Soil and Groundwater Monitoring, Sampling, and Analysis
Domain scope
This domain tests sampling design, soil and groundwater sampling methods, QA/QC, preservation and holding times, and analytical data usability.
Core rules and concepts
- Define data quality objectives before sampling; choose discrete versus composite samples accordingly.
- Volatile organic compounds require minimal disturbance, cold storage, and appropriate preservation, such as EPA Method 5035 for soil.
- Low-flow groundwater purging stabilizes pH, temperature, specific conductance, dissolved oxygen, ORP, and turbidity before sampling.
- QA/QC includes trip blanks, field blanks, duplicates, matrix spikes, and chain-of-custody records.
- Holding times and preservation must match the analytical method.
Worked example
A well has 5 cm diameter and 10 m water column. Radius = 0.025 m. Water volume = πr²h = π × 0.025² × 10 = 0.0196 m3 = 19.6 L. Three well volumes = 58.9 L. Low-flow purging may use less, but stabilization parameters must be met.
Traps that cost marks
Using a bailer for volatile samples; sampling before water-quality parameters stabilize; omitting field duplicates; and exceeding holding times.