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Mercury from Metal Stampling

Thanks so much everyone for your helpful suggestions.  Since most of the responses came to me directly, I thought I would compile them for the listserve, in case anyone else has a similar situation.

Here they are:

It would help to know a little more about the facility.  Just a thought, but some machinery (older machinery) use mercury switches.  Could it be that the switches are old and leaking into the stamping pits (which normal discharge to the wastewater (IWTP or POTW)?\.

Mercury may be trapped in the drain traps of sinks, etc., from past practices,  and is constantly leaching into the water. Take all of the drain traps apart and clean them.

What kinds of metals are they working with?  Are there cleaning and/or coating operations involved?  Are there testing or R&D labs at this facility?  Is the wastewater strictly from industrial processes or are there sanitary sources connected to this system?  Is there any history of this company or a previous occupant of the facility having used any products containing mercury?  Answering these questions may provide some leads.  Otherwise, my recommendation would be to conduct sampling and testing for mercury at internal points in the facility in an attempt to isolate the source.

This may be a silly response to your inquiry, but something to think about.  Perhaps in the monitoring of temperature of chemical tanks are thermometers used?  I know that as a course of business when I worked in a facility and the production crew had to obtain temperature of chemicals in production tanks and raw product rail cars they carried long thermometers to dip in the vessel and get readings.  To facilitate moving on to the next task they would slip the thermometers in the back pockets of their pants.  Sometimes they would forget about them and sit down, breaking the thermometers and releasing the mercury contained within them. At the time, I wasn't thinking of all the places that mercury could end up.  Perhaps the company could seek the answers in the daily routines of the production and lab crews?  

Wendy, Check the alkaline cleaners.  Some caustic soda used in cleaners is made with the old mercury cell technology.  Mercury from the caustic in these cleaners tends to cycle up in cleaning baths.  As the cleaner system is used, alkalinity drops and more cleaner is added.  Some cleaner ingredients - and impurities-   tend to built up over time.  Trace amounts of mercury then become detectable in the cleaning solutions.  These solutions are  eventually dumped to waste treatment.  The stamping compounds may have trace amounts also.  Sodium salts of fatty acids are sometimes used in metal forming compounds.  Caustic soda ( sodium hydroxide)  is used to make these sodium salts.  The alkaline cleaners are used to clean off the metal forming compounds that  end up in the alkaline cleaner solutions.

Are any caustic or acid solutions used for meatal cleaning?  They could easily contribute that much.  Or even dirt or dust deposited from air could cause that high of a level.