AbstractRoadway infrastructure is spatially extensive, linear, and by design restricts infiltration. Traffic impacts the coupled hydrology, chemistry, and loads transported by increased runoff and hydraulic stresses. Green infrastructure or low-impact development (LID) such as a partial exfiltration reactor (PER) can mitigate impacts by infiltrating and sequestering runoff and loads. This study modeled surface–subsurface hydrologic quantities for an infiltrating–exfiltrating linear PER as integrated infrastructure at a highway monitoring station with a database and calibrated modeling. The PER combined cementitious permeable pavement (CPP) as an infiltrating-filtration surface over an oxide-coated media (OCM) bed as a green infrastructure retrofit to conventional roadway underdrainage. Calibrated surface [Storm Water Management Model (SWMM)] and subsurface [Variably Saturated 2D Transport Interface (VS2DTI)] model components for the catchment and PER were implemented based on published studies. In contrast to previous design and historical storms, 1 year of hydrologic and dissolved Zn loads was simulated. The PER infiltrated 95% of catchment runoff, exfiltrated 27.1% to clayey glacial till soil, evaporated (potential) 3.9%, and discharged 63.9% to the underdrain. The CPP separated 80% of particulate matter (PM). With a simulated macropore in the oxide-coated sand media (OCS) bed, Zn was reduced by 99%, compared with 98% from event-based published data. Traffic turbulence increased evaporation from the catchment by 28.9%. A calibrated continuous simulation model is a viable tool to examine longer-term behavior of green infrastructure and LID systems for implementation, functionality, and sustainability in roadway and paved urban land uses.

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