Trenchless cured-in-place pipe (CIPP) is a pipe renewal method involving a liquid thermoset resin-saturated material inserted into the existing pipeline by hydrostatic or air inversion or mechanically pulling in and inflating. The liner material is cured in place using hot water, steam, or ultraviolet (UV) light, resulting in the CIPP product. Despite CIPP advantages, the release of styrene—a volatile organic compound (VOC) frequently utilized in polyester resins—has become a subject of concern due to its potential adverse effects on human health and the environment. The purpose of this paper is to provide a comprehensive review of styrene emissions during the different CIPP installation processes using a polyester (styrene-based) resin by evaluating the contamination levels and defining an adequate safe distance for workers and the surrounding public outside of the operational zones. Styrene emissions are evaluated by the United States Environmental Protection Agency (USEPA), the Occupational Safety and Health Administration (OSHA), and the National Institute for Occupational Safety and Health (NIOSH). The research used a real-time monitoring method with a photoionization detector (PID) and collected time-weighted data over summa canisters, placed at the perimeters of the work zones before installation and during the lining and curing phases. Evaluation of PID data was conducted based on NIOSH-recommended exposure limits (REL), taking into consideration various operational parameters such as curing methods, curing temperature, curing duration, pipe diameter, pipe length, and environmental conditions to discover their relationship with styrene emissions. The results indicate that the peak concentrations of styrene were detected promptly upon the opening of the liner truck and directly above the termination maintenance hole during the curing process. A notable decrease in emissions was observed within a 5-ft radius downwind of the termination maintenance hole. This paper will demonstrate that time-weighted styrene concentrations were greater in hot water-cured projects than in steam-cured installations, contrary to previous findings that classify steam curing as the worst scenario.
Beigvand et al. (Thu,) studied this question.