Greene et al. (1998) conducted ex situ microcosm tests and estimated a postlag sulfolane biodegradation rate constant of 0.9-d in groundwater at 8 C, in a sand aquifer, under aerobic conditions, and given sufficient nitrogen and phosphorous macronutrients (Canadian Council of Ministers of the Environment, 2006). Given the rate constant, what order of rate equation applies to sulfolane degradation in this case? Assuming a permeable reactive barrier (PRB) can be constructed to achieve a rate constant that is half that determined from the ex situ microcosm test, calculate the minimum required PRB thickness, Xmin, to reduce sulfolane concentrations in groundwater to satisfy the Alberta Tier 1 Guideline (final concentration) of 0.09 mg/L (Alberta Environment and Parks, 2017, 2019). The following equation can be used: Xmin = Uxt =- Kxi In(Cr/C) -1.0m Use the following information in the calculations and state assumptions as required: the average (initial) sulfolane concentration in groundwater is 10 mg/L; the water table is at 3 metres below ground surface (mbgs); the aquifer has an average hydraulic conductivity of 510-5 m/s; the top of an aquitard underlying the aquifer is at 10 mbgs; assume the hydraulic gradient is 0.028 m/m (AEP, 2019); and the total porosity is 0.3 and the mobile porosity is 0.2. Comment on how this PRB should be installed and the preferred type of granular material. Provide rationale for your recommendations. (1)