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Testing for Mercury in Plant Effluent. Gary Grey HydroQual, Inc. The Mercury Sampling Debate. NJDEPs stated purpose for the effluent sampling requirement: Evaluate the effect of the Dental Amalgam Rule on the release of mercury to the environment.
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Testing for Mercury in Plant Effluent Gary Grey HydroQual, Inc.
The Mercury Sampling Debate NJDEPs stated purpose for the effluent sampling requirement: • Evaluate the effect of the Dental Amalgam Rule on the release of mercury to the environment. • DEPs intent is to look at POTW effluent mercury concentrations before and after dentists comply with the Amalgam Rule. • It is not DEPs intent to use this data to establish effluent limits. AEA position on the effluent sampling requirement: • POTWs remove mercury and may mask some of the effectivness of Amalgam Rule compliance. • POTW influent sampling would be more appropriate for evaluating the effect of the Rule. • Low level sampling is sensitive to contamination DEP response: • Requirement remains as effluent sampling but DEP will welcome influent sampling as well.
EPA Method 1631E SampleMDL (ng/L) Clean Blanks 0.05 to 0.2 Effluent 1 to 50 Influent 50 to 500 Current NJ WQ standard = 50 ng/L FW 51 ng/L SE/SC NY DEC WQ standard = 0.26 ng/L or MDL (wildlife based criterion) EPA DW MCL = 2,000 ng/L
Buried in the Method 1631E Protocol is a Statement that Clean Methods Sampling Is Required NJDEP is requiring grab samples
Method 1669 Clean Sampling Method • Two person sampling team – “Clean Hands” and “Dirty Hands” • Segregates “diry” operations from “clean” operations. • “Clean Hands” handles the sample bottle, collects the sample and returns the bottle to the inner sample bag. • We have seen blank detections of 0.2 to 0.4 ng/L in a clean laboratory setting. • Wisconsin DNR has helpful information posted on their website: http://www.dnr.state.wi.us/org/water/wm/ww/mercury/mercury.htm • NJDEP will be posting mercury sampling Q&A and guidance in their website
Mercury Sources Affecting POTWs Ask Hypo suppliers for metals assay
Wisconsin POTW Monitoring Results(used to trigger Mercury Management Plans if > 12 ng/L)
Summary • Make sure the lab is: • Certified for Method 1631E • Can achieve an MDL < 1 ng/L • Will provide sample bottles and Hg-free blank water • Low level mercury sampling MUST be a separate effort to itself and not combined with other sampling efforts. • Use dedicated and clean sampling equipment • USE CLEAN METHOD SAMPLING • Collect grab samples and field blanks • Expect plant effluent results at 1 to 50 ng/L. • Influent sampling should be conducted as well. • NJDEP will be posting Q&A regarding the mercury sampling program as well as some guidance on sampling methods.