Environmental Mitigation Associated With the Installation of a Natural Gas Pipeline in the Vicinity of an Artesian Well
Bibliographic record
Abstract
In the fall of 2001, Enbridge Consumers Gas proposed to install a 190 mm extra-high pressure steel pipeline in proximity to an artesian well on the Oak Ridges Moraine in southern Ontario. This well is located within the Regional Municipality of Durham and it is used by over 300 persons per day as their drinking water source because of very high water quality. Potential impacts to drinking water quality have taken on greater importance because of the Walkerton tragedy, in which a number of people died from drinking contaminated municipal water. The Region of Durham was especially concerned because of the large number of people who use this artesian well as their drinking water source. The Region did not want to close the well during construction as this could be taken as an admission that construction might negatively impact water quality. At the same time, they wanted to ensure that water quantity and quality was maintained. SENES Consultants Limited (“SENES”) was retained to develop and implement an environmental management plan to ensure that no negative impacts would occur during construction. The plan involved characterization of the water-bearing zone in terms of depth, type of deposit and direction of flow, relative to the drinking water source. This was undertaken through the use of test pits, boreholes and piezometers. Potential construction impacts were identified. In this case, the natural gas pipeline was to be installed by a directional drill that injects bentonite (drilling mud) to provide lubrication and to keep the drill hole from collapsing. Mitigation measures related to containment of bentonite and fuel handling in the vicinity of the artesian well were prescribed. The rationale for directional drilling this section of the pipeline was to prevent erosion of the steep slopes and to undercross a watercourse. The water-bearing deposit consisted of a sandy-gravel layer that was found to occur at a depth of 3.65 meters. Every effort was made to maintain the drill hole for the pipeline above this depth. In addition to sampling the artesian well for chemical and bacterial parameters in advance of construction and upon completion of work in the vicinity, water from the artesian well and one of the piezometers was checked for turbidity every two hours. Other contingency plans included digging “burp-holes” to reduce the potential for bentonite frac-outs and having a water supply truck on stand-by should turbidity levels reach unacceptable levels. Construction proceeded smoothly. Minor frac-outs occurred and were appropriately contained. The turbidity readings and water quality samples taken before, during and post-construction confirmed that there were no negative impacts on the artesian well. The methods used on this project are directly applicable to other pipelines that may be constructed in the vicinity of artesian wells.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".