Mitigating the Risks of Styrene Emissions to the Environment from the Curedin-Place Pipe (CIPP) Process By NASSCO Technical Advisory Council Member Kaleel Rahaim, CIPP Consulting Styrene emissions from the CIPP process are a concern when they exceed regulatory levels. NASSCO contracted with the Trenchless Technology Center at Louisiana Tech University (TTC) to delineate styrene levels at various parts of the CIPP process. That study, which should be completed by the end of August 2022, focuses on two areas of study: Styrene accumulation in the back of a refrigerated truck used to store and transport wet-out bags containing a styrenated resin; and emissions from a hot air (steam) cured liner (see Figure 1). Water-cured CIPP liners would have the same emissions in the refrigerated truck but would also have concerns with styrene migrating into the process water, and water running through the cured liner for a period after reinstatement and being emitted into the environment. There are several techniques for minimizing emissions. Two established processes that may be used to minimize styrene emissions into the environment are the use of Granular Activated Carbon (GAC) towers, and wet scrubbing. Each of these methods has pluses and minuses. While the GAC process may be used in both water and air cures, the wet scrubbing process may only be used in the hot air cured process. The GAC method involves a canister of a designed size dependent on the flow and concentration of styrene in the flow. The flow may either be liquid or air. This process can handle effluent from processing the CIPP liner or may also treat the air inside of the refrigerated transport truck prior to opening the truck door at the job site. Once the calculated amount of effluent at the measured styrene concentration has been processed through the GAC cannister, the activated carbon must either be regenerated or replaced. Figure 1. Emissions from an air cure CIPP Project