Epa Core Knowledge Epa Core Knowledge Environmental Monitoring & Sampling 2 — Questions and Answers
Question 1: What is the correct protocol for purging a groundwater monitoring well before sampling?
- Remove 3 to 5 casing volumes of water until field parameters stabilize (Correct answer)
- Pump the well until it runs dry
- Add chlorine to disinfect, then wait 24 hours
- Sample immediately without purging
Correct answer: Remove 3 to 5 casing volumes of water until field parameters stabilize
EPA protocols require removing 3 to 5 well volumes and waiting for field parameters to stabilize to ensure the sample represents the true aquifer conditions.
Question 2: Which type of sample provides a snapshot of contaminant concentrations at a single point in time?
- Grab sample (Correct answer)
- Composite sample
- Continuous sample
- Passive sample
Correct answer: Grab sample
A grab sample is collected at a single point in time and location, providing an instantaneous snapshot of contaminant concentrations.
Question 3: What is the purpose of a duplicate sample in environmental monitoring?
- To assess the precision of sampling and analytical methods (Correct answer)
- To increase the volume of sample available for testing
- To provide a backup in case the primary sample is lost
- To calibrate laboratory instruments
Correct answer: To assess the precision of sampling and analytical methods
Duplicate samples are collected side by side to evaluate the reproducibility and precision of the sampling and analytical procedures.
Question 4: Under EPA regulations, how should soil samples collected for metals analysis be stored and preserved?
- Chilled to 4°C in sealed containers and analyzed within specified holding times (Correct answer)
- Frozen at -20°C immediately after collection
- Stored at room temperature in open containers
- Mixed with preservative acid before transport
Correct answer: Chilled to 4°C in sealed containers and analyzed within specified holding times
Soil samples for metals must be kept chilled at 4°C in sealed containers and analyzed within EPA-specified holding times to prevent degradation.
Question 5: What does a 'trip blank' test for in VOC sampling?
- Cross-contamination that occurs during transport of samples to the laboratory (Correct answer)
- Contamination introduced during laboratory preparation
- Background VOC levels at the sampling site
- Instrument calibration drift
Correct answer: Cross-contamination that occurs during transport of samples to the laboratory
A trip blank is an unexposed sample that travels with the collected samples to detect any VOC contamination introduced during transport.
Question 6: Which EPA guidance document provides protocols for collecting representative soil samples at contaminated sites?
- SW-846 (Correct answer)
- 40 CFR Part 136
- EPA Method 5030
- Technical Standard 200.7
Correct answer: SW-846
EPA SW-846 (Test Methods for Evaluating Solid Waste) provides the official methods and protocols for sampling and analyzing solid and hazardous waste, including soils.
Epa Core Knowledge Epa Core Knowledge Environmental Monitoring & Sampling 2
What is the correct protocol for purging a groundwater monitoring well before sampling?