RMGA Emergency Response Procedures 2 — Questions and Answers
Question 1: What concentration of natural gas in air (expressed as % LEL) typically triggers evacuation procedures?
- 1% LEL
- 10% LEL
- 25% LEL (Correct answer)
- 50% LEL
Correct answer: 25% LEL
Most standard operating procedures require evacuation and emergency response actions when gas concentrations reach or exceed 25% LEL to provide a safety margin below the explosive range.
Question 2: What agency must a natural gas operator notify if a gas incident causes a death or injury requiring hospitalization?
- OSHA only
- PHMSA National Response Center (Correct answer)
- State Department of Commerce
- Federal Energy Regulatory Commission
Correct answer: PHMSA National Response Center
49 CFR Part 191 requires operators to notify the PHMSA National Response Center by telephone for incidents involving death, injury requiring hospitalization, or significant property damage.
Question 3: What is 'backfilling and compaction' important for after a gas main repair?
- Restoring original soil conditions to protect the pipe and prevent future settlement (Correct answer)
- Removing excess gas from the repair area
- Documenting the repair in the GIS system
- Calibrating the pressure regulator after restarting service
Correct answer: Restoring original soil conditions to protect the pipe and prevent future settlement
Proper backfilling and compaction restore soil support around the repaired pipe, prevent ground settlement, and protect the pipe from future damage.
Question 4: Who is typically responsible for shutting off gas service during a structure fire when the fire department requests it?
- The homeowner only
- The gas utility upon request from fire department or emergency responders (Correct answer)
- The building contractor
- The local gas appliance dealer
Correct answer: The gas utility upon request from fire department or emergency responders
The gas utility is responsible for safely shutting off service when requested by fire or emergency personnel during a structure fire.
Question 5: What is the purpose of 'purging with inert gas' before restarting a gas main?
- To add odorant to the gas before customer delivery
- To displace oxygen from the piping before introducing flammable gas, preventing a combustible mixture (Correct answer)
- To test pressure integrity of the repaired section
- To clean residual dirt from the pipe interior
Correct answer: To displace oxygen from the piping before introducing flammable gas, preventing a combustible mixture
Purging with nitrogen or another inert gas displaces air (oxygen) from the piping so that when natural gas is introduced, no flammable mixture can form.
Question 6: What information must a gas operator collect when responding to a public report of a gas odor?
- Customer's monthly gas bill amount
- Location, time, description of odor, and whether anyone is inside the affected structure (Correct answer)
- Customer's social security number
- Nearest intersection only
Correct answer: Location, time, description of odor, and whether anyone is inside the affected structure
First responders must collect the exact location, time of report, odor description, and occupancy status to prioritize and direct an effective emergency response.
RMGA Emergency Response Procedures 2
What concentration of natural gas in air (expressed as % LEL) typically triggers evacuation procedures?