Recent research by Matthews et al. at the Louisiana Tech University Trenchless Technology Center (TTC) regarding styrene emissions produced during steam-cured, styrene-based cured-in-place pipe (CIPP) installation was compared to data from six relevant, independent studies. As part of this analysis, data in the reviewed studies were compared to exposure guidelines published by the Environmental Protection Agency (EPA), National Institute of Occupational Safety and Health (NIOSH), and Occupational Health and Safety Administration (OSHA). Measurement methodology and goals were considered and briefly described in the analysis. Finally, this paper highlights differences and similarities in the conclusions and measurements of the reviewed studies while searching for and identifying conclusions and trends that are common across the reviewed studies.

Cured-in-place pipe (CIPP) is one of the most popular in situ rehabilitation techniques to repair sewer and water pipes. While there are multiple approaches to curing CIPP, steam-curing of styrene-based resins has been found to be associated with air-borne chemical emissions. Health officials, utilities and industry representatives have recognized the need to know more about these emissions, especially styrene. Such concern has led to multiple studies investigating the concentrations of volatile organic compounds on CIPP installation sites. This study expands upon previous effort by modeling worst-case, steam-cured CIPP emissions over a 5-year weather record. The effort also includes calibration of the model to emissions averages over the work day rather than instantaneous field measurements. Dispersion modelling software, AERMOD, was utilized to model the styrene component of CIPP emissions on two CIPP installation sites in the US. Based on the analysis results, it was found that the styrene emitted from stacks dissipates rapidly with styrene concentrations only exceeding minimum health and safety threshold levels at distances close to the stack (2 m or less). The values predicted by the model analysis are comparable with the field measured styrene concentrations from other studies. Current safety guidelines in the US recommend a 4.6-m (15-ft) safety perimeter for stack emission points. The results of this study indicate that significant and lasting health impacts are unlikely outside recommended safety perimeter. The results also validate the importance of enforcing recommended safety guidance on steam-cured CIPP sites.