EVALUATION OF SELECT TRADE-OFFS BETWEEN GROUNDWATER REMEDIATION AND WASTE MINIMIZATION FOR PETROLEUM REFINING INDUSTRY

An investigation comparing environmental remediation alternatives and attendant costs for a hypothetical refinery site located in the Arkans as River alluvium was completed. Transport from the land's surface to and through the ground water of three spill sizes was simulated, repre senting a base case and two possible levels of waste minimization. Rem ediation costs were calculated for five alternative remediation option s, for three possible regulatory levels and alternative site locations , for four levels of technology improvement, and for eight different y ears. The work focused on the refinery manager charged with complying with environmental regulations within an economically sound framework. These individuals are typically confronted with the mandate of meetin g environmental regulation without access to necessary information. It is appropriate from environmental and economic perspectives to initia te significant efforts and expenditures that are necessary to minimize the amount and type of waste produced and disposed during refinery op erations; or conversely, given expected improvements in technology, is it better to wait until remediation technologies improve, allowing gr eater environmental compliance at lower costs? These types of decision s are made more difficult given the uncertainties associated with futu re regulatory levels necessary to ensure compliance. The present work used deterministic models to track a light non-aqueous phase liquid (L NAPL) spill through the unsaturated zone to the top of the water table . Benzene leaching from LNAPL to the ground water was further routed t hrough the alluvial aquifer. Contaminant plumes were simulated over 50 yr of transport and remediation costs assigned for each of the five t reatment options for each of these years. The results of these efforts show that active remediation is most cost effective after a set point or geochemical quasiequilibrium is reached, where long-term improveme nts in technology greatly tilt the recommended option toward remediati on. Finally, the impacts associated with increasingly rigorous regulat ory levels present potentially significant penalties for the remediati on option, but their likelihood of occurrence is difficult to define.