Writing prompt Grade 10 Science
Stormwater Rules for the Mardenfield Mill Site
A grade 10 science argument prompt where students take a position on whether a redevelopment must control runoff on site or pay into a downstream detention basin.
Objectives
- Students will state and defend a claim about a stormwater permit condition.
- Students will use peak-flow evidence to support a claim about runoff control.
- Students will address a counterclaim about cost and downstream benefit.
Vocabulary
Key words: runoff coefficient, peak flow, bioretention, fee in lieu, counterclaim
Teacher overview
A planning board that approves a redevelopment must decide where the site's rainwater will go. The board can require the developer to hold and soak in runoff on the property, or it can accept a payment toward a larger basin downstream. Both choices reduce flooding, yet they protect different stretches of stream and cost different amounts. This prompt asks students to take a position on that choice and defend it with peak-flow evidence.
Prompt
Background: The fictional town of Tindale is reviewing a plan to redevelop the old Mardenfield Mill. The site covers 12 acres. Almost all of it is roof and pavement today, and it drains straight into Bellamont Creek at the property line.
Engineers estimate peak runoff with the rational method, written as Q equals C times i times A. In that equation Q is the peak flow in cubic feet per second, C is a runoff coefficient, i is the rainfall intensity in inches per hour, and A is the drainage area in acres. Pavement has a runoff coefficient near 0.9. A lawn has a coefficient near 0.2.
The board is using a design storm of 2 inches per hour. As the site stands, its coefficient is about 0.9, so its peak flow is 0.9 times 2 times 12, or 21.6 cfs. The town has two options in front of it.
Option A requires runoff control on the property. Permeable pavement, planted bioretention beds, and a green roof would lower the site's coefficient to about 0.55. The peak flow would then be 0.55 times 2 times 12, or 13.2 cfs. A fictional cost estimate prepared for the town puts this work at $1,400,000.
Option B lets the developer pay a fee in lieu of on-site work. The fictional fee is $900,000, and the town would put it toward a regional detention basin two miles downstream. That basin would protect the Fenner Street neighborhood, which floods in most large storms. It would do nothing for the reach of Bellamont Creek between the mill and the basin, including the half mile just below the site that holds the creek's only remaining trout spawning gravel.
Writing task: The Tindale planning board has asked for written comment before it votes. Write an argument that states a clear claim about which option the board should choose. Support the claim with evidence from the background above, including the peak-flow numbers. Address at least one counterclaim a reasonable person on the other side would raise, and explain why your position still holds.
Planning Organizer
| Category | Your notes |
|---|---|
| Claim: which option should the board choose? | |
| Reason 1 and the evidence that supports it | |
| Reason 2 and the evidence that supports it | |
| The peak-flow figure that matters most to your case, and why | |
| Counterclaim someone on the other side would raise | |
| Your rebuttal to that counterclaim | |
| Concluding statement |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Exemplar & Rubric
Exemplar response:
The Tindale planning board should require on-site runoff control at the Mardenfield Mill rather than accept the fee in lieu. The half mile of Bellamont Creek below the site is the part of the stream that the site's runoff actually damages, and it is the part the regional basin cannot help. A basin two miles downstream begins working only after the water has already scoured that reach. Protecting the trout gravel means slowing the water where it enters the creek rather than well downstream of it.
The peak-flow numbers support this position directly. As the site stands, its runoff coefficient of about 0.9 produces a peak flow of 21.6 cfs in the design storm. Permeable pavement and bioretention would lower the coefficient to about 0.55 and the peak flow to 13.2 cfs. That is nearly 40 percent less water arriving at the creek bank in the worst hour of the storm, and it arrives at the exact point where the site's own pavement created the problem. The fee-in-lieu option leaves the site discharging its full 21.6 cfs into the creek every large storm for the life of the building.
Someone arguing for the fee would point out that it costs $500,000 less and that it protects Fenner Street, where houses take on water. That is a serious argument, and the flooding on Fenner Street is a real harm to real households. Yet the town does not have to choose between those neighbors and the creek. The regional basin is a separate project with its own funding path, and approving one developer's payment does not build it. On-site control is the only measure that is guaranteed to exist because this permit exists. Once the mill site is built out, the chance to shape how it drains is gone for decades.
The board should approve the redevelopment with on-site runoff control as a condition. The evidence shows the on-site option cuts the peak flow to the damaged reach by nearly 40 percent, while the fee leaves that reach unchanged and depends on a basin the town has not yet built.
Rubric:
| Criterion | Emerging | Developing | Proficient | Advanced |
|---|---|---|---|---|
| Claim | No clear position stated | States a position that shifts or stays vague | States one clear, consistent position on the board's choice | States a clear position and previews the reasoning that will support it |
| Evidence and reasoning | No evidence from the background | Restates one figure without explaining its relevance | Uses at least two specific figures and explains how each supports the claim | Uses several figures, explains each, and shows which one carries the most weight |
| Counterclaim | No counterclaim addressed | Mentions an opposing view with no rebuttal | States a counterclaim and offers a specific rebuttal | States a counterclaim fairly, rebuts it with evidence, and ties the rebuttal back to the claim |
| Organization and conventions | Ideas disconnected; errors block meaning | Some organization; errors are noticeable | Clear paragraphs and few errors | Purposeful structure, strong conclusion, and virtually error-free |
Differentiation
Support
Give students the organizer with the claim row already filled in for one side, and provide sentence frames such as "One reason the board should choose ___ is ___, because the background says ___." Allow the counterclaim and rebuttal to be written as a single paragraph.
Extension
Ask students to write a second, shorter comment arguing the opposite position as persuasively as they can, then to explain in two sentences which of the two comments they find stronger and why.
ELL supports
Pre-teach "runoff," "peak flow," "bioretention," and "fee in lieu" with a labeled sketch of rain falling on pavement and on a planted bed. Allow the organizer to be completed in phrases before drafting, and permit a first draft in a student's home language.