June 2013

Follow-Up Review of Air Monitoring Data

June 27-July 1, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 27 to the afternoon of July 1, 2013. On June 7, DHSS began issuing follow-up reviews of the daily air quality screening data on a twice-weekly basis.

On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to strong odors at locations south and southeast of the landfill during this time period.

  • Winds were predominantly from the south, west, northwest, and southwest.
  • The DNR contractor detected moderate odors south and southeast of the landfill on June 27 and 28, strong odors south of the landfill on June 29, light odors south of the landfill on June 30, and moderate odors south of the landfill on July 1 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 7.3 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • For three hours on June 27 at the AreaRAE monitoring location east of the landfill, average concentrations of reduced sulfur compounds exceeded a health-based guideline for acute exposure to hydrogen sulfide. These compounds detected by AreaRAE monitors are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were below levels of public health concern.

  • Sulfur dioxide was periodically detected at the monitoring location south of the landfill. However, average concentrations were below 0.01 parts per million (ppm) and did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • For three hours on June 30 and two hours on July 1 at the monitoring location east of the landfill, total VOC concentrations slightly exceeded a level that indicates the need for compound-specific sampling.
  • DNR is performing VOC compound-specific sampling in locations upwind and downwind of the landfill on a routine basis. The laboratory results are submitted for DHSS review of public health concerns.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 27, 2013

The Department of Health and Senior Services (DHSS) has reviewed air sample data collected for the Department of Natural Resources (DNR) near Bridgeton Landfill June 27, 2013. Samples were collected at two locations upwind of the landfill and two locations downwind of the landfill for laboratory determination of concentrations of volatile organic compounds (VOCs), aldehydes, reduced sulfur compounds and sulfur dioxide. DHSS has reviewed this data for evaluation of potential public health concerns of short-term health effects.

VOCs

Concentrations of VOCs were well below levels of public health concern. Downwind of the landfill, 24 VOCs were detected in ambient air in concentrations that generally exceeded concentrations detected upwind of the landfill. However, these concentrations, which ranged from 0.1 parts per billion (ppb) to 25.7 ppb, did not exceed health-based screening levels for acute exposure.

Aldehydes

Concentrations of aldehydes were well below levels of public health concern. Downwind of the landfill, 9 aldehydes were detected, which ranged in concentration from 0.11 ppb to 2.65 ppb and did not exceed health-based screening levels for acute exposure.

Reduced Sulfur Compounds

Reduced sulfur compounds were not detected in any of the samples. While low concentrations of hydrogen sulfide were detected by the Jerome meter in downwind locations on the same day, those concentrations were less than the detection limit of the laboratory analysis. During the 4-hour sample collection period, reduced sulfur compounds were also detected by the AreaRAE monitor located in the nearby downwind location. However, those were total reduced sulfur compound concentrations. Concentrations of individual compounds were apparently less than the detection limit of the laboratory analysis.

Sulfur Dioxide

Sulfur dioxide was detected in an upwind sample location. DHSS identified a concentration of 45 ppb from one upwind air sample collected for a four-hour time period west of the landfill that exceeded a health-based screening level for acute exposures lasting up to two weeks (10 ppb). Concentrations that exceed this screening level may cause irritation or respiratory effects in asthmatics or other sensitive individuals; however, it should be noted that concentrations above a screening level do not necessarily identify a public health risk is present, but that further investigation is warranted. While this concentration of sulfur dioxide was above the acute screening level for exposures lasting up to two weeks, it did not exceed the acute screening level for sulfur dioxide protective for exposures lasting up to eight hours (200 ppb) or the 1-hour or 3-hour National Ambient Air Quality Standards (75 ppb and 500 ppb, respectively).

June 24-27, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 24 to the afternoon of June 27, 2013. On June 7, DHSS began issuing follow-up reviews of the daily air quality screening data on a twice-weekly basis.

On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to strong odors at various locations north, northeast, and east of the landfill during this time period.

  • Winds were predominantly from the south and southwest.
  • The DNR contractor detected moderate odors northeast of the landfill on June 24, moderate to strong odors northeast of the landfill on June 25, moderate odors north and northeast of the landfill on June 26, and light odors south and southeast of the landfill on June 27 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 7.2 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • On June 24, average concentrations of reduced sulfur compounds exceeded a health-based guideline for acute exposure to hydrogen sulfide for one hour at the AreaRAE monitoring location south of the landfill and for four hours at the monitoring location east of the landfill. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
  • For four hours on June 26, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located east of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were below levels of public health concern.

  • For one hour on June 24, the average concentration of sulfur dioxide was 0.01 parts per million (ppm) at the monitoring location east of the landfill. This concentration did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • From 8pm on June 24 to 8am on June 26 at the monitor location east of the landfill, average total VOC concentrations exceeded a level that indicates a need for compound-specific sampling.
  • DNR is performing VOC compound-specific sampling in locations upwind and downwind of the landfill on a routine basis. The laboratory results are submitted for DHSS review of public health concerns.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates
  • Gamma radiation rates were well below levels of public health concern.
  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 20-24, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 20 to the afternoon of June 24, 2013. On June 7, DHSS began issuing follow-up reviews of the daily air quality screening data on a twice-weekly basis.

On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to strong odors at various locations north, northeast, and east of the landfill during this time period. Winds were predominantly from the south and southwest.

  • The DNR contractor detected moderate odors northeast of the landfill on June 20, moderate odors northeast of the landfill on June 21, moderate to strong odors north and northeast of the landfill on June 22, light odors north, northeast, east, and south of the landfill on June 23, and light odors northeast of the landfill on June 24 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 9.1 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • For one hour on June 20, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located east of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide.
  • On June 21, average concentrations of reduced sulfur compounds exceeded a health-based guideline for acute exposure to hydrogen sulfide for one hour at the AreaRAE monitoring location east of the landfill and for four hours at the monitoring location south of the landfill.
  • For two hours on June 22, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located west of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide.
  • For one hour on June 23, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located south of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide.
  • These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were below levels of public health concern, except for several hours at one monitoring location near the landfill.

  • For six hours on June 20, the average sulfur dioxide concentration at the monitoring location south of the landfill was 0.02 parts per million (ppm) and exceeded a health-based guideline for acute exposure.
  • For nine hours on June 21, average sulfur dioxide concentrations at the monitoring location south of the landfill ranged from 0.02 to 0.03 ppm and exceeded a health-based guideline for acute exposure.
  • For two hours on June 22, the average sulfur dioxide concentration at the monitoring location south of the landfill was 0.02 parts per million (ppm) and exceeded a health-based guideline for acute exposure.
  • While exposure to these concentrations of sulfur dioxide may cause irritation and other short-term symptoms, considerable dispersion is expected to reduce potential exposure levels at nearby residential areas.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • For seven hours on June 23 at one monitor west of the landfill and one hour on June 24 at one monitor east of the landfill, average total VOC concentrations exceeded levels that indicate a need for compound-specific sampling. However, these elevated concentrations were not verified by other AreaRAE monitors stationed at the same locations.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 3, 2013 DHSS Review of Air Sample Data from the Bridgeton Landfill Area

The Department of Health and Senior Services (DHSS) has reviewed air sample data collected for the Department of Natural Resources (DNR) near Bridgeton Landfill on June 3, 2013. Samples were collected at one location upwind of the landfill and three locations downwind of the landfill for laboratory determination of concentrations of volatile organic compounds (VOCs), aldehydes, and reduced sulfur compounds. DHSS has reviewed this data for evaluation of potential public health concerns of short-term health effects.

VOCs

Concentrations of VOCs were well below levels of public health concern. Downwind of the landfill, 20 VOCs were detected in ambient air, which ranged in concentration from 0.08 parts per billion (ppb) to 20.6 ppb and did not exceed health-based screening levels for acute exposure.

Aldehydes

Concentrations of aldehydes were well below levels of public health concern. Downwind of the landfill, six aldehydes were detected, which ranged in concentration from 0.17 ppb to 1.89 ppb and did not exceed health-based screening levels for acute exposure.

Reduced Sulfur Compounds

Individual reduced sulfur compounds were not detected in any of the air samples. While low concentrations of hydrogen sulfide were detected during the daily monitoring by the Jerome meter in downwind locations on the same day, those concentrations were less than the detection limit of the laboratory analysis for hydrogen sulfide. Additionally, while low concentrations of reduced sulfur compounds were detected during the daily monitoring by AreaRAE monitors located in the nearby downwind locations on the same day, the laboratory analysis for the individual compounds did not confirm these detections.

April 16, May 7, and May 8 Comprehensive Air Sampling at Bridgeton Landfill

The Missouri Department of Health and Senior Services (DHSS) has reviewed the air sample data from the April 16, May 7, and May 8 comprehensive sampling event at Bridgeton Landfill. DHSS evaluated air samples collected from two on-site locations and from three locations upwind and three locations downwind from the site. DHSS reviewed the data for evaluation of potential public health concerns of short-term health effects.

Samples were collected for aldehydes, amines, ammonia, carboxylic acids, hydrogen chloride, hydrogen cyanide, mercury (elemental), sulfur dioxide, dioxins/furans, polynuclear aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and reduced sulfur compounds. Of these, only aldehydes, carboxylic acids, dioxins/furans, PAHs, and VOCs were detected in the samples.

Aldehydes

Aldehydes were detected on-site, upwind, and downwind of the landfill; however, all concentrations were below levels of public health concern.

  • Of the 12 aldehydes sampled for, 11 were detected in the downwind sampling locations; however, these concentrations were low and did not exceed available health-based screening levels for acute exposure.
Carboxylic Acids

Carboxylic acids were detected in one on-site sample; however, concentrations were below levels of public health concern and were not detected in ambient air downwind of the landfill.

Dioxins/Furans

Dioxins and furans were detected on-site, upwind, and downwind of the landfill; however, all concentrations were below levels of public health concern.

  • Due to the absence of health-based screening levels for acute exposures, data were compared to a chronic screening level for dioxins/furans using the standard approach for evaluating human health risks from dioxin like compounds. This provides a very health protective evaluation.
  • Of the 17 dioxins and furans sampled for, 14 were detected in a downwind sampling location; however, these concentrations were low and did not exceed available health-based screening levels (for chronic exposure).
  • Although laboratory quality assurance issues were identified, the data were evaluated as provided. However, additional dioxin/furan analysis is being conducted to ensure quality data.
PAHs

PAHs were detected on-site, upwind, and downwind of the landfill; however, the concentrations were low and are not expected to pose a public health risk.

  • Of the 19 PAHs sampled for, 2 were detected in a downwind sampling location. The specific compounds detected do not have health-based screening levels available; however, only very low concentrations were detected and these detections are not expected to pose a public health risk.
VOCs

VOCs were detected on-site, upwind, and downwind of the landfill. All concentrations of VOCs were below acute screening levels except benzene, which was above an acute screening level, but is not expected to pose a public health risk.

  • Of the 68 VOCs sampled for, 29 were detected in the downwind sampling locations. All of these detections were below available health-based screening levels for acute exposure except for one benzene detection.
  • DHSS identified a benzene concentration of 21.8 ppb from one downwind air sample collected for a four-hour time period on May 7 southwest of the landfill that exceeded a health-based screening level for acute exposures lasting up to two weeks (9 ppb). Concentrations that exceed this screening level may cause eye/nose/throat irritation or immunological effects; however, it should be noted that concentrations above a screening level do not necessarily identify a public health risk is present, but that further investigation is warranted.
  • The detected concentration did not exceed the acute screening level for benzene that is protective for exposures lasting up to six hours (400 ppb).
  • Additionally, the sample was collected near the landfill property line and dispersion is expected to reduce exposure downwind of the sample location.
It should also be noted that benzene is an important component of gasoline and this sample was collected near an automotive shop, which may have contributed to the detection of benzene. The other downwind air sample collected on that day did not show a concentration of benzene above an acute screening level.

June 17 - 20, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 17 to the afternoon of June 20, 2013. On June 7, DHSS began issuing follow-up reviews of the daily air quality screening data on a twice-weekly basis.

On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to strong odors at various locations south, southwest, and east of the landfill during this time period, depending on wind direction. Winds were predominantly from the south and southwest on June 17 and 20, from the north and northwest on June 18, and from the east and northeast on June 19.
The DNR contractor detected moderate odors east of the landfill on June 17, moderate odors east and south of the landfill on June 18, and moderate to strong odors east, west, and south of the landfill on June 19 using a Nasal Ranger olfactometer.

  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 10.3 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • For one hour on June 18, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located west of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide. However, these compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were below levels of public health concern, except for several hours at two monitoring locations near the landfill.

  • On June 18, average sulfur dioxide concentrations periodically exceeded a health-based guideline for acute exposure at the monitoring locations west and south of the landfill. For three hours, average concentrations ranged from 0.04 to 0.09 parts per million (ppm) west of the landfill. For six hours, average concentrations ranged from 0.02-0.03 ppm south of the landfill.
  • On June 19, average sulfur dioxide concentrations periodically exceeded a health-based guideline for acute exposure at the monitoring locations west and south of the landfill. For seven hours, average concentrations ranged from 0.02 to 0.05 ppm west of the landfill. For four hours, the average concentration was 0.02 ppm south of the landfill.
  • On June 20, average sulfur dioxide concentrations periodically exceeded a health-based guideline for acute exposure at the monitoring locations west and south of the landfill. For three hours, average concentrations ranged from 0.03 to 0.08 ppm west of the landfill. For three hours, the average concentration was 0.02 ppm south of the landfill.
  • While exposure to these concentrations of sulfur dioxide may cause irritation and other short-term symptoms, considerable dispersion is expected to reduce potential exposure levels at nearby residential areas.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • For seven hours on June 19 at one monitor east of the landfill and three hours on June 20 at one monitor west of the landfill, average total VOC concentrations exceeded levels that indicate a need for compound-specific sampling. However, these elevated concentrations were not verified by other AreaRAE monitors stationed at the same locations. 
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 18, 2013

The Department of Health and Senior Services (DHSS) has reviewed air sample data collected for the Department of Natural Resources (DNR) near Bridgeton Landfill June 18, 2013. Samples were collected at two locations upwind of the landfill and two locations downwind of the landfill for laboratory determination of concentrations of volatile organic compounds (VOCs), aldehydes, and reduced sulfur compounds. DHSS has reviewed this data for evaluation of potential public health concerns of short-term health effects.

VOCs

Concentrations of VOCs were well below levels of public health concern. Downwind of the landfill, 26 VOCs were detected in ambient air in concentrations that generally exceeded concentrations detected upwind of the landfill. However, these concentrations, which ranged from 0.07 parts per billion (ppb) to 70.1 ppb, did not exceed health-based screening levels for acute exposure.

Aldehydes

Concentrations of aldehydes were well below levels of public health concern. Downwind of the landfill, 8 aldehydes were detected, which ranged in concentration from 0.135 ppb to 2.01 ppb and did not exceed health-based screening levels for acute exposure.

Reduced Sulfur Compounds

Reduced sulfur compounds were not detected in any of the samples. While low concentrations of hydrogen sulfide were detected by the Jerome meter in downwind locations on the same day, those concentrations were less than the detection limit of the laboratory analysis. During the 4-hour sample collection period, reduced sulfur compounds were also detected by the AreaRAE monitor located in the nearby downwind location. However, those were total reduced sulfur compound concentrations. Concentrations of individual compounds were apparently less than the detection limit of the laboratory analysis.

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June 13 - 17, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 13 to the afternoon of June 17, 2013. On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported low and moderate to strong odors at various locations north, northwest, south, and east of the landfill during this time period, depending on wind direction. Winds were predominantly from the northwest on June 13 and from the south and southwest on June 14-17.

  • The DNR contractor detected moderate odors south of the landfill on June 13, low odors northwest of the landfill on June 14, moderate odors north and east of the landfill on June 15, moderate to strong odors north and northeast of the landfill on June 16, and low odors south of the landfill on June 17 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 8.0 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • For several hours on June 16-17, average concentrations of reduced sulfur compounds detected by the AreaRAE monitor located east of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide. However, these compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were well below levels of public health concern.

  • For three hours on June 13, average sulfur dioxide concentrations ranged from 0.03 to 0.04 parts per million (ppm) and exceeded a health-based guideline for acute exposure at the monitoring location south of the landfill. However, these concentrations were not verified by a second field monitor.
  • At other times and monitoring locations, average concentrations equaled or were less than 0.01 parts per million (ppm) and did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • For several hours on June 14-17 at one monitor west of the landfill, June 14-16 at one monitor east of the landfill, and June 14-17 at one or two monitors south of the landfill, average total VOC concentrations periodically exceeded levels that indicate a need for compound-specific sampling. However, these elevated concentrations were not verified by other AreaRAE monitors stationed at the same locations. 
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 17 - 18, 2013

The Missouri Department of Health and Senior Services (DHSS) has reviewed the air sample data from the June 17-18 sampling event at Bridgeton Landfill. Samples were collected from one on-site location and from one location upwind and one location downwind of the landfill for laboratory determination of concentrations of dioxins/furans and polynuclear aromatic hydrocarbons (PAHs). DHSS reviewed the data for evaluation of potential public health concerns of short-term health effects.

Dioxins/Furans

Dioxins and furans were detected on-site, upwind, and downwind of the landfill; however, all concentrations were below levels of public health concern.

  • Due to the absence of health-based screening levels for acute exposures, data were compared to a chronic screening level for dioxins/furans using the standard approach for evaluating human health risks from dioxin-like compounds. This provides a very health protective evaluation.
  • Of the 17 dioxins and furans sampled for, 3 were detected in the downwind sampling location; however, these concentrations were low and did not exceed available health-based screening levels (for chronic exposure).
PAHs

PAHs were detected on-site, upwind, and downwind of the landfill; however, the concentrations were low and are not expected to pose a public health risk.

  • Of the 19 PAHs sampled for, 8 were detected in the downwind sampling location; however, these concentrations were low and did not exceed available health-based screening levels for acute exposure. Some of the specific compounds detected do not have health-based screening levels available; however, only very low concentrations were detected and these detections are not expected to pose a public health risk.

June 13, 2013

The Department of Health and Senior Services (DHSS) has reviewed air sample data collected for the Department of Natural Resources (DNR) near Bridgeton Landfill June 13, 2013. Samples were collected at one location upwind of the landfill and three locations downwind of the landfill for laboratory determination of concentrations of volatile organic compounds (VOCs), aldehydes, and reduced sulfur compounds. DHSS has reviewed this data for evaluation of potential public health concerns of short-term health effects.

VOCs

Concentrations of VOCs were well below levels of public health concern. Downwind of the landfill, 26 VOCs were detected in ambient air in concentrations that generally exceeded concentrations detected upwind of the landfill. However, these concentrations, which ranged from 0.09 parts per billion (ppb) to 49 ppb, did not exceed health-based screening levels for acute exposure.

Aldehydes

Concentrations of aldehydes were well below levels of public health concern. Downwind of the landfill, 8 aldehydes were detected, which ranged in concentration from 0.088 ppb to 1.03 ppb and did not exceed health-based screening levels for acute exposure.

Reduced Sulfur Compounds

Reduced sulfur compounds were not detected in any of the samples.  While low concentrations of hydrogen sulfide were detected by the Jerome meter in downwind locations on the same day, those concentrations were less than the detection limits of the laboratory analysis. During the 4-hour sample collection period, reduced sulfur compounds were also not detected by the AreaRAE monitor located in nearby downwind locations.

June 10 - 13, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 10 to the afternoon of June 13, 2013. On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to moderate to strong odors at various locations north, south, and east of the landfill during this time period, depending on wind direction. Winds were predominantly from the northwest on June 10 and 13 and from the south on June 11-12.

  • The DNR contractor detected very strong odors south of the landfill on June 10, moderate odors east and northeast of the landfill on June 11, moderate odors east of the landfill on June 12, and moderate odors south and east of the landfill on June 13 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 8.8 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • On June 11-12, average concentrations of reduced sulfur compounds detected by the AreaRAE monitors located east and south of the landfill exceeded a health-based guideline for acute exposure to hydrogen sulfide. However, these compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were well below levels of public health concern, except for a limited time period at one monitoring location near the landfill.

  • For three hours on June 13, average sulfur dioxide concentrations ranged from 0.02 to 0.04 parts per million (ppm) and exceeded a health-based guideline for acute exposure at the monitoring location south of the landfill.
  • Exposure to these concentrations of sulfur dioxide may cause irritation and other short-term symptoms.
  • At other times and monitoring locations, average concentrations were less than 0.01 parts per million (ppm) and did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • From the evening of June 12 to the morning of June 13, average total VOC concentrations exceeded levels that indicate a need for compound-specific sampling at monitoring locations east of the landfill.
  • On June 10-11 at one monitor south of the landfill, June 11-12 at one monitor east of the landfill, and June 13 at one monitor south of the landfill, average total VOC concentrations periodically exceeded levels that indicate a need for compound-specific sampling. However, these elevated concentrations were not verified by other AreaRAE monitors stationed in the same locations. 
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 6 - 10, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 6 to the afternoon of June 10, 2013. On April 23, DNR began routine, twice daily surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, total volatile organic compounds (VOCs) and gamma radiation at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

DNR reported moderate to strong odors at various locations north, south, and east of the landfill during this time period, depending on wind direction.

  • Winds were predominantly from the north and west on June 6-7 and from the south and west on
    June 8-10.
  • The DNR contractor detected moderate odors east and southeast of the landfill on June 6, moderate odors south of the landfill on June 7, moderate to strong odors north of the landfill on June 8, strong odors east and northeast of the landfill on June 9, and moderate to strong odors north and northeast of the landfill on June 10 using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 8.5 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • On June 8, AreaRAE monitors detected low concentrations of reduced sulfur compounds at the monitoring location west of the landfill. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations were well below levels of public health concern.

  • On June 9 and 10, sulfur dioxide concentrations were briefly detected at the monitoring location south of the landfill. However, average concentrations were less than 0.01 parts per million (ppm) and did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • At monitoring locations east and south of the landfill, average total VOC concentrations periodically exceeded levels that indicate a need for compound-specific sampling. However, these elevated concentrations were not verified by other AreaRAE monitors stationed in the same locations. 
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels. 

June 4 - 6, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 4 to the afternoon of June 6, 2013. On April 23, DNR began routine, twice daily surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, total volatile organic compounds (VOCs) and gamma radiation at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

Odors were reported by DNR as being strong the afternoon of June 4 and moderate on June 5 at locations southwest of the landfill.

  • Winds were variable with no predominant wind direction during this period.
  • The DNR contractor detected low to moderate odors south and southwest of the landfill and only low odors at other locations surrounding the landfill using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 25.6 parts per billion (ppb) during routine monitoring. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • AreaRAE monitors periodically detected low concentrations of reduced sulfur compounds at monitoring locations west and south of the landfill.
  • For three hours on June 4 at the monitoring location west of the landfill, the average concentration of reduced sulfur compounds exceeded a health-based guideline for acute exposure to hydrogen sulfide. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
  • For five hours on June 5 at the monitoring location west of the landfill, the average concentration of reduced sulfur compounds exceeded a health-based guideline for acute exposure to hydrogen sulfide. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity. DNR data verification with the Jerome meter showed only low concentrations of hydrogen sulfide.
Sulfur Dioxide

Average sulfur dioxide concentrations did not exceed levels of public health concern.

  • Sulfur dioxide was detected at the monitoring locations west and south of the landfill. However, average concentrations of sulfur dioxide were below 0.01 parts per million (ppm) and did not exceed health-based guidelines for acute exposure.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • Average total VOC concentrations were not at a level that indicates a need for compound-specific sampling.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates were well below levels of public health concern.

  • Gamma radiation rates continue to be at levels that are at or near natural background levels.

June 4, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 3 to the afternoon of June 4, 2013. On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

Odors were reported by DNR as being strong today at locations southwest the landfill. Winds were variable, predominantly from the south and east.

  • The DNR contractor detected moderate to strong odors south and southwest of the landfill using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 8.6 parts per billion (ppb) during routine moniroting. Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • AreaRAE monitors detected low concentrations of reduced sulfur compounds at monitoring locations east, west, and south of the landfill. For one hour at the monitoring location west of the landfill, the average concentration of reduced sulfur compounds slightly exceeded a health-based guideline for acute exposure to hydrogen sulfide. However, DNR data verification with the Jerome meter showed that the approximate average concentration of hydrogen sulfide at that location did not exceed 10 ppb. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Sulfur dioxide was not detected in ambient air at any of the monitoring locations near the landfill.

Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • Average total VOC concentrations were not at a level that indicates a need for compound-specific sampling.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates continue to be at levels that are at or near natural background levels.

  • Gamma radiation levels are monitored continuously at three locations around the site using AreaRae instruments equipped with radiation detectors.

June 3, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of June 2 to the afternoon of June 3, 2013. On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

Odors were reported by DNR as being very strong in the morning today, especially at locations south and southwest the landfill. Winds were light and variable, although predominantly from the north-northwest and northeast.

  • The DNR contractor detected moderate odors south and southwest of the landfill using a Nasal Ranger olfactometer.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 6.4 parts per billion (ppb). Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • AreaRAE monitors detected low concentrations of reduced sulfur compounds at monitoring locations west and south of the landfill. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations did not exceed levels of public health concern, except for a limited time period at one monitoring location near the landfill.

  • For approximately two hours on the afternoon of June 2S, the average sulfur dioxide concentration at the monitoring location south of the landfill was 0.05-0.08 parts per million (ppm), exceeding a health-based guideline for acute exposure.
  • Exposure to these concentrations of sulfur dioxide may cause irritation and other short-term symptoms.
Benzene and Total VOCs

Benzene was detected in low concentrations in ambient air in several locations, mostly south of the landfill.

  • Benzene concentrations of 0.05 ppm were detected today in several surveillance locations and a residential area located approximately one mile south of the landfill. These detections were reported to be intermittent, not lasting longer than 5 minutes at each location.
  • Exposure to these concentrations of benzene may cause irritation and other short-term symptoms.
  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • Average total VOC concentrations were not at a level that indicates a need for compound-specific sampling.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates continue to be at levels that are at or near natural background levels.

  • Gamma radiation levels are monitored continuously at three locations around the site using AreaRae instruments equipped with radiation detectors.

June 1-2, 2013

The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill from the afternoon of May 31 to the afternoon of June 2, 2013, while construction work at the landfill was temporarily suspended due to adverse weather conditions. On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill. In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations. DHSS has reviewed both sets of data to identify potential public health concerns for short-term health effects. Generally, samples are collected near the property boundary and dispersion is expected to reduce exposure downwind of the sample locations.

Odors

Odors were reported by DNR as being moderate to strong at locations south and southeast the landfill on Sunday, June 2. Winds were predominantly from the north-northwest on that day.

  • DNR detected low odors at several locations around the landfill using a Nasal Ranger olfactometer on Saturday, June 1 and early in the morning on Sunday, June 2. Stronger odors were reported on Sunday afternoon.
  • DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms. Symptoms associated with exposure to strong odors include headache, nausea, and fatigue. Symptoms generally associated with strong odors typically disappear once the odors dissipate.
Hydrogen Sulfide and Other Reduced Sulfur Compounds

Hydrogen sulfide concentrations were well below levels of public health concern.

  • The maximum concentration of hydrogen sulfide detected was 5.2 parts per billion (ppb). Hydrogen sulfide concentrations were detected by the Jerome meter, which is highly sensitive and specific to hydrogen sulfide.
  • AreaRAE monitors detected low concentrations of reduced sulfur compounds at monitoring locations south and west of the landfill on Sunday, June 2. Low reduced sulfur concentrations were also briefly detected east of the landfill on the afternoon of Friday, May 31st. These compounds are not just hydrogen sulfide but primarily another reduced sulfur compound with lower toxicity.
Sulfur Dioxide

Average sulfur dioxide concentrations did not exceed levels of public health concern, except for a limited time period at one monitoring location near the landfill.

  • For approximately three hours on the afternoon of May 31, the average sulfur dioxide concentration at the monitoring location east of the landfill was 0.02-0.03 parts per million (ppm), exceeding a health-based guideline for acute exposure.
  • For approximately three hours on June 2nd, the average sulfur dioxide concentration at the monitoring location south of the landfill was 0.09-0.11 parts per million (ppm), exceeding a health-based guideline for acute exposure. However, these elevated concentrations were not confirmed by a second measurement of sulfur dioxide concentrations taken by DNR field staff.
  • While exposure to these concentrations of sulfur dioxide may cause irritation and other short-term symptoms, considerable dispersion is expected to reduce potential exposure levels at nearby residential areas.
Benzene and Total VOCs

Benzene was not detected in ambient air at any of the surveillance locations around the landfill.

  • Previous sampling has shown that, while several VOCs are present in the landfill source gas, benzene may be a primary VOC of public health concern.
  • Total VOC concentrations were not at a level that indicates a need for compound-specific sampling.
Carbon Monoxide

Average carbon monoxide concentrations were well below levels of public health concern.

Radiation Rates

Gamma radiation rates continue to be at levels that are at or near natural background levels.

  • Gamma radiation levels are monitored continuously at three locations around the site using AreaRae instruments equipped with radiation detectors.