Predicting the longevity of permeable reactive barriers installed in acid sulfate soils
Predicting the longevity of permeable reactive barriers installed in acid sulfate soils
Column experiments were conducted to evaluate the potential use of calcitic limestone as a reactive material in permeable reactive barriers (PRBs) and its clogging behaviour in the presence of continuous acidic flow containing Al, Fe, and acidophilic bacteria. The findings revealed that the biogeochemical clogging in the column was not consistent along the flow path, with the ability to neutralise the acid at the inlet zone losing effectiveness after 75 days, whereas the acid neutralisation at the outlet remained satisfactory throughout 245 days. Additionally, a numerical model was employed to estimate the longevity of the limestone assembly in regards to neutralising acid and removing excessive concentrations of metals. This model incorporates the governing equations for contaminant transport through porous media and the biogeochemical reactions between the acidic input and the alkaline PRB media using MODFLOW and RT3D software codes. The model predictions aligned with the laboratory findings and affirmed that the chosen calcitic limestone batch, which has a 97% CaCO3 composition, is appropriate to serve as a reactive material in a PRB installed in an acid sulfate soil site in NSW, Australia. The lifespan predicted by the numerical model for this PRB is approximately 16 years.
S. Medawela; B. Indraratna
9th International Congress on Environmental Geotechnics (ICEG2023)
Engineered Barriers
Geoenvironmental Engineering, Groundwater & Seepage, Biogeotechnical Engineering
https://doi.org/10.53243/ICEG2023-240
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