A new model for coupled multicomponent NAPL dissolution and aqueous-phase transport, with application to creosote dissolution in discrete fractures

This paper concerns a new modeling approach to multicomponent NAPL dissolution and transport, based on analytic solutions and Laguerre series. This approach allows virtually any of the numerous existing 1-D analytic transport solutions in the literature to be coupled with arbitrary boundary conditions stemming from nonlinear NAPL dissolution, as dictated by Raoult's Law. A computer implementation of this approach to coupled dissolution and transport in parallel fractures - which no other screening tool known to the authors covers - is presented. This is verified against an existing analytic transport solution that assumes a constant boundary condition. Subsequently, the model is demonstrated via a study of separation of PAH and phenolic plumes generated by dissolution of creosote, using the new computer implementation. The PAH and phenolic constituents of creosote strongly differ in both their dissolution and their transport behavior, and this is shown to necessitate the use of a tool that can account for both processes, such as the one developed here. We also find the possibility of PAH and phenolic plumes becoming entirely disjoint. Key Points New model presented for dissolution of NAPL and transport of its constituents Model can employ almost any existing 1-D analytic transport solution Weathering of creosote may lead to entirely disjoint PAH and phenolic plumes