The Project
Trilogy was engaged to construct a 3D geological model of the aquifer materials at a former industrial site using Leapfrog, integrating all available investigation data — from Trilogy's own program and from prior investigations by others — into a single spatially consistent subsurface model. The model was delivered to the project team as a shared spatial reference for groundwater assessment and remediation planning.
The site presented a complex contamination scenario: dense non-aqueous phase liquid (DNAPL), including free-phase product, identified across multiple investigation locations and multiple aquifer units. Understanding the spatial distribution of DNAPL in relation to aquifer stratigraphy is central to assessing groundwater risk and satisfying regulatory requirements.
At a site with DNAPL present across multiple investigation locations and multiple aquifer units, a 2D plan-view presentation of results cannot answer the questions that matter: Where does the contaminant sit relative to aquifer contacts? Which aquifer units are connected? Where are the aquitards that might be containing vertical migration? A 3D model makes these relationships visible and queryable.
Data Integration
The model was built from investigation data spanning multiple programs at the site. The total dataset used to constrain the model comprised:
- Q1 aquifer: 111 investigation locations — the most data-dense unit, reflecting its critical role as the primary contaminant-bearing horizon at shallow depth
- Q2 aquifer: 24 locations — constraining the geometry of the second aquifer unit and the intervening aquitard contact
- Q3 aquifer: 14 locations — deeper unit with sparser coverage, reflecting decreasing investigation density with depth
- Q4 aquifer: 8 locations — deepest mapped unit, providing the base of the aquifer sequence
All investigation locations were georeferenced to MGA coordinates and incorporated into the model as borehole objects — each trace intersecting the relevant aquifer polyhedrons and carrying the logged material description and groundwater observation data attributed to that location.
Model Structure and Navigation
The model was structured with a layered navigation panel allowing individual units to be toggled on and off — enabling the project team to interrogate specific aquifer contacts, isolate individual units for volume calculation, or examine borehole intersections within a particular stratum without visual interference from overlying units.
In addition to the aquifer polyhedrons, the model incorporated:
- Fill extent and depth mapping — spatially constraining former pughole and backfilled areas, with direct relevance to understanding contaminant migration pathways through anthropogenic fill
- DNAPL observation layer — investigation locations coded by observation type (globules/odour/sheen; measurable sheen; measurable free-phase product) providing a spatially referenced picture of contaminant distribution at the surface of the Q1 aquifer
- Aerial photography and surface topography — providing spatial context and enabling direct comparison of subsurface model extents with surface features
- Prior site investigation extents — integrated as a reference layer for assessing fill geometry and contaminant concentration zones
Delivery and Use
The model was delivered as a Leapfrog project file accessible via the free Leapfrog Viewer — distributed to all project stakeholders for independent interrogation without requiring a full Leapfrog licence. Any team member can navigate the model, query unit attributes, and examine borehole data directly.
For regulatory reporting, the 3D model provided a spatial reference for evaluating the extent and connectivity of contaminant-bearing horizons. For hydrogeological assessment, the aquifer geometry provides the structural framework for groundwater flow modelling and receptor pathway analysis. For Trilogy's own reporting, the model is the primary reference for cross-section production, volume calculations, and stratigraphic descriptions in technical reports.
Outcomes
- Complete 3D representation of aquifer stratigraphy from 157 investigation locations — the first spatially integrated picture of the subsurface at the site
- Four aquifer units and intervening aquitards mapped as georeferenced polyhedrons, each queryable for volume and spatial extent
- DNAPL distribution spatially referenced to aquifer contacts — enabling direct assessment of which units carry product and which aquitards are providing containment
- Shared spatial reference delivered to all project stakeholders via free Leapfrog Viewer — no licence required
- Baseline model for ongoing site management — updatable as new investigation data is collected to refine aquifer geometry and track remediation progress