The Effect of Contaminated Soil and Groundwater on Subsurface Utilities, Surface Water and Drainage Payam Hosseini Sultan Alhomair Zahra Faeli Mohammed Gabr Detlef Knappe Mohammad Pour-Ghaz Department of Civil, Construction, and Environmental Engineering North Carolina State University DRAFT NCDOT Project #2017-08 Dec 2019 The Effect of Contaminated Soil and Groundwater on Subsurface Utilities, Surface Water and Drainage FINAL REPORT - DRAFT Prepared by: Payam Hosseini Sultan Alhomair Zahra Faeli Mohammed Gabr Detlef Knappe Mohammad Pour-Ghaz A report on research sponsored by: THE NORTH CAROLINA DEPARTMENT OF TRANSPORTATION Dec 2019 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. …leave blank… …leave blank… 4. Title and Subtitle 5. Report Date The Effect of Contaminated Soil and Groundwater on Subsurface Utilities, July 31st 2019 Surface Water and Drainage 6. Performing Organization Code …leave blank… 7. Author(s) 8. Performing Organization Report No. Payam Hosseini; Sultan Alhomair; Zahra Faeli; Mohammed Gabr; Detlef …leave blank… Knappe; Mohammad Pour-Ghaz 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) NORTH CAROLINA STATE UNIVERSITY …leave blank… Department of Civil, Construction, and Environmental Engineering 11. Contract or Grant No. Campus Box 7908, Raleigh, NC 27695-7908 …leave blank… 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered North Carolina Department of Transportation Final Report Research and Development Unit 104 Fayetteville Street August 1st 2016 - July 31st 2019 Raleigh, North Carolina 27601 14. Sponsoring Agency Code NCDOT Project #2017-08 Supplementary Notes: …leave blank… 16. Abstract Information in this report documents the results from experimental and modeling studies to quantify the effect of subsurface contaminants on installed subsurface utilities (pipelines) commonly employed by the North Carolina Departments of Transportation. The focus of the study was on quantifying and modeling the effect of benzene and tetrachloroethylene (PCE) on the durability of PVC and concrete pipes as well as neoprene (polychloroprene), nitrile (acrylonitrile butadiene rubber or Buna-N), and Grade A Viton® (fluoroelastomer rubber or FKM) gaskets. In addition, migration of contaminates through utility installation areas was investigated using several saturated and unsaturated flow scenarios to provide a better understanding of the alternation of the contaminant transport regime with the installation of pipes in contaminated subsurface media. Modeling also included the effect of several mitigation measures on the migration of contaminants into concrete pipes with an assumed level of damage, and therefore quality, of concrete and gaskets. Benzene and PCE are selected as contaminants in the study because of their prevalence within the Right of Way in North Carolina and also represent petroleum-based and dry-cleaning solvent contaminant categories. The experimental results were used to develop a degradation model for the tested materials with proposed approach to account for the effect of contaminant concentration on the degradation rate. The experimental results also included data on the effect of benzene and PCE on the compressive strength of concrete material. Experimental measurements of the rate of absorption and vapor diffusion of benzene and PCE through concrete used for pipe manufacturing are reported. The effect Xypex® as a waterproofing agent on the rate of absorption and vapor diffusion is measured and reported. The results from computational simulations were used to evaluate the transport of benzene in saturated and unsaturated subsurface media within the pipeline trench over an extended period of time (10-20 years.) The computational simulations included contaminant transport from a continuous source and transient sources; the efficiency of mitigation strategies and plumb migration prevention on contaminant transport were also evaluated. Modeling results provided the breakthrough of benzene concentration and mass as a function of time for the various analyses scenarios considered herein. 17. Key Words 18. Distribution Statement Degradation modeling; PVC, Neoprene, Nitrile, …leave blank… Viton®, gasket, benzene, PCE, concrete pipe, mass transport, diffusion, saturated flow, unsaturated flow, contamination 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 154 …leave blank… Form DOT F 1700.7 (8-72) Reproduction of completed page authorized DISCLAIMER The contents of this report reflect the views of the author(s) and not necessarily the views of the University. The author(s) are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of either the North Carolina Department of Transportation or the Federal Highway Administration at the time of publication. This report does not constitute a standard, specification, or regulation. 4 ACKNOWLEDGMENTS The authors would like to acknowledge the support of the North Carolina Department of Transportation Office of Research and Development. The authors thank the project’s steering committee members for their valuable technical input, including providing site data and facilitating site visit, throughout the project period, especially those of Mr. Cyrus Parker. The technical support provided by NC State Constructed Facilities Laboratory (CFL) staff, Mr. Jerry Atkinson and Mr. Johnathan McEntire, is greatly acknowledged. 5 EXECUTIVE SUMMARY This report documents the results from the experimental and computational studies that were performed to quantify the effect of subsurface contaminants on installed subsurface utilities (pipelines) commonly employed by the North Carolina Departments of Transportation. The focus of the study was on quantifying and modeling the effect of benzene and tetrachloroethylene (PCE) on the durability of PVC and concrete pipes as well as neoprene (polychloroprene - CR), nitrile (acrylonitrile butadiene rubber or Buna-N), and Grade A Viton® (fluoroelastomer rubber or FKM) gaskets. In addition, migration of contaminates through subsurface utility installation areas, using several saturated and unsaturated flow scenarios, are performed to provide a better understanding of the alternation of the contaminant transport regime with the installation of pipes in contaminated subsurface media. Modeling included the effect of installed mitigation measures on the migration of contaminants into concrete pipes with different quality of concrete and gaskets. Benzene and PCE are selected as contaminants in the study because of their prevalence adjacent to transportation corridors; they also represent petroleum-based and dry-cleaning solvent categories. The experimental results of degradation of mechanical properties of gaskets have been used to develop a degradation model for the tested materials. Modifications to the model are proposed to account for the effect of concentration on the durability of the material. Also reported herein, are the experimental results showing the effect of benzene and PCE on the compressive strength of concrete material. Experimental measurements of the rate of absorption and vapor diffusion of benzene and PCE through concrete, used for pipe manufacturing, are also reported. The effect of Xypex® as a waterproofing agent on the rate of absorption and vapor diffusion is measured and reported. Modeling effort included computational simulations to evaluate the transport of benzene in saturated and unsaturated subsurface pipeline trench corridors over an extended period of time (10-20 years). The computational simulations included contaminant transport from continuous sources and transient sources; the efficiency of three different mitigation strategies in reducing the rate of contaminant transport was also evaluated. Modeling results provided the breakthrough of benzene concentrations as a function of time for the various analyses scenarios considered herein. Experimental results indicate that benzene is more detrimental than PCE in terms of degradation of the tensile strength of PVC and rubber gasket materials. Among rubber gaskets, Viton® performed the best, followed by nitrile and then neoprene when exposed to benzene and PCE aqueous solutions at their solubility limits (i.e. 1790 mg/L and 206 mg/L, respectively). Severe swelling was observed for neoprene and nitrile samples when exposed to benzene solution at an elevated temperature of 140 oF (accelerated condition). The experimental results of degradation of tensile strength is used to develop a degradation model for these materials. Modifications to the model are proposed to account for the effect of concentrations below saturation levels on the degradation rate. 6 Also reported herein are the experimental results showing the effect of benzene and PCE on the compressive strength of concrete materials. Results indicated that benzene and/or PCE did not affect the compressive strength of concrete in statistically significant manner. Experimental measurements of the rate of absorption and vapor diffusion of benzene and PCE through concrete used for pipe manufacturing were performed. The effectiveness of Xypex® as a waterproofing agent on the rate of absorption and vapor diffusion is measured and reported. The presence of PCE did not affect the rate of water absorption in concrete. In addition, the application of Xypex® did not reduce the sorption rate