Preferential flow in geosynthetic clay liners exhumed from final covers with composite barriers
Bibliographic record
Abstract
Geosynthetic clay liners (GCLs) were exhumed from final covers with composite barriers (geomembrane over GCL) at two municipal solid waste landfills in the USA. Preferential flow and high hydraulic conductivity (>2 × 10 −9 m/s) was observed in eight of the 18 GCL samples collected from both sites. At one site, manganese oxide precipitate was concomitant with bundles of needle-punched fibers that conducted preferential flow. Nearly complete replacement of Na by Ca on the bentonite surface occurred in all GCL samples. GCLs with and without preferential flow could not be differentiated by physical and chemical properties commonly used to differentiate GCLs with high and low hydraulic conductivities (exhumed water content, swell index, mole fraction monovalent cations, soluble cation concentrations). The relative abundance of soluble cations in the pore water of GCLs exhibiting preferential flow was comparable to the relative abundance in the subgrade pore water, whereas the pore water in GCLs with distributed flow was more sodic than the pore water in the subgrade. Hydration experiments indicated that bentonite in GCLs initially hydrates in a zone surrounding bundles of needle-punching fibers. Cation exchange during this hydration process may create zones of higher hydraulic conductivity surrounding the fiber bundle, permitting preferential flow.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.000 |
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 teacher head, 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".