Classroom activity Grade 11 Engineering & Design

Brellin Vale Control Room: An Alarm Triage Simulation

A grade 11 role-play in which shift teams triage eight simultaneous plant and distribution alarms, rank them by consequence, and state the first operator action.

Grade: Grade 11
Subject: Engineering & Design
Material: Classroom activity
Time: 45 min
Prep: Low prep
Materials: Eight printed alarm cards, one per alarm in the handout, A whiteboard or chart paper for the shift log, Timer

Standards

HS-ETS1-2 NGSS

Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

How this material aligns: Questions 1 through 8 break one plant-wide upset into eight subsystem problems, each needing its own first action from the role that owns that part of the plant, which is the decomposition into manageable problems this standard describes.

All materials for HS-ETS1-2 →

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: Questions 9 and 10 have students rank responses against prioritized criteria of public-health consequence, remaining equipment redundancy, and regulatory reporting rather than against arrival order, which is the prioritized evaluation this standard describes.

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 2026-09-03.

Objectives

Students will rank simultaneous alarms by public-health consequence rather than by arrival order.
Students will state a defensible first operator action for each alarm.
Students will identify which alarms trigger a report to the state drinking-water program.

Vocabulary

Clearwell: A clearwell is a large storage tank at a treatment plant that holds finished water right after it comes out of the filters. It gives the disinfectant enough time to work before the water is pumped out to homes and businesses.

Also: alarm triage, free chlorine residual, filter breakthrough, shift log

Teacher overview

This is a timed role-play for a class working in shift teams of four, set in the control room of a small surface water plant on the morning after a storm. Eight alarm cards are dealt over three rounds, and each team must place every alarm on a consequence ranking, name the subsystem it belongs to, and commit to a first action written into a shift log. The activity teaches triage directly, because alarms arrive in the order equipment happens to fail rather than in the order that matters, and the team that works the list top to bottom will spend its first ten minutes on a tripped motor while the distribution system loses pressure. The misconception to name at the start is the belief that the most alarming-sounding alarm is the most urgent one, since a pump trip reads as a bigger failure than a low distribution pressure reading even though a standby pump covers the first while the second can pull contamination into the mains through a leaking joint.

Activity Directions

Before class, print the eight alarm cards from the Student Handout and cut them apart. Draw a shift log on the board with columns for time, alarm, subsystem, ranking, and first action.
Assign four roles inside each team: plant operator, distribution operator, laboratory contact, and shift supervisor. The supervisor writes the log and is the only member who may change a ranking once it is written.
Round one, eight minutes. Deal alarm cards A, B, and C to every team at the same time. Teams rank the three alarms against each other and record a first action for each.
Round two, eight minutes. Deal cards D, E, and F. Teams must now merge six alarms into a single ranked list, which forces them to move earlier entries rather than simply appending new ones.
Round three, eight minutes. Deal cards G and H. Announce that the state drinking-water program is on the telephone and that the supervisor has one minute to say which alarms are being reported.
The simulation ends after round three, when every team has one ranked list of eight alarms and a first action recorded for each.
Post the rankings side by side. Ask two teams that disagree about the same alarm to defend their positions before you comment.
Debrief with two questions. First, which alarm did your team move the furthest during round two, and what changed your mind? Second, which alarms would still matter if every piece of equipment in the plant were working perfectly?

Brellin Vale Control Room: An Alarm Triage Simulation — Grade 11 Engineering & Design

Name: ____________________________ Date: ______________

Student Handout

You are a shift crew at the fictional Brellin Vale Water District, a small surface water plant serving the fictional town of Brellin Vale. The night shift has just handed over after a heavy storm. All readings below are hypothetical values written for this simulation.

Alarm cards:

Alarm A, clearwell. Free chlorine residual leaving the clearwell has fallen to 0.08 mg/L and is still dropping.
Alarm B, filtration. Filter 3 effluent turbidity has risen to 0.42 NTU and continues to climb.
Alarm C, high-service pumping. High-service pump 2 has tripped on motor overload. The standby pump has started.
Alarm D, storage. North tank level reads 8 feet and is falling during the morning demand peak.
Alarm E, raw water intake. Screen differential is high after the storm, and raw water flow to the plant is falling.
Alarm F, distribution. Pressure at the Elm Street monitoring point reads 18 psi.
Alarm G, filtration. The Filter 4 backwash waste valve did not close at the end of the backwash cycle, and filtered water is running to waste.
Alarm H, laboratory. The contract laboratory reports a total coliform positive on a routine distribution sample collected yesterday.

Reference values your district works to: finished-water turbidity at or below 0.3 NTU, a maximum residual disinfectant level of 4.0 mg/L for chlorine, a minimum disinfectant residual of 0.2 mg/L in water entering the distribution system, and a minimum distribution pressure of 20 psi.

State the first action the shift should take on Alarm A.
State the first action the shift should take on Alarm B.
State the first action the shift should take on Alarm C.
State the first action the shift should take on Alarm D.
State the first action the shift should take on Alarm E.
State the first action the shift should take on Alarm F.
State the first action the shift should take on Alarm G.
State the first action the shift should take on Alarm H.
Name the three alarms that carry an immediate public-health consequence and must be reported to the state drinking-water program.
Explain why Alarm C ranks below Alarm F even though both involve pumping.

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

Answer Key

Every reading named below is a hypothetical value from the fictional Brellin Vale scenario.

Answer: Increase the chlorine feed and confirm the reading with a bench test.
A residual this low means water leaving the clearwell may not carry disinfectant into the mains. Confirming the analyzer against a hand-held test tells the operator whether the problem is chemistry or instrumentation before the feed is changed a second time. Because the reading is below the 0.2 mg/L minimum for water entering the distribution system, the supervisor must also report it to the state drinking-water program by the end of the next business day.
Answer: Remove Filter 3 from service and backwash it.
Rising effluent turbidity is filter breakthrough, and the plant works to a finished-water turbidity of 0.3 NTU or lower. Taking the filter offline stops the poorer water from reaching the clearwell.
Answer: Confirm the standby pump is carrying the flow, then lock out pump 2.
The redundancy has already done its job, so the operator verifies discharge pressure and flow, then isolates the failed motor for the electrician rather than restarting it blind.
Answer: Bring additional high-service pumping online to refill the tank.
A falling tank during peak demand means the plant is sending out less than the town is using. Restoring the fill rate protects both the storage volume and the pressure it holds on the system.
Answer: Clean the intake screen and reduce raw water flow until it clears.
Storm debris has blinded the screen, so lowering the demand on the intake protects the raw water pumps while the screen is raked or backwashed.
Answer: Notify the supervisor and restore pressure immediately.
The reading sits below the 20 psi minimum most states require, so the district must raise pressure at once and consult the state drinking-water program about a precautionary advisory for that area.
Answer: Close the backwash waste valve manually and take Filter 4 out of service.
Filtered water running to waste is both a loss of treated water and a sign the valve actuator has failed. Isolating the filter stops the loss until the valve is repaired.
Answer: Collect repeat samples and notify the state drinking-water program.
A coliform positive triggers repeat sampling at the original site and at points upstream and downstream, along with the reporting the state requires.
Answer: Alarms A, F, and H.
A residual below 0.2 mg/L in water entering the distribution system must be reported to the state by the end of the next business day; low distribution pressure can draw contamination into the mains through leaking joints; and a coliform positive is direct evidence of a possible contamination event. All three carry reporting obligations that the equipment alarms do not.
Answer: The standby pump already covers Alarm C, while Alarm F is affecting customers now.
Alarm C is a reliability problem with the redundancy still intact, so the water leaving the plant is unaffected. Alarm F describes water already in the distribution system at a pressure low enough to allow contamination, which is a present risk to the public rather than a future one.

Differentiation

Support

Give these teams a printed consequence ladder with four rungs, from equipment redundancy intact through to public-health event, and have them place each fictional alarm on a rung before writing any action. Provide the first action for Alarm C as a worked example so the format of a shift-log entry is clear.

Extension

Ask these students to write the twenty-four-hour follow-up plan the fictional district owes after Alarm H, naming who samples, where, and what result would end the event. Then have them identify which of the eight fictional alarms would have been prevented by a maintenance task rather than by a faster response, and argue what that implies about maintenance budgets.

ELL supports

Preteach the alarm vocabulary with a labeled plant schematic showing intake, filters, clearwell, high-service pumps, tank, and distribution. Allow students to record first actions as short imperative phrases rather than full sentences, and provide the frame "This alarm is more urgent because ___" for questions 9 and 10 about the fictional scenario.

Extensions

Invite an operator from a nearby utility to describe a real morning when several alarms arrived together, and have students compare the sequence that operator followed against their own ranked list. As a written follow-up, students can draft a one-page standard operating procedure for the fictional district covering only the low-pressure alarm, naming the trigger, the notification chain, and the conditions that would end the event. Students who want a systems view can sketch how the eight fictional alarms connect to one another, since a plugged intake screen, a falling tank, and low distribution pressure are often three symptoms of the same cause.