Towards an Improved Understanding of Plastic Pollutant Generation and Minimization Processes for Cured-in-Place-Pipe Manufacture

Water infrastructure is critical to the safety and economic health of communities. The restoration and maintenance of water supply and wastewater infrastructure are ongoing challenges for the Nation. Cured-in-place pipe (CIPP) technology is a popular method for repairing buried sewer pipes.

This is due in large part to economic considerations, as it can be 60-80% less costly than other repair alternatives. Unfortunately, the process of emplacement and curing of new plastic inside the damaged pipe can release hazardous materials into the air. These releases have resulted in exposures, illnesses, and at least one fatality of a worker where chemical exposure was a significant contributing factor.

The overall goal of this research is to reduce chemical volatilization from CIPP by understanding mechanisms of chemical volatilization. This goal will be achieved through specific research objectives designed to: i) determine the factors that control chemical emission under various curing techniques, ii) examine how injecting steam to create the CIPP impacts the distribution of emitted chemicals, and iii) estimate the toxicity reductions that could result from alterations in the process.

Successful completion of this research will clarify how manufacturing processes influence the emission of chemicals from CIPP. This information can be used by regulators, public health professionals, and other stakeholders to develop policies and guidelines to minimize pollutant release and protect public health. This will be facilitated through direct engagement of stakeholders to disseminate the project findings and accelerate industry adoption.

Further benefits to society result from a training module to assist user groups in making decisions regarding the use of CIPP for wastewater pipe upgrades.

Sewer pipes are being repaired using CIPP technology to create a new plastic liner inside existing damaged pipes in situ. Dozens of chemical exposure incidents have been documented from CIPP utilization. Gaseous releases from CIPP are a complex mixture of volatile and semi-volatile organic compounds that are known to pose significant risks to human and ecological health.

However, the underlying mechanisms and ways to reduce such emissions has been relatively understudied. The overall aim of this research is to elucidate mechanisms of CIPP emissions towards the goal of reducing pollution and protecting health. Specific objectives designed to achieve this goal are to: i) identify factors that control chemical emission distribution and magnitude for various CIPP formulations using various curing techniques, ii) explore how injected steam impacts the magnitude and distribution of emitted chemicals, and iii) study air exposure and associated toxicity reductions resulting from emission reduction control measures.

Successful completion of this research will produce urgently needed data to prevent emissions and protect human health. Results have potential to transform the CIPP industry and broader plastic composites sector by providing fundamental knowledge on the roles resin, initiators, and steam curing have on pollutant emissions. This research directly addresses multiple National Academy of Science, Engineering, and Medicine grand challenges focused on restoring infrastructure, sustainably supplying water, building healthy cities, and reducing pollution.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.