Wastewater Mercury Investigation – Ohio

STONE collected semi-annual industrial wastewater samples at the facility, and one sample detected a mercury concentration of 0.8 µg/L, which exceeded the 0.5 µg/L one-day maximum limit specified in the client’s wastewater permit. This, along with a sample collected by the City of Wilmington seven weeks prior, constituted a violation of the client’s permit. Samples collected by STONE prior to this exceedance, at various locations within the facility for a separate project, detected mercury in discharge from the extrusion line vacuum pumps. The client had a similar issue 8 years prior, and determined that the source of the mercury contamination was a failing pump with a liquid-ring, mercury seal. The client requested STONE to investigate the source of the mercury to prevent future exceedances. STONE conducted a site visit and performed visual observations of the facility and equipment, collected grab samples throughout the facility, reviewed available safety data sheets for raw materials and additives. Analytical results of samples collected within the facility indicated that mercury was only present in discharge from the lines. STONE collected an inventory of pumps on these lines and researched which pumps were and were not likely to contain mercury. STONE prepared a letter report summarizing the investigation with the recommendation to replace pumps. STONE also prepared a compliance plan for the client to submit to the City, as required by their permit due to the violation.