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Lesson plan Grade 10 Social Studies & Civics

Halvern's Sewer Overflow Consent Decree: A Grade 10 Policy Lesson

A grade 10 civics lesson comparing a storage tunnel with green infrastructure as the fictional city of Halvern negotiates a sewer overflow consent decree.

Objectives

  1. Students will explain what a consent decree is and why a court, a federal agency, and a city all have roles in one.
  2. Students will compare the costs and capture rates of two overflow-control plans using the handout figures.
  3. Students will evaluate each plan for intended and unintended outcomes and defend a recommendation.

Vocabulary

Combined sewer overflow
In some older cities, one pipe carries both sewage and rainwater. A combined sewer overflow happens when a big storm fills the pipe past what the plant can handle, and the extra mix spills into a river untreated.
Green infrastructure
Green infrastructure uses soil and plants, like rain gardens, green roofs, and street trees, to soak up rainwater where it falls instead of piping it away. It copies the way nature handles rain.
Debt service
The money a utility must pay back each year on loans it took out to build big projects, much like a family paying its mortgage. These payments come out of customers' water bills.

Also: consent decree, compliance

Teacher overview

Many older cities carry sewage and stormwater in the same pipes, and during heavy rain the combined flow can exceed what the treatment plant handles, spilling untreated into the nearest river. When a city violates the Clean Water Act this way for years, the usual legal outcome is a consent decree, a court-approved agreement in which the city commits to a construction schedule that will stop the overflows. This lesson uses the fictional city of Halvern, which is negotiating such a decree, to teach students how courts, federal regulators, and city councils share power, and to have them evaluate two genuine engineering paths to compliance. A common misconception this lesson addresses is that the plan with the lower price tag is automatically the better policy; the handout has students compute cost per gallon captured alongside total cost, and the discussion adds the maintenance obligations and neighborhood effects that neither figure shows.

Procedure

Hook (5 min): Ask students what happens to rain that lands on a city street. Then explain that in the fictional city of Halvern, the storm drains and the sanitary sewers are the same pipes, and that after a hard rain the mixture overflows into the Halvern River. Ask who they think can force the city to fix this, and record their guesses.

Direct instruction (12 min): Define combined sewer overflow, then walk through how a consent decree works: the federal government sues under the Clean Water Act, the city negotiates rather than going to trial, and a judge approves a binding schedule of projects with penalties for missed deadlines. Emphasize that the decree is a policy document as much as a legal one, because the city chooses how to comply. Present Halvern's two options: a deep storage tunnel that holds overflow until the plant can treat it, and a citywide green infrastructure program of rain gardens, permeable pavement, and restored streambeds that keeps stormwater out of the pipes in the first place.

Case comparison (15 min): Project the plan summaries. In our scenario, the tunnel would cost $400 million to build and capture about 98 percent of the yearly overflow volume, while the green plan would cost $250 million and capture about 85 percent. In pairs, students list one intended outcome and one plausible unintended outcome for each plan. Prompt them toward outcomes such as construction disruption, jobs, neighborhood greening, maintenance burdens, and what happens if plants and gardens are not kept up. Collect one intended and one unintended outcome from at least four pairs on the board.

Handout work (15 min): Students complete the four Student Handout questions individually, using calculators. Circulate and check that students are dividing the construction cost by households and by captured volume, not simply comparing totals. This is the formative check for the numeracy objective; if more than a third of the class stalls on question 2, work it on the board before continuing.

Exit ticket (8 min): Each student writes a recommendation to Halvern's council, naming the plan they would sign into the decree and the single strongest reason, drawing on either the outcome discussion or the handout math. Collect the tickets and sort them into cost-based, capture-based, and neighborhood-benefit reasons to open the next class.

Halvern's Sewer Overflow Consent Decree: A Grade 10 Policy Lesson — Grade 10 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Handout

The fictional city of Halvern must sign a consent decree to stop its combined sewer overflows. The council is weighing a deep storage tunnel against a green infrastructure program. Answer each question using only the numbers given in that question.

  1. The tunnel plan would cost $400 million to build, and the green infrastructure plan would cost $250 million. How many more dollars would the tunnel cost than the green plan?
  2. The $400 million tunnel would be paid for by Halvern's 80,000 water and sewer households over 25 years. Ignoring interest, how much would each household pay in total, and how much is that per household per year?
  3. Suppose the tunnel would capture 98 percent of Halvern's yearly overflow and the green plan would capture 85 percent. In an average year with 1,000 million gallons of overflow, how many more million gallons would the tunnel keep out of the river than the green plan?
  4. The tunnel costs $400 million and captures 980 million gallons each year; the green plan costs $250 million and captures 850 million gallons each year. Which plan has the lower construction cost per million gallons captured each year? Show both rates.

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: $150 million. 400 million minus 250 million equals 150 million dollars more for the tunnel.
  2. Answer: $5,000 per household in total, which is $200 per household per year. 400,000,000 divided by 80,000 households equals 5,000; 5,000 divided by 25 years equals 200.
  3. Answer: 130 million gallons. The capture difference is 98 minus 85, or 13 percentage points, and 13 percent of 1,000 million gallons is 130 million gallons.
  4. Answer: The green infrastructure plan has the lower cost per million gallons captured. The tunnel rate is 400 divided by 980, about $408,000 per million gallons each year, while the green rate is 250 divided by 850, about $294,000 per million gallons each year.

Differentiation

Support

Provide the division for question 2 already set up in two labeled steps, and let students work the handout in pairs. For the case comparison, supply a two-column outcomes chart with one intended outcome for each plan already filled in as a model.

Extension

Ask students to draft one enforceable milestone for the consent decree, with a date, a measurable target, and a stated penalty, and to explain why regulators insist on milestones instead of a single final deadline.

ELL supports

Pre-teach "consent decree," "overflow," and "compliance" with a simple diagram of a combined pipe in dry and wet weather. Provide a sentence frame for the exit ticket: "Halvern should choose the ___ plan because ___."

Extensions

Have students research how their own city or a nearby city handles stormwater, using only materials the teacher provides, and compare its approach to the two Halvern plans in a short paragraph.