Reading ComprehensionDifficulty: Medium

PT116 S1 P1 Q5 Explanation

Oil Drilling Contamination

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsApplicationScience

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Passage

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. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with earth that supplies wells and springs—provide a case in point.

When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled many drinking-water wells near the oil well sites began to produce unpotable, oil-contaminated water.

The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.

Regulations currently govern the kinds of casing and cement that can be used in these practices; however, “the hazards of insufficient knowledge” persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.

What this question is testing

Application

Your task

Pin down exactly what the question asks about the passage — a detail, the author's view, the structure, or the main point — before looking at the choices.

Common trap

Answers that restate a true detail from the passage but don't answer the specific question being asked.

Winning move

Anticipate the answer in your own words from the passage, then find the choice that matches that prediction.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
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,

Answer choices

  1. Too Strong: unlikely10% picked this

    Groundwater contamination is unlikely because the well did not strike oil and hence will not

    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).

  2. Too Strong: unlikely1% picked this

    Danger to human health due to groundwater contamination is unlikely because large cities generally have more than one

    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.

  3. Out of Scope: plugged / abandoned14% picked this

    Groundwater contamination is likely unless the well is plugged

    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".

  4. Out of Scope: dilute1% picked this

    Groundwater contamination is unlikely because the groundwater formation’s large size will safely dilute any saline

    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."

  5. Correct74% picked this

    The risk of groundwater contamination can be reduced if casing is set properly and monitored

    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.

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