1. Start with the governing plan
Identify the approved method, analytes, roles, decision criteria, collection sequence, documentation, quality controls and purge-water route. Do not replace project requirements with example values from a general guide or calculator.
2. Confirm the well and work area
Match the well ID to the construction record. Record casing and screen dimensions, reference point, total depth, condition, access, potential hazards and any discrepancy that changes intake placement or volume.
3. Prepare calibrated equipment
Record instrument IDs, calibration checks, tubing internal diameter and wetted length, pump or chamber volume, flow-cell volume and other wetted components. Prevent cross-contamination using the approved decontamination or dedicated-equipment approach.
4. Measure water levels before pumping
Use the specified reference point and record initial depth to water before disturbing the well. Recheck total depth only when the plan and conditions support doing so safely.
5. Place the intake deliberately
Compare intake depth with the screen interval and measured water level. Maintain submergence and follow the plan for screen position; the setup checker reports geometry conflicts but does not choose the placement.
6. Establish and observe flow
Begin and adjust pumping under the approved method. Record actual flow and depth to water together so drawdown is tied to the same operating condition. A nominal pump setting is not a measured rate.
7. Respect equipment displacement
Calculate the wetted equipment volume and the time required for the entered number of exchanges. Schedule readings so the water observed at the instruments can be related to the field interval.
8. Keep a complete time-ordered log
Record every required parameter, time, flow and depth-to-water observation. Preserve checks, adjustments, calibration events, interruptions, unusual appearance and field decisions rather than deleting inconvenient rows.
9. Compare only approved criteria
Use the analyzer with criteria transcribed from the governing plan. Review each parameter result separately; MET means only that the entered numeric comparisons passed for the selected consecutive window.
10. Hand off the complete record
Retain the original field sheet or local file, well and equipment identifiers, units, calibration evidence, water-level reference, pump changes, purge volume, criteria source, field lead decision and required chain-of-custody material under the project procedure.
Worked example
A 50 mm ID well with an 8 m water column contains about 15.7 L. A 6 mm ID, 20 m tubing run plus 400 mL of other wetted equipment totals about 0.97 L, so one entered exchange needs about 3.86 minutes at 0.25 L/min. These calculations support scheduling; they do not determine when sampling is authorized.
Sources
- U.S. EPA — Groundwater Sampling Operating Procedure (EQASOP-GW4)
- U.S. EPA — Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures
- U.S. Geological Survey — Purge Analyzer Tool (PAT)