EPA (2008; 2010) explicitly defines a cost of 4.90 2008$ ft -1 in -1 to build-up wells to be suitable for CO 2 flow. This cost is converted to base-year dollars (i.e. 265 2002$ m -2 ) and directly used as the first cost term within the parenthesis in Equation S43. The second term in Equation S43 is a least squares fit to account for the remaining difference in cost between the genGEO 25 cm monitoring water well and the three Kemper CO₂ injection wells.