2022 journal article
A new monitoring approach for sustainability assessment of subsurface utilities gasket materials against gasoline and chlorinated solvents: Field evaluation and model development
Journal of Environmental Management.
Once installed, underground concrete pipes with rubber gaskets might be exposed to contaminated soil and groundwater. A pipe material monitoring capsule (PMMC) has been developed to evaluate volatile organic compounds (VOCs) breaking through three types of pipe gaskets; Neoprene, Buna-N, and Viton. The PMMCs were deployed in three contaminated sites: two with gasoline and one with chlorinated solvent (CS). A 3-D field-domain numerical model has been developed for each site to calibrate equivalent hydraulic parameters of each gasket material (ke, D) against benzene and PCE diffusion. The calibrated parameters were then used to compute the concentrations as well as rate of breakthrough of the two study contaminants. A protocol was developed for installing/retrieval of PMMCs to monitor PCE and benzene mass breaking through the gasket material with time. Employing PMMC, benzene concentrations breaking through the Neoprene and Buna-N after 4 months were approximately 70% and 60% respectively of the monitoring wells concentration. The corresponding value for PCE breakthrough after 4 months was 60% for both the Neoprene and Buna-N. Both gasket materials of Neoprene and Buna-N yielded similar performances, including higher rate of contaminant breakthrough compared to Viton. A nonlinear relationship of mass breaking through the gaskets of benzene and PCE with time was discerned from the modeling and field data.