Monitoring, Sampling, Laboratory Analysis and Reporting
What you must know
A sample is only as good as its collection. Know site selection, aseptic technique for bacteriology (100-mL bottle with sodium thiosulfate, no rinsing, adequate headspace, chilled), container choice (plastic for metals, amber glass for VOCs and DBPs), preservation (nitric acid for metals, chilling to 4 C), holding times, chain of custody, and field blanks and duplicates.
Field analyses: free and total chlorine by DPD, turbidity by nephelometry, pH, temperature, conductivity, dissolved oxygen. Laboratory: alkalinity and hardness by titration, fluoride by ion-selective electrode, nitrate by ion chromatography, BOD5 at 20 C over 5 days with depletion of at least 2 mg/L and residual DO of at least 1 mg/L. QA/QC: calibration curves, continuing checks, method detection limit, control charts, matrix spikes.
Reporting: routine compliance monitoring versus process control, discharge monitoring reports under NJPDES, monthly operation reports, exceedance notification, and electronic submittal to NJDEP.
Traps
- Quoting a holding time that belongs to a different parameter.
- Forgetting chlorine residual has essentially no holding time - analyze on site.
- Confusing a monitoring or reporting violation with an MCL violation.
Worked example - routine coliform samples
Use the population table: 1,001 to 2,500 people means 2 per month; 2,501 to 3,300 means 3; 3,301 to 4,100 means 4. A system serving 3,300 people takes 3 routine samples monthly, plus repeat samples within 24 hours of any total-coliform-positive result.