Quiz & test questions Grade 11 Engineering & Design

Harkin Row Campus Stormwater Retrofit: Design Assessment

A grade 11 engineering assessment on a campus stormwater retrofit, covering impervious area, runoff volume, bioretention storage, drawdown time, and cost per gallon.

Grade: Grade 11
Subject: Engineering & Design
Material: Quiz & test questions
Time: 45 min
Prep: No prep
Materials: Calculator

Standards

HSG-MG.A.3 Common Core Math

Apply geometric methods to solve design problems (e.g., designing an object or structure to satisfy physical constraints or minimize cost).

How this material aligns: Items 4 and 7 size a bioretention cell's storage from its area, media depth, porosity, and ponding depth against a capture target, the design-under-constraint geometry this standard requires.

All materials for HSG-MG.A.3 →

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 3, 5, 6, and 9 carry square feet, inches, gallons, hours, and dollars through the runoff, drawdown, and unit-cost calculations, keeping units consistent as this standard requires.

All materials for HSN-Q.A.1 →

HS-ETS1-3 NGSS

Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

How this material aligns: Items 8 and 10 have students choose between two stormwater controls on cost, maintenance, and overflow, weighing prioritized criteria and trade-offs as this standard requires.

All materials for HS-ETS1-3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will calculate runoff volume and impervious cover for a developed site.
Students will size a bioretention cell and test it against a capture target and a drawdown limit.
Students will compare two stormwater controls on installed cost and long-term maintenance.

Vocabulary

Impervious surface: An impervious surface is any hard surface, like a road, roof, or parking lot, that rain cannot soak through. The more impervious surface a town has, the more stormwater rushes off it.
Porosity: Porosity measures how much empty space a rock or soil has between its grains, which tells you how much water it can hold. A sponge has high porosity, while a piece of glass has almost none.

Also: bioretention, drawdown time, runoff coefficient

Teacher overview

This 45-minute assessment is worth 40 points and checks whether students can size a stormwater retrofit for a paved site. It mixes two multiple-choice items, one short-answer item, and seven computation items, all built on a single fictional campus so that later items depend on earlier results. Teachers should scan item 4 first when grading, because a student who forgets that only the pore space in the soil media stores water, rather than the whole media volume, will carry that error into items 5, 9, and 10.

Harkin Row Campus Stormwater Retrofit: Design Assessment — Grade 11 Engineering & Design

Name: ____________________________ Date: ______________

Assessment

Use these values for the fictional Harkin Row campus on every item.

Total campus area: 60,000 square feet of lawn and planting beds, 40,000 square feet of asphalt parking lot, and 20,000 square feet of building roof, for 120,000 square feet in all.
Design storm: 1.0 inch of rain.
Runoff conversion: area in square feet times rainfall in inches times 0.623 equals gallons of runoff.
Proposed bioretention cell: 3,000 square feet of surface, 18 inches (1.5 feet) of engineered soil media at 30 percent porosity, plus 6 inches (0.5 feet) of ponding above the media.
Volume conversion: 1 cubic foot holds 7.48 gallons.
Native soil beneath the cell accepts water at 0.5 inches per hour, and the local rule requires ponded water to drain within 48 hours.
Installed cost of the bioretention cell: $18 per square foot of surface.

(3 points) Which surface on the fictional campus would have the highest runoff coefficient, meaning the largest fraction of rainfall that runs off rather than soaking in?
- A) The mowed lawn
- B) The asphalt parking lot
- C) A gravel maintenance path
- D) The planted bioretention cell
(3 points) The parking lot covers 40,000 square feet and the roof covers 20,000 square feet, out of 120,000 square feet of campus. What percent of the campus is impervious?
(4 points) Using the conversion area times rainfall times 0.623, find the gallons of runoff the 40,000-square-foot parking lot produces in the 1.0-inch design storm.
(5 points) The cell has 3,000 square feet of surface, 1.5 feet of media at 30 percent porosity, and 0.5 feet of ponding. Find the storage volume in cubic feet, then convert it to gallons using 7.48 gallons per cubic foot.
(4 points) Divide your answer to item 4 by your answer to item 3 and multiply by 100. What percent of the parking-lot runoff does the cell hold? Round to the nearest whole percent.
(4 points) The 6 inches of ponded water must soak into native soil that accepts 0.5 inches per hour. How many hours does the ponded water take to drain, and does that meet the 48-hour rule?
(3 points) Which single change would add the most storage volume to the cell, if its 3,000-square-foot surface stays the same?
- A) Deepening the ponding from 6 inches to 12 inches
- B) Raising the media porosity from 30 percent to 35 percent
- C) Adding 6 inches to the media depth
- D) Planting shrubs with deeper roots
(5 points) The bioretention cell costs $18 per square foot to install and needs mulch and weeding each spring. An underground detention vault holding the same volume would cost $95,000 installed and would need a contractor to pump out sediment every year. Recommend one option for the fictional campus and justify it with one cost reason and one reason that is not about cost.
(4 points) Find the installed cost of the 3,000-square-foot bioretention cell at $18 per square foot, then divide that cost by the gallons of storage you found in item 4 to get the cost per gallon of storage. Round to the nearest cent.
(5 points) Take the parking-lot runoff in gallons from item 3 and subtract the cell's storage in gallons from item 4. How many gallons does the storm produce that the cell cannot hold, and what must the design include so those gallons leave the site safely?

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: B, the asphalt parking lot. Pavement sheds close to all the rain that falls on it, with a runoff coefficient near 0.9, while a mowed lawn is nearer 0.2 and the gravel path and planted cell fall between.
Answer: 50 percent. The impervious area is 40,000 plus 20,000, which is 60,000 square feet; 60,000 divided by 120,000 equals 0.50, or 50 percent.
Answer: 24,920 gallons. Multiplying 40,000 square feet by 1.0 inch by 0.623 gallons per square foot per inch gives 24,920 gallons.
Answer: 21,318 gallons. Storage per square foot is 1.5 feet times 0.30, which is 0.45 feet, plus 0.5 feet of ponding, for 0.95 feet; 3,000 times 0.95 equals 2,850 cubic feet, and 2,850 times 7.48 equals 21,318 gallons.
Answer: 86 percent. Dividing 21,318 gallons by 24,920 gallons gives 0.8555, which is 85.55 percent, rounding to 86 percent.
Answer: 12 hours, yes. Six inches divided by 0.5 inches per hour equals 12 hours, which is well inside the 48-hour limit.
Answer: A, deepening the ponding to 12 inches. Ponding stores water at full depth, so adding 0.5 feet of ponding adds 0.5 feet of storage per square foot, while 5 more points of porosity adds only 0.075 feet and 6 more inches of media adds 0.15 feet.
Answer: either option, with two supported reasons. The bioretention cell costs $54,000 installed, which is less than the $95,000 vault, and it also treats pollutants in the soil media rather than only storing water; a student choosing the vault should cite the parking spaces it preserves or its smaller footprint, and should acknowledge the annual pumping contract.
Answer: $2.53 per gallon. The cell costs 3,000 times $18, which is $54,000; dividing $54,000 by 21,318 gallons gives $2.533, or about $2.53 per gallon of storage.
Answer: 3,602 gallons. Subtracting 21,318 gallons from 24,920 gallons leaves 3,602 gallons, so the design needs an overflow structure, such as a raised outlet or a weir, that carries the excess to the storm drain without eroding the cell.

Differentiation

Support

Provide a formula card listing the runoff conversion, the storage-per-square-foot expression, and the cubic-feet-to-gallons factor in the order the items use them, and print the setup for item 4 with blanks under each factor. Allow these students to answer item 8 in two sentences rather than a paragraph, and give partial credit on items 5, 9, and 10 when a student carries a wrong earlier value forward correctly.

Extension

Ask students to find the gallons of runoff the fictional campus roof produces in the same design storm, then decide whether one bioretention cell of the size given could hold both the roof runoff and the parking-lot runoff. Have them state what surface area the cell would need to hold both, keeping the same media depth, porosity, and ponding depth.

ELL supports

Provide a labeled cross-section of a bioretention cell showing the ponding layer above the media layer, with the depth of each marked, so students can see which layer item 4 counts at full depth and which only at its pore space. Post the sentence frame "I recommend ___ because it costs ___ and because it also ___" for item 8, and allow item 6 to be answered with the number of hours plus a circled yes or no.