Graduation Semester and Year

Summer 2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Mohammad Najafi

Second Advisor

Vinayak Kaushal

Third Advisor

Kyeong Rok Ryu

Fourth Advisor

Edmund Prater

Abstract

The aging underground pipelines in the United States, which include sewer and water supply systems, have exceeded their design lifespan and will have to be renewed or replaced to continue providing these vital services to communities. Two methods can be used to replace the pipes: open-cut and trenchless technologies. Trenchless methods offer several advantages in urban areas: a small work area, lower operational and maintenance costs, and fewer negative impacts on the surrounding communities. Among the trenchless options, the CIPP method has been chosen for this research since it minimizes surface disruption, making it particularly well-suited for densely populated areas where maintaining normal activities during pipe rehabilitation is critical. Despite these advantages, however, there are environmental concerns about the chemical compounds used in this method. This dissertation focuses on evaluating volatile organic compounds (VOCs) that are emitted from CIPP liners during their installation and curing process and compares the emission concentrations with regulatory standards established by the Occupational Safety and Health Administration, (OSHA), National Institute for Occupational Safety and Health (NIOSH), and vi American Conference of Governmental Industrial Hygienists (ACGIH) to evaluate the potential risk to workers and nearby residential buildings. Rehabilitation projects of sewer pipelines in Soapstone Valley Park, Washington D.C., as well as Forney, TX, and Garland, TX, were selected as case studies for this research. Six CIPP installations were carried out, employing a range of resins, insertion techniques, inflation, and curing methods, and various sizes of host pipes. These installations utilized both styrene-based and non-styrene resins, air pressure, and winched pull inversion methods, as well as UV light, hot water, and steam curing processes. Air monitoring was conducted at all six locations before and during the CIPP installation process, including the curing period. The equipment used to capture the emissions included three PIDs, summa canisters, worker samples, and EPA TO-18 that were placed in different locations such as upwind and downwind of the insertion manhole. As expected, the chemical emissions varied with the type of resin, curing method, inversion method, installation technique, size, and geometry of the pipes. The UV light curing method used with a non-styrene-based resin liner proved to be the most environmentally friendly, as most of the emissions were lower than the threshold established by OSHA, NIOSH, and ACGIH. It should be noted, however, that using non-styrene-based resin with the hot water curing method may have a greater impact on the ecosystem. The styrene-based resin combined with the steam curing method produced the most emissions during the curing phase.

Keywords

Trenchless Technology, CIPP, Underground Infrastructure, Pipeline, CIPP Emission, Urban Infrastructure

Disciplines

Civil Engineering | Construction Engineering and Management | Environmental Engineering

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