(Problem 7.6) Soil venting, coupled with granular activated carbon (GAC) for off-gas treatment, is being considered for a site impacted by PCE (C2Cl4). The PCE removal efficiency by GAC is 95% and the discharge limit to atmosphere is 0.05 kg PCE/day. There are two GAC units (2,500 kg GAC in each unit) operated in series and the actual adsorption capacity is 0.2 kg PCE/kg GAC. (a) Determine the maximum allowable PCE loading rate to the GAC system (in kg/day) (b) Estimate the breakthrough time if the system is running continuously (in days)