Permafrost Questions - Care & Maintenance by Kalina Malowany

Expand existing monitoring and characterization network to other areas on site.

kmalowany — 2024-05-01 20:08:11 UTC

Potential deepening of permafrost monitoring within the Dome Creek Valley

kmalowany — 2024-05-01 20:09:37 UTC

Important areas for permafrost characterization (i.e. pit area)

kmalowany — 2024-05-01 20:14:08 UTC

Considerations for thermal erosion, and slope stability on North Aspects (i.e. tension cracking, separation scars)

kmalowany — 2024-05-01 20:15:19 UTC

We have high resolution satellite information, we have LiDar data at 1m. Potential to do some annual surveys.

Changes to GW flowpaths:

2024-05-01 20:15:22 UTC

Potential for increased groundwater discharge from the pit to Dome Creek valley?

Potential for increased groundwater discharge through the base of the tailings storage facility?

Rate of permafrost change

2024-05-01 20:16:26 UTC

Use historical permafrost data and historical climate date to create a model with inputs: climate (snow, rain, temp, solar radiation); outputs: ground temp; use that model to project possible thaw under future climate scenarios.

Links of water chemistry and permafrost thaw

2024-05-01 20:18:43 UTC

This is the object of my (Elliott's) recent research. Considerations top of mind:

(1) Increased sulfide mineral weathering rates, increased acid generation rates;

(2) Changes in groundwater redox conditions driven by either rising or declining water tables (water saturation). Reducing conditions trigger mobilization of iron, manganese, arsenic, and other metal(loid)s associated with oxyhydroxides (Skierszkan et al., 2024). This would be an important consideration given the geochemistry of the tailings and the potential for increased water saturation in the tailings.

Possible approaches

2024-05-01 20:22:31 UTC

(1) Do a water balance. Does the recent rise in water levels relate to increased snowmelt/rainfall? Increased groundwater discharge because of increased hydrogeology. If a water balance can explain the increased water levels, then permafrost thaw might not be responsible; if the observations cannot be reconciled by a water balance, it could be a permafrost-driven process. Piezometric data might also provide information on hydrogeological responses to thawing permafrost or increased recharge/discharge rates.

(2) Consider isotopic or geochemical tracers to identify the origin of water into the tailings. Various isotopes could be considered (water stable isotopes; uranium isotopes; tritium; radiocarbon). Geochemical tracers could also be considered. Ideally, this would require samples of groundwater from discharge zones immediately upgradient of the tailings.

General predictions

2024-05-01 20:23:45 UTC

The literature generally documents increased groundwater recharge and discharge rates as permafrost retreats.

We should consider transient effects too (perhaps short-term increased discharge as previously confined waters are allowed to drain down, until they have reached a new steady state).

Field tests of volumetric ice

kmalowany — 2024-05-01 20:28:13 UTC

Potential use of single bead thermistors installed below the active layer.

kmalowany — 2024-05-01 20:30:03 UTC

Collection of LiDar or InSAR data, new LiDAR dataset to be considered for detailed engineering design of remediation project.

kmalowany — 2024-05-01 20:37:07 UTC

Thermal analysis

2024-05-01 20:38:56 UTC

Thermal modelling. Forecast time scales, the shorter the term the better; the longer the predictive timescales the more uncertainty/inaccuracy.

We might have sufficient, but not ideal, temporal data.

Ground temperatures from tailings dam may be useful for tracking trends and assigning parameters.

Benefits of modelling vs adaptive management.

Modelling - order of magnitude of changes.

Thermal modelling may be more useful around the PCS, to try to predict what the timeframes will be, from where will thaw begin.

Consider 1D thermal modelling near the TSF @BH3, but it will be limited

kmalowany — 2024-05-01 20:47:11 UTC

It will contain several assumptions. Better thermal modelling would require data collection of > 3 years

GW flow path changes

2024-05-01 20:53:44 UTC

Water balance studies underway. Updating groundwater surface water interactions study done in 2013. Feed these studies into global understanding of what is going on at Site. Changes in permafrost at eastern part of the dam have been understood, flow measurements, accounting for losses through the diversion channel.

Local knowledge

2024-05-01 21:02:23 UTC

Knowledge and observations on how the site and surrounding area has changed over time, i.e. where slides have occurred, sluffing, etc.

Collect samples at frozen wells, to see if they are producing groundwater. Consider putting thermistors within frozen MWs to determine ground temperatures.

2024-05-01 21:34:38 UTC