CWD Risk Assessment & Management 3 — Questions and Answers
Question 1: A well driller discovers H2S gas during drilling. Which action should be taken FIRST?
- Continue drilling at reduced speed
- Immediately evacuate personnel upwind and monitor air quality (Correct answer)
- Increase drilling fluid weight to suppress the gas
- Cap the borehole and resume the next day
Correct answer: Immediately evacuate personnel upwind and monitor air quality
H2S is immediately dangerous to life and health (IDLH) at 100 ppm; immediate upwind evacuation and air monitoring are the required first responses.
Question 2: What risk management technique involves transferring financial liability for a drilling project's environmental damage to a third party?
- Risk avoidance
- Risk retention
- Risk transfer via insurance (Correct answer)
- Risk reduction through engineering controls
Correct answer: Risk transfer via insurance
Purchasing environmental liability or contractor's pollution liability insurance transfers the financial risk of environmental damage to the insurer.
Question 3: When assessing risk from drilling near a septic system, the primary concern is:
- Methane ignition during drilling
- Microbial contamination of the aquifer from wastewater (Correct answer)
- Vibration damage to the septic tank
- Increased permit fees
Correct answer: Microbial contamination of the aquifer from wastewater
Septic systems release pathogens and nitrates that can migrate into the aquifer if minimum setback distances are not maintained.
Question 4: In a risk matrix, a hazard rated as 'high likelihood, high severity' should be:
- Monitored but allowed to proceed
- Accepted as part of normal drilling operations
- Immediately controlled or work halted until controls are in place (Correct answer)
- Documented and reviewed after project completion
Correct answer: Immediately controlled or work halted until controls are in place
High likelihood combined with high severity places a hazard in the unacceptable risk zone, requiring immediate corrective controls before work proceeds.
Question 5: Which condition on a drilling site most increases the risk of cave-in or borehole instability in unconsolidated formations?
- Low ambient temperature
- Presence of saturated fine sand or silt (running sand conditions) (Correct answer)
- Hard rock encountered at shallow depth
- High mud weight drilling fluid
Correct answer: Presence of saturated fine sand or silt (running sand conditions)
Saturated fine-grained soils lose their structural strength and flow into the borehole, creating running sand conditions that risk borehole collapse.
Question 6: What is the role of a Site Safety Plan (SSP) during well drilling operations?
- Tracks equipment maintenance schedules
- Documents all site-specific hazards and emergency response procedures (Correct answer)
- Serves as the billing record for the project
- Satisfies state well registration requirements
Correct answer: Documents all site-specific hazards and emergency response procedures
An SSP is a living document that identifies site-specific hazards, defines control measures, and outlines emergency procedures for all personnel on site.
Question 7: A driller is working adjacent to an active agricultural field. Which risk is MOST specific to this setting?
- Rock fall from nearby cliffs
- Pesticide and fertilizer contamination of shallow groundwater (Correct answer)
- Salt water intrusion from the ocean
- Volcanic gas emissions
Correct answer: Pesticide and fertilizer contamination of shallow groundwater
Agricultural chemicals including nitrates, herbicides, and pesticides commonly leach into shallow aquifers and pose contamination risk to new wells drilled nearby.
CWD Risk Assessment & Management 3
A well driller discovers H2S gas during drilling.
Which action should be taken FIRST?