Determining the Unlikely Source of Acetone Exceedances at a Plastic Manufacturing Facility

Our client is a manufacturer of plastic products in Pennsylvania, and conducts quarterly wastewater effluent monitoring in accordance with the facility's wastewater discharge permit. During a 1999 quarterly sampling event, the facility exceeded the discharge limit for acetone. Subsequent analysis confirmed that the exceedance was not an anomaly, indicating that a source of acetone discharge was present at the facility. Acetone is used at the facility in two locations — the “Dip Room” as a fine-polishing step for the product, and the “Paint Room” as a cleaning and thinning agent. All acetone usage in these locations, however, is confined to negatively pressured rooms that have no hydraulic connection to the sanitary sewer.A variety of on-site activities were initiated to isolate the source of acetone. Liquid grab samples were obtained from a variety of locations within the facility; almost all samples taken from within the manufacturing area were found to contain acetone (including a city tap water sample). Additionally, an experiment was conducted to evaluate whether vapor-phase acetone could be absorbing into liquid. Deionized water was exposed to the facility's atmosphere for ten minutes. Vapor-phase acetone was found to quickly absorb into the deionized water at a concentration exceeding the permitted discharge limit.Concurrent to on-site investigation, a dialogue was initiated with the Regulating Authority, assuring them that the facility was actively pursuing the acetone source. The facility requested and the Authority approved a mass-based acetone discharge limit throughout the duration of the study. The Authority required that a concentration-based limit be reimposed once the source of the acetone was isolated and corrected.Ultimately, it was determined that vapor-phase acetone was escaping from the negatively pressured Dip Room and absorbing into water at the facility. The extent and relative concentration of vapor-phase acetone was evaluated with an organic vapor analyzer (OVA) to plot isocontours of volatile organics in the air. When negative pressure in the Dip Room was increased, vapor-phase organics were significantly reduced and the effluent acetone concentration returned to below the discharge limit. Since that time, the facility has been within all effluent discharge parameters.