GROUNDWATER ABATEMENT ALTERNATIVES FOR REMOVAL OF ORGANIC CONTAMINANTS

Abstract

ABSTRACT Losses and spills of refined petroleum products have in some cases become a groundwater problem of major significance. The effects of fugitive volatile organics in the subsurface are various. Common concerns are the contamination of potable water supplies, long-term health problems associated with inhalation of hydrocarbon vapors and odors, and flammable concentrations of vapors in homes, utility conduits, and buildings. The sources of petroleum losses are also quite varied, ranging from small losses at homeowners' fuel storage tanks to major leaks at commercial refining, storage, transfer, and retailing facilities. Although recent years have seen marked increases in the safe handling, control, and transfer of refined organic products, inadvertent, accidental, and certainly unintentional losses of organics still occur. When these problems occur, it is common for the smaller losses at retail outlets (service stations) to have the greater social and environmental impacts. This is true because the retail outlets are often located in close proximity, if not immediately adjacent, to commercial and residential establishments. Such facilities may rely on individual groundwater supplies that are subject to degradation by the lost hydrocarbon products, or they may be serviced by common utilities, whose backfilled pathways act as conduits for transmission of the fugitive product and associated vapors. These factors of physical proximity and reliance on groundwater, when coupled with the introduction of refined organic products to the subsurface, generate problems of local significance and sensitivity. Cleanup programs must entail mechanisms of thorough definition, symptoms treatment, and comprehensive removal or abatement of the organic product in the subsurface. These aproaches must be technically sound, acceptable to governing regulatory agencies, physically and economically possible to enact, and acceptable to affected parties. Groundwater Technology has carried out many such programs. This paper discusses two case histories. One case history describes the successful collection and removal of approximately 8,000 gallons of offending unleaded gasoline that had threatened closure of public buildings. This remedial action was accomplished by the application of a specially designed, sensor-controlled, two-pump recovery system that removed the product from an unconsolidated sand aquifer. The second case history shows the success of employing a program combining bioreclamation, air stripping, and granular activated carbon usage to abate contamination of a bedrock aquifer. The contamination problem involved soluble components of unleaded gasoline that affected more than 10 water supply wells.