Air Quality Dispersion Modelling to Evaluate CIPP Installation Styrene Emissions

Abstract

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.

Diversity of organic components in airborne waste discharged from sewer pipe repairs

“…Polymerization reactions in the resin are initiated by using heat or by ultraviolet light. 2 The most popular and least expensive curing approach involves blowing steam through the uncured resin tube and out an exhaust pipe into the air. 3 Until 2017, emissions from this operation were reported to only contain a small amount of gas-phase volatile organic compound (VOC) styrene near 3 ppmv.…”

“…5,6 Additional work found styrene levels were diluted in the ambient air, as suggested by dispersion model analysis. 2,7 However, eld measurements showed that very complex and highly dynamic mixtures of multi-component chemical pollutants are in fact emitted into the atmospheric environment around the installation sites. 4,8,9 Although the chronic effects from occupational exposure require additional scrutiny, 10 acute environmental impacts of the chemicals and particulates in the emission plume have been associated with air pollution and human toxicity.…”