A Review of Data Recording & Reporting for Composite Samples

At a recent meeting, members of the MWWCA Pretreatment Committee found that several plants have the same concerns with how some analytical laboratories are reporting sampling dates.

Operators, laboratory managers and pretreatment coordinators working for both publicly owned wastewater treatment systems and licensed private facilities must report data to Maine DEP and the USEPA in accordance with 40 CFR 136. While Maine DEP is an NPDES delegated State, licensed treatment plants and pretreatment program industrial users must still collect data that is legally defensible under the federal Clean Water Act. Therefore, when choosing between opposing State and Federal rules, it is necessary to choose the most stringent.

Some independent Maine environmental laboratories (contract labs) that collect and report data on composite samples use the last day of collection as the sample date. Although the federal rule and Maine DEP policy differ, reporting the second day of a composite as the sampling day may not be acceptable under either rule or policy. Portions of the rule and policy are included below, for your reference.

40 CFR 136 Table II footnote 4.

“For a set of grab samples to be composited, and that are all collected on the same calendar date, the date of collection is the date on which the samples are collected. For a set of grab samples to be composited, and that are collected across two calendar dates, the date of collection is the dates of the two days; e.g., November 14-15. For a composite sample collected automatically on a given date, the date of collection is the date on which the sample is collected. For a composite sample collected automatically, and that is collected across two calendar dates, the date of collection is the dates of the two days; e.g., November 14-15.”

Maine DEP O & M News May 2007

“If you put on your reading glasses and work really hard you will see that footnote 4 under Table I in Part 136 says something a bit funky. It basically says that when you collect an automated composite sample that spans two calendar dates you have to report the collection date using the 2 days –like November 14-15. The Department does not believe this is necessary and is recommending that facilities continue to report the collection date for the day the largest portion of the composite sample was collected.”

The Maine Wastewater Control Association Pretreatment Committee recommends that the following sampling day reporting be done:

1. On the chain of custody, record the start date and end date (for example Nov 14-15) and the start time and end time (for example 8:00 am – 8:00 am). Note: Both dates and times must be reported, because under Pretreatment Program rules in 40 CFR 403, the exact time of sample collection must be reported.

2. On the lab receipt report, the day the sample is received at the lab is acceptable.

3. On the report of analysis, the laboratory will report either the EPA stipulated version (for example, Nov 14-15) or the day on which the largest portion of the sample was collected (for example Nov. 14).

The Committee has written a “Form Letter” that wastewater treatment plant operators could use when discussing sampling dates with their labs. Please refer questions to: Vivian Matkivich (vmatkivich@lawpca.org) or Mike Micucci Chairman (Mike.Micucci@ch2m.com).

Thank you.
 

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