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Worksheet Grade 7 Science

Cinderwood's Well 3: Reading Drawdown in a Pumping Test

A grade 7 groundwater worksheet using a fictional town's well-pumping data to calculate drawdown, compare two wells, and reason about the cone of depression.

Objectives

  1. Students will calculate drawdown from static and pumping water-level measurements.
  2. Students will compare drawdown at two wells to explain how distance from a pumping well affects groundwater levels.
  3. Students will evaluate well data against a stated operating limit.

Vocabulary

Drawdown
Drawdown is how far the water level in a well drops when a pump pulls water out. The harder and longer you pump, the bigger the drawdown gets.
Cone of depression
A cone of depression is the dip in the water table that forms in a circle around a well while it is pumping, like a shallow bowl scooped out of the underground water surface. The harder a well pumps, the wider and deeper this dip becomes.
Aquifer
An aquifer is an underground layer of rock, sand, or gravel that holds water in the tiny spaces between its grains. Wells reach down into aquifers to bring water up to the surface.

Also: static water level, pumping water level

Teacher overview

In the fictional town of Cinderwood, a single municipal well called Well 3 supplies part of the community's drinking water. Whenever a well pumps, the water level inside it drops below the level of the surrounding aquifer, and that drop, called drawdown, can be measured and calculated. This worksheet uses a six-hour pumping test at Well 3, plus a second reading from a nearby observation well, to give students real numbers for practicing the drawdown formula and for reasoning about why wells closer to a pumping well show more drawdown than wells farther away.

Cinderwood's Well 3: Reading Drawdown in a Pumping Test — Grade 7 Science
Name: ____________________________ Date: ______________

Student Worksheet

Use these facts from Cinderwood's Well 3 pumping test for every problem below.

  • Before pumping starts, the water level in Well 3 sits 42 feet below the ground surface. This is called the static water level.
  • Well 3 then pumps continuously for a scheduled 6-hour test. At the end of the 6 hours, the water level inside Well 3 has dropped to 67 feet below the ground surface. This is called the pumping water level.
  • An observation well sits 300 feet away and draws from the same aquifer. Its water level starts at the same static level, 42 feet below ground, and after the same 6-hour test its level has dropped to 51 feet below ground.
  • Cinderwood's water system sets a maximum allowed drawdown of 30 feet for Well 3, to keep the pump intake safely below the water surface at all times.
  • During the test, the pump removes water from Well 3 at a steady rate of 40 gallons per minute.
  1. Define "static water level" and "pumping water level" in your own words, using Well 3 as your example.
  2. Calculate the drawdown in Well 3 after the 6-hour test. Use the formula: Drawdown = pumping water level − static water level.
  3. Calculate the drawdown in the observation well after the same 6-hour test.
  4. Well 3's drawdown is much larger than the observation well's drawdown, even though both wells reach into the same aquifer. Explain why distance from the pumping well affects how much a water level drops.
  5. What percent of Well 3's drawdown does the observation well's drawdown represent? Round to the nearest whole percent.
  6. Does Well 3's drawdown during the test stay within Cinderwood's 30-foot maximum drawdown limit? By how many feet does it clear or miss the limit?
  7. How many total gallons did the pump remove from Well 3 during the full 6-hour test, running at a steady 40 gallons per minute?
  8. Four hours after the pump shuts off, Well 3's water level has recovered to 49 feet below ground. How many feet has the water level risen since pumping stopped?
  9. A second well, Well 5, is planned 150 feet from Well 3, closer than the 300-foot observation well. Based on the pattern in this worksheet, would you expect Well 5 to show more or less drawdown than the observation well during a similar test? Explain your reasoning using the cone-of-depression idea.
  10. Cinderwood's engineer wants to keep future drawdown at Well 3 under a tighter goal of 20 feet. Based on this test's result of 25 feet of drawdown, does Well 3 currently meet that tighter goal? Explain.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: static water level and pumping water level.
    The static water level is the depth to water in a well before any pumping begins; Well 3's static level is 42 feet below the surface. The pumping water level is the depth to water after pumping has been running, once the level has stabilized; Well 3's pumping level is 67 feet below the surface after 6 hours.
  2. Answer: 25 ft.
    67 ft − 42 ft = 25 ft of drawdown at Well 3.
  3. Answer: 9 ft.
    51 ft − 42 ft = 9 ft of drawdown at the observation well.
  4. Answer: the cone of depression is steepest near the pumping well.
    Pumping pulls water toward the well from every direction, forming a funnel-shaped drop in the water table called a cone of depression. The drop is steepest right at the pumping well and becomes gentler with distance, so a well 300 feet away sits farther out on that funnel and shows a smaller water-level change.
  5. Answer: 36 percent.
    9 ft ÷ 25 ft × 100 = 36%. The observation well's drawdown is a little more than a third of Well 3's own drawdown.
  6. Answer: yes, by 5 ft.
    Well 3's drawdown of 25 ft is less than the 30 ft limit: 30 − 25 = 5 ft of margin remaining before the limit would be reached.
  7. Answer: 14,400 gal.
    6 hours × 60 minutes/hour = 360 minutes. 360 minutes × 40 gallons/minute = 14,400 gallons.
  8. Answer: 18 ft.
    The pumping water level was 67 ft below ground; four hours after shutoff it recovered to 49 ft below ground. 67 − 49 = 18 ft of rise. (The well has not fully recovered: it remains 49 − 42 = 7 ft below its original static level.)
  9. Answer: more drawdown.
    Well 5 sits closer to Well 3 than the 300-foot observation well does, and drawdown is greater closer to a pumping well on the cone of depression, so Well 5 should show more drawdown than the observation well's 9 feet, likely somewhere between 9 and 25 feet.
  10. Answer: no.
    Well 3's drawdown during this test was 25 feet, which is above the engineer's proposed 20-foot goal. Some combination of a shorter pumping schedule, a lower pumping rate, or additional wells sharing the load would be needed to meet the tighter target.

Differentiation

Support (below grade level)

Provide the drawdown formula written out as an arrow rule ("pumping level minus static level equals drawdown") on a printed strip, and complete problem 2 together as a class before students attempt problem 3 independently. Allow a number line or vertical diagram of the well, marked in feet below ground, to make the subtraction concrete.

Extension (above grade level)

Ask students to sketch a rough graph of drawdown (y-axis) against distance from Well 3 (x-axis), plotting the two known points (0 feet away, 25 feet of drawdown; 300 feet away, 9 feet of drawdown), and to estimate where on that graph the 150-foot Well 5 from problem 9 would likely fall.

ELL supports

Pre-teach "static," "pumping," "drawdown," and "recover" with a labeled diagram of a well showing the water level before pumping, during pumping, and after recovery, using arrows and depth numbers rather than dense text. Allow item 1 and item 4 to be answered with labeled diagrams supported by short phrases instead of full paragraphs.