GEOCHEMISTRY PROVIDES DISCERNMENT OF LANDFILL AND NON-LANDFILL RELATED SOURCES AND AIDS IN PROPER PLACEMENT OF CONTAINMENT SYSTEMS

Monitoring requirements for licensed landfills in Maine routinely require collection of groundwater samples and analyses for a variety of cations and anions in order to facilitate identification of landfill impacts. At this active industrial waste landfill in western Maine, the extensive historical dataset has provided excellent opportunities to analyze time-series data sets to identify sources of impacted waters. The monitoring network includes extensive collection of water levels in addition to groundwater chemistry. Through detailed analysis of groundwater flow patterns and chemistry, the landfill owners have been able to implement targeted containment systems to mitigate migration of impacted waters from the landfill boundaries. The geochemical data has also been able to differentiate between landfill related impacts from various areas of the landfill based on knowledge of historic operations as well as differentiation of road-salt related impacts to groundwater. The historical operations have included closure of various landfill sites on the property, and the on-going operation of the related containment systems and monitoring networks. Phased closures of various cells within the active landfill footprint are reflected in the responses of indicator parameters as evidenced in the time-series data. The on-going sampling program also allows for the evaluation of the efficacy of applied containment alternatives. Data and interpretations will be presented that highlight the use of the extensive dataset, monitoring network, and groundwater containment systems in the successful mitigation of landfill related groundwater impacts.