Sampling and Reporting Pressure After an Inconsistent DMR
A small plant submits a discharge monitoring report monthly. The permit requires weekly fecal coliform samples and daily pH and flow. The operator has been taking coliform samples on an irregular schedule, sometimes two in one week and none the next, because the sampler was unavailable. The latest DMR shows all parameters within limits, but the coliform results were entered as a single monthly value rather than the required weekly values. The state inspector is scheduled in two weeks. The plant's records include bench sheets, calibration logs, and the sampler's maintenance records, but the coliform bench sheets for two weeks are missing. The operator is unsure whether to reconstruct the data or report the gap.
1. Explain the regulatory problem with the coliform reporting and missing bench sheets, and why reconstructing data is not acceptable.
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The permit requires weekly coliform samples, so reporting a single monthly value does not demonstrate compliance with the required sampling frequency. Missing two weeks of bench sheets means the plant cannot show it met the monitoring requirement for those weeks. Under most permits, failure to monitor is itself a violation and must be reported, often with the DMR marked accordingly rather than filled with estimated values.
Reconstructing or estimating coliform results is not acceptable because the data would not be real measurements and would misrepresent compliance. Falsifying or fabricating monitoring data is a serious violation that can carry enforcement consequences beyond the original sampling gap. The correct approach is to report the actual data available, identify the missing sampling periods, explain the cause (sampler unavailability), and describe corrective actions. The inspector will look at whether the plant has a reliable sampling schedule and whether the records support the reported values.
2. What should the operator do before the inspection to correct the record and prevent recurrence?
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Before the inspection: (1) Review all DMRs for the past year for similar frequency or reporting errors and correct them through the proper amendment process if the permit allows. (2) Document the missing coliform periods honestly, including the cause and the dates. (3) Assemble the available records: bench sheets, calibration and maintenance logs, and sampler records. (4) Notify the appropriate regulatory contact if the permit requires notification of missed monitoring. (5) Put a written sampling schedule in place with backup coverage so weekly samples are taken even when the primary sampler is unavailable, and train a second person.
During the inspection, present the facts clearly and show the corrective actions. The goal is an accurate record and a credible plan, not a clean-looking report. Keeping a log of the corrective actions and the new schedule demonstrates good-faith compliance.