CWD Risk Assessment & Management 2 — Questions and Answers
Question 1: When drilling near an underground storage tank (UST), what is the PRIMARY risk assessment concern?
- Increased drilling costs
- Potential cross-contamination of the aquifer (Correct answer)
- Equipment corrosion from fuel vapors
- Permit processing delays
Correct answer: Potential cross-contamination of the aquifer
USTs can leak petroleum hydrocarbons that may contaminate the aquifer if drilling penetrates contaminated soil or connects pathways to groundwater.
Question 2: A driller notices unexpectedly high artesian pressure during well construction. What is the most critical immediate risk?
- Bit wear acceleration
- Uncontrolled blowout and potential borehole collapse (Correct answer)
- Increased pump sizing requirements
- Casing thread damage
Correct answer: Uncontrolled blowout and potential borehole collapse
Uncontrolled artesian flow can cause blowout, borehole collapse, and flooding of the work area, posing serious safety and environmental hazards.
Question 3: Which document is essential for identifying subsurface hazards BEFORE drilling begins on a new site?
- Driller's log from a nearby well (Correct answer)
- Material Safety Data Sheets (SDS) for drilling fluids
- Well pump test report
- State water use permit
Correct answer: Driller's log from a nearby well
Nearby driller's logs reveal formation sequences, aquifer depths, and known hazards such as lost circulation zones or contaminated intervals.
Question 4: What risk does drilling through a confining layer (aquitard) pose if not properly managed?
- Increased fuel consumption
- Hydraulic connection between aquifers of different quality (Correct answer)
- Bit deflection in hard rock
- Slower penetration rates
Correct answer: Hydraulic connection between aquifers of different quality
Breaching a confining layer can allow poor-quality water from one aquifer to migrate into a better-quality aquifer, causing permanent contamination.
Question 5: Under OSHA regulations, what is the minimum safe distance workers must maintain from an unsupported borehole edge?
- 1 foot
- 3 feet (Correct answer)
- 6 feet
- 10 feet
Correct answer: 3 feet
OSHA requires workers to remain at least 3 feet from the edge of an unsupported excavation or borehole to prevent falls.
Question 6: Which hazard classification applies to a drilling site located within a 100-year floodplain?
- Low risk — floods rarely occur
- High risk — well construction standards must address flood inundation (Correct answer)
- Moderate risk — only affects surface equipment
- No special classification required
Correct answer: High risk — well construction standards must address flood inundation
Drilling in a 100-year floodplain is high-risk because floodwaters can inundate and contaminate a newly constructed well, requiring elevated wellhead designs.
Question 7: What is the purpose of a pre-task Job Hazard Analysis (JHA) on a drilling site?
- To calculate daily equipment depreciation
- To identify, evaluate, and control hazards before work begins (Correct answer)
- To document crew overtime hours
- To verify water quality compliance
Correct answer: To identify, evaluate, and control hazards before work begins
A JHA systematically identifies potential hazards for each task step and assigns controls to reduce or eliminate risk before work starts.
CWD Risk Assessment & Management 2
When drilling near an underground storage tank (UST), what is the PRIMARY risk assessment concern?