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Catastrophic release of heavy metals from the King River mine in Colorado and the Minas Gerais dam in Brazil have brought to the forefront the importance of contaminant stabilization and remediation in surface waters. Permeable reactive materials are currently utilized for the remediation of heavy metals and other pollutants by employing reactive media to remove contaminants. This research investigated the use of fly ashes with loss on ignition or sulfur trioxide exceeding ASTM C618 limits to enhance pollutant removal in pervious concrete. The high carbon and sulfur contents of the noncompliant fly ashes provide additional capacity to remove lead, cadmium, and zinc. High-sulfur and high-carbon fly ashes were less effective in metal removal at higher metal concentrations but improved removal at lower concentrations. These results suggest pervious concrete can be designed as an effective remedial technique for use in many infrastructure applications, including beneath permeable pavement, permeable asphalt, revetment, permeable shoulders, gabions for slope stability, mine tailing dams, and emergency surface water cleanup. 

Permeable reactive barriers (PRBs) are a well-known technique for groundwater remediation using industrialized reactive media such as zero-valent iron and activated carbon. Permeable reactive concrete (PRC) is an alternative reactive medium composed of relatively inexpensive materials such as cement and aggregate. A variety of multimodal, simultaneous processes drive remediation of metals from contaminated groundwater within PRC systems due to the complex heterogeneous matrix formed during cement hydration. This research investigated the influence coarse aggregate, portland cement, fly ash, and various combinations had on the removal of lead, cadmium, and zinc in solution. Absorption, adsorption, precipitation, co-precipitation, and internal diffusion of the metals are common mechanisms of removal in the hydrated cement matrix and independent of the aggregate. Local aggregates can be used as the permeable structure also possessing high metal removal capabilities, however calcareous sources of aggregate are preferred due to improved removal with low leachability. Individual adsorption isotherms were linear or curvilinear up, indicating a preferred removal process. For PRC samples, metal saturation was not reached over the range of concentrations tested. Results were then used to compare removal against activated carbon and aggregate-based PRBs by estimating material costs for the remediation of an example heavy metal contaminated Superfund site located in the Midwestern United States, Joplin, Missouri.