Protection of groundwater from oil pollution in the vicinity of airports

Abstract

Airports are potential, and quite frequently also actual, sources of serious groundwater pollution. This is due to the large amounts of liquid fuel being handled all the time, to the physicochemical properties of oil hydrocarbons, and often to technical errors in the transport and storage of fuels. The environment is further affected by liquid and gaseous emissions escaping during the take-off and landing of aircraft

Snow in the vicinity of runways has been found to contain oil hydrocarbons in concentrations of tenths to units of milligrams per liter Moreover, soil tends to accumulate carcinogenous benzopyrenes.

In rock formations, oil hydrocarbons spread as a separate layer as well as in solution in porous permeable formations, pollution by a free product affects areas on the order of tens of meters, while hydrocarbons in solution penetrate to distances of hundreds of meters or even kilometers. More complex conditions for the spreading of oil-based substances arise in fissured rocks. Aviation kerosene as a separate phase was found to migrate over 700 meters within 5 months through fissure systems in sandstones

Prevention is the most efficient way of protecting groundwater from oil pollution. Preventive surveys are based on the drilling of observation wells at suitable points of the potentially endangered areas. Monitoring of these wells provides timely detection of possible leaks of oil products into the aquifer

In the case of an emergency, it is necessary to remove, as soon as possible, the oil substances from the surface or to remove the contaminated soil. When the contaminant has penetrated into the aquifer, the reparatory measures are usually based on hydraulic protection which consists of a system of boreholes. The respective hydrocarbon product is removed from the formation by pumping, the process being speeded up by the change in groundwater flow caused by the creation of depression cones

The example of Prague Airport is suitable for describing a successful, although complex and expensive, purification of a Chalk aquiter polluted among other things by a leak amounting to 300 m³ of aviation kerosene. Vapex filters have proven very satisfactory for purifying the contaminated water

Preventive protection of groundwater and mineral waters using monitoring devices is being carried out at Karlovy Vary Airport No groundwater pollution has so far been observed in this instance. However, a seasonal variation in the content of hydrocarbons dissolved in groundwater has been established. The highest content occurs in the spring months. Observation wells situated in the tectonic zone can also be utilized for reparative pumping