Trinity needed to find the source of the benzene that wasn’t accounted for in the TAB calculations—a process that required analysis and investigation, including challenging prior assumptions and estimates. Trinity reviewed existing waste stream characterization data, evaluated oil-water separator water and oil concentrations and flow rates, examined wastewater management equipment and procedures during field tours, and interviewed people working in operations, management, and maintenance roles—everyone from environmental experts to vacuum truck operators. Because the end-of-line sampling wasn’t consistent with prior TAB calculations, Trinity worked to identify potential waste streams that weren’t previously included.

Trinity created and implemented a sampling plan with strategic waste sampling locations—a process that went far beyond the requirements under BWON and allowed the team to isolate sources of benzene to a specific zone of the sewer system. This plan enabled the team to work more quickly and efficiently by zeroing in on areas of concern, disregarding the 90% of streams that were not a concern. In addition, because organic-phase liquids have the ability to impart benzene to low-benzene-containing waste streams, the team also tested mid-stream levels to uncover additional areas where benzene may have been underestimated.

During this process, the Trinity team was able to improve the characterization of specific waste streams and identify a previously unknown waste stream. In addition, the team was able to recommend process improvements that would reduce the amount of benzene being sent to the sewer system.