Reading Comprehension

PT116 · S1 · P1 · Q5 Oil Drilling Contamination

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The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells.

Topic

The environmental impact of oil well drilling on groundwater and the ongoing challenges in regulating and preventing contamination.

Framework

Problem / Solution

Main Point

Efforts to prevent groundwater contamination from oil drilling have often been reactive rather than proactive, and recent disasters show that regulatory and technological solutions are still limited by incomplete scientific knowledge. *The most valuable sentence appears at the end of the first paragraph:*

P1: Overview of the Regulatory Lag

Scientific understanding and regulation of environmental impacts from oil drilling often come only after problems are noticed—especially with groundwater contamination.

P2: Early Focus of Regulation and Emerging Problems

At first, regulations protected oil from being contaminated by water, but no one thought about protecting groundwater from oil until people started finding oil in their drinking water wells.

P3: How Contamination Happens and Industry Responses

Drilling can connect different underground layers, letting oil or salty water leak into groundwater; attempts to seal off fresh water have evolved from using hollow trees to modern metal casings with cement.

5.

Based on the information in the passage, if a prospective oil well drilled near a large city encounters a large groundwater formation and a small saline water formation, but no oil, which one of the following statements is most likely to be true?

  1. Groundwater contamination is unlikely because

    Too Strong: unlikely

    The 3rd sentence of the 3rd paragraph says that wells that penetrate both groundwater and oil or saline will contaminate the groundwater. The well doesn't need to hit oil for contamination. Hitting unpotable saline is enough to contaminate (if safeguards aren't in place).

    10% picked this

  2. Danger to human health due

    Too Strong: unlikely

    This is a very unalarmed take. We have support for the idea that, "without safeguards, the groundwater will be inevitably contaminated!" This answer is very blasé, like "we'll be fine. We have other sources of water that won't be contaminated." We don't know anything about this hypothetical city that allows us to speculate that they have lots of other uncontaminated water supplies.

    1% picked this

  3. Groundwater contamination is likely unless

    Out of Scope: plugged / abandoned

    We'd be okay with this answer if it said, groundwater contamination is likely unless appropriate safeguards are taken. The author didn't give us reason to panic to this degree of, "If we don't plug it and abandon it, we're probably going to contaminate." It was more like, "We'll put down casings and try to the best of our abilities to keep the flow in the pipe from leeching into the subsurface formations, but no one really knows over time how long that will work".

    14% picked this

  4. Groundwater contamination is unlikely because

    Out of Scope: dilute

    This is tempting at first from a real world common sense point of view. If you have a large amount of freshwater and put in a small amount of salt water, it will dilute the salt water. So will it even be contaminated? Well, actually ... yes? Picture taking a pint of drinking water from the fridge and then tossing in a shot of ocean water. That would be straight nasty. Even a small amount of salt water can taint a fresh water supply. We have a line in the passage that says "if the well penetrates groundwater and saline, contamination is inevitable (w/o safeguards)". That rule doesn't hedge and say, "I mean ... inevitable unless it's a classic battle between Large fresh vs. Small salt."

    1% picked this

  5. Correct

    The risk of groundwater contamination

    Why this is right

    This reinforces our 3rd sentiment, "without safeguards, contamination is inevitable". That suggests that "with safeguards, there would be lower risk of contamination". This answer goes on to list some of those safeguards: properly set casing monitored routinely for breakdown

    Skill tested: Application · how this choice captures the passage's function is the move to repeat next time.

    74% picked this

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