INTEGRATING MULTIPLE SITE INVESTIGATION METHODS TO CHARACTERIZE GROUNDWATER/SURFACE WATER IMPACTS AND DEVELOP AN OPTIMIZED REMEDIATION STRATEGY

We present a case study from the northeast United States where multiple investigations were used to characterize a source of impacted groundwater located adjacent to a river. The Site is located in an area with a long history of industrialization. Groundwater and surface water impacts were originally identified without a clear release mechanism or source area. Through multiple phases of investigation, an area of impacted fill material was identified as the source of metals. The fill material contributes to a shallow groundwater plume that discharges locally to the river.

We performed multiple investigations to understand the degree and extent of impacted soil and groundwater and to characterize how those impacts are affecting surface water quality. The work included a high-resolution grid of soil and groundwater samples that were used to develop a detailed conceptual site model (CSM). Investigation data were combined with hydrogeological characterization and the results from a numerical groundwater flow model to further understand and characterize groundwater and surface water impacts.

The detailed CSM was used to develop and support site-specific cleanup goals based on groundwater discharge to surface water under low-flow conditions. Geotechnical testing and laboratory treatability testing evaluated several in-situ remedial technologies to stabilize metals in soil and to treat impacted groundwater. The detailed CSM and treatability testing allowed for development of an optimized remediation approach that relies on multiple technologies targeted to specific portions of the site resulting in reduced lifecycle remediation costs.