Field parameter comparison
| Parameter | Typical field evidence | Analyzer method | Critical boundary |
|---|---|---|---|
| pH | Calibrated reading with time and temperature context | Absolute range across entered consecutive readings | No universal acceptance value is supplied |
| Temperature | Flow-cell or approved field measurement | Relative range = range ÷ |mean| × 100 | Unit conversion and instrument equilibration matter |
| Conductivity | Calibrated reading with stated units and compensation | Relative range | Trend does not identify individual dissolved constituents |
| Dissolved oxygen | Maintained sensor under approved flow-cell conditions | Relative range | Air contact, bubbles and sensor response can alter readings |
| Oxidation-reduction potential | Electrode reading with reference and maintenance context | Absolute range in mV | Response can be slow and method-dependent |
| Turbidity | Appropriate clean field cell and instrument record | Relative range | Disturbance and bubbles may dominate a reading |
| Depth to water | Consistent surveyed reference and time | Absolute range over the comparison window | Setup checker separately compares total drawdown |
| Flow | Measured rate at the same operating condition | Absolute range in selected flow units | Pump setting alone is not a measured rate |
Calculation and record rules
- Use at least three consecutive, strictly time-ordered data rows.
- Do not silently omit blank, malformed or inconvenient rows.
- Keep criteria values and their governing source with the result.
- Integrate purge volume from each time interval and its preceding measured flow.
- Report each parameter as PASS or CHECK; one CHECK keeps the overall result at NOT YET MET.
- Retain calibration, equipment, water-level, adjustment and interruption records outside the numeric table.
MET is deliberately narrow. It means only that the selected consecutive readings passed every user-entered numeric criterion. It does not establish representativeness, approve sample collection, specify laboratory handling or authorize purge-water disposal.
Reference boundary. Do not convert an indicative value into a universal design, health or legal requirement. Check the cited source, laboratory context, certified claim and applicable jurisdiction.
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)