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A Historical and Technical Review and Analysis of TCE Contamination in the
South Hill Area of Ithaca, New York
A report to the Citizens of South Hill
By
Students in BEE/EAS 471 with input from faculty and citizens of Ithaca
June15, 2006
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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.
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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
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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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About the Authors
After getting a BS degree in Environmental Engineering from Mersin University (Turkey) in 2002, M. Ekrem Cakmak received a MS degree from the Department of Environmental Engineering at Cukurova University (Turkey) in 2004. From there Ekrem was admitted as a PhD student in Biological and Environmental Engineering at Cornell University in Jan 2005. At Cornell, Ekrem is studying in the Soil and Water Laboratory under Tammo Steenhuis. Previously he was employed as a research assistant beginning in Dec 2003 and has been supported since Jan 2005 by Cukurova University. After completing PhD program Ekrem will return to Cukurova University. Contact: [email protected] Web: www.geocities.com/mecakmak Larry Cathles joined the Cornell faculty as Professor in 1987, having worked at Kennecott’s Ledgemont Research Laboratory, Penn State University, and Chevron Oil Field Research. His main focus of research is the organic and inorganic chemical interactions associated with natural fluid. Recent topics considered include defining current natural hydrocarbon fluxes, capillary and dynamic controls on permeability, physical-chemical aspects of hydrate deposition and dissolution, and the rapid controlled venting of volatiles from intrusions. Cathles is a fellow of the American Association for the Advancement of Science and a member of several professional societies. He has served on committees of the National Research Council and is a past associate editor of Economic Geology. In 1985 he won the Extractive Metallurgy Science Award of the Metallurgical Society of the American Institute of Mining, Metallurgical, and Petroleum Engineers. He has taught Ground Water Hydrology with Steenhuis and others since 1987. Ken Deschere has been a resident of Ithaca since 1967, and has lived on South Hill Terrace since 1981. Ken received his BA in Applied Mathematics (Computer Science) from Cornell in 1971 and specializes in design and maintenance of database systems for international health insurance administration. He is Vice President of International Educational Exchange Services. He and Regina have two sons, Jonathan and Brian. Rachel Dunn got her master's degree in Chemical Engineering at King Mongkut's University of Technology Thonburi in Thailand and her bachelor's degree in Environmental Engineering at the University of Waterloo in Ontario. She recently joined Cornell's Biological and Environmental Engineering department to study watershed management both in Ithaca and in Thailand.
James W. Gillett (Ph.D. Biochemistry, UC-Berkeley; BS, Chemistry, Kansas) came to Cornell University in 1983 from the USEPA Corvallis Environmental Research Laboratory and the Environmental Health Sciences Center at Oregon State University to start an ecotoxicology program concentrating on exposure to pesticides, hazardous wastes, and toxic chemicals. He was the director of Cornell's Institute for Comparative
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& Environmental Toxicology (`86-`92) and headed the Cornell Superfund Basic Research Program (`93-`02) which emphasized work on volatile organics, PCBs, and lead. Recent efforts have expanded physical, mathematical and conceptual modeling of exposure assessment in ecosystems to risk analysis, management and communication more broadly. This has led to long-term efforts with the Mohawks at Akwesasne on the St. Lawrence and assisting citizens adjacent to superfund sites, such as the Elmira Southside High School and Seneca Army Depot.
Adrian Harpold is a Ph.D. student working for Dr. Tammo Steenhuis in the Biological and Environmental Engineering Department at Cornell University. Adrian's interests center around Land and Water Engineering related to nonpoint source pollution, physical hydrology, public policy, and soil and water conservation in developing countries. Adrian has a B.S. and M.S. from Virginia Tech in Biological Systems Engineering. His Ph.D. work will look at developing travel time estimations using chemical signatures in watersheds in the Catskills, NY. Adrian is from Seattle Washington, but has lived in Winston-Salem, NC, Blacksburg, VA, and Logan UT. Veronica Morales is a first year M.Sc./PhD student in the department of Biological and Environmental Engineering at Cornell University, working under the supervision of Dr. Tammo Steenhuis. She finished a B.S. degree from the University of California, Santa Barbara in 2004 in the field of Environmental Science, Hydrology. Her research interests include the transport and fate of pollutants in the subsurface. In the past, Veronica has worked on other TCE research projects through the University of California, Davis on the Evaluation of Field Methods for Measuring Contaminant Mass Discharge in Flowing Aquifers at Vandenberg Air Force Base in California. Rachel Shannon received her B.A. in geology from the University of Colorado at Boulder in May of 2002. During her undergraduate, she had the opportunity to work in a variety of geological applications. Most of her time was spent in a geophysics lab as part of a larger project to develop a new method to detect the movement of contaminant plumes (such as TCE) through the ground. She was also involved in some shorter-term projects she did mostly for fun: one summer she spent hiking and mapping the Blue Ridge Mountains in North Carolina, and during her senior year she worked in an isotope geochemistry lab age-dating rocks and archaeological artifacts. After graduation, she went to work as a geologist for a company that makes software used by oil companies to help locate and evaluate oil reserves. After two years there, she came to Cornell for her Master's degree. With Larry Cathles, her adviser, she is studying the source of a large copper deposit in Montana. Rachel will graduate in the summer of 2006. Brianne Smith is a junior in the School of Engineering at Cornell University. She is majoring in biological engineering as well as environmental engineering. Brianne is a co-op employee at Merck & Co. and plans to begin work on a Masters of Engineering degree in the spring of 2007. Jennifer Smith is a Master of Science student at Cornell University in the Department of Biological and Environmental Engineering. She is graduating from the Environmental
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Engineering program, with a minor in Risk Assessment, Communication and Policy. Her undergraduate degree was from the University of Idaho, in Biological Systems Engineering with an Environmental Engineering emphasis and a minor in Mathematics. She will be working at a consulting firm starting this summer in Seattle, WA. Ian Toevs is currently finishing his Master of Science degree at Cornell University in the Biological and Environmental Engineering department with an emphasis in Soil and Water Engineering and studying under Tammo Steenhuis. Ian received his BS degree in Agricultural Engineering from the University of Idaho in 2004 with a minor in Outdoor Recreation Leadership. Ian will start work in the summer of 2006 at Barton and Loguidice, P.C. in Syracuse as an environmental engineer and geohydrologist. Tammo Steenhuis is Professor of Water Management in the Department of Biological and Environmental Engineering. He runs a group of 20 graduate students, 3 research associates and one post doctoral assistant and is an expert in the transport of water and chemicals in the landscape. He is concerned with determining the best methods of managing soil and water resources and landscape processes in both the USA and developing countries by better understanding of the complex interrelations among morphology, water flow, plant growth, and fertility. His group’s findings are incorporated in models that require only easily available data. Research proceeds from basic processes to fundamental and universally applicable solutions to engineering design problems in water management and pollution control. Current projects concern the movement and fate of pathogens, metals, pesticides and phosphorus in the Catskills, Ethiopia, Mali and Ghana. For more information see: http://www.bee.cornell.edu/swlab/SoilWaterWeb/index.htm
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Table of Contents Executive Summary ............................................................................................................ ii Tammo Steenhuis.............................................................................................................. vii Introduction......................................................................................................................... 1 Section 1: Site History ....................................................................................................... 4
The early years................................................................................................................ 4 Growth through the 20th century.................................................................................. 12
Section 2: Toxicological Profile for Trichloroethylene (TCE)........................................ 20 Introduction................................................................................................................... 20 Environmental Fate ...................................................................................................... 21 Exposure ....................................................................................................................... 24 Toxicological Endpoints ............................................................................................... 25 TCE Metabolism ........................................................................................................... 27
Section 3: Economic Analysis .......................................................................................... 29 Real Estate Value .......................................................................................................... 29 Mitigation Operating Cost ............................................................................................ 30 Overall Economic Analysis........................................................................................... 31 Conclusions................................................................................................................... 34
Section 4: Geology............................................................................................................ 36 Section 5: Hydrology ....................................................................................................... 40
General information about water transport through the subsurface............................ 40 Physical controls on groundwater movement at South Hill ......................................... 42
Geologic and Soil Controls on Groundwater Movement ......................................... 43 Human Induced Transport Mechanisms ................................................................... 45
Conclusions................................................................................................................... 47 Section 6: Spring Water and Basement Air Sampling...................................................... 48
Spring Water Sampling ................................................................................................. 48 Basement Air Sampling................................................................................................. 51 Conclusions................................................................................................................... 60
Section 7: Subsurface Transport of TCE ......................................................................... 63 Section 8: Mechanisms of TCE Transport at South Hill .................................................. 66
Deep Percolation of TCE into the Bedrock .................................................................. 66 “Back Diffusion” of TCE in the Bedrock ..................................................................... 68 Contaminated Water Reaching the Surface .................................................................. 68 Degradation of TCE in Soil .......................................................................................... 70 Diffusion of TCE in Soil and Air................................................................................... 71 Vapor Intrusion of Contaminated Soil Air.................................................................... 72
Section 9. Operational Suggestions .................................................................................. 75 Appendix A. Glossary of Terms ...................................................................................... 78 Appendix B. GIS Maps.................................................................................................... 82 Appendix C: Relative Magnitudes of Diffusion and Vapor Intrusion…………………..86 Appendix D: References ................................................................................................... 88
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List of Figures
Site History: Figure 1-1: Lower South Hill 1905 Page 5 Figure 1-2: National Cash Register Ad – 1962 Page 7 Figure 1-3: Morse Ad- 1962 Page 9 Figure 1-4: Therm Ad 1990 Page 11 Figure 1-5: Sanborn" Map of Morse Chain Site, early 1960's Page 13 Figure 1-6: Outfall Discharge Map Page 15 Economics: Figure 3-1: Worst case scenario of contaminated area. Page 32 Geology: Figure 4-1: Diagram of a hypothetical slice through South Hill Page 37 Figure 4-2: Schematic Drawing of Rock Joints Page 38 Hydrology: Figure 5-1: Water Transport Mechanisms Page 40 Figure 5-2: Water Transport: Seeps and Springs Page 42 Figure 5-3: Water Table Heights for 5 Measuring Wells Located Near the Fire Reservoir Page 44 Figure 5-4: Electrical Resistivity Results for South Hill Moving in a Southwest Direction Page 45 Figure 5-5: Garage Where Water Can Be Transported Through a Wall Built in the Topsoil Page 46 Spring Water and Basement Air Sampling: Figure 6-1: Passive Diffusion Sampler for Organic Vapor Page 54 Figure 6-2: Active Sampling Set-up Page 56 Figure 6-3: Chromatogram (Carbon Disulfide and TCE Peaks) Page 58 Groundwater/Transport: Figure 7-1: Transport Processes in Subsurface Page 63
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Figure 7-2: Mean annual earth temperatures at individual stations, superimposed on well water temperature contours Page 64 Mechanisms of TCE Transport at South Hill Figure 8-1: One possible scenario for TCE transport in a fractured
bedrock scenario Page 67 Figure 8-2: Process of transport and back-diffusion in a simplified fracture channel Page 67 Figure 8-3: Graph of Concentration of TCE in water versus the volume necessary to achieve 5 ppb TCE in the air of a 40 X 40 X 10 ft basement Page 69 Figure 8-4: Schematic of a house where tile drains are used to drain a high water table Page 70 Figure 8-5: The rising water table can move TCE into the soil pores near the surface Page 72 Figure 8-6: Diagram of ‘Stack Effect’ Page 74 Figure 8-7: Vapor intrusion occurs along a below-ground sewer pipe Page 74 Figure 8-8: Possible scenario for TCE movement in shallow soil Page 74
List of Tables Table 1-1: Groundwater TCE readings in the summer from MW-3-31 Page 17 Table 1-2: Groundwater TCE readings in 2003 from MW-3-31 Page 17 Table 1-3: Repeat TCE analyses of basement air Page 19 Table 6-1: EPA Recommended Sorbent Materials Page 56
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Introduction L. M. Cathles and T.S. Steenhuis
In December of 2004, Gary Stewart of Cornell University sent an email to
potentially interested faculty on behalf of President Lehman’s office. The email
forwarded a request from Assemblywoman Barbara Lifton asking help in examining data
related to the Emerson TCE spill. Lifton’s request indicated that affected homeowners
would value “another set of eyes” on the groundwater and other data related to the
Emerson contamination.
In the spring of 2005 Professors Steenhuis (Department of Biological and
Environmental Engineering) and Cathles (Department of Earth and Atmospheric
Sciences) used the Emerson TCE case as a project in their Introduction to Ground Water
Hydrology (BEE&EAS 471) class. The class produced a report on the geology,
hydrology and chemistry of the site. That report can be found at
(http://www.bee.cornell.edu/swlab/SoilWaterWeb/testimony/southill.htm). Professors
Steenhuis and Cathles presented the conclusions of the class study at a DEC public
hearing (http://assembly.state.ny.us/comm/Encon/20060201/) that spring.
In the fall of 2006 several homeowners contacted Cathles and Steenhuis to request
Cornell’s assistance and analysis on the matter. Again, the Ground Water Hydrology
class was used to investigate the complex situation at Emerson. In the spring of 2006, the
class self-organized as a “task group” under the leadership of Ian Toevs, a MS student
who had been involved in the study the previous year, to investigate all aspects of the
TCE problem near Emerson. The group was advised mainly by Cathles and Steenhuis,
but received substantial input and guidance from Professors Brown, Gillett, Gossett,
O’Rourke, and other faculty at Cornell. The students also solicited presentations from
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Dr. Shree Giri (sampling and measurement methods of volatile organics) and Dr. Darien
Simon (sociology of communications in contamination cases), along with open and
exceptionally useful communications with Carl Cuipylo of the New York State
Department of Environmental Conservation. A subgroup of students had one detailed
meeting with Mr. Cuipylo and Jim Burke at the DEC offices in Syracuse. Dr. Brown
facilitated the use of ground penetration radar survey on part of the affected
neighborhood. A group of three homeowners (Regina and Ken Deschere and Stanley
Scharf) attended every one of the weekly class sessions throughout the Spring 2006
semester. They guided the class with the information they had already assembled, and
provided an invaluable perspective that helped the class sift through the masses of
Emerson material available in the Tompkins County Library. The introductory (history)
chapter of this report was written by Ken Deschere.
The product of the class task group is this report to the homeowners. It digests a
large amount of information and describes poorly understood phenomena of TCE
transport with "fresh eyes” in a way that is intended to be clear to non-technical readers.
Thus, the intent is to elucidate what appears to be occurring at this TCE site as well as all
the problematic aspects associated with it.
Best efforts have been made to ensure that the report contains no major errors and
the report has been augmented and edited slightly by Cathles and Steenhuis. At its heart
it is a class report and should be treated as such. Suggestions are given, but should be
taken as the products of brainstorming by students rather than as official
recommendations of Cornell University or any of its components. Formal
recommendations are for the homeowners or city representatives to make, and are not the
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purview of an academic class. Similarly, where conclusions have been suggested or
implied, they should be recognized as attempts to clarify or crystallize the implications of
the discussion. Conclusions are the purview of city/state agencies, or the affected
homeowners.
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Section 1: Site History Ken Deschere
The early years
South Hill was settled and developed much later than the downtown "core" of
Ithaca because Six Mile Creek formed a natural boundary to the south of the town. Much
of the "flats" west of South Hill (west of Cayuga Street, south of Green Street) were
swampy areas, and the initial settlement was centered in areas between the Inlet and
Aurora Street. (See the 1873 and 1882 "Birds-Eye" views of Ithaca in these maps from
The History Center. The maps show just modest development along Prospect, Pleasant,
and Columbia Streets on "lower" South Hill.)
In 1870 an iron bridge was built over Six Mile Creek at Aurora Street, which
eased access between South Hill and downtown Ithaca. The Morse Chain Company was
incorporated in 1898, and the early 20th Century saw considerable settlement and
development of lower South Hill, including the establishment of a large factory site, west
of Aurora Street and south of the railroad loop, which extended down the hill to
"Mechanics Street" (now Hillview Place) near Aurora Street.
Tioga Street was extended up South Hill from the intersection of Prospect Street
and "Spencer Place" (now known as East Spencer Street), which started southwest
toward Cayuga Street. This section of Tioga Street is now known as "Turner Place" - a
reference to Samuel B. Turner and his brother, Ebenezer T. Turner, who owned a large
parcel of land West of Tioga Street, running from Spencer Place up the hill to the rail
line. The K.P. Crandall map (dated May 1905 and reproduced here as Figure 1-1) is the
basis for most of the property lines dividing up the 38 lots they offered for sale. Note the
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"Ithaca Water Works" property, showing a city reservoir that was where the Morse "R &
D Lab / Service Building" was later built.
With a school and grocery delivery, homes were built in neighborhoods that
developed downhill from and east of the factory, including many of the lots owned by the
Turner brothers. There were a few cigar makers, a dairy, and a coal yard (which became
Southside Fuel Company, downhill from Coddington St. on Aurora St.).
Figure 1-1: Lower South Hill - 1905 - for a printable version, click here.
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Ithaca Gun was the first large factory operation to be established in Ithaca. It was
located on Lake Street, near the Ithaca Falls, where waterpower was readily available.
Since then, South Hill has hosted various industrial ventures. The first to be established
was the Morse Chain Company, which incorporated in 1898 in Trumansburg, growing
from a carriage-spring and bicycle-chain business into a developer of chain and power-
transmission equipment. The firm moved into their South Hill site in 1906. There were
many other product lines they worked with, including aircraft, typewriters, and adding
machines. The Thomas-Morse Scout plane was part of the aircraft industry centered at
what is now The Hangar Theater at Cass Park.
The Morse adding machine business was merged into a firm known as Allen-
Wales. In 1943 it was bought by National Cash Register Company. A new plant was
constructed further up South Hill in 1957-8, where the business continued until the
demise of mechanical adding machines in the 1970's. NCR moved into electronic point-
of-sale systems, and was taken over by Axiohm before the facility was closed around
2000. The owners of this factory site are applying for participation in the New York State
Brownfield Cleanup Program.
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Figure 1-2: National Cash Register Ad - 1962 (Source: Manning's Ithaca Directory Vol. LIX, 1962)
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Morse Chain and the many affiliated industries located in the same site expanded
through much of the 20th century, joining the Borg-Warner Corporation in 1929. Their
product lines evolved, including electronic controller components for power transmission
systems, manufactured in the building formerly occupied by the adding machine
operation.
In the early 1980s, the automotive portions of the business were moved to a new
facility on Warren Road near the airport. The Industrial products portion remained on
South Hill. The company was sold by Borg-Warner to Emerson in 1983, and is now the
main site for the Emerson Power Transmission operation.
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Figure 1-3: Morse Ad – 1962 (Source: Manning's Ithaca Directory Vol. LIX, 1962 )
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Therm has developed a large facility on Hudson St. Extension, with a 130,000
square-foot facility and recognized specialties in machining turbine blades. Therm has
also had many forays into other lines: typewriter components, television screens, engine
components and glassware.
While Therm has managed to avoid some of the serious scrutiny placed on the
Aurora Street sites, they have had to renew their State Pollutant Discharge Elimination
System (SPDES) permits after spills, which discharged down the hill into Six Mile
Creek.
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Figure 1-4: Therm Ad – 1990 (Source: Ithaca City Directory, 1990)
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Growth through the 20th century
The Morse facility on South Hill expanded through its first seven decades, with
the most significant and lasting development in power transmission equipment for
industrial and automotive applications: drive chains, timing chains, sprockets, gears and
combinations in various housings for front-wheel and four-wheel drive systems. The
plant layout and functions are suggested by the "Sanborn" map shown in Figure 1-5
below. This is a 1929 map that was updated to the early 1960's.
Activities included metal stamping, punching, grinding, milling, heat-treating, oil-
quenching, parts washing and product assembly. Other operations started in the 1960's
and 1970's included copper and cadmium plating, and wire drawing. Many of these
processes require the use of "cutting oils" which must be removed from the pieces after
the process. The removal steps involved a variety of solvents including mineral spirits,
Freon, 1,1,1-trichloroethane, TCE, and tetrachloroethane. While TCE use was
discontinued in 1977 or 1978, peak usage was reported to be about 1200 gallons per week
(per Radian consultants’ report, July 13, 1987).
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Figure 1-5: "Sanborn" map of Morse Chain Site, early 1960's for a printable version, click here.
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Environmental awareness and concerns about carcinogenic effects of the various
lubricants and solvents were not as developed in the mid-20th century as they are today.
However, the Morse facility, like many other industrial and military sites across the
country, became the focus of attention as neighbors reported odors, and strange colors
and oil slicks in water streaming downhill from the plant.
Some of the identified problems are documented in correspondence between
Morse employees and local and State health officials. Walter Hang of Toxics Targeting
Inc, has collected many of these documents. Cutting oils used in processing the metal
parts were widely dispersed. Oils coating the finished parts dripped off pieces of scrap
and shavings which were hauled in bins from the plant to recycling centers.
Polychlorinated biphenyls (PCBs) were found in this oil, and as our knowledge of the
problems with these synthetic chemicals grew, so did concern about the oil runoff from
the plant.
The use of chlorinated solvents as degreasing agents (to remove the oil from the
metal) increased in an attempt to limit the spread of the PCB-laden oil. However, as it
was learned that some of the active agents in these solvents themselves presented
problems, efforts were made to reduce their use.
The volumes of metal, cutting oils, solvents, and water that moved through the
plant site are large. The amount of metal scrap, and the oil with which it was treated, are
the subject of ongoing discussions between Morse staff and County Health officials. The
solvents used and the water taken in and discharged by the plant are detailed in the 1981
application Morse filed for a discharge permit (Figure 1-6).
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Figure 1-6: Map submitted as part of SPDES Permit Application, showing location of Outfall Discharges. A "Google Earth" view of these locations may be viewed here. The locations are: - uphill from the top of South Cayuga Street, and - below West Spencer Street, near the intersection of Wood and South Geneva
S
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In 1987, TCE was found in oil that had been taken from the surface of the large
fire reservoir on the plant site. Further tests disclosed that TCE was present in the
reservoir water as well.
According to the "Record of Decision" issued by NYSDEC in December, 1994,
these steps were taken over the next years:
February 1987: EPT notified NYSDEC of the discovery of TCE in oil skimmed off the surface of an underground fire reservoir. At this time, EPT hired Radian Corporation to prepare a preliminary environmental assessment to address TCE contamination in the fire reservoir and to investigate whether TCE had impacted groundwater. As part of this work, the reservoir was emptied and cleaned using high-pressure water and five monitoring wells were installed. Samples were collected of the groundwater from those wells, soil, surface water and sediment from Six Mile Creek, and seeps. This sampling showed local groundwater was contaminated and that the fire reservoir was likely a source. The study also detected petroleum hydrocarbons in soil taken from the railroad ditch. July 1987: The site was added to the New York State Registry of Inactive Hazardous Waste Disposal Sites. July 1988: EPT signed a consent order with the NYSDEC for a remedial investigation/feasibility study (RI/FS) and remedial program at the site. February 1990: Radian Corporation submitted the RI. This information was used to evaluate interim remedial measure (IRM) alternatives and to complete the Feasibility Study (FS). May 1991: EPT entered into a consent order for an IRM. August 1991: EPT finished construction of a groundwater extraction and treatment system (henceforth referred to as "pump and treat system") to operate as an IRM prior to completion of the FS. May 1991: NYSDOH collected air samples from homes near the Morse site. Based on these samples, the NYSDOH requested and EPT agreed to install vadose zone monitoring wells to assess the potential for impacts adjacent to the site. August 1992: The Fire Reservoir was rehabilitated and put back into service. Cracks in the concrete were patched and a liner was installed.
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February 1994: EPT completed a pilot test using the Xerox Two-Phase Vacuum Extraction system, which was initiated in October 1993. Pilot test objectives included: evaluating system effectiveness for removing VOCs from the soil, dewatered bedrock, and groundwater; comparing system performance to the pump and treat system; and evaluating the benefit of supplementing or replacing the pump and treat system with two-phase vacuum extraction for remediation. The pilot test results showed that the two-phase vacuum extraction system outperforms the pump and treat system. The two-phase vacuum extraction system removes greater quantities of groundwater, has higher VOC removal rates, and has a greater zone of influence. June 1994: Four vadose monitoring wells were installed and will be sampled on two occasions. This investigation will be completed concurrently with the monitoring program for the remedy selected by the PRAP. Should the need for further remediation or other mitigation be identified it will be evaluated as a component of the operation and maintenance program for the site.
The groundwater extraction system continued to be used, and results were
monitored. Readings from one well (MW-3-31, located East of the top of South Cayuga
Street, between the Fire Reservoir and the NYSEG Substation) are summarized in this
February 2004 report prepared by Radian. The readings vary wildly from season to
season and year to year: for TCE, summer readings
are listed in Table 1-1. These readings are all much
higher than the NYS DOH guideline of 5 μg/L
(micrograms per liter). Within 2003, the last year
reported, the results varied significantly as well,
shown in Table 1-2. After more than a dozen years
of groundwater extraction, levels were still very high
and showing little sign of abating.
In May 2004, Walter Hang, President of
Toxics Targeting, Inc. held a Press Conference
Table 1-2: Groundwater TCE readings in 2003 from MW-3-31.
Month TCE level (mcg/L) March 20 000 June 21 000 August 5 800 November 28 000
Table 1-1: Groundwater TCE readings in the summer from MW-3-31.
Year TCE level (mcg/L) 1996 6 900 1997 1 100 1998 82 000 1999 260 2000 43 000 2001 78 000 2002 28 000 2003 21 000
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below the Morse Plant to discuss the first of two letters he would send to Emerson and to
the NYSDEC, referencing the historic documents and maps his firm had collected and
prepared. The attention Mr. Hang's actions drew helped spur a variety of actions, many of
which are ongoing today.
The Toxics Targeting site has an archive of newspaper articles on these actions,
(through 2005), as does the Ithaca Journal, in which most of the articles first appeared.
Unfortunately, the Journal's archive stops at August 2005, and it seems as though no back
issues were kept online for public reference. Some of the articles are referenced at the
Yahoo! site - see below.
Many of the actions taken, documents involved, and opinions expressed are
available for review at the Yahoo! Groups site for Ithaca-SHIP. The focus of much
attention has been the continuing testing of the air and groundwater. Timothy Weber has
assembled a thorough database of the results of these tests, with interactive mapping to
help "see the forest for the trees". His database contains, among other data, all available
analyses of indoor TCE from three phases of testing (372 analyses in total; access from
above database link by selecting Chemicals by name, just site related in table, and then
selecting 1,1,1-Trichloroethane). As analyzed by Larry Cathles for this report, that data
shows that 35% (31) of the 89 basements tested (see Figure 3-1 for locations) contain
measurable levels of TCE. The TCE levels are generally in the 1 to 2 μg/m3 range (~0.2
to 0.5 ppbv). Several of the houses have been tested repeatedly. The repeatability of the
measurements appears good (about ±1 μg/m3), as shown in Table 1-3.
19
Table 1-3. Repeat TCE analyses of basement air samples taken from the same house. All measurements are in μg/m3 TCE. The data are from Ithaca-SHIP Yahoo web site of Timothy Weber. House #1 7.92, 7.16 House #2 3.7, 1.2, 1.37, 0.765,2.02, 1.09 (average 1.7 ± 1) House #3 1.3, 1.97 House #4 1.04, 0.492 House #5 2.3, 0.874 House #6 0.93, 0.82 House #7 1.4, 1.2, 0.437, 0.328 Not Detected 9 houses in two samplings 2 houses in 3 samplings
20
Section 2: Toxicological Profile for Trichloroethylene (TCE)
Jennifer Smith
Introduction
Trichloroethylene (TCE) is a legal organic chemical commonly used
commercially and in industry. It can be used as a solvent to clean grease from metal, a
paint stripper, an ingredient in paints and varnishes, an adhesive solvent and a chemical
to manufacture other organic chemicals. Consumer products that contain TCE include
typewriter correction fluids, paint removers/strippers, adhesives, spot removers, and rug
cleaning fluids (ATSDR 1997). Some common uses of TCE prior to an FDA ban in 1977
were as an anesthetic, grain fumigant, wound disinfectant, and pet food additive (ATSDR
1997). There were only two manufacturers of TCE in the United States as of 1986, with
a combined production of 320 million pounds annually (ATSDR 1997). In 1993, 16.3
million pounds of TCE was imported into the US and 72.6 million pounds of TCE was
exported (Fisher et al. 1998). In New York State there were 55 facilities that used TCE
for on-site use/processing in 1993 as a reactant, for repackaging, as a chemical processing
aid, as a manufacturing aid, or for other uses (ATSDR 1997).
The current limit for TCE in air for New York State according to the New York
State Department of Health (NYSDOH) is 1 ppbv (1 ppbv is one part per billion by
volume, e.g., 1 volume of gaseous TCE per billion volumes of air). OSHA allows an 8-
hour time weighted average exposure limit of 100,000 ppbv; the 15-minute time
weighted average limit for exposure is 300,000 ppbv (OSHA 1993). The threshold limit
value for occupational exposure is 50,000 ppbv (American Conference of Governmental
Industrial Hygienists 1997). The threshold limit value is the maximum value that most
21
adult workers are expected to be able to tolerate without adverse effects. Time weighted
average means that the value has been averaged over an 8-hour day/forty hour workweek.
For reference, TCE can be smelled at levels of 120,000 to 500,000 ppbv.
The National Institute for Occupational Safety and Health set a 60-minute ceiling
occupational exposure limit of 2,000 ppbv. Though these limits are higher than the
NYSDOH standard for indoor air (1 ppbv), a complicating factor in assessing the risk of
TCE exposure is that other contaminants are also generally present in environmental
cases that can act synergistically to increase risk. Additionally, sensitive individuals such
as children, pregnant mothers, the elderly, those who drink and those who smoke may
require a significantly lower level to ensure minimal risk.
Environmental Fate
TCE is the most commonly reported organic groundwater contaminant (Bourg et
al. 1992). In addition, between 9 and 34% of drinking water in the United States has
TCE contamination (ATSDR 1997). TCE is classified as a dense non-aqueous phase
liquid (DNAPL), since the specific gravity (ratio of chemical density to that of water) is
1.46 (US EPA 2005). TCE also has low solubility in water. This can potentially make
assessments of transport difficult, since migration into the vapor phase is dependent on
water concentrations, water table depth and fluctuations, and temperature. Migration in
the liquid phase can occur at increased rates compared to groundwater, due to the fact
that liquid TCE has a higher density than water. The organic carbon-partitioning
coefficient (Koc) for TCE has also been experimentally derived, with values from 106-
460 (Garbarini and Lion 1986). Koc is a measure of a chemical’s affinity for organic
matter in soils, where higher values correspond with higher retention in organic matter
22
(values greater than 1000). This indicates TCE will not sorb readily to organic matter in
saturated soils. TCE dissolved in groundwater is expected to move with groundwater
rather than sticking to organic matter. However, TCE may be physically trapped as
puddles of liquid TCE inside geological formations (discussed in geology and transport
sections).
Volatilization of TCE into a vapor phase in air occurs rapidly. The volatilization
half-life of 1 mg/L TCE was experimentally investigated as 21 minutes at 25oC (Diling et
al. 1975). Volatilization from the aqueous phase occurs at a much higher rate than the
volatilized TCE is degraded by photolysis or hydrolysis (Jensen and Rosenburg 1975).
Moreover, chemical hydrolysis only occurs at very high temperatures and pH - not under
normal conditions encountered in a natural environment (ATSDR 1997). Photolysis is
the degradation of a compound due to exposure to light, where photons break chemical
bonds. Hydrolysis occurs when chemical bonds are split by water. This indicates that if
liquid TCE or TCE dissolved in water is exposed to air, it will rapidly evaporate into the
vapor phase and increase the amount of TCE in air that may intrude into nearby
buildings. The amount of TCE that can be introduced into air by water containing TCE
or by liquid pools of TCE is very large compared to the health standards. The Henry’s
Law constant for TCE dissolved in water is 0.3 .rliter wate / TCE mg
airliter / TCE mg⎥⎦
⎤⎢⎣
⎡ The vapor
pressure of liquid TCE is 73 mm Hg. This means that air in contact with water saturated
with TCE (1100 mg TCE per liter of water) will contain 330,000 mg TCE per m3 air (or
>60,000,000 ppbv TCE). Air in equilibrium with a puddle of liquid TCE will contain
96,000,000 ppbv of TCE.
23
In deep subsurface regions, degradation (biotic or abiotic) is minimal. Rates of
biodegradation will be influenced by nutrient availability, temperature and weather TCE-
consuming organisms are present. Biodegradation of TCE can occur completely if
present in aerobic (oxygen present) conditions. Biodegradation may also occur under
anaerobic (oxygen absent) conditions, via reductive dehalogenation. This process occurs
when hydrogen replaces chlorine (the halogen) in a chlorinated compound sequentially.
However, the last chlorine in this process is very difficult to remove and therefore takes a
long time to completely degrade or mineralize to ethene (a benign degradation
compound). The second to last product is vinyl chloride, a known carcinogen. Vinyl
chloride can be mineralized biotically if aerobic conditions are then present. In nature,
conditions are commonly aerobic above the ground water table or in areas of rapid inflow
of surface water. In areas of relatively stagnant water below the water table, conditions
are generally anaerobic.
Bioconcentration refers to increased concentrations of a chemical in organism
tissues relative to environmental conditions. Biomagnification occurs when there is a
cumulative increase in the concentration of a chemical in organisms at successively
higher levels of the food chain. Bioconcentration and biomagnification of TCE are
virtually negligible. A study by Saisho et al. (1994) found bioconcentration factors of
4.52 and 2.71 for blue mussel and killifish, respectively. Biomagnification was
investigated in the aquatic food chain, where concentrations were less than 100-fold in
fish liver, sea bird eggs and sea seal blubber, suggesting some biomagnification (Pearson
and McConnell 1975). Laboratory studies of fruits and vegetables have found uptake of
TCE in the foliage of carrot and radish plants; bioconcentration factors were between 4.4
24
and 63.9 (Schroll et al. 1994). Bioconcentration factors that are less than 200 are
considered to be negligible in magnitude.
Exposure
The primary exposure pathways are: ingestion of contaminated drinking water or
inhalation (Wu and Schaum 2000). Inhalation is the primary route of exposure on the
South Hill. TCE is present in ambient air across the nation. In 1993 alone, 30.2 million
pounds of TCE was emitted into the atmosphere (ATSDR 1997). Ambient air
concentrations of TCE found in the United States ranged from 0.04-0.72 ppb, 0.39 ppb,
0.21-0.59 ppb in Oregon, Pennsylvania, and New Jersey, respectively, during 1983-84
(Ligocki et al. 1985, Sullivan et al. 1985, Harkov et al. 1984). Air concentrations in these
studies were found to vary between the fall/winter and spring/summer seasons. Wallace
et al. (1985) found indoor air to contribute more overall TCE exposure than outdoor air,
where the ratio of indoor to outdoor concentrations was about 5:1 in North Carolina.
Indoor air concentrations have been measured as 5 ppb in a North Carolina office
building, 0.14 ppb in a Washington, DC school and 0.15 ppb in an elderly home in
Washington, DC (Hartwell et al. 1985). The average inhalation uptake in the United
States can be estimated as 11-33 mg/day, and uptake due to oral exposure is
approximately 2-20 mg/day (Wu and Schaum 2000). Upon inhalation exposure to TCE,
about half will be absorbed into the bloodstream and the other half exhaled. Once in the
bloodstream, TCE will either be exhaled or modified in the liver and kidneys for urinary
excretion.
Other exposures to TCE can occur through food: dairy products such as milk,
cheese and butter (0.3-10 ppb), oils and fats (0-19 ppb), beverages such as canned fruit
25
drink, ale, instant coffee, tea and wine (0.02-60 ppb), fruits and vegetables (0-5 ppb) and
bread (7 ppb) (McConnell et al. 1975). Breast milk has also been shown to contain TCE
in 8 of 8 mothers sampled who resided in urban areas (Pellizzari et al. 1982). Though
these routes are generally not the primary mechanism of exposure, it is important to
consider the cumulative effects of these background levels with any additional sources.
Toxicological Endpoints
This is not a complete list of all toxicological endpoints of TCE, but a compilation
of the most studied effects found in the literature. The International Agency for Research
on Cancer has classified TCE as a probable human carcinogen, because there is sufficient
evidence in experimental animals but limited evidence in humans (Iavicoli 2005). TCE
toxicity in humans has been fairly well studied at higher concentrations, especially with
regards to occupationally exposed adults: over 80 published articles on TCE’s
carcinogenicity to humans, more than 20 reports on occupationally exposed groups, 40
case-control studies and more than a dozen community-based studies (Watenberg et al.
2000). The most common effects from TCE inhalation exposure include neurotoxicity,
heptatoxicity and nephrotoxicity. Reproductive and developmental toxicity have been
extensively studied, with largely negative results (Barton et al. 1996). Chemically
induced genetic mutation inducing tumors in humans does not appear to be caused by
TCE or its metabolites. This is because very high levels of TCE are required to cause
genotoxicity (Moore and Harrington-Brock 2000). Liver and lung tumors and
lymphomas have been reported in mice inhalation studies (Watenberg 2000).
Humans occupationally exposed to TCE have increased incidence of liver,
kidney, and cervical cancers, as well as non-Hodgkin’s Lymphoma, Hodgkin’s disease
26
and multiple myeloma (Wartenberg et al. 2000), though these concentrations are many
orders of magnitude higher than air in homes measured on the South Hill. A study by
Axelson et al. (1994), found no evidence that trichloroethylene was a human carcinogen
for an average occupational inhalation exposure level of 20,000 ppbv when studying
inhalation effects in 1,424 men and 249 women from 1955 until 1987. This is because
average cancer rates were lower than expected. Some other effects of TCE inhalation
exposure are neurological, liver and kidney effects (Barton and Clewell III 2000). Ertle
et al. (1972) reported “psycho-organic syndrome”, characterized as unrest, generalized
fatigue, disturbed vision and neurological aberrations, to be caused by exposure to TCE.
Headaches, sleepiness, fatigue and/or drowsiness have occurred at approximately
100,000 ppbv and are characteristic of neurological toxicity (Barton and Clewell III 2000,
Barton and Das 1996). Headache (27,000 ppbv) and drowsiness (81,000 ppbv) occurred
in human volunteers exposed to TCE for 1-4 hours (Nomiyama and Nomiyama 1977).
One study on low level occupational exposure (average 6,000 ppbv) found that TCE had
negative effects on the immune system (Iavicoli 2005).
Information on toxicological effects on the order of magnitude of those on the
South Hill of Ithaca (i.e. at the ppb range) was difficult to obtain for inhalation exposures.
There is still a significant gap in the scientific knowledge on what the long term
consequences could be. However, information on the toxicological effects from oral
exposure (due to contaminated drinking water wells) was available at lower doses.
Residents in Wobum, Massachusetts had increased adverse effects on the immune system
causing increased risk to respiratory infections (asthma, bronchitis, and pneumonia) and
increased cases of leukemia in children orally exposed to 267 ppb of TCE between 1971
27
and 1979 (Byers et al. 1988). Three hundred sixty two individuals exposed to 6 to 500
ppb of TCE and other chemicals through drinking water wells in Tuscon, Arizona found
increased frequencies of 10 systemic lupus erythematosus symptoms, arthritis, Raynaud’s
phenomenon, malar rash, skin lesions related to sun exposure, seizure or convulsions, and
mood disorders, as well as decreased blink reflex, eye closure, choice reaction time, and
intelligence test scores (Kilbum and Warshaw 1992, 1993). A study of 80,938 births and
594 fetal deaths in New Jersey linked with contaminated drinking water (>10ppb TCE)
found an association with oral clefts, central nervous system defects, neural tube defects,
and major cardiac defects (Bove et al. 1995).
TCE Metabolism
TCE inhaled will either be exhaled before being absorbed into the bloodstream by
tissues, or metabolized and excreted through the urinary tract (Dobrev et al. 2002).
Toxicological effects of TCE are largely due to the metabolites, including
trichloroacetaldehyde, chloral hydrate, dichloroacetate, trichloroacetate, trichloroethanol
and trichloroethanol-glucuronide (Barton et al. 1996). Other parent compounds that
produce the same metabolites are tetrachloroethylene (PERC), methyl chloroform (MC),
1,1,1,2-tetrachloroethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,2-
dichloroethylene and 1,1-dichloroethane (Wu and Schaum 2000). Exposures to TCE,
PERC and MC simultaneously at their respective time-weighted average threshold limit
values, has been shown to result in elevated (22% increase) TCE blood levels compared
with individual chemical exposures (Dobrev et al. 2001). The reason kidney and liver
cancer are the most common cancers associated with TCE exposure is because of
metabolites. There are two major pathways of TCE metabolism in the body, one
28
involving oxidation with cytochrome P450s and the other is conjugation with glutathione
(Lash et al. 2000). Cytochrome P450s are very versatile enzymes, found in high
concentrations in the liver (86% of the body’s P450s), which can perform a host of
reactions. However, in the case of TCE degradation, the metabolites produced in the
liver are carcinogenic. These metabolites include chloral hydrate, trichloroacetate, and
dichloroacetate (Lash et al. 2000). The second major pathway of TCE metabolism is
glutathione conjugation, in which glutathione, a peptide of amino acids, is attached to
TCE. This primes it for urinary excretion. However, metabolites that occur in the
kidneys from this conjugation have been associated with kidney cancer. The P450
pathway has higher activity and affinity than glutathione conjugation (Lash et al. 2000).
Behaviors that can increase the risks of cancer from TCE exposure include
alcohol consumption and smoking. Alcohol can interfere with TCE excretion and
metabolism, increasing the formation of trichloroethanol, a metabolite also associated
with cancer. Individuals who consume alcohol may be in a particularly sensitive
population (Barton et al. 1996). Smoking may also increase the risk of genotoxic effects
from TCE exposure (Seiji et al. 1990). Mothers who are breast-feeding should also be
aware that TCE could accumulate in breast milk (noted earlier). With regards to TCE
toxicity, it is most important to note that there are significant gaps in the scientific
knowledge of long-term low-level exposures. This is largely due to the difficulty in
finding a human population not exposed to low levels of TCE against which exposed
groups can be compared.
29
Section 3: Economic Analysis Ian Toevs
The potential impact of an environmental contamination problem almost always
extends beyond health and peace of mind. Often an economic component is involved.
The situation on South Hill is no different; in fact, these issues are very closely related.
However, it is unclear how substantial their impacts may be. Possible economic burdens
the on the homeowners include a lowering of real estate values and the cost of operating a
mitigation system. A proactive sampling and mitigation strategy by Emerson could help
reduce their overall cleanup expenses while easing the anxiety of the affected residents.
Real Estate Value
Through the assistance of Kathy Hopkins, a real estate agent of Audrey Edelman
& Associates, and Jay Franklin, from the Tompkins County Department of Assessment,
insight was gained regarding the current behavior of the South Hill real estate market. In
order to address a fluctuation in real estate values, the record of sales and assessed values
were examined. May 2004 was the first public meeting in which the South Hill
contamination issue resurfaced. From May 2004 to April 2006, there were 22 houses
sold directly in, or bordering, the study area. Of these transactions the average selling
price was $150,180. On average, this is 26% higher than the corresponding assessment
values. Similar data were compared for the greater South Hill area as well as for all of
Ithaca. From 2003 to 2005 the average increase of selling price to assessed value for
houses in the greater South Hill area was 38.9% while for all of Ithaca it was 30.3%.
From 2004-2005 the increase for South Hill was only 19.6%. However, this must be
compared with the same time period for Ithaca, which only had an increase of 6.3%.
This shows that the housing values have increased at South Hill in parallel to the trend for
30
the rest of Ithaca. Although this is a relatively small sample size over slightly less than
two years, there is no quantitative indication that the selling prices for homes on South
Hill have shown any negative trends to April 2006.
An additional impact that is less obvious in sales and assessment data is the
amount of time that houses are on the market and the number of bids received for a sale.
Those who live in Ithaca and have had any exposure to the real estate market know that it
is extremely active. As a result, it is not uncommon for a house to be on the market for a
matter of weeks or less and receive numerous bids. Anecdotal evidence from home-
owners in the South Hill area have indicated that following the May 2004 rebirth of the
TCE contamination issue, houses have remained on the market longer and have seen
significantly fewer potentially interested buyers. An article in the Ithaca Journal (Daley
2005) provides support for this perception. Ultimately, the amount of information known
about the extent of the pollution problem will play a substantial role in the buyers’
purchasing decision. New discoveries, either positive or negative, may influence the
behavior of the South Hill housing market, and according to the Tompkins County
Department of Assessment, the situation is under close monitoring, and assessment
values will be adjusted if a trend is identified.
Mitigation Operating Cost
Currently, the most effective method known for alleviating the threat of indoor
vapor intrusion is the installation of a suction system (essentially identical to a radon
mitigation system) that removes the air from below the concrete slab of the mitigated
house and vents it into the atmosphere. Emerson has agreed to cover the costs associated
with the mitigation system installation, maintenance, and repair. However, another
31
potential expense that must be accounted for by either the homeowner or Emerson is the
cost of powering the mitigation exhaust fans, which must run continuously. Fantech lists
fans rated from 13-248 watts. Assuming energy costs of $0.12 per kilowatt-hour, the cost
to operate one fan ranges from $13 to $260 per year. Some mitigation systems may
require the use of two fans or a high suction fan rated up to 320 watts. As currently
advertised from Infiltec, this system would cost up to $336 annually. These costs, over
the lifetime of a house, are quite significant and as energy costs continue to rise, they will
increase.
Another point is important to make. Mitigation cannot just consist of “pumping
under the slab” because this will be ineffective unless the macro and micro-integrity of
the floor and walls is assured. The surface should be sealed with an epoxy paint, and
connections between the slab and outside (sumps, French drains and the like) need to be
severed. Perhaps 50% of the residences on South Hill lack complete slabs. Laying
complete slabs and sealing properly the walls of basements could cost $10’s of
thousands of dollars per residence. On the positive side, the needed mitigation will
provide drier basements with increased livability, and add to the value of the property.
Would property owners be willing to allow such major renovations that might have other
code implications? Are such renovations feasible in all the houses that might be
affected? These are major facets of mitigation that will need to be addressed.
Overall Economic Analysis
The effectiveness and success of Emerson’s strategy for mitigating harmful
effects from the contamination on South Hill can be measured in many ways. The
primary objective, of course, is to quickly reduce the exposure of people to the
32
contaminants in order to prevent further exposure. A secondary issue is to do so in an
economical manner. A strategy that could address both of these issues is to offer a
universal mitigation approach to all who live in the area of contamination. Unfortunately
there has not yet been a clean perimeter established. As a result, the present strategy is to
test for volatile organic compounds (VOCs) while expanding the perimeter and retesting
in an attempt to delineate the boundary of contamination. There are many problems with
this strategy:
1. This practice is very time consuming (the delay between sampling and receiving
test results is typically 8 to 12 weeks). This is exasperated by the fact that testing
is only performed during the heating season (late fall through early spring).
2. As discussed later in this report, there is high variability in TCE transport
processes, so the test results may falsely show no detection.
3. Related to (2), the current standard of installing mitigation systems only for
residences that have detectable levels of TCE in the indoor air is inadequate. It is
not known how long the concrete will act as an effective barrier.
4. Testing for TCE and other VOCs in a certified lab costs approximately $800 per
sample. Each house typically has three or four samples taken for one round of
sampling, assuming the house is of the proper construction to obtain the necessary
samples. Some of the houses currently under observation are on the third round
of sampling which brings the cost per house to a maximum of $9600. According
to the U.S. Environmental Protection Agency the general cost to install a radon
mitigation system (which is essentially identical to a TCE mitigation system)
ranges from $800 to $2500 with an average of $1200
33
(http://www.epa.gov/radon/pubs/consguid.html). Although follow-up testing is
required to verify that the system is working effectively, a mitigation system and a
round of follow-up testing is approximately equal to two rounds of initial testing.
Either strategy for mitigation should include continued follow-up monitoring for
VOCs. It is also necessary to note that many of the houses in the South Hill area
would cost much more than the average mitigation expenses listed here due to
many influences, including: a dirt floor basement or a partial concrete slab, houses
constructed directly on top of solid rock, or extremely permeable foundations
such as a laid-up stone wall. A worst-case scenario for the extent of the
contamination plume (Figure 3-1) would include approximately 375 properties
beyond what has already been tested. Assuming the maximum typical price
($2500 per system), the cost of mitigation and one round of follow-up sampling
would be approximately $2.1 million. In comparison, the price of running 2
phases of sampling on all houses would cost $2.4 million plus the cost of the
mitigation systems and follow-up testing that would be required based on the
sampling results. These prices are approximately equal. However, the blanket
mitigation approach would provide additional benefits to the residents by
providing a sense of assurance and improve Emerson's public relations.
34
Figure 3-1: Worst case scenario of contaminated area.
Conclusions
• Fortunately at this time there has not been evidence of a significant economic
impact on the residents of South Hill; however, it is unknown whether this will
happen in the future.
• A concern still remains about the cost of operation for the mitigation systems.
While most systems will not be unduly expensive to run, increasing energy costs
will increase the expense.
35
• One of the main concerns is the amount of time that is spent in determining who
is eligible to receive a mitigation system. Based on the rough calculations of total
expenses to Emerson and the intrinsic benefit of having a supportive group of
community members, it could be mutually beneficial to Emerson and community
members to offer a wide scale blanket mitigation scheme.
36
Section 4: Geology Rachel Shannon
The geology on South Hill is an important factor which influences the direction
and speed with which water and contaminants can move through the ground. This section
includes a short description of the geology of the area, as well as some suggestions for
the role that geology may play in the movement of contaminants.
Figure 4-1 is a diagram of a hypothetical slice of the subsurface, built for this
paper from information in “Groundwater Evaluation of Remediation Area, Emerson
Power Transmission Facility Ithaca, New York,” a report prepared by ESC and received
at Tompkins County Public Library on March 18 2005. This report concludes that the
geology in the area can be divided into four distinct zones. Zone A is glacial till (a type
of soil deposited by retreating glaciers- see glossary), and is about 5-10 feet thick in most
places in the area. According to the report cited above, the glacial till in the South Hill
area is mostly clay, but there are small amounts of gravel mixed in. The till could be
permeable where the gravel content is high. Below the glacial till, the bedrock is
siltstone. All of the siltstone is fractured, but the extent of the fracturing depends on the
depth. Therefore, the siltstone is divided into three separate zones based on how
fractured the rock is. Zone B is directly under the glacial till and reaches a maximum
depth of 22 feet below the surface. It is highly weathered and fractured. Zone C starts at
the base of zone B and reaches a maximum depth of about 55 feet below the surface,
showing less fracturing than zone B. Zone D starts at the base of zone C and reaches a
maximum depth of 145 feet. The rock in zone D has much fewer fractures that are more
widely spaced.
37
In the Ithaca area, the bedrock fractures, called "joints", are generally evenly
spaced and perpendicular to each other in all three dimensions. This seems to hold true on
South Hill. The first set of fractures runs approximately north-south, the second set runs
approximately east-west, and the third set runs horizontally. The result is that the bedrock
is cut into blocks, and each block is surrounded on all sides by fractures (Figure 4-2).
Openings along the fractures vary in size; large openings are inches wide, while the
smaller ones can be less than a millimeter wide. Because most of these fractures are deep
underground, it is impossible to estimate where exactly all the fractures occur, or even
Figure 4-1: Diagram of a hypothetical slice through South Hill. Layer A is glacial till with a variable low to very low permeability. Some water will infiltrate through this layer. Layer B is weathered and fractured bedrock of moderate to low permeability. Layer C is an "intermediate" zone; it is less fractured and less permeable than layer B. Layer D is much less fractured than the layers above it, and as a result it is probably much less permeable. Section constructed from “Groundwater Evaluation of Remediation Area, Emerson Power Transmission Facility Ithaca, New York,” an ESC report received at Tompkins County Public Library on March 18 2005
38
how many there are. On the West Spencer Street road cut, fractures can be seen every
few feet.
Following are a few observations/ideas from a geologic perspective. The role the
fractures may be playing is discussed in more detail in Section 7.
• The rainwater that does not run off into sewer drains flows downward through the
uppermost layer of glacial till into the siltstone bedrock layers.
• Fractures in the bedrock can either act as water conduits or as barriers. If they are
open, water can flow through them very quickly. However, often fractures get
filled up with clay and silt from the soil. In those cases, fractures may actually
stop the water and cause it to be stored in the rock. It is possible that both
Figure 4-2: Schematic drawing of rock joints. The rock is divided into blocks, and each block is surrounded by fractures on all sides. The fractures could provide pathways through which water can flow.
39
scenarios are true on South Hill: some fractures are conducting water while others
are blocking it.
• Siltstone itself is fairly impermeable to water. Therefore, water flows through the
fractures in the rock.
• Variations in the fracturing of the bedrock will produce variations in permeability
and cause the depth of the water table to vary, perhaps greatly, from location to
location.
• If water moving through a particular chain of fractures encounters a liquid puddle
of TCE, the TCE can dissolve in the water and be carried to a basement if the
fracture chain intersects a house. A different fracture path intersecting a
neighboring house may not have encountered TCE and the basement of this house
may therefore, even though damp, be free of TCE contamination. The fractured
nature of the bedrock at South Hill makes the transport of TCE and contamination
of the basement of houses much more complex.
40
Section 5: Hydrology Brianne Smith and Adrian Harpold
General information about water transport through the subsurface
To gain an understanding of TCE transport mechanisms, knowledge of
groundwater and water balances must first be attained. This is, perhaps, most easily
explained with the use of a diagram:
The water cycle begins with evaporation (E) from a lake or from the ground or by
transpiration (T) from plants; the combined process is called evapotranspiration (ET).
The amount of water that evaporates or transpires varies depending on atmospheric
factors, plant type and degree of saturation of the soil. The water comes back into contact
with the soil as precipitation (P). Upon contact with the ground, it will either saturate the
soil or, if the soil is already saturated, it will flow over the land as overland flow (O),
commonly called "runoff". The water that saturates the soil has a similar fate; it can flow
Figure 5-1: Water transport mechanisms.
41
through the top layer of soil as interflow (I), or it can continue to move down through the
soil as recharge (R). The amount of water that moves as interflow can be determined
using the slope of the surface as well as the depth of the saturated layer and the ease with
which the water moves through the soil. The recharge will move vertically downward
under the force of gravity until it reaches an impermeable layer and saturates (fills 100%
of the pores), forming a perched water table. The groundwater can then travel
horizontally as interflow. At some depth the ground becomes saturated everywhere.
This is called the water table. Below the water table water may move horizontally as
base flow (B). Base flow will always move in a direction from higher hydraulic head to
lower hydraulic head with a speed determined by the magnitude of the head difference
and the permeability of the rock or soil. The hydraulic head is the elevation (above sea
level) or water in a well. Scientifically these head-measuring wells are called
piezometers, which are long tubes with small holes in the bottom that are buried in the
ground to the depth of interest. The elevation of the water in the piezometer tube is the
head of the water. Water will flow from an area with a higher piezometer water height to
an area with a lower piezometer water height.
A water balance may be done on an area of soil by setting the sum of all above
water fluxes equal to the change is storage of water within the soil (S). So for an area of
soil spanning from the ground level to the top of the water table, a water balance would
be equated by the following:
S = P – ET + Oin – Oout + Iin – Iout – R
The groundwater situation for South Hill is a more complicated version of the
diagram shown above. One complication is that much of the South Hill area is made of
42
fractured rock. The rock itself is relatively impermeable but water can rapidly flow
through fractures in the rock. The glacial till above this fractured rock is not very thick.
Springs or seeps occur groundwater table or a perched water table is intersected by the
ground surface. This results in wet spots and possibly in water flowing out of the ground.
Wet spots on the side of a hill may indicate perched water tables.
Physical controls on groundwater movement at South Hill
As explained in the previous section, groundwater movement is complex and
difficult to measure in the best case. At the South Hill in Ithaca, groundwater movement
is complicated by a very heterogeneous (many different types of materials and properties)
geology and human disturbances above and below ground. This section of the report
seeks to explain the major controls on groundwater movement at South Hill and identify
important possible pathways for TCE transport in the subsurface.
Figure 5-2: Water transport: seeps and springs.
43
Geologic and Soil Controls on Groundwater Movement
At the South Hill site, groundwater occurs in both the top layer (fill and glacial till
material) and in the fractured bedrock below (see Geology Section). However, some of
the monitoring wells installed did not encounter a groundwater table, and in other places
the ground water table varied in elevation in an erratic (anomalous fashion). The well
measurements indicate a clear hydraulic connection between the topsoil and bedrock.
This means that water (and TCE) can be transmitted through the till layer to the bedrock.
A rising water table can move TCE from the bedrock into the till. Movement of water in
the till can be estimated with some accuracy. However, water flow in the bedrock is
controlled by fractures in the rock and the size, length, and interconnection between
fractures. The complexity of movement in the bedrock makes estimating detailed
groundwater movement nearly impossible at South Hill.
Water table measurements were made in 1987, 1988, 1989, and 2003. The
measurements show that the groundwater is moving northeast to northwest depending on
the exact location on the hillslope. The direction of movement is generally in the
direction of the declining hillslope moving north (northeast) of the Emerson plant.
Unfortunately, the measurements made are incomplete in several ways. First, there are
numerous anomalies in the measurements. This is due to the complex geologic controls
in the fracture bedrock that we discussed in the previous section. Unfortunately, this
makes measurements from the deep wells (into the bedrock) unreliable indicators of the
directions of ground water and contaminant flow. Another issue with the groundwater
measurements is that three of the measurements were made between September and
November. Typically, this time of year has the lowest water table levels. The data allow
44
very little to be said about the seasonal movements of the groundwater table. Five wells
were measured in May 1987 and results are shown in Figure 5-3. Site MW-3-13 is the
only well screened from the topsoil, which was almost two feet higher in the spring. All
but one of the wells show higher levels in the spring compared to fall, as expected. The
fluctuation of the groundwater in the topsoil is an important transport process for TCE
(explained subsequently).
Figure 5-3: Water table heights for five measuring wells located near the fire reservoir. Water levels are higher in the spring than fall. Additionally, the well in the topsoil shows a more significant variation in water height, which is important for TCE transport.
An electrical resistivity (ER) test was performed in July 2005 to assess the
subsurface hydrogeology at South Hill (ESC 2005). The results of the test show a
complex pattern in electrical conductivity (Figure 5-4). The survey is purported by the
Ground Water Depths
0
5
10
15
20
25
MW-1 MW-2 MW-3-13 Soil MW-3-31 MW-4 Well Number
Depth to GW (ft)
May 1987 October 1988 September 1989 November 2003
45
company that made the measurements to suggest patterns of groundwater flow, but these
suggestions are very preliminary and have no independent verification.
Figure 5-4: Electrical Resistivity results for South Hill moving in a Southwest direction. Red boxes indicate saturate areas at the surface and deeper into the subsurface. Note the low resistivity (blue) near the surface appears to connect to deeper areas (red box). Source: ESC, Geophysical Survey Investigation. 10/31/05.
During the site assessment, rising and falling head well tests were used to estimate
the hydraulic conductivity (the permeability to ground water flow) of the subsurface. The
permeability (hydraulic conductivity) of the soil and bedrock decreases with depth. A
trend in reduced permeability is consistent with boreholes, core logging, and geologic
mapping at South Hill. The permeability ranges from 1.6 X 10-4 cm/sec (moderate) to 4.4
X 10-7 cm/sec (low) in the shallow bedrock. The permeability is slightly less in the deep
bedrock, ranging from 1.5 X 10-6 to 1.9 X 10-7 (Radian, 1987). As expected, the deeper
bedrock is less permeable than the more fractured shallow bedrock.
Human Induced Transport Mechanisms
Human activities on South Hill such as paving, removal and filling of topsoil,
installation of subsurface pipes, and artificial control of the canal leading to Cayuga Lake
have changed possible TCE transport pathways. .
46
Development on the South Hill has led to a significant portion of the area being
either paved or put under the footprint of a building. The pavement has had severe
impacts on water transport issues. First, the hillside is subject to less groundwater
recharge because more water moves over streets and into sewers. This likely means that
groundwater levels fluctuate less and there is less groundwater moving through the
system. In the steeper sections of South Hill the residential housing has been built into
the hillside. Change in grade (from steep to flat) will often cause the groundwater to
come closer to the surface. Unfortunately, basements and crawlspaces can often become
damp as a result, and the water seeping into them can introduce TCE if TCE is dissolved
in it. For example, the garage shown in Figure 5-5 was built into the hillside and seeps
groundwater in an area contaminated with TCE.
Figure 5-5: Garage where water can be transported through a wall built in the topsoil. White pipe in top-right corner drains water outside. Photograph by Regina Deschere.
47
There have been significant alterations to the soil on South Hill that can directly
affect water transport. Large pipes going down steep grades often have water moving
through the disturbed/filled zones adjacent to the pipes. Additionally, the houses all have
individual utility pipes. Pipes were found in the ground penetrating radar (GPR) survey
we performed in the Spring 2006. These unnatural conduits could transport vapor and/or
water with dissolved TCE, and will be discussed in the next section.
Conclusions
Groundwater in the glacial till and the fractured bedrock moves towards the
northwest, propelled by gradients in hydraulic head that are often very steep.
The water table fluctuates in both the bedrock and topsoil depending on rainfall.
Water tables are highest in the spring.
Groundwater flow in the bedrock is controlled by fractures. Despite low
hydraulic conductivities reported, rapid movement of water is expected in the
fractures.
Well tests and an electrical resistivity survey suggest that water will flow through
the glacial till into the bedrock.
Human activity has influenced the pathways for water and TCE on South Hill.
These influences include: increases in asphalt, removal and filling of topsoil, and
installation of subsurface pipes.
The total amount of groundwater flow in the subsurface is small and therefore
TCE movement in the vertical direction likely dominates over lateral movement.
48
Section 6: Spring Water and Basement Air Sampling Veronica Morales and Rachel Dunn
Chemical analysis of water and air samples is fundamental to understanding TCE
transport and risk in South Hill. Current analyses are expensive and are conducted
sparingly. This section details methods that might allow samples to be analyzed less
expensively and also sets forth sampling plans.
Spring Water Sampling
The identification of dissolved TCE or its degradation daughter products in spring
water could provide evidence of possible DNAPL sources upstream of the spring. Due to
the proximity of the homes to springs, dissolved TCE in the spring water may also be
indicative of possible intrusions of contaminated water into the homes, and/or presence of
volatilized TCE in the unsaturated soil that envelops nearby basements. Although spring
water sampling in the past had non-detectable concentrations of TCE, it is important to
continue monitoring this potential contaminant pathway.
A. Identified Springs
i. 100 block of S. Hill Terrace -spring sometimes visible from the street
ii. Hillview Park -center of park, South of the “Acropolis Cooperative” apartment building
iii. End of 100 block of S. Hill Terrace -water drips out of rocks in the back of the house and periodically from a large open rock in the driveway wall
iv. 100 block of E. Spencer St. -weepy outcropping
v. 200 block of W. Spencer St. -weepy outcropping
vi. 600 block of S. Cayuga St. -plant treated effluent water running parallel to the east side of the street
B. Sampling Strategy
49
Our spring water sampling strategy consists of collecting and analyzing duplicate
water samples from identified springs while they are active. Collaboration with
homeowners should be established to monitor the springs and determine appropriate
timing for each sampling event. Analysis of the collected samples could be done in a
qualitative way, as the concentration of dissolved TCE will undoubtedly be lower in the
exposed spring water than in the unexposed ground water. This weakened concentration
is attributed to the ambient contact and agitation of spring water as it emerges from its
source, increasing the chances of TCE volatilization from its dissolved state. The
sampling period is intended to last from the time the water starts to flow until water yield
from springs is exhausted for the season, and sample collection should initially be done
with a frequency similar to that of basement air sampling.
C. Sampling Method
NEMI Method 524.2 - VOCs in Water Using GC/MS
Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry Sources: U.S. EPA National Exposure Research Laboratory (NERL) Microbiological and Chemical Exposure Assessment Research Division (MCEARD)
The methodology selected calls for the utilization of 40 mL of pre-acidified glass
bottles to collect the liquid samples. The amount of acid should be approximately 2 drops
of 1:1 HCl to adjust the water pH to less than 2. This will prevent further degradation of
the compound of interest until time of analysis. All samples should be collected in
duplicate, minimizing agitation of the water as it enters the sample bottle. The bottles
should be overfilled with no bubbles or headspace and capped tight so as to not lose the
sample during storage time. The lid or septum used to cap the bottles should not be made
50
of silicon as this material absorbs volatile compounds. Teflon is a recommended material
when TCE is the compound of interest. Samples should be stored at less than 4oC (38oF)
until analysis.
D. Method of Analysis
NEMI Method 524.2 is applicable for VOC concentration ranges of 0.02-200μg/L.
From Section 2, concentration greater than about 1 μg/L may be of concern. For this
particular method, an inert gas is bubbled through a water sample to purge volatile
organic chemicals into the container’s headspace. Once in the gas phase, the compounds
are trapped in a tube containing a suitable sorbent material (typically use a specific type
of activated charcoal for the detection range desired) in order to concentrate them. The
tube with concentrated and adsorbed VOCs is then heated to desorb the trapped
compounds and is then directly injected to the Gas Chromatograph where they are
analyzed.
E. Discussion
At a meeting in April with Cornell students, the DEC expressed interest in collecting
data from spring water samples. Proper documentation and permission to enter residents’
property is a time consuming and required procedure that the department would need to
obtain in order to collect this data themselves. Due to the heavy workload and time
constraints of the DEC, spring water sampling has been postponed for its time-consuming
preparation work, which they currently are not able to contend with. Cornell students on
the other hand have the advantage of requiring only informal permission from
homeowners to enter and collect such samples in private property. During the earlier
weeks of the spring semester 2006, Mr. Carl Cuipylo (DEC geologist) had proposed
51
collaborative work with the TCE student group for sampling South Hill’s springs. He
proposed to provide the sampling equipment and have his laboratory perform the analysis
if Cornell students took it upon themselves to obtain permission from homeowners and
collected the water samples. Unfortunately, this arrangement could not be worked out for
the Spring 2006 semester.
F. Recommendations
Since some of the analytical equipment on campus was unavailable to conduct these
tests due to time and monetary constraints, the sampling of water was omitted for this
semester’s project. It would be advantageous to have the DEC reconsider working with
students to accomplish the sampling of springs in the future and have their laboratories
analyze the samples formally.
If in the future, students were to conduct water sampling and analysis, the thermal
desorber method may be exchanged with the solvent method presented in the following
section for analyzing air samples. This method consists of using carbon disulfide as a
solvent to desorb the concentrated compounds from the sample tube rather than heat.
Basement Air Sampling
Community members of South Hill have expressed strong concerns regarding the
biannual sampling strategy used to determine the toxicity levels of TCE in their homes.
Since the irregular sampling procedure from Emerson’s consulting company determines
which homes are eligible to receive mitigation as remediation action, South Hill residents
wish to confirm that the few samples collected are justifiable averages of the indoor
conditions within their homes. This matter beckoned the need for the development of a
sampling approach that would better account for time variations and could be extended
52
beyond the currently used temporal boundaries. Because of the limited financial
resources that Cornell students had available for this project, it was not possible to
undertake the expense of hiring a consulting firm to perform the necessary professional
analysis at the cost of $800 per sample. As an alternative, a more economic but still
official sampling and analytical procedure was selected that could be performed by
students using campus equipment.
A. Sampling Strategy
It is important to determine how well a single sample represents the long-term air
concentration of TCE in the basements of the community members. In order to
accomplish this, we propose that three to five houses with TCE indoor concentrations
close to the 5μg/m3 (1 ppbv) limit (The NYSDOE limit for indoor air, see Section 2)
and/or very high sub-slab concentrations be tested repeatedly over a period of several
weeks or months. The data from such samples would ideally provide some insight on the
variability of TCE concentrations over pre-established time intervals. The results could
then be used to determine weekly, monthly or seasonal trends. For shorter time intervals,
the results could be correlated to changing weather conditions such as precipitation and
temperature. Correlation to meteorologic and geologic/ground water observations should
be attempted. Determining correlations with outdoor temperature, barometric pressure,
rainfall, and the like could help establish optimum sampling conditions for indoor air
sampling of TCE. At present, indoor vapor sampling is conducted during the fall/winter
season because homes tend to have the windows closed, thus trapping intruded TCE
within the home. Most importantly, the results of the proposed detailed sampling and
53
analysis could confirm or refute that homes classified as ‘No Further Action’ are
truthfully out of risk.
Once this methodology is tested, and we are confident we can reliably measure TCE
levels in a house, samples from houses never tested could be taken, and the perimeter of
the affected area on South Hill determined more quickly and more cost effectively than is
possible under the current DEC/Emerson procedures. Additionally, because the
presented sampling methods do not require a particular type of slab or a degree of
basement sealant, these tests could theoretically be done in any basement with typical
humidity, and airflow conditions. Collected data will initially be analyzed for the
following parameters:
a. Time variations b. Spatial analysis c. Ground water level variations
B. Sampling Method
Three general methods of sampling were identified in this preliminary investigation:
1. Vacuum tube 2. Passive diffusion onto sorbent 3. Active sampling with sorbent The vacuum tube method is the simplest. Here a tube is evacuated, sealed,
opened in the air of interest, sealed again, and then taken to the lab for analysis. The
problem with this method is that the TCE in the sample taken is only as concentrated as
the TCE in the air, which is in our case below the detection limit of most widely used
analytical instruments. In addition, this method only provides a snapshot of the TCE
concentration of air in one location and at an instant of time, which might not be
representative of true average (over time) basement concentrations.
54
Sampling onto a sorbent material concentrates the compound of interest and
accumulates the sample over a protracted period. If the passive diffusion method is used,
then a certain amount of sorbent is passively exposed to the air of interest for a
predetermined period of time (see Figure 6-1 for passive diffusion sampler). If the active
sampling method is used, a pump is used to push air through the sorbent medium at a
constant rate, allowing a large volume of basement air to come into contact with the
sorbent material. The larger air volume that is exposed with the active sampling method
will theoretically provide a more realistic average (over time) of the entire room’s
contaminant concentration.
Figure 6-1: SKC Passive diffusion sampler for organic vapors. <http://www.skcinc.com/prod/575-001.asp> In order for any of these sampling methods to be effective, the concentration
collected must fall within the detection limits of the analytical instrument at hand.
Summaries of three methodologies developed by the Environmental Protection Agency
(EPA) and the National Institute of Occupational Health and Safety (NIOSH) are given
below. Full methodologies can be found at the websites in Appendix D.
55
EPA TO-15 EPA TO-15 Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air: Determination of Volatile Organic Compounds (VOC) In Air Collected In Specially Prepared Canisters and Analyzed By Gas Chromatography/Mass Spectroscopy (GC/MS)
The EPA method TO-15 can be used to detect VOC concentrations above
0.5ppbv (parts per billion in volume) in ambient air. The method requires the use of
vacuumed sampling canisters for sample collection. A known sample volume is removed
from the canister and injected into a GC/MS system. However, in order to achieve the
necessary sensitivity, the GC/MS must also have a sampling/concentrator system, which
allows a more concentrated volume of VOCs to pass through the detector.
EPA TO-17
EPA TO-17 Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air: Determination of VOCs in Ambient Air Using Active Sampling Onto Sorbent Tubes
This method can be used to measure VOC concentrations in ambient air between
0.5 and 25 ppbv. Samples are collected using a suction pump that draws air into a
thermal desorption sampling tube (see Table 6-1 for EPA recommended sorbent
materials) where the desired analyte is concentrated. The sample is analyzed using a
GC/MS unit (or a GC with a combination FID/ECD detector system). In order to remove
the VOCs from the sorbent, the GC must also have a two-stage thermal desorption unit.
The first unit heats the sorbent, releasing the VOCs in the sample. The secondary trap
unit traps and concentrates the sample once more for analysis by the GC/MS system.
This method is intended to detect between 27,000 and 875,000 ppbv in a 3.4-L air
sample. This method uses a suction pump (in our case, calibrated and reversed fish
aeration pumps were used) and sorbent tubes to collect the sample (see Figures 6-2 for
56
Table 6-1: EPA recommended sorbent materials.
Sorbent Strength Surface Area per gram Of Sorbent (m2/g)
Type of Sorbent
Weak < 50 Tenax® Carbopack TM/trap C Anasorb® GCB2
Medium strength 100-500 Carbopack TM/trap B Anasorb ® GCB1 All Porapacks and Chromasorbs
Strong 1000 Spherocarb ® Carbosieve TM S-II Carboxen TM 1000 Anasorb ® CMS series sorbents
NIOSH 1022
NIOSH Manual of Analytical Methods Method 1022: Determination of Trichloroethylene Using Sorbent Tubes, GC/FID, and CS2
active sampling set-up). Once the sampling period is over, the TCE is removed
from the sorbent material u--sing a solvent (carbon disulfide CS2) instead of the thermal
desorption unit used for the previous two methods. The extracted CS2/TCE solution can
then be injected directly into a GC unit with a flame ionization detector (FID) for
analysis.
Figure 6-2: Active sampling set-up.
57
A representative from SKC, the distributor of the sorbent tubes purchased for this
project, indicated that increasing the time over which the sample is taken and/or placing
sorbent tubes in series may lower the detection limit of this method. SKC strongly
discourages increasing the airflow rate as an unsafe alternative to decrease the detection
limit of the tubes, given that the higher airflow pressure may cause the glass tubes to
break.
C. Method of Analysis
After the collection period is over, the sorption tubes are removed from the sampling
set up, capped on both open sides, labeled, and packed securely for shipment to an
analytical laboratory. Once ready for analysis, the sorbent sections of each sample are
carefully pushed out of the glass tube and placed in individual 2 mL glass vials. Here 1
mL of carbon disulfide sorbent is added and the vials capped tightly. The sample is
allowed to stand for 30 minutes with occasional agitation. During this waiting period, the
gas chromatograph is set to pre-established operating parameters. A microliter syringe is
used to inject approximately 2 μL of the CS2 /TCE solution into the GC/FID for analysis,
and the mass of TCE found in the sample is calculated with an equation provided in
method 1022 from peak heights in the chromatogram. The chromatogram in Figure 6-3
shows the peaks expected for carbon disulfide and TCE at 4.29 and 9.18 minutes
respectively.
58
Figure 6-3: Chromatogram (carbon disulfide and TCE peaks).
D. Results & Discussion
The Civil and Environmental Engineering (CEE) and Microbiology departments were
approached to inquire about available instruments already set up for TCE analysis. The
CEE department indicated that several GC units could be made available, but none had a
detection limit low enough for the air samples of interest. Although one GC with an
electron capture detector (ECD) was stored in the basement, no one knew of its current
functionality since it had been out of use and disassembled for several years.
Dr. Eugene Madsen from the Microbiology department had both a GC/FID and a
GC/MS unit accessible to our group. However, no lab on campus had a thermal
desorption unit. Because of this we decided to gain experience with the NIOSH 1022
method. To distinguish between the mass of TCE and CS2 in the sample, it was found
necessary to modify the computer program that analyzes the chromatogram. The
59
parameters were changed with the aid of a skilled chromatographer, and the new program
saved for future use in the Microbiology laboratory.
New operating parameters:
Temperature injection (deg C) 53 Isothermic time (min) 6.0 Ramp rate (deg C/min) 20 Ramp max temp (deg C) 200 Isothermic time #2 (min) 0.5 Total run time (min) 13.85
Regrettably, mass balance calculations around the new sorbent tube mass and
extended sampling times showed that even with basement concentrations at the EPA’s
health limit, and sampling time of seven days, it was unlikely that the amount of TCE
captured in the sorbent tube would be sufficiently high for analysis with the NIOSH 1022
methodology.
When samples are collected it will be important to follow DEC procedures to assure
that the air samples are not compromised by household chemicals. These procedures are:
60
In addition, according to Ken Deshere “advice was passed from neighbor to neighbor as
"folk wisdom" - taking things outside of the house, packing cleaners and solvents into
plastic bins with lids sealed on with duct tape.” Household products commonly
containing TCE include: glues, adhesives, paint removers, spot removers, rug cleaning
fluids, paints, metal cleaners and typewriter correction fluid. Care should be taken to
follow the same procedures as were followed in previous sample collection.
Conclusions
• The equipment at the Civil and Environmental Engineering, Microbiology and
Biological and Environmental Engineering departments of Cornell University is
available for TCE analysis, but a key piece of equipment (a thermal desorber) is
needed to increase existing equipment’s sensitivity.
• Even with the equipment measuring TCE at concentrations below 0.8 μg/m3, low
air concentrations may be difficult to analyze.
• Should a further study investigating air concentrations be undertaken by students
at Cornell University, we suggest:
1. Purchasing or renting a thermal desorber or an electron capture
detector to lower the chromatographic detection limit. In the past,
some companies have been willing to extend an “education”
discount to this kind of community improvement projects or
donate outdated, but still usable equipment. With a thermal
desorber the fish pump sampling method could be used to collect
and analyze samples following the EPA TO-17 methodology.
61
Although new sampling tubes would need to be purchased, the
thermal desorption tubes are reusable.
2. Solicit official analytical laboratories to analyze the student-
collected samples for an educational or no fee.
• Future testing should be pursued to determine changes in ground water levels and
seasonal changes affect TCE vapor intrusion into South Hill basements.
Contacts:
• VWR Scientific Products-(CS2 supplier) <http://www.vwrsp.com> Daniel Frank – Cornell University campus sales representative [email protected] (800)947-4270 x 4238 (607) 564-0521 (FAX) (800)932-5000 (VWR)
• EMD Chemicals Inc.-(CS2 carrier) <http://www.emdchemicals.com/analytics/EMD_Analytics.asp> (800) 222-0342
• SKC Inc.-Gas and vapor sampling equipment. (Sorbent sample tube supplier) <http://www.skcinc.com/product.asp> Sales department (724) 941-9701
• PETCO-(pump supplier) Account info: Tammo Steenhuis, [email protected], account pass word 1234vero, sm4y6 (petco discount)
• John Terry-Cornell University Chemical Collector [email protected] (607) 255-4389
• Carl Cuipylo DEC Geologist [email protected]
• Dr. Eugene Madsen–Laboratory contributor Department of Microbiology B57A Wing Hall Office phone (607) 255-2417 Laboratory phone (607) 255-6030 [email protected]
• Dr. Jack Liou-Post-Doc, Gas Chromatography expert Department of Microbiology B75A Wing Hall Office phone (805) 531-3185
62
• Dr. James Gossett–researcher and consultant on remedial action technologies for contaminated land and ground water.
Department of Civil and Environmental Engineering 319 Hollister Hall [email protected]
63
Section 7: Subsurface Transport of TCE M. Ekrem Cakmak
TCE is a colorless solvent with an odor similar to ether. TCE liquid is denser than
water (1.46 g/cm3 > 1.00 g/cm3); this results in the fast downward movement of TCE
through soil until it encounters an impermeable layer. After being confined, TCE will
form Dense Non-Aqueous Phase Liquid (DNAPL) pools. These pools may then dissolve
in water moving past them. The TCE in the water may then sorb onto soil particles, or
degrade under the action of bacteria. This is illustrated for PCE DNAPL by Clement et
al. (2004) in Figure 7-1.
Figure 7-1: Transport processes in subsurface from Clement et al. (2004)
Solubility of TCE in water is 1100 mg/L). This relatively low solubility means that
TCE pools will be dissolved very slowly in the subsurface, and, since there is little TCE
in the water, biodegradation will also be slow (Russell et al., 1992). However, TCE is a
very volatile chemical. It prefers to be in gas phase rather than the liquid phase. Because
of this, the lifespan of TCE in the unsaturated zone can be much less than the lifetime of
64
TCE in the saturated zone (Kueper et al., 2003). TCE will volatilize as it moves
downward through the unsaturated zone above the water table. The TCE-laden air may
vent to the atmosphere or into basements (see the section on Vapor Intrusion). Also
because TCE vapor is 4.5 times denser than air, it can drain gravitationally down slopes
in the water table or other barriers impermeable to it in the subsurface.
Figure 7-2: Mean annual earth temperatures at individual stations,
superimposed on well-water temperature contours. (http://www.geo4va.vt.edu/A1/A1.htm)
TCE can be adsorbed by soil to some extent. However its retardation due to
adsorption is negligible (Russell et al., 1992). The retardation factor for TCE is two,
meaning that it will move half as fast as the water in which it is dissolved.
Biodegradation of TCE depends on many factors such as geology, hydrology,
solubility, climate, and microbial flora of the area. There are two kinds of biological
degradation that can occur for TCE. The first is aerobic, performed by aerobic
microorganisms, which occurs in the presence of oxygen; the second is anaerobic, which
65
occurs in the absence of oxygen. Aerobic microorganisms need oxygen in order to
degrade substances through oxidation. Since TCE is at a highly oxidized state, it does not
submit easily to degradation by aerobic microorganisms. However, there is way to
degrade TCE aerobically under certain conditions (Olniran et al., 2004). Anaerobic
microorganisms can only work without the presence of oxygen and generally need
moderate temperatures.
In the Ithaca region, groundwater temperature varies from 42 to 57º F (Figure 7-2)
and the water table on South Hill can be quite deep (Figure 5.3). Conditions on South
Hill are thus not favorable for biodegradation of TCE. However study of new methods of
bioremediation might be warranted
66
Section 8: Mechanisms of TCE Transport at South Hill Adrian Harpold
Deep Percolation of TCE into the Bedrock
It is the opinion of this study that deep percolation of TCE into the subsurface at
South Hill is likely to have occurred TCE liquid is heavier than water and will displace
water and move vertically downward until it is impeded by a low permeability layer or
dissolves and/or degrades (Figure 8-1). In fractured bedrock, TCE will occupy fractures
smaller than water (because it is denser) and accumulate. Typical fractured rock can
store between 200 mL and 2 L of TCE per cubic meter of bedrock (about 0.1% by
volume) (Keuper et al., 2003). If sizeable pools of TCE accumulate or if groundwater
access to TCE accumulations is minimal, the TCE accumulations may remain in the
subsurface for a very long time (order of hundreds of years).
67
Figure 8-1: One possible scenario for TCE transport in a fractured bedrock (UK Environmental Agency, 2006). This scenario seems plausible for South Hill because fractures are present there and TCE contamination has persisted long after any possible spill. TCE stored in fractured or jointed rock is very difficult to remediate. Figure is from Keuper et al. (2003).
Unfortunately, the geology at South
Hill is conducive to TCE transport in the
bedrock. The bedrock is highly fractured
perpendicular to the surface and bedding
planes occur parallel to the surface. The fire
reservoir may have introduced TCE directly
into the fractured bedrock. Well
measurements near the fire reservoir on the
Emerson site show the highest concentrations
of TCE in the shallow fractured bedrock; Figure 8-2: Process of transport and back-diffusion in a simplified fracture channel. . Figure is from Keuper et al. (2003).
68
however, TCE is present in the glacial till as well as the deep bedrock. Concentrations
have decreased over time (1987-2003) in most monitor wells. This indicates that the
TCE is either moving down-gradient in fractured bedrock, or degrading, or being
removed by remediation efforts.
“Back Diffusion” of TCE in the Bedrock
If TCE is transported in fractured bedrock it will diffuse into the surrounding rock
(Figure 8-2). This is important because ‘back diffusion’ occurs after TCE is flushed from
the fracture. Even if TCE is present in a fracture for only a short time, back diffusion can
continue for many decades. This means that even if TCE is removed from some fractures
by remediation efforts, back diffusion may cause TCE contamination to persist for a long
period of time.
Contaminated Water Reaching the Surface
A likely transport mechanism for TCE at South Hill is water containing dissolved
TCE coming into contact with the pore space air, which then moves into basements.
Concentration of TCE in air in contact with contaminated water can be very high
(60,000,000 ppbv, see Section 2) compared to the levels of TCE tolerable in a basement
(1 ppbv). Only a little air entering a basement from the airspace provided by the tile
drains (see Figure 8-4) can therefore be a problem. As commented earlier, movements in
the ground water table can propel pore space air.
Many basements on South Hill are damp at least at times. Only a very small
amount of contaminated water can produce significant levels of TCE in the basement air.
Figure 8-3 shows how much water is required to raise TCE levels in a 40 X 40 X 10 ft
69
basement to 5 ppbv, assuming that the TCE in the water degasses totally into the
basement air once the water enters the basement. If TCE is saturated in water (1100
mg/L), approximately 10 cm3 of water is required to raise the basement TCE levels to 5
ppbv. This volume is about the size of a grape. Well measurements on South Hill
indicate that groundwater concentrations of TCE are less than 300 mg/L and are usually
on the order of 10 μg/L. At 300 mg/L about 5 grape volumes would be required, and at
10 μg/L a very large amount of water would be required (more than 250 gallons).
Volume vs. Concentration necessary to Exceed 5 ppb TCE in the air
0
50
100
150
200
250
300
350
400
450
0 200 400 600 800 1000
Conc. (mg/L)
Vw (c
m^3
)
Figure 8-3: Graph of Concentration of TCE in water versus the volume necessary to achieve 5 ppb TCE in the air of a 40 X 40 X 10 ft basement. Even at low concentrations only a very small amount of water will cause dangerous air quality.
70
Figure 8-4: Schematic of a house where tile drains are used to drain a high water table. This common situation is problematic because the basement walls may come into direct contact with TCE-contaminated air or water. Figure is from McAlary (2002).
Another means of water and TCE reaching the surface is through seeps. Despite
reports of TCE-type smells at the surface, TCE was not found in the seeps nearby the site.
However, it may be necessary to sample during and after storms, which could cause
different flowpaths to become active. Despite this, it is the opinion of the authors that the
fractures are probably highly flushed and not a major transport pathway at normal flows.
Degradation of TCE in Soil
Degradation of TCE in soil and groundwater is poorly understood. As explained
in the previous section, TCE degrades best under anaerobic conditions. We speculate
that TCE degradation is relatively small because of the low temperatures in the ground
water (reactions are slower at lower temperatures). Previous consultant conclusions were
that TCE may have been present long enough to completely or mostly degrade are
questionable in our opinion because: Measurements over long-periods of time are only
71
available for wells near the fire reservoir. These measurements show decreasing TCE
levels, but do not account for loss of TCE from the remediation system. Additionally, the
byproducts of TCE breakdown do not seem to be sufficient to explain all of the reduction
in TCE. Finally, byproducts do not verify degradation because the original industrial-
grade TCE that was spilled likely contained byproducts.
Diffusion of TCE in Soil and Air
Diffusion is the random movement of molecules and a possible cause of TCE
vapor movement to the surface. A rising water table could introduce TCE-contaminated
water to rock or till at shallower depths. As the water table falls the TCE-rich water is
left clinging to minerals and the TCE will volatilize into air filling the pores. It can then
diffuse through or move with the air. A soil-gas survey performed on South Hill in 2005
found TCE (among five other VOCs) at concentrations from 39.3 to 536 μg/m3 (7.3 to
100 ppbv) (ESC, 2005). This suggests this mechanism may be important at South Hill.
The rate of diffusion depends on the concentration of TCE in the groundwater, how close
the groundwater comes to the surface, and temperature. Results found by other
researchers indicate that diffusion can be a dominant mechanism for TCE loss (Env. Sci.
Tech.). On the other hand, a study by the Department of Energy found that passive
diffusion only contributed 5% of the total TCE transfer to the air (DOE). An illustrative
calculation is given in Appendix C.
72
Groundwater encounters soil contamination and adds to advective transport
Capillarity hold some groundwater with VOCs above the water table which
increases diffusion
Figure 8-5: The rising water table can move TCE into the soil pores near the surface. The closer vapor is to the surface, the more diffusion will contribute to TCE in indoor air. Figure is from McAlary (2002).
Vapor Intrusion of Contaminated Soil Air
Vapor intrusion is the process by which TCE-contaminated air in the soil pores
moves up to the surface and into buildings. Some factors that contribute to the vapor
intrusion problem at South Hill are as follows: steep topography, shallow soils, and
fluctuating water tables. No differentiation is typically made between diffusion (random
movement of TCE molecules) and other vapor intrusion mechanisms. However, it should
be noted that diffusion is a constant slow process, whereas other vapor intrusion
mechanisms, which are driven by movements of the water table or changes in barometric
pressure, can be episodic, and at times can transport TCE much more rapidly than
diffusion alone.
Gas-phase TCE is 4.5 times heavier than air and therefore can move down steep
gradients in the water table through the overlying strata (Figure 8-8). TCE could reach
73
the surface if the hillside intersects the strata through which the TCE-saturated air is
draining. Disturbances to the subsurface, such as pipes, can allow gas-phase TCE to
move preferentially (Figure 8-7).
The ‘Stack Effect’ is a recognized mechanism that brings TCE into residences in
the winter (Figure 8-6). When the home is being heated (or is warmer than the outside)
the pressure difference will move air out of the top of the house and draw air from the
basement. This may be part of the rationale for testing air quality in the winter.
However, testing at additional times in the year would help determine if the Stack Effect
is an important TCE transport mechanism at South Hill.
74
Figure 8-7: Vapor intrusion along a below-ground sewer pipe. The TCE vapor displaced by water or diffused along subsurface. Figure is from McAlary (2002).
Figure 8-6: Diagram of ‘Stack Effect’. Warm air in the house rises out of the top and air is moved into the house from other sources (including soil air). Figure is from McAlary (2002).
Movement of vapor TCE along water table
Figure 8-8. Possible scenario for TCE movement in shallow soil. TCE-laden air in the soil layer above a perched water table could drain down along the top of the water table and drain out near where the perched water table is intersected by the surface (at second house, for example). Figure is from McAlary (2002).
75
Section 9. Operational Suggestions
Entire group including Cathles, Steenhuis, (and Gillett?)
An executive summary of this document is provided at the beginning. Here we
give our perspectives on issues confronting the community.
1. The most important concern is human health, and the most immediate need is to
assure that all of the households that could be affected by TCE contamination are
either tested or appropriately mitigated such that testing is forgone. Figure 3-1
shows that only about ¼ of the potentially affected houses have been tested.
Means should be found to quickly test the houses in this area that have not yet
been tested, in order for these residents to assess the extensive use of basement
facilities or consider mitigation. As an alternative, the presumption would be that
houses would be appropriately mitigated.
2. The concern is with low levels of volatile organic chemicals (VOCs) in indoor air.
Low levels of TCE in drinking water appear (Section II) to be the more serious
health risk, but this is not a factor in South Hill. All residents are served by city
water, which has no TCE contamination.
3. So far 31 of the 89 basements tested (35%) show measurable levels of TCE. The
TCE concentration of all but 3 of the basement samples are below the current
indoor health threshold of 5 μg/m3 (1 ppbv). This does not necessarily mean it is
safe to work for prolonged periods (decades) in these basements, or that the low
level exposure is not hazardous to the young, old, or particularly susceptible. We
do not know the health effects of very long exposure to low levels of TCE.
However, the TCE contamination is low enough that, with mitigation, exposure
76
levels will approach those that would normally be encountered in the human
environment. TCE is a very widely used chemical.
4. The repeatability of the indoor air TCE measurements to date is good. The
standard error of repeat sampling appears to be about 1 μg/m3 (0.2 ppbv).
However, the short-duration of sampling to date cannot preclude that higher levels
of contamination might have episodically occurred.
5. The cost of collecting and analyzing indoor air samples to determine if a house
has TCE in basement air is similar to the cost of mitigating many houses by
installing pumps to sparge the subslab airspace. Because of this, it may make
sense to reduce repeat testing prior to mitigation and offer mitigation to any
homeowner in the potentially affected area that requests it, regardless of the level
of TCE in the tested air. Houses that require extensive repairs or changes (such as
pouring a concrete floor) to seal the basement will be more expensive to mitigate.
Follow up testing to assess the efficacy of mitigation might still be needed.
6. So far about 35% of the homes tested have detectable TCE in basement air, and so
far the sales price of houses on South Hill have risen at the same rate as houses in
Ithaca in general. Since a major concern of homeowners is a decline in house
value, it might make sense to guarantee the house values on South Hill continue
to track the Ithaca average. Under this suggestion, if all offers on a South Hill
house fell below the Ithaca-wide market value for a comparable house, the
homeowner would be reimbursed for the difference between the projected market
value and the top offer received upon acceptance of that offer.
77
If these steps were taken, it appears to us that the adverse consequences to
homeowners of the TCE contamination could be largely contained. The cost of these
steps would not seem to be unduly large, so they may be worth considering. At the same
time, steps could continue to remediate the South Hill area. Because of the fractured
nature of the bedrock and the likely very wide dispersal of the TCE DNAPL, we are not
optimistic that economically feasible or visually acceptable remediation will have much
impact on subsurface TCE contamination, but any reasonable remediation steps should be
considered.
The greatest need as we see it is to define the extent of contamination and
determine the variability of TCE in South Hill basements. The application of methods of
long term monitoring may be particularly valuable. Inexpensive sample collection and
analysis might be provided by Cornell as a community outreach service. This may be the
best way for Cornell to continue to help the South Hill and broader Ithaca community.
78
Appendix A. Glossary of Terms
Activated charcoal: Treated charcoal with increased ability to have chemicals adhere to
it. Adsorption: The gathering of a gas, liquid, or dissolved substance on the surface or
interface zone of another substance Advection: Transportation of contaminants by the flow of a current of water or air Aerobic degradation: Degradation in the presence of air Anaerobic degradation: Degradation in the absence of air Aquifer: An underground geological formation, or group of formations, containing
water; sources of groundwater for wells and springs. Bedrock: solid rock that lies beneath the soil layers Biodegradation: Decomposition (or degradation) of a compound in sequential steps
mediated by biological activity. Carrier gas: The gas that carries the sample in gas chromatography. Chromatographic program/operating parameters: A temperature program that burns
off the compounds in a sample under specified parameters so that each individual substance can travel through the gas chromatograph at known time and temperature.
Conjugation: Alteration of a compound during metabolism by binding to a substance
(typically glucose or glutathion) with a carboxylic acid group. This makes the chemical biologically inactive (generally), water-soluble, and prepares it for urinary excretion in the body.
Degradation: Chemical or biological breakdown of a complex compound into simpler
compounds Dehalogenation: Removal of a bonded halogen (in the case of TCE the chlorines are
halogens) from a chemical. Dense Non-Aqueous Phase Liquid (DNAPL): A liquid that is not water-based (and
does not easily dissolve or mix with water (i.e. immiscible)) and is denser than water. It therefore sinks to the bottom of a well or body of water.
79
Detector: Device that senses and receives a signal (associated with particular and individual chemicals) that is used to process information.
Dispersion: the spatial property of being scattered about over an area or volume Dissolution: Process where a substance is dissolved into a liquid. Electron capture detector (ECD): A type of detector that measures loss of electrons as
individual substances pass through the Gas Chromatograph. Flame ionizing detector (FID): A type of detector that measures changes of current as
individual substances pass through the Gas Chromatograph. Gas chromatograph (GC): A method of separating and measuring individual substances
in a mixture. Genotoxicity: Adverse health effect from a compound that causes a genetic mutation,
which can lead to the development of tumors. Glacial till: the type of topsoil found on South Hill. It is made up of clay, sand, and
gravel-sized pieces of soil and rock mixed together. Headspace: The volume left at the top of a filled bottle before sealing. Heptatoxicity: Adverse health effect from a substance that alters the normal function of
the liver. Hydraulic Head: The elevation of water in an open well. Hydrolysis: Degradation of a chemical compound by breaking bonds that split up the
parent compound using water (H20). One of the parts get an OH and the other gets an H from water.
Impermeable Layer: A layer of material (e.g. clay) in an aquifer through which water
does not pass Joints: Natural fractures in rock that cause it to break into regular, evenly spaced blocks Koc: Organic carbon partitioning coefficient. Gives an estimate of how readily a
compound will be in the organic matter in soils. Larger numbers correspond to higher organic matter partitioning.
Mass spectrometry (MS): An instrument used to identify chemicals in a substance by
their mass and charge.
80
Matrix (rock): Enclosing rock or soil. For example, the open spaces between soil and rocks are called pores. The pores are in the rock/soil matrix.
Mineralize: Degradation of an organic substance into an inorganic phase. Generally
refers to the complete degradation of a compound into CO2 and water. In the case of TCE, mineralization would result in chloride ions, CO2 and water.
Multisorbent concentrator: Equipment used in conjunction with gas chromatography to
concentrate the sample before it is analyzed. Nephrotoxicity: Adverse health effect from a substance that alters the normal function of
the kidneys. Neurotoxicity: Adverse health effect from a substance that alters the normal function of
the nervous system. Oxidation: Oxidation is the addition of oxygen, removal of hydrogen, or the removal of
electrons from an element or compound. In the environment, organic matter is oxidized to more stable substances.
Permeability: The degree to which groundwater can move freely through an aquifer Photolysis: Degradation of a chemical compound by breaking bonds with light energy. Reductive Dehalogenation: Chemical reaction where a halogen (in the case of TCE this
would refer to the chlorides) is replaced with a hydrogen. Saturated zone: The area below the water table where all open spaces are filled with
water under pressure equal to or greater than that of the atmosphere. Siltstone: A fine-grained sedimentary rock similar to shale, but slightly coarser grained.
Water does not flow easily through unfractured siltstone. Solvent: A liquid (carbon disulfide in this case) that can dissolve a substance. Sorbent: A material (activated charcoal in this case) that has the capacity of adsorbing
another substance (TCE). Sorption: Can refer to either absorption or adsorption. Absorption is the incorporation of
a substance from one state into another (i.e. substance A goes into substance B). Adsorption is the physical binding of a substance onto the surface of another molecule (i.e. substance A is on the surface of substance B).
Thermal desorber: A laboratory instrument used as a type of oven to accelerate
volatilization of compounds from sampling media (the media in this case is activated charcoal).
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Unsaturated zone: The area above the water table where soil pores are not fully
saturated, although some water may be present. Volatile organic compound (VOC): Organic substances, which easily become vaporous
or gaseous. Volatility: The ability of a material to evaporate.
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Appendix B. GIS Maps
Figure B1: The spacial location and extent of the area potentially affected by contamination. Property parcels, city roads, streams, and waterways digital data are from the Thompkins County ITS/GIS website: ithacamaps.org. Elevation digital data from the United States Geological Survey website: www.usgs.gov
83
Figure B2: Map of the orientation of joint sets measured by Carl Carl Cuipylo of the New York State Department of Environmental Conservation, and provided for this report via personal communication. The black lines which form right angles show the directions of the fracture planes from several fractures measured on South Hill. Note that most of the fractures point nearly north/south and east/west, and that there are many more fractures on South Hill than are depicted here. Property parcels, city roads, streams, and waterways digital data are from the Thompkins County ITS/GIS website: ithacamaps.org.
84
Figure B3: Location of soil vapor and groundwater monitoring sites, digitized from DOH maps provided as handouts at the February 2006 public meeting. Property parcels, city roads, streams, and waterways digital data are from the Thompkins County ITS/GIS website: ithacamaps.org.
85
Figure B4: The utility lines buried underground in the area of interest. Data digitized from ithacamaps.org and from Figure 4 of "Onsite Assessment of Former BorgWarner-Morse Chain Facility 620 N Aurora St. Ithaca, NY", a report prepared by Environmental Strategies Consulting, received at the Thompkins Couty Public Library on December 13, 2005. Property parcels, city roads, streams, and waterways digital data are from the Thompkins County ITS/GIS website: ithacamaps.org.
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Appendix C: Relative Magnitudes of Diffusion and Vapor Intrusion Adrian Harpold
Goal: Find the relative importance of diffusion of TCE through the soil versus vapor
intrusion caused by water table movement.
Estimating Diffusive Flux:
Using Fick’s law the diffusion flux can be estimated for several different scenarios:
dXdCDJ ed −= , where Jd is the diffusion flux, De is the adjusted diffusion coefficient, C is
concentration and X is distance. Diffusion (D) of TCE in air can be estimated to be 0.1
cm2/s or 8500 cm2/day. Equivalent diffusion (De), accounting for diffusion through soil
pores, can be estimated using 2
3/10
φφa
e DD = , where фa is the air filled porosity (0.2) and
ф is the total porosity (0.4). As a result De equals 2500 cm2/day.
Distance to water table (m)
Dissolved Concentration
(mg/L)
Difference in Vapor Concentration
(ug/m^3) between surface and groundwater
Diffusion flux (ug/m^2/day)
1 0.0001 26.3 6.575 1 0.004 1052 263 5 0.0001 26.3 1.315 5 0.004 1052 52.6
10 0.0001 26.3 0.6575 10 0.004 1052 26.3
Estimating Flux of TCE from Rising Water Table:
Flux of vapor TCE caused by a rising water table can be estimated using
φ∗∗Δ= CGJ W , where J is the vapor intrusion flux, ΔGW is the height the ground water
87
rises, and ф is the porosity of the soil. This method assumes that the air in the pores
above the water table contains vapor TCE. The flux of TCE from vapor intrusion is
estimated for various changes in water table height and TCE concentrations.
Change in GW table (m/day)
Vapor Concentration
(ug/m^3)
Vapor flux (mg/m^2/day)
0.5 26.3 2.630.5 1052 105.2
1 26.3 5.261 1052 210.42 26.3 10.522 1052 420.8
Conclusion:
Vapor TCE fluxes are similar for diffusion and vapor intrusion for the scenarios given.
However, the scenario for vapor intrusion is valid when the groundwater table is rising,
which only occurs during small portions of the year. Diffusion of TCE occurs at all times
and therefore is a more critical TCE transport pathway.
88
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