Worksheet Grade 12 Engineering & Design

Alder Flats Well Field: Drawdown and Specific-Capacity Worksheet

A grade 12 engineering worksheet where students compute well drawdown, specific capacity, and daily yield for two wells in a fictional well field, then compare them.

Grade: Grade 12
Subject: Engineering & Design
Material: Worksheet
Time: 35 min
Prep: No prep
Materials: Calculator

Standards

HSN-Q.A.1 Common Core Math

Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays.

How this material aligns: Items 1 through 8 carry feet, gpm, and hours through the drawdown, specific-capacity, and MGD calculations, the multi-step unit reasoning this standard requires.

All materials for HSN-Q.A.1 →

HSN-Q.A.2 Common Core Math

Define appropriate quantities for the purpose of descriptive modeling.

How this material aligns: Items 5, 6, and 9 use specific capacity, the yield per foot of drawdown, as the quantity that describes and compares each well's productivity and tracks its decline over time, the descriptive-modeling choice this standard describes.

All materials for HSN-Q.A.2 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-17.

Objectives

Students will calculate well drawdown and specific capacity from static and pumping water levels.
Students will compare two wells and interpret a change in specific capacity over time.

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, yield

Teacher overview

The fictional Alder Flats well field pumps groundwater from two wells. Operators track each well's drawdown, which is how far the water level drops while the pump runs, and its specific capacity, which is the yield for each foot of drawdown. This worksheet has students compute both values, compare the two wells, and interpret what a falling specific capacity means over time.

Alder Flats Well Field: Drawdown and Specific-Capacity Worksheet — Grade 12 Engineering & Design

Name: ____________________________ Date: ______________

Student Worksheet

Use these facts about the fictional Alder Flats well field. Drawdown = pumping water level - static water level. Specific capacity = yield / drawdown, in gpm per foot.

Well 1 has a static water level of 40 feet and a pumping water level of 95 feet. Find its drawdown.
Well 1 yields 300 gpm. Find its specific capacity, in gpm per foot. Round to the nearest hundredth.
Well 2 has a static water level of 38 feet and a pumping water level of 78 feet. Find its drawdown.
Well 2 yields 260 gpm. Find its specific capacity, in gpm per foot.
Which well has the higher specific capacity?
Explain what a higher specific capacity tells you about a well.
Well 1 runs at 300 gpm for 18 hours in one day. Find the total gallons pumped that day.
Convert the daily volume from item 7 to million gallons per day (MGD).
After five years, Well 1's specific capacity falls to 3.9 gpm per foot at the same 55-foot drawdown. Estimate its new yield in gpm.
A falling specific capacity often signals a problem. Name one likely cause and one action an operator might take.

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

Answer Key

Answer: 55 feet.
Drawdown = 95 feet - 40 feet = 55 feet.
Answer: 5.45 gpm per foot.
Specific capacity = 300 gpm / 55 feet = 5.4545, which rounds to 5.45 gpm per foot.
Answer: 40 feet.
Drawdown = 78 feet - 38 feet = 40 feet.
Answer: 6.5 gpm per foot.
Specific capacity = 260 gpm / 40 feet = 6.5 gpm per foot.
Answer: Well 2.
Well 2's specific capacity of 6.5 gpm per foot is higher than Well 1's 5.45 gpm per foot.
Answer: It is more productive.
A higher specific capacity means the well produces more water for each foot the level drops, so it is more efficient and productive for the same drawdown.
Answer: 324,000 gallons.
300 gpm x 60 minutes x 18 hours = 324,000 gallons.
Answer: 0.324 MGD.
324,000 gallons / 1,000,000 = 0.324 MGD.
Answer: 214.5 gpm.
Yield = specific capacity x drawdown = 3.9 gpm per foot x 55 feet = 214.5 gpm. The lower specific capacity means the well now produces less water at the same drawdown.
Answer: Clogging; rehabilitate the well.
Accept any sound pair. A common cause is mineral scale, sand, or bacterial buildup clogging the well screen. A common action is to rehabilitate or redevelop the well to restore its capacity.

Differentiation

Support

Provide a labeled cross-section of a well showing the static level, the pumping level, and the drawdown between them. Work item 1 as a class example, and give the two formulas on a printed card.

Extension

Ask students to find the difference in daily yield between Well 1 and Well 2 if both run 18 hours at their listed rates, then explain why Well 1 delivers more water each day even though Well 2 has the higher specific capacity, and how a daily difference of that size adds up over a year.

ELL supports

Pre-teach "static," "pumping level," "drawdown," and "yield" with the labeled cross-section and a home-language gloss where possible. Allow students to answer items 6 and 10 with a labeled sketch plus a short phrase rather than full sentences.