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South Hill TCE Report - Executive Summary

Trichloroethylene, or TCE, was used by the Borg-Warner Corporation in their Morse Chain facilities on Ithaca’s South Hill in the 1960’s and 70’s.  In 1987, four years after the site had been acquired by Emerson, Emerson found TCE in oil that had been taken from the surface of the large fire reservoir on the plant site.  Further tests disclosed that TCE had entered the subsurface environment near the fire reservoir.  Other TCE spills of unknown amounts and locations may have also occurred.
Both the health effects and economic fallout due to TCE contamination and transport are of major concern to the current residents of South Hill.  Assemblywoman Barbara Lifton asked Cornell University to provide “another set of eyes” to examine data related to the spill on behalf of the community members.  The purpose of this document is to provide the community members of South Hill with a report that addresses the scientific basis of these concerns as well as the limitations of our current understanding.

Toxicological effects of TCE have been shown, at least at the occupational level, to increase the risk of some cancers, liver and kidney damage, and headache/drowsiness.  At lower concentrations, effects on the immune system, respiratory system and neurological system have been reported.  However, low-level long-term toxic effects of TCE are not as well studied.  Economic impacts of concern include house devaluation and the operating costs associated with TCE mitigation systems.  One of the main concerns of the community members is the process by which the determination of who will receive a mitigation system is made.  Based on the rough calculations of total expenses to Emerson and the intrinsic benefit of having a supportive group of community members, it may be beneficial to examine alternative testing and mitigation strategies.

Testing and mitigation alone will not solve this contamination problem.  It is necessary to know how TCE behaves in the subsurface to understand the persistence of TCE and identify possible pathways through which TCE enters homes on the South Hill.  Information on site characteristics of the South Hill, including geology and hydrology, aided in attempting to understand TCE behavior in this report.  For example, some site-specific properties that influence TCE behavior are the fractured shale and climate.  TCE inhabits the fractured shale and forms pools and residuals that are extremely difficult to locate and are likely impossible to entirely remediate.  The transport of TCE from the subsurface pools to the ground surface is not entirely understood.  Mechanisms described in this report include: diffusion, vapor intrusion, and arrival of contaminated water to the surface.  However, it is very difficult to deduce the relative importance of the different pathways without additional monitoring.  Understanding the pathways is crucial to developing effective remediation strategies, as it is the limitations on this understanding which shape the decision fabric.

The unpredictable variability of measured TCE concentrations indicates the need for more extensive sampling to understand how patterns in seasonal fluctuations, spatial variations and ground water trends influence the behavior of TCE.  Because current sampling methods available to residents are expensive, a review of simple and inexpensive sampling and analytical strategies that could be pursued by Cornell students has been provided herein.  Successful collection of data with the proposed plan for spring water and basement air sampling may aid in determining optimum conditions for indoor air sampling, as well as confirm that current sampling strategies provide justifiable long-term averages of indoor contaminant concentrations.

Finally, TCE degrades more readily in an oxygen-free environment than in areas where oxygen is present.  TCE has a low solubility in water, which limits mobility and biological degradation.  Additionally, TCE degradation at the South Hill is retarded by the cold subsurface temperatures.  As a result, TCE can stay in the subsurface for decades.  Further research on the microbiological flora, groundwater, pollution source(s), and sampling strategies is necessary in order to better understand what is happening to TCE in the subsurface.  However, this report concludes that TCE could be present in small pockets within the subsurface, several mechanisms are likely transporting TCE to the surface (although molecular diffusion likely dominates), and that remediation measures that focus on reducing TCE entering homes, rather than the subsurface sources, will be more effective in protecting the health and welfare of residents.

The overall objectives of this report are to address the following questions:   How is TCE, a chemical last used more than a quarter of a century ago, still of concern to the residents downhill of the source? How dangerous is it? How does it move? What is its future?

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