Quiz & test questions Grade 10 Careers & CTE

Thorncastle Main Replacement: A Construction Inspector Quiz

A grade 10 careers quiz on the water main construction inspector role, covering pipe volume, disinfection dosing, pressure testing, and trench quantity math.

Grade: Grade 10
Subject: Careers & CTE
Material: Quiz & test questions
Time: 40 min
Prep: No prep
Materials: Calculator

Standards

HSG-MG.A.1 Common Core Math

Use geometric shapes, their measures, and their properties to describe objects (e.g., modeling a tree trunk or a human torso as a cylinder).

How this material aligns: Items 3 and 7 ask students to model a length of pipe as a cylinder and a trench as a rectangular prism to compute working volumes.

All materials for HSG-MG.A.1 →

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 4, 6, and 8 carry gallons, million gallons, pounds, feet, psi, and gpm through chained conversions with units held consistent throughout.

All materials for HSN-Q.A.1 →

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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 describe what a water utility construction inspector verifies on a main replacement job.
Students will compute pipe and trench volumes from stated dimensions.
Students will calculate a disinfection dose in pounds and a hydrostatic test pressure.

Vocabulary

Key words: construction inspector, hydrostatic test, main disinfection, bedding, pay quantity

Teacher overview

This 40-minute quiz is worth 30 points and checks whether students understand the work of a utility construction inspector on a water main replacement job. It mixes multiple-choice recall, short-answer judgment items, and six computation items on pipe volume, disinfection dosing, pressure testing, and excavation quantities. The scenario is set in the town of Thorncastle, a fictional community replacing an aging cast iron main, which is ordinary work given that a water main breaks somewhere in the United States roughly every two minutes. One point is worth clearing up before the quiz. Pipe that has never carried water is not therefore clean, because it sits open on a job site for weeks and collects soil, rain, and rodents. Every new main is disinfected, flushed, and sampled for bacteria before the inspector allows it into service.

Thorncastle Main Replacement: A Construction Inspector Quiz — Grade 10 Careers & CTE

Name: ____________________________ Date: ______________

Assessment

(2 points) On a water main replacement job, what is the utility construction inspector's main responsibility?
- A) Designing the pipe alignment and preparing the drawings
- B) Verifying that the contractor builds the main to the specifications and documenting the work
- C) Operating the excavator and laying the pipe
- D) Setting the water rates that pay for the project
(2 points) Why must a newly installed main be disinfected, flushed, and sampled before it is connected to the system?
- A) New pipe is manufactured with a chlorine coating that must be washed off
- B) Pipe stored on a job site collects soil, water, and debris that can carry bacteria
- C) State law requires the pipe to be tested for lead content after installation
- D) Flushing is the only way to check the pipe for leaks
(4 points) The fictional Thorncastle job installs 1,200 feet of 12-inch main, which has an inside diameter of 1.0 foot. Using the cylinder volume formula, which is 0.785 times the diameter squared times the length, find the volume of the new main in gallons. Use 7.48 gallons per cubic foot and round to the nearest gallon.
(4 points) The inspector must confirm the chlorine charge before the contractor fills the new main. The specification calls for a dose of 25 mg/L in the 7,046 gallons the main holds. Using the pounds formula, which is concentration times volume in million gallons times 8.34, find the pounds of chlorine required. Round to the nearest hundredth.
(3 points) The Thorncastle specification requires a hydrostatic test at 1.5 times the system's normal working pressure. The working pressure at this location is 65 psi. What test pressure must the contractor hold?
(3 points) The fictional Thorncastle storage tank's overflow sits 152 feet above the new main. Using 0.433 psi per foot of head, find the static pressure the main will see when the tank is full.
(4 points) The trench for the same 1,200-foot run is 3.0 feet wide and 5.5 feet deep. Find the volume of material excavated, in cubic yards, using 27 cubic feet per cubic yard. Round to the nearest tenth.
(3 points) To flush the new main, the crew must move water through it at 2.5 feet per second. Using Q equals area times velocity, with an area of 0.785 square feet for the 12-inch pipe, find the required flushing rate in gallons per minute. Use 448.8 gpm per cubic foot per second and round to the nearest tenth.
(3 points) The inspector finds that the contractor has bedded the pipe in native clay rather than the crushed stone the specification requires. Describe what the inspector should do and what should go in the daily report.
(2 points) Name one route a person could take into construction inspection for a water utility, and state one credential or experience that route would build.

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 inspector verifies that the contractor builds the main to the utility's specifications and documents what was installed; design, construction labor, and rate setting belong to other roles.
Answer: B. Pipe stored on an open job site collects soil, water, and debris that can carry bacteria, so the main is disinfected, flushed, and sampled before it goes into service.
Answer: 7,046 gallons. The cross-sectional area is 0.785 times 1.0 squared, or 0.785 square feet, and 0.785 times 1,200 feet gives 942 cubic feet. Then 942 times 7.48 equals 7,046.16, which rounds to 7,046 gallons.
Answer: 1.47 pounds. The volume in million gallons is 7,046 divided by 1,000,000, or 0.007046. Then 25 times 0.007046 equals 0.17615, and 0.17615 times 8.34 equals 1.469, which rounds to 1.47 pounds of chlorine.
Answer: 97.5 psi. Multiplying the working pressure by the test factor gives 65 times 1.5, which equals 97.5 psi held for the duration the specification states.
Answer: 65.8 psi. Multiplying head by the pressure conversion gives 152 times 0.433, which equals 65.816, rounding to 65.8 psi.
Answer: 733.3 cubic yards. The trench volume is 1,200 times 3.0 times 5.5, which equals 19,800 cubic feet, and 19,800 divided by 27 equals 733.33, rounding to 733.3 cubic yards.
Answer: 880.8 gpm. First, 0.785 square feet times 2.5 feet per second equals 1.9625 cubic feet per second. Then 1.9625 times 448.8 equals 880.77, which rounds to 880.8 gallons per minute.
Answer: The inspector stops that portion of the work, notifies the contractor's foreman and the utility's project engineer, and requires the pipe to be re-bedded in the specified crushed stone before backfill continues. The daily report records the station numbers affected, the material actually used, photographs, the time the deviation was found, who was notified, and the correction agreed to. Accept any answer that includes both stopping or correcting the work and written documentation with notification.
Answer: Accept any one route with a matching credential or experience. Reasonable answers include years in a pipe-laying or utility construction crew, which builds field knowledge of installation practice; a two-year civil or construction technology degree; a public works inspector certification earned by exam; and promotion from a distribution operator position, which builds knowledge of the system the new main will join.

Differentiation

Support

Provide a formula card listing the cylinder volume formula, the pounds formula, the head-to-pressure conversion, and the flow equation, with one worked example on a different fictional job. Allow a calculator on every item, and let students answer item 9 as a short bulleted checklist rather than a paragraph.

Extension

Ask students to prepare the pay estimate line the inspector would submit for the excavation in item 7, given a fictional unit price the teacher supplies, then explain in two sentences why a utility pays for excavation by the cubic yard rather than by the day. Students should notice that a measured quantity protects both the utility and the contractor from disputes.

ELL supports

Pre-teach "specification," "bedding," "hydrostatic test," "backfill," and "pay quantity" with a labeled cross-section drawing of a trench showing the pipe, the stone bedding, and the backfill. Provide a sentence frame for item 9: "The inspector should ___ because the specification says ___, and the report must record ___."

Extensions

Have students compare the fictional Thorncastle job with a real construction bid tabulation, which most public works departments post online, and identify which line items are measured by length, by volume, and by each unit installed. Students can then trace how the inspector's daily quantities become the contractor's monthly payment, so the accuracy of a field measurement determines what the contractor is paid.