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4Disposal guidance: heavy metals

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  • Dave Waddell
    Feb 21, 2006
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      Hi Everyone:

      I'm writing from Seattle, Washington and am wondering if our guidance
      for disposal of chemical wastes from schools is similar to that given
      in Florida. Please note that this guidance is not for disposal of
      legacy chemical stockpiles but is for those wastes we see commonly
      generated as part of the process of teaching. I'll send out the info
      in two separate posts so it's not too long.

      Here's the guidance we give out regularly regarding heavy metal solutions:

      Most hazardous waste generated from high school demonstrations are
      metal-bearing aqueous solutions, such as Benedict's Solution. These
      liquids are typically collected in a large wide-mouthed container in a
      fume hood so most of the water can be evaporated. The settled solids
      must then be disposed as hazardous waste. This is an effective way to
      reduce your disposal costs by reducing the volume of waste needing

      Evaporation of hazardous waste is considered treatment by generator
      (TBG). One requirement under the state's TBG guidelines is that a log
      needs to be kept of all chemicals that are undergoing treatment. I've
      enclosed an evaporation treatment log sheet for you to photocopy and use.

      Entries need to be made every time a solution is added to the
      evaporation container. The goal is to have an accurate record of the
      resulting solid waste mixture in the evaporation container. This can
      then be evaluated to determine if the waste is hazardous so it can be
      properly disposed. Label this container as Hazardous Waste, Heavy
      Metal Solution (see enclosed labels). Many schools now collect their
      metal salt solutions in a sliding lock plastic bag. This allows the
      container to be closed once the liquids have evaporated and protects
      the beaker from being encrusted with the residual solids.
      Does this look like a best management practice to you? We find it
      cuts school's disposal costs for this waste stream by about 90%

      Dave Waddell
      Sr. Investigator, King County Hazardous Waste Management Program
      Principal, Waddell Environmental LLC
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