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ATSDR obtains the community's concerns, and other medical, toxicological, demographic, andenvironmental factors that may affect the health of a community exposed to hazardous substances. Todetermine if health effects are likely to occur within the community, ATSDR health professionalsconsider the toxicity of the contaminant, the concentration (how much), the time of exposure (howlong), and how the chemical gets into the body (breathing, eating, drinking, or skin contact). Inaddition, other factors are considered; occupation, personal habits, age, nutritional status, generalhealth, and genetics. These factors affect how a contaminant is absorbed, distributed, metabolized,and eliminated from the body. Contaminants are evaluated in a health assessment to determinewhether exposure to them has public health significance. ATSDR selects and compares on- and off-site concentrations of contaminants with ATSDR comparison values for noncarcinogenic andcarcinogenic effects. Comparison values are concentrations of contaminants in specificenvironmental media (air, soil, drinking water) that are not expected to produce an adverse healtheffect in people who are exposed. These values are used only as screening values, listing acontaminant in a table of "chemicals of concern" does not mean that it will necessarily causeadverse health effects if exposure occurs at that specified concentration. When the concentration ofa contaminant detected on or off the site is above the comparison value it is further evaluated todetermine the potential for adverse health effects. The focus of the evaluation is on health effectsthat could plausibly result from exposures to site related contaminants. ATSDR considers bothadults and children when developing comparison values. The potential health effect on children isconsidered separately since in certain situations children may be more sensitive and more exposed tocontaminants. Finally, ATSDR presents its conclusions and recommends appropriate actions.

On-site Air Sampling

Limited air sampling data are available for the Yaworski Landfill site. No ambient air data wereavailable to review for this site evaluation. ATSDR reviewed the available environmental datawhich included 1994 soil gas sampling data collected at various on-site locations around theYaworski Landfill, and soil gas sampling conducted at the riser pipes and at random sites on theformer "active" landfill area in December 1995 to 1996.

Landfill Soil Gas Sampling Data (1994)

Limited landfill gas sampling was conducted at the Yaworski Landfill on four occasions fromNovember thru December 1994 (12). The first air sampling was conducted on November 21, 1994;three samples were taken at the bulky waste and six at the closed municipal solid waste sections ofthe landfill. Because all samples exceeded the nitrogen concentration, they were considered invaliddue to intrusion of ambient air and not analyzed further for organic compounds. Therefore, thesesamples were invalidated when the quality assurance/quality control procedures were applied. Tensamples (A-1 to A-10) were obtained from the former "active" landfill section on November 30,1994. The third sampling event occurred on December 12, 1994; three samples (A-4, A-7, and A-8) were taken at the former "active" section, six samples (C-1 to C-6) were taken at the closedsection, and one sample (B-3) was taken at the bulky waste section of the landfill. The last samplingevent occurred on December 22, 1994. Three samples (A-11 to A-13) were taken at the former "active" section and three samples (B-1, B-2, and B-4) were taken at the bulky waste section of the landfill.

Random samples were also analyzed for methane and carbon dioxide. Methane gas was not detectedat the bulky waste section of the landfill. Methane concentrations detected at the closed sectionvaried with a maximum detection of 57.4% by volume (C-3 #2). Five samples taken at the former"active" section of the landfill demonstrated the presence of methane production whereconcentrations ranged from 49.7% (A-12) to 62.7% (A-5) by volume. Methane forms explosivemixtures in air and the hazard range for explosions is 5 to 14% methane with 8.5 to 9.5% methanethe most dangerous (13). Air that contains above 14% methane by volume, burns without noisewhen ignited. Methane is a tasteless, odorless, colorless liquid that can be produced naturally duringanaerobic fermentation processes that occur in some landfills. It is extremely flammable and maybe ignited by heat, sparks, or flames. Depending on weather conditions, areas where methaneproduction has been detected above the upper explosive limit have the potential to rapidly drop intothe potentially explosive limit (5 to 14%). Methane may replace available oxygen particularly in lowlying areas on-site and presents a potential health hazard to workers and other persons visiting thesite. In addition, methane migration was known to be moving toward the residential areas in thepast, potential also exists for accumulation of methane in the confined areas of basements. Therefore, ATSDR recommends ambient air sampling onsite and in the basements of residents livingnear the active landfill to better characterize methane migration.

Table 1 provides a list of contaminants, detected in soil gas samples collected in 1994 at theYaworski landfill site, which are above ATSDR's comparison values and the odor detectionthreshold range established for specific contaminants by the American Conference of GovernmentalIndustrial Hygienists (ACGIH) (14, 15). The odor detection threshold range is the best estimate ofthe concentration range of a specific chemical where the odor is recognizable and is determined by anumber of physical and chemical factors. ATSDR provided a consultation regarding this data to CTDEP in April 1996 (12). There was some question regarding the sampling method/shipment and theaccuracy of the contaminant concentrations reported. Samples from the bulk waste section andclosed section of the landfill demonstrated similar contaminants. In general, the former "active"section of the landfill had the highest contaminant concentrations. Fourteen chemicals were detected(Table 1) in gas samples obtained on-site in 1994 that were above health comparison values and odordetection threshold values including aromatic hydrocarbons (benzene, toluene, ethylbenzene,trimethylbenzene, and xylenes), chlorinated aliphatic hydrocarbons (1,1-dichloroethyne, 1,4-dichlorobenzene, fluorotrichloromethane, methylene chloride, tetrachloroethylene, trichloroethane,and vinyl chloride), hydrogen sulfide and methyl ethyl ketone. The highest concentrations weredetected in sampling sections A-1, A-2, A-5, and A-10, along the north and northeastern section ofthe open landfill, nearest to Packer Road. It is unlikely that people would be exposed to contaminantlevels detected from soil gas samples collected several feet below the surface of the landfill. However, the former "active" section of the landfill remains uncapped and during periods ofexcavation activities, workers on-site and persons frequenting the recycling area of the landfill wouldbe potentially exposed to these contaminants (Table 4, Appendix A). Residents may potentially beexposed to these contaminants during wind shifts and during seasonal weather changes (Table 5,Appendix A). Ambient air sampling data are not available and represents a data gap to evaluatepotential on site and off site exposures.

Data Gaps

In the April 1996 consultation (12), ATSDR identified data gaps needed to make a determination ofwhether landfill gas exposures to residents living near the landfill would likely result in ill healtheffects. The following recommendations to obtain air sampling were made: 1) Conduct perimeterambient air sampling to determine if residents and off-site workers are exposed through inhalation ofcontaminants released from the landfill. Initially, additional sampling should include EPA prioritypollutants, VOCs, volatile sulfur compounds, ammonia/amines from the landfill vents, the gasmigration interceptor trench, and leachate. 2) Perimeter sampling should be conducted for arepresentative and/or worst case time period/conditions, to include meteorological data, andsampling locations closest to the residential areas. 3) Until soil migration is better characterized,ATSDR recommends that methane monitoring be conducted in the basements of residents livingadjacent to the former "active" landfill. Initially, conduct a screening survey to identify animmediate problem, if identified, continuous sampling for a year is recommended to ensure thatmethane concentrations do not fluctuate to significant levels with seasonal weather changes.

Since a landfill matrix consists of a wide range of heterogenous waste streams, the air sampling datacollected in 1994 may not represent the contents of the area to be excavated. Excavation activitiesmay have adverse health effects to off-site residents or on-site workers, especially because of thelevels of hydrogen sulfide and other contaminants identified on site may cause odors from airemissions, fires, explosions, and cave-ins. The following sampling is recommended to address theseissues; 1) On-site air monitoring and continuous sampling should occur in addition to perimetersampling when any excavation occurs. 2) Time-weighted air sampling should occur at the perimeterto ensure that excavation activities are not releasing significant contamination to off-site areas. 3)Establish action levels for air monitoring equipment, if the action level is exceeded on-site, a workslowdown or shutdown procedure should be employed to avoid reaching potential levels of healthconcern off-site. 4) Provide a site safety plan that defines worker protective devices, air monitoring,air sampling, and a contingency plan for an emergency situation to include a notification plan for nearby populations.

Table 1.

Yaworski Landfill - On-site Soil-Gas Sampling Results - November thru December, 1994a
Contaminant Concentration
Range (µg/m3)b
Location of Maximum Concentration Odor Detection Threshold Rangec (µg/m3) Comparison Value
Value (µg/m3) Source
Benzene ND-7,347.8 A-10 2,492-511,084 0.1 CREGd
12.8 iEMEGe
1,1-Dichloroethyne(DCA) ND-86,016.9 A-10 49-1,359 520 RBCf
1,4-Dichlorobenzene ND-22,848.2 A-2 <15 1202.5 iEMEG
Ethylbenzene ND-35,169.6 A-1 399-2,605 868.4 iEMEG
Fluorotrichloromethane ND-241,644 A-10 NA 73 RBC
Hydrogen Sulfide ND-68,410.9 A-2 0.001-0.18 125.5 iEMEG
Methylene Chloride ND-39,603.9 A-5 4,168-1,528,000 3.0 CREG
1042.1 iEMEG
Methyl Ethyl Ketone (MEK) ND-13,564.8 A-5 2-85 1000 RBC
Tetrachloroethylene (PCE) ND-949.6 A-10 2-71 2.0 CREG
271.3 cEMEG
Toluene ND-56,144.7 A-5 0.79-259,999 1809.4 cEMEG
1,1,1-Trichloroethane ND-192,626.8 A-10 87,310-3,896,191 3819.8 iEMEG
Trimethylbenzenes ND-24,185.5 A-1 0.006-2.4 6.2 RBC
Vinyl Chloride ND-409 C-1 #2 10-20 76.7 iEMEG
Total Xylenes ND-54,708 A-1 353-173,677 3,039.4 iEMEG

a Landfill gas sampling was conducted four times; November 21 and 30, December 12 and 22, 1994. The former "active" landfill was sampled all dates except November 21, 1994. (Fuss and O'Neill Inc.)
b µg/m3 = microgram per cubic meter
c American Conference of Governmental Industrial Hygienists (ACGIH)
d CREG = ATSDR Cancer Risk Evaluation Guide (see Appendix B)
e iEMEG = ATSDR Intermediate Environmental Media Evaluation Guide
f RBC = EPA Risk Based Concentration.

Air Modeling

To determine if residents living near the landfill were exposed to contaminants from air emissions,the CT DEP proposed collecting gas samples from the landfill to develop a database of landfillemission rates. These values would then be used to model the predicted off-site air emissions. AirModeling at the Yaworski Landfill was a two-phased project. The initial phase consisted ofobtaining data using an air sampling program to measure soil gas emissions. Samples were collectedand tested for volatile organic compounds (VOCs), semi-volatile organic compounds (sVOCs),methane, and sulfur compounds. These data were used with established air emission and dispersionmodels (16) to predict emissions from the closed, bulky waste, and the former "active" landfillsections. The model was used to predict the concentrations and location of contaminants that arelikely to be emitted from the landfill and impact the surrounding community.

Landfill Air Sampling Data (1996)

Soil Gas Core Samples

Soil gas samples were taken from 13 locations (A-1 to A-13) (Figure 3, Appendix A) within theformer "active" section of the landfill during the winter of 1995 to 1996 (17, 18). These 13 areaswere selected to better represent individual multiple-area sources for the landfill emission model.Three locations were sampled within each of the 13 areas. A stainless steel gas probe was driven to adepth of approximately three feet below the landfill cap for closed areas and five feet below thesurface for open areas. Summa canisters collected gas samples which were subsequently tested fornon-methane VOCs by gas chromatography/mass spectrometry. Table 2 lists the adjustedconcentration of the contaminants detected from these samples. Twenty-three of the thirtycontaminants detected were above health based comparison values. The location of the maximumcontaminant concentrations were near the recycling area and the north/northeast section of theformer "active" landfill near Packer Road.

Riser Pipe Stack Samples

The migration of landfill gas was reported to be moving toward the residential area. A gascollection system was installed and the eastern side of the landfill (closest to residential areas) wasexcavated and regraded. This portion of the landfill had previously been overfilled. In 1990, CTDEP required Yaworski Inc., to recover and burn gasses emitted from the former "active" landfill. The flare was constructed and went into operation in June 1993. Seven methane extraction wellswere placed in this area with more to be added at a later date. The system was shut downtemporarily in April 1994 due to diminished performance. Another gas flare system was installed inJanuary 1996.

A 500 foot (ft) long trench was excavated to intercept the horizontal migration of landfill gas throughthe soil. Three passive perforated pipes were placed vertically at 75 ft intervals along this trench andthe trench was backfilled. Air samples were taken from each of these riser pipe stacks (stacks 1 to 3or south, center, and north pipe) in the winter of 1995 to 1996 (17, 18) and analyzed for non-methane VOCs. Table 3 lists the organic contaminants detected in these samples. Theseconcentrations were used in the landfill emissions model as stack emission rates from point sources. Twenty-one of the fifty-eight contaminants detected were above comparison values.

Table 2.

Yaworski Landfill-Soil Gas Core Sample Results-December 1995 to1996a
Contaminant Concentration Range (µg/m3)b Location of Maximum Concentration Comparison Value
Value (µg/m3) Source
Acrylonitrile 21.7-368.8 A-1 2.0 RFCc
0.01 CREGd
Benzene 63.9-8,210.3 A-10 0.1 CREG
12.8 iEMEGe
Carbon Tetrachloride 62.9-818 A-2 0.07 CREG
314.6 iEMEG
Chloroform 48.8-634.7 A-2 0.04 CREG
244.1 iEMEG
1,1-Dichloroethane 40.5-96,177 A-10 520 MRLf
1,2-Dichloropropane 46.2-600.8 A-2 32.3 iEMEG
1,2 Dichlorobenzene 60.1-781.6 A-2 3.3 RBCg
1,4-Dichlorobenzene 60.1-29,221.6 A-2 1,202.5 i EMEG
Ethylbenzene 43.4-40,059.6 A-1 868.4 iEMEG
Fluorotrichloromethane 56.2-270,134.2 A-10 73 RBC
Hydrogen Sulfide 69.7-87,423.2 A-2 125.5 iEMEG
Methylene Chloride 34.7-45,544.5 A-5 3.0 CREG
1042.1 iEMEG
Methyl Ethyl Ketone (MEK) 29.5-25,390 A-11 1,000 RFC
Naphthalene 52.4-681.4 A-2 10.5 cEMEGh
Tetrachloroethylene (PCE) 67.8-1,695.7 A-6 271.3 cEMEG
Toluene 37.7-64,585.2 A-5 1809.4 cEMEG
1,1,1-Trichloroethane 54.6-215,381.9 A-10 3,819.8 iEMEG
1,1,2-Trichloroethane 54.6-709.4 A-2 0.06 CREG
0.11 RBC
Trichloroethylene 53.7-967.4 A-13 0.6 CREG
537.4 iEMEG
Trimethylbenzenes 98.3-43,602.7 A-12 6.2 RBC
Vinyl Chloride 25.6-332.3 A-2 76.7 iEMEG
Xylenes (total) 43.4-625,671 A-1 3,039.4 iEMEG

a. Soil gas sampling results obtained 1995 to 1996 from the former "active" landfill section of the Yaworski Landfill. (Anchor Engineering Services, Inc.).
b µg/m3 = microgram per cubic meter
c RFC= Environmental Protection Agency (EPA) Reference Concentration
d CREG = ATSDR Cancer Risk Evaluation Guide (see Appendix B )
e iEMEG =ATSDR Intermediate Environmental Media Evaluation Guide
f MRL = ATSDR Minimal Risk Level
g RBC = EPA Risk Based Concentration.
hcEMEG = ATSDR Chronic Environmental Media Evaluation Guide

Table 3.

Yaworski Landfill- Riser Pipe Stack Test Sample Results-December 1995 to1996a
Contaminant Concentration (µg/m3)b Comparison Value
South Pipe Center Pipe North Pipe Value (µg/m3) Source
Benzene 1,663.9 544.3 552.8 0.1 CREGc
12.8 iEMEGd
Bromomethane 348.6 410.5 416.9 194.2 iEMEG
Carbon Tetrachloride 541.2 0 0 0.07 CREG
314.6 iEMEG
Chlorbenzene 26,372.1 10,074 10,230.5 21 iEMEG
Chloroethane 18,918.6 2,527.0 2,566.3 10,000 RFCe
Chloromethane 859.3 650.7 660.8 413 iEMEG
1,2-Dibromo-3-Chloropropane 397.7 0 0 1.9 iEMEG
1,1-Dichloroethane 8,962.1 1,279.5 1,299.4 520 MRLf
cis-1,2-Dichloroethene 114.9 0 0 37 iEMEG
Dichlorfluoromethane 3,269 944 958.7 NA  
1,4-Dichlorobenzene 4,126.5 1,561.2 1,585.5 1202.5 iEMEG
Ethylbenzene 47,332.3 18,317.9 18,602.5 868.4 iEMEG
Isopropylbenzene 3,479.9 1,014.2 262.0 NA  
p-Isopropyltoluene 6,899.0 2,197.4 2,231.6 NA  
Methylene Chloride 464.5 481.3 489.0 3.0 CREG
1042.1 iEMEG
Naphthalene 308.1 0 0 10.5 cEMEGg
N-Propylbenzene 3,884.5 1,074.8 1,091.5 NA  
Styrene 1,027.7 258.0 262.0 255.6 cEMEG
Toluene 16,894.0 3,059.7 3,107.2 1809.4 cEMEG
1,1,1-Trichloroethane 2,168.4 0 0 3,819.8 iEMEG
Xylenes (total) 85,820.9 31,492.6 31,981.8 3039.4 iEMEG

a Riser pipe (stack) gas sampling results obtained 1995 to 1996 from the former "active" section of the Yaworski Landfill. (Anchor Engineering Services, Inc.).
b µg/m3 = microgram per cubic meter
c CREG = ATSDR Cancer Risk Evaluation Guide (see Appendix B)
d iEMEG =ATSDR Intermediate Environmental Media Evaluation Guide
e RFC= EPA Reference Concentration
f MRL = ATSDR Minimal Risk Level
g cEMEG = ATSDR Chronic Environmental Media Evaluation Guide

Air Modeling Results-Predicted Landfill Emissions

Environmental sampling data obtained from landfill gas core samples (estimates of area sourceemissions) and landfill vent (stack) emissions (estimates of point source emissions) were used alongwith other landfill factors (waste quantity, age, topography, and other physical features), andmeteorological data to estimate landfill contaminant emission rates (19, 20). Meteorological dataused for the model were obtained from the National Weather Service Station at Bradley Airport forthe years 1970 and 1972. Not all the same contaminants were sampled for during the gas coresampling and the stack sampling events. The model may under predict these contaminantconcentrations. Estimated emission rates were placed in a database of an air dispersion computermodel and used to predict one-hour average and annual average contaminant concentrations. Patterns of air dispersion to receptor locations surrounding the landfill site were also predicted bythis model. The Industrial Source Complex Model (16) was used to evaluate contaminantconcentrations from a variety of sources. ATSDR evaluated the use of this model for predictingemissions from the Yaworski Landfill (21). Emission rates from the 13 source areas and the threepoint sources (stack) were used to calculate ambient concentrations from the center of the landfill andto predict concentrations at receptor points. These receptor points were defined at the landfillproperty line and within a radius of 1000 meters with receptors located at 100, 200, 500, 600, 700,800, and 1000 meter intervals. The receptors were selected based on the worst-case wind directionfor landfill emissions and should include areas of nearby residences. In addition, three nearbyresidences were specifically selected as receptor points.

ATSDR reviewed the non-methane organic compound emissions and dispersion modeling proceduresfor the Yaworki landfill in September 1998 (21). The 1995 to 1996 landfill gas and the stacksampling data were reviewed along with the assumptions and predictions of the emission anddispersion models. Please refer to Appendix C for specific technical issues discussed.

In summary, ATSDR concludes that the methods used for evaluating the impact of air emissions ofnon-methane organic compounds from the Yaworski Landfill is sufficient as a screening evaluationof long-term and short-term impact, however, refined methods for sampling and modeling isrecommended. The annual and one-hour average concentrations of contaminants, predicted by theISCST3 model at the maximum receptor and at the three residential areas, were not at levels ofhealth concern. However, these contaminants were predicted from a source located in the center ofthe landfill and not at the location of the maximum contaminant concentrations detected fromprevious on-site sampling, which was identified near the recycling area and close to residential areason Packer Road. Due to limitations in the sampling, analysis, and modeling described above, thesepredicted values may not give a realistic evaluation of potential maximum exposures received by on-site workers, residents who may frequent the site for recycling activities, and residents who live nearthe landfill. Ambient air data should be obtained for more than one sampling event, in the section ofthe former "active" landfill where the highest concentrations of non-methane organic compoundswere identified and these concentrations modeled for emissions using at least five years ofmeteorological data. Due to limited environmental data and limitations of the model, ATSDR couldnot evaluate the health hazard for on-site workers and people who frequent the on-site recycling area. Environmental data are not available to determine potential off-site emissions and exposures to nearby residential areas. Therefore, ATSDR could not determine the public health impact of these exposures.


The data currently available to ATSDR are insufficient to form the basis of a health call, at this time. The soil gas measurements in Tables 1 and 2 do not represent concentrations that anyone is likely tobe exposed to; they represent concentrations inside pipes driven several feet into the ground forextracting subterranean VOCs to be burned off at the surface. The only way to assess the extent towhich nearby residents are exposed to these gaseous contaminants is by evaluating ambient airmonitoring data. Such data are not available at this time. However, ATSDR considers that the veryhigh levels of contaminants in these riser pipes, combined with the likelihood that these gasses willenter on-site ambient air whenever the flames are not lit, is sufficient justification for stronglyrecommending that useful ambient air data be collected and evaluated.

The maximum recorded concentrations, inside the pipe, of many of the contaminants listed in Tables1 and 2 (e.g., benzene, fluorotrichloromethane, hydrogen sulfide, methylene chloride, andtrimethylbenzenes) exceed relevant comparison values (e.g., intermediate EMEGs and noncancer-based RBCs) by factors of hundreds or even thousands. Therefore, some of these maximumconcentrations inside the pipe exceed not only ATSDR's comparison values, but the incorporatedsafety factors as well. These concentrations might not be of health concern if the landfill gases werebeing effectively burned off. Even if they were not, they might be substantially diluted soon afterentering the atmosphere, perhaps even to concentrations below comparison values, some distancefrom the pipe. However without ambient air data available to review this remains speculation. It istherefore essential that ambient air data both on- and off-site be collected so that ATSDR candetermine the public health implications of potential emissions from the Yaworski Landfill.


Citizens were concerned about a perceived increase in the incidence of cancer within theircommunity. The Connecticut Department of Health evaluated cancer rates in Canterbury, Plainfield,and two other surrounding towns in Connecticut compared to expected rates for cancers occurringwithin populations of similar size in the United States (2). Cancer incidence rates for reportedcancer cases occurring over a twenty year period (1971 to 1990) were obtained. The analysisdemonstrated that no differences were observed in the number of cancer cases reported in thepopulations in Connecticut compared to the number of cases that would be expected. Therefore, noincrease from the expected cancer rates were observed.

Respiratory difficulties and irritations of the eyes, nose, sinuses, and throat were reported. Sincethese types of conditions are not consistently reported to hospitals and community health clinics, theincidence of these conditions can not be evaluated. Other nuisances reported by members of thecommunity included; odors, dust, and truck traffic. The off-site air sampling conducted in 1993,suggested that dust may create a nuisance and recommendations were made that dust abatementactivities related to the site should be implemented. The Yaworski Landfill site represents a potentialhealth hazard on site to workers and people using the recycling area, however, there are no ambientair data available. Data does not exist to evaluate the off-site emissions and exposures to residentialareas along Packer Road. Therefore, ATSDR could not determine the public health implication of these exposures.

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