Comparison of Environmental and Social Costs of Trenchless Cured-in-Place Pipe Renewal Method with Open-Cut Pipeline Replacement for Sanitary Sewers
[Thesis]
Kaushal, Vinayak
Najafi, Mohammad
The University of Texas at Arlington
2019
192
Ph.D. C.E.
The University of Texas at Arlington
2019
The development of underground infrastructure, environmental concerns, and economic trends is influencing society, resulting in the advancement of technology for more efficient, environment-friendly, and cost-effective pipeline installation and renewal. Comparison of environmental and social costs of a pipeline renewal and replacement is an essential element when considering sustainable development of underground infrastructure. Project owners, decision makers, design and consulting and contractors commonly take into consideration the construction costs only, and overlook the environmental and social cost aspects while making a choice between trenchless and open-cut pipeline installation. Trenchless Cured-in-Place Pipe (CIPP) involves a liquid thermoset resin saturated material that is inserted into the existing pipeline by hydrostatic or air inversion, or by mechanically pulling-in and inflating. The liner material is cured-in-place using hot water, steam or light cured using UV light resulting in the CIPP product. The primary objective of this dissertation is to compare environmental and social costs of trenchless CIPP renewal method with open-cut pipeline replacement for small diameter sanitary sewers and to identify influencing factors Impacting costs An actual case study based on the City of Pasadena, California, river basin was used for this research to evaluate the environmental and social costs implication of small diameter CIPP renewal and open-cut replacement. The results of this dissertation, for the case study used, show that the total environmental and social costs of trenchless CIPP method is 90% less as compared to open-cut pipeline replacement for small diameter sanitary sewers, such as 8 in. to 12 in. diameters. For this case study, it was determined that the environmental impacts of CIPP will be more than its social impacts. For open-cut, the social impacts are found to be more than environmental impacts. The methodology used in this dissertations can be applied for larger pipe diameters and other locations to develop a decision tool. CIPP renewal caused less ozone depletion, global warming, smog, acidification, eutrophication, non carcinogenics, respiratory effects, ecotoxicity effects, and fossil fuel depletion. The liner, felt, and resin influenced environmental cost the most for CIPP compared to open-cut where power consumption of construction equipment, and pipe material drove the environmental cost. Cost of fuel for detour roads, detour delay, and pavement restoration were negligible for CIPP renewal method as compared with open-cut replacement that contributed a major social cost factor (approximately 75%).