The City and County of Broomfield has been contracting low-level mercury analyses for many years. The permit requires monthly sampling of the effluent.  We also collect upstream and influent samples for comparison. The sampling requires two people to grab four samples a day (every two hours) and then prepare a flow proportional composite from these samples.  The contract lab was awesome because they would provide us with a cooler with everything that we needed for the sampling event (pre-cleaned bottles, bags, gloves).  We would send them the individual bottles and then they would composite the samples based on the flow data that we provided.  However, on several occasions, the bottles broke during transit.  Also, it often took weeks to get the results to us.  Since this is a required monthly test, this was stressful, because we would need to know before the end of the month if there was an issue with the sample, so we could resample if necessary.

As we were planning for a laboratory expansion in 2015, we discussed the possibility of bringing this analysis in-house.  We visited the City of Ft. Collins wastewater lab and Ginger Wynne and the staff were kind enough to give us a tour of their lab and show us their low-level mercury setup.   We realized that we didn’t need a “clean” room, so we started thinking that this could work for us. We worked with the design team to create a metals/mercury lab with PVC fume hoods and polypropylene cabinets. The instrument’s autosampler can be covered to prevent contamination from environmental factors in the laboratory.

We purchased the mercury analyzer with the expansion and waited until we had everything else set-up in the lab before we brought in the instrument.  The laboratory was completed in August 2017 and the analyzer setup and training occurred the first week of October 2017.  After the initial training, it took a few more weeks to get the argon gas sparging system setup.  By April 2018, the method development was complete, and the first monthly samples were analyzed in-house.  Starting in August 2018, we will also begin analyzing our industrial pretreatment samples in-house.

So, if you were thinking that you have to have a Class 1 cleanroom to perform low level mercury analyses, maybe this will make you realize that isn’t necessary.  You do need to have a dedicated “clean” space that is not near any analyses that have mercury in a reagent (looking at you TKNs) and analysts that are diligent about keeping that space clean.

Lesa Julian is the Wastewater Laboratory Supervisor for the City and County of Broomfield.