Pump-and-Treat Remediation of Chlorinated Solvent Contamination at a Controlled Field-Experiment Site
Bibliographic record
Abstract
Pump-and-treat (P&T) remediation and associated concentration tailing are investigated at the field scale in a mildly heterogeneous sandy aquifer through the extraction of dissolved chlorinated solvent plumes that had developed over 475 d from a multicomponent dense nonaqueous-phase liquid (DNAPL) source intentionally emplaced in the aquifer at the Borden (ON) research site. Extraction was accomplished via a source-containment well located 25 m from the source and two further downgradient plume-centerline wells to remove the advancing high-concentration dissolved plumes. The 550 days of detailed P&T field data demonstrated the following: remediation, albeit slowly, of the leading 25-60 m plume section to around typical drinking water standard concentrations; concentration tailing (reduction) over 4 orders of magnitude in the plume; a steady-state concentration "plateau" in the source-containment well capturing the steadily dissolving DNAPL source; influences of extraction rate changes (concentration rebounds); and, lengthy tailing from inter-well stagnation-zone areas. Much of the contaminant behavior during the P&T appeared to be "ideal" in the sense that with appropriate specification of the source term and pumping regime, it was reasonably predicted by 3-dimensional numerical model (HydroGeoSphere) simulations that assumed ideal (macrodispersion, linear sorption, etc.) transport. Supporting lab studies confirmed nonideal sorption was, however, important at the point sample scale with enhanced PCE (tetrachloroethene) sorption to low- and high-permeability strata and moderate nonlinear and competitive sorption influences. Although there was limited evidence of nonideal tailing contributions to the field data (underprediction of some tailing curve gradients), such contributions to P&T tailing were not easily discerned and appeared to play a relatively minor role within the mildly heterogeneous aquifer studied.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".