-time analysis and model
adjustments provides a powerful data synthesis tool • Use to optimize drilling programs and process new
data efficiently • Aids in monitoring and mitigation of potential
and/or pre-existing impacts • Opens the door for follow-up project work • Greatly reduces cost associated with developing
numerical groundwater flow models if a CSM completed at project outset
Questions?