Performance of GCL after 10 Years in Service in the Arctic
Bibliographic record
Abstract
The performance of a geosynthetic clay liner (GCL) installed as part of a geocomposite barrier (geomembrane/GCL) to contain a hydrocarbon spill adjacent to the Arctic Ocean was evaluated by examining sacrificial samples exhumed after 1, 4, 6, 7, and 10 years in service. The hydraulic and chemical characteristics of the GCL were most affected by the location within the soil profile relative to the water table (typically about 1.3 m below ground level). The bentonite in the GCL samples exhumed from a depth of 0.0–0.8 m was well hydrated with a dispersed structure. Despite the significant cation exchange that took place between these GCL samples and the surrounding soil (the percentage of the exchangeable sodium decreased from 68% to 10–15%), there was no change in the hydraulic conductivity (k) of GCL for tap water or jet fuel. A similar bentonite structure was observed for GCL samples exhumed from 0.8 to 1.3 m below ground level; however, an observed network of horizontal and vertical microcracks (200–400 μm wide) in the bentonite layer was attributed to the formation of ice lenses. As a result, the k of these GCL samples increased by one to two orders of magnitude when permeated by both tap water and jet fuel. The bentonite in GCL samples exhumed from below the water table after 6 and 10 years was flocculated with relatively high free pore space. The k values of these samples increased by one to four orders of magnitude for tap water and jet fuel. Despite this increase in k at some depths, there was no evidence of migration of hydrocarbons through the barrier over the last 10 years, indirectly suggesting that the subsurface geocomposite barrier system is still performing well.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".