Unleaded gasoline has at least 15 hazardous substances including toluene (35%) and is classified as highly volatile and will result in vapour lock where combustion does not take place1.
When mixed in water, most of the gasoline could evaporate if the water is open, but much of it cannot evaporate in underground water making a big proportion to dissolve and this will be absorbed by sediments. For aquatic organisms, this product will be quite toxic, depending on their size and resistance capability.
Corrective action is necessary starting with site investigation. Hydrocarbon contamination with the groundwater should be stopped immediately. Its discharging point should be plugged and the nearest drains, water bodies should be sealed off, so that further contamination to distant water bodies does not happen. Residents could be evacuated if gasoline has already spread into drinking, using and sewage water or if that is not the case, water supply should be disconnected immediately and alternative water source should be provided. Complete groundwater monitoring should start immediately. Instead of one single action, it is better to perform by-monthly actions to remove all traces of gasoline from ground water, to ensure that dissolved contaminants are effectively vanishing. And groundwater sampling should be done on a regular basis through tracer testing.
If widespread presence is detected, human exposure to it should be suspended immediately. Dissolved contamination level should be identified and ecological profile should be drawn, followed by remedial programme identified with the Corrective Action Plan. Public participation may be necessary in the entire operation to some extent.
This method is called Dynamic Underwater Stripping, in which steam drives contaminated water towards extraction wells. Where steam cannot penetrate, electrical heating dries and distils the clays, volcanic rocks and limestone. Heating of the soil also could do the same. It is very difficult to clean the underground contamination and this process is accepted as cost worthy, less cumbersome and minimum time consuming. Cleaning has to be done both above and below the water table. Clay has very low permeability, and the usual pump-and-treat method would be time consuming and more expensive and might not work below water level.
Dynamic stripping could work even below water table, and by vacuum extraction, it could remove the gasoline and contaminated water2. This method relies on Steam Injection, Electrical heating, and underground imaging and all have proved very effective and reasonably cheaper. It has many additional advantages like being effective in low permeable soils, being capable of removing contaminant below and above water table. It is not risky to population, because the action is quick and decisive.
Gasoline (one of the Volatile Organic Compounds) contamination in ground water can cause major health hazards to people and ruin the river and water bodies' ecosystems completely. It can contaminate soil with hazardous results. MTBE in it creates alarming tension whenever leaks happen. Health of all 5,000 populations could be at risk by this environmental hazard, while the