Math problem set Grade 6 Careers & CTE

Undercliff Well Field Log: A Groundwater Technician's Math

A grade 6 careers problem set on a well field technician's daily log, covering drawdown, specific capacity as a unit rate, percent share, and a flow conversion.

Objectives

  1. Students will calculate well drawdown from static and pumping water levels.
  2. Students will express specific capacity as a gallons-per-minute-per-foot unit rate.
  3. Students will find a percent share and convert a daily demand into gallons per minute.

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.

Also: static water level, pumping water level, specific capacity, well field

Teacher overview

Every problem in this set comes from one morning of readings at the fictional Undercliff well field, where a groundwater technician records water levels and pump rates as the wells start for the day. The set follows the order the technician actually works in, moving from raw readings to drawdown, then to a rate that lets three unequal wells be compared, and finally to the town's demand. One misconception runs through the whole topic and is worth naming before students begin: many students report the pumping water level as the drawdown. Drawdown is the difference between the pumping level and the static level, so the reading alone is never the answer.

Answer Key

  1. Answer: 20 feet.
    Drawdown equals the pumping level minus the static level. 60.5 feet minus 40.5 feet equals 20.0 feet of drawdown.
  2. Answer: 16 feet.
    54.5 feet minus 38.5 feet equals 16.0 feet of drawdown.
  3. Answer: 25 gallons per minute per foot.
    Specific capacity equals the pump rate divided by the drawdown. 350 gallons per minute divided by 14 feet equals 25 gallons per minute for each foot of drawdown.
  4. Answer: 12.5 gallons per minute per foot.
    The drawdown from problem 1 is 20 feet. 250 gallons per minute divided by 20 feet equals 12.5 gallons per minute for each foot of drawdown.
  5. Answer: 1,000 gallons per minute.
    350 plus 250 equals 600, and 600 plus 400 equals 1,000 gallons per minute for the whole field.
  6. Answer: 40 percent.
    400 divided by 1,000 equals 0.4, and 0.4 written as a percent is 40 percent.
  7. Answer: 694 gallons per minute.
    The town uses 1.0 million gallons per day, and each million gallons per day equals 694 gallons per minute. 1.0 times 694 equals 694 gallons per minute.
  8. Answer: 288,000 gallons.
    In one hour the well pumps 400 gallons per minute times 60 minutes, which equals 24,000 gallons. Over 12 hours, 24,000 gallons times 12 equals 288,000 gallons.
  9. Answer: 7.5 gallons per minute per foot.
    Last year Well 2 gave 20 gallons per minute for each foot of drawdown, and problem 4 shows it now gives 12.5. 20 minus 12.5 equals a drop of 7.5 gallons per minute for each foot.

Differentiation

Support

Give these students a vertical drawing of one well with the ground surface at the top, a line labeled static level, and a lower line labeled pumping level, and have them mark the drawdown as the gap between the two lines before starting problem 1. Provide problems 3 and 4 with the division already set up, and assign only problems 1 through 6.

Extension

Ask students to decide which well at the fictional Undercliff well field the technician should schedule for cleaning first, using the specific capacity figures from problems 3, 4, and 9. Students write a short paragraph naming the well, citing the numbers, and explaining why a falling specific capacity is a warning even while the pump still delivers water.

ELL supports

Pre-teach "static," "drawdown," and "specific capacity" with the well cross-section drawing and a card showing each term beside a one-sentence meaning. Provide the sentence frame "The drawdown at Well ____ is ____ feet because ____ minus ____ equals ____." Allow students to say answers aloud before writing them.

Extensions

Have students track how the specific capacity of a single well would change if the drawdown grew by one foot each year while the pump rate stayed the same, calculating the figure for three years and describing the trend in a sentence. Students then explain what the technician would recommend before the well reaches half its original specific capacity.