Environmental Technician how-to
How to Collect a Groundwater Sample with Low-Flow Purging
Low-flow methods collect water representative of the aquifer while minimizing disturbance.
Low-flow methods collect water representative of the aquifer while minimizing disturbance. In short: measure; lower; pump, then complete the remaining steps below.
Step by step
Measure and record the depth to water before purging.
Lower the pump intake to the middle of the screened interval.
Pump at a low rate while monitoring water level drawdown.
Measure field parameters (pH, conductivity, temperature, DO, turbidity) every few minutes.
Begin sampling once parameters stabilize within the plan’s criteria.
Fill bottles in the order specified, starting with volatiles, without headspace for VOC vials.
Label, preserve, place on ice and document on the chain of custody.
Safety reminders for environmental technicians
- Follow the site health and safety plan and wear required PPE
- Monitor air for VOCs and hazardous gases when required
- Use traffic and weather precautions for field work
- Handle sample preservatives (acids) with gloves and eye protection
Key terms
Chain of custody · Grab sample · Composite sample · Low-flow purging · PID · VOCs: see the full environmental technician glossary.