Impact on groundwater of concurrent leakage and diffusion of dichloromethane through geomembranes in landfill liners
Bibliographic record
Abstract
Although intact geomembranes are excellent barriers to fluid flow, there are still two possible pathways for the transport of organic contaminants into the environment: leakage through defects in the geomembrane, and diffusion through the intact geomembrane. Analytical, semi-analytical and numerical techniques for calculating leakage rates have been developed. However, no previous attempt has been made to rigorously model the interaction between leakage through a hole in a wrinkle and diffusion. To address this shortcoming, finite-element analyses in two-dimensional space are performed to simulate the transport of dichloromethane (DCM) through a leaking HPDE geomembrane (GM) for eight cases involving composite liners, including both compacted clay liners and geosynthetic clay liners. Equations of steady-state seepage and time-dependent diffusion-advection in saturated soils are solved. Transport through the GMs is simulated by a novel, mass-conserving equivalent boundary condition that renders the problem computationally more tractable. Results are compared with those obtained from widely used one-dimensional methods, namely the Rowe equation for leakage through a wrinkle and the POLLUTEv7 program for mass transport. It is shown that predictions of leakage and transport by the one-dimensional method (POLLUTEv7) are within a maximum 30% of two-dimensional values under conditions of perfect mixing in the aquifer. When no horizontal mixing is present, concentrations of DCM are found to increase by up to 43% in two-dimensional analyses. It is concluded that one-dimensional analyses are adequate for most practical purposes.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".