1、Identifying and Delineating Hidden Sources Within a Larger Chlorinated Solvent PlumeKristin Robrock,Ph.D.,P.E.and Peter Mesard,P.E.,P.G.,C.Hg.ExponentOakland,CAOutline Commingled plume problem at site Methodology Results and suggestions for implementationCommingled Plume Problem TCE,PCE,and other ch
2、lorinated solvents are commonly commingled at contaminated sites and in groundwater at industrial urban areas How to distinguish and delineate where one plume ends and another begins?Particularly difficult when different sites have released the same chemicalIs all this ours?Site A being blamed for a
3、ll TCE in plume Objectives:Is all this TCE from Site A?If not,what are the other sources?Can we delineate the extent of Site A TCE?Complicated site with multiple on-site sources Site operated 1907 present Multiple vapor degreasers Degreasers moved locations over time Multiple different solvents over
4、 timeSite AGroundwater flow complicated by hydraulic divide Groundwater divide due to pumping Divide appeared 1970 On-site pumping wells impacted groundwater flow locallyTCE contours suggest other contributors to the plume TCE contours show hot spots and anomalies inconsistent with the direction of
5、groundwater flow TCE flowing onto Site from upgradient source(s)PCE plume looks very different from TCE PCE plume ends shortly downgradient of Site A Similar short plumes for other solvents,like 1,1,1-TCA Therefore,there must be other sources of TCEMany suspicious industrial sites in the area Site i
6、n an urban industrial area Many historical metal plating facilities,machine shops,dry cleaners,and other industrial sites with the potential to have used and released chlorinated solventsPotential chlorinated solvent users may explain TCE anomalies TCE hotspots located adjacent to documented chlorin