Transportation line facilities such as highways, runways, and railways typically traverse wide swaths of land over which many different surface water and groundwater conditions are encountered.
Therefore, the appropriate mitigation measures will depend on the particular location as well as the project type and scope.
For each type of condition encountered, mitigation measures may be recommended at the location planning stage or carried out at the phase of facility construction operations or maintenance.
These generally involve preemptive measures that decrease the magnitude of the impacts or palliative measures that strive to reduce the severity of impacts that have already occurred.
(a) Groundwater Impacts At the operations phase that involves disposal of used transportation vehicles and parts, careful selection of disposal sites can help minimize the effect of leaching and consequent groundwater pollution. At the maintenance phase, leachate generation from petrochemical and herbicide storage facilities could be checked using liners and leachate collection systems. For right-of-way (ROW) and median maintenance activities that involve the use of herbicides, the timing, rate, and extent of applications can be planned such that the risk and exposure of water resources to adverse impacts will be minimal. To compensate for possible groundwater deprivation due to a transportation project, construction of a wetland could be made a part of the project