CDS Quality Control & Inspection 3 — Questions and Answers
Question 1: During selective demolition, a QC inspector identifies unexpected asbestos-containing material (ACM) behind a wall. Under NESHAP regulations, what is the first required action?
- Remove the material immediately using standard PPE
- Stop work in the affected area and notify the project owner and regulatory agency (Correct answer)
- Cover the material and continue work in adjacent areas
- Test additional samples before making any notifications
Correct answer: Stop work in the affected area and notify the project owner and regulatory agency
NESHAP requires immediate work stoppage in the affected area and notification of the owner and applicable regulatory authority upon discovering unexpected ACM.
Question 2: What does a 'pre-demolition inspection checklist' typically verify regarding underground utilities?
- That all utilities have been upgraded to current code
- That all utilities have been located, marked, and disconnected or capped per utility company requirements (Correct answer)
- That utility easements have been purchased by the demolition contractor
- That utility meters have been transferred to the new owner
Correct answer: That all utilities have been located, marked, and disconnected or capped per utility company requirements
Pre-demolition checklists require verification that utilities are located, marked, and properly disconnected or capped to prevent strikes and service disruptions.
Question 3: A supervisor notices that a subcontractor's concrete saw operator is not using the dust control water suppression system. Which standard is most directly violated?
- OSHA 29 CFR 1926.1153 (Respirable Crystalline Silica) (Correct answer)
- OSHA 29 CFR 1926.502 (Fall Protection)
- ANSI Z87.1 (Eye Protection)
- EPA 40 CFR Part 63 (NESHAP)
Correct answer: OSHA 29 CFR 1926.1153 (Respirable Crystalline Silica)
OSHA 29 CFR 1926.1153 requires engineering controls such as water suppression when cutting concrete to limit silica dust exposure.
Question 4: What is the correct procedure when a quality control inspection reveals that a debris chute is missing its required spark arrestor near a hot-work zone?
- Document the finding and address it at the next weekly safety meeting
- Remove the chute from service and install the required spark arrestor before resuming (Correct answer)
- Allow continued use if no ignition sources are visible
- Request a variance from OSHA before taking corrective action
Correct answer: Remove the chute from service and install the required spark arrestor before resuming
A debris chute near hot-work must have a spark arrestor in place before use; removing it from service until corrected is the required QC action.
Question 5: Which measurement tool is used during demolition inspections to verify that wall tilt or lean has not exceeded safe limits?
- Laser level or digital inclinometer (Correct answer)
- Tape measure and plumb bob
- Total station theodolite only
- Ground-penetrating radar
Correct answer: Laser level or digital inclinometer
A laser level or digital inclinometer provides precise measurement of wall tilt or lean to verify structural stability during demolition.
Question 6: When reviewing an as-built drawing during a demolition QC inspection, a supervisor finds that post-tensioned tendons were not shown. Why is this critical?
- Post-tensioned tendons increase concrete recycling value
- Cutting post-tensioned tendons releases stored energy and can cause sudden, violent structural collapse (Correct answer)
- Tendons must be removed before structural steel salvage
- Post-tensioned systems require special EPA disposal permits
Correct answer: Cutting post-tensioned tendons releases stored energy and can cause sudden, violent structural collapse
Post-tensioned tendons store significant energy; unplanned cutting can cause explosive release of that energy, resulting in catastrophic structural failure.
Question 7: A QC inspector is reviewing air monitoring data collected during interior demolition. Which permissible exposure limit (PEL) governs worker exposure to lead dust?
- 50 μg/m³ as an 8-hour TWA (Correct answer)
- 100 μg/m³ as an 8-hour TWA
- 10 μg/m³ as a ceiling limit
- 200 μg/m³ as a short-term exposure limit
Correct answer: 50 μg/m³ as an 8-hour TWA
OSHA's PEL for lead is 50 micrograms per cubic meter of air averaged over an 8-hour work shift (29 CFR 1926.62).
CDS Quality Control & Inspection 3
During selective demolition, a QC inspector identifies unexpected asbestos-containing material (ACM) behind a wall.
Under NESHAP regulations, what is the first required action?