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HEALTH CONSULTATION

Public Health Evaluation of the (Proposed) Air Monitoring Plan of the Preliminary Design Report for the Ciba-Geigy Superfund Site
(Operable Unit 2)

CIBA-GEIGY CORPORATION
TOMS RIVER, OCEAN COUNTY, NEW JERSEY


SUMMARY

At the request of the U.S. Environmental Protection Agency (EPA) Region II and the Citizen's Action Committee on Childhood Cancer Cluster (CACCCC), the New Jersey Department of Health and Senior Services (NJDHSS), under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR), has reviewed the Air Monitoring Plan [the "Plan"] of the Preliminary Design Report for remediation of the on-site source areas at the Ciba-Geigy Chemical Corporation (CGC) Superfund site located in Dover Township (Ocean County), New Jersey. The proposed Plan, which has been prepared by Ciba Specialty Chemical (Ciba), has been evaluated to determine whether the monitoring procedures and action levels for contaminants that may be released to ambient air will be protective of public health. Moreover, this Health Consultation is a culmination of a review of various drafts of the Plan and numerous discussions with EPA regarding the proposed air actions levels and other aspects of the air monitoring plan. During the course of these reviews and discussions, several recommendations were put forth by ATSDR and the NJDHSS that have been addressed by EPA and incorporated into the Plan. These changes are reflected in this Health Consultation. Moreover, ATSDR and NJDHSS provided a draft copy of this health consultation to the CACCCC, the Toxic Environment Affect Children's Health (TEACH) group, the Ocean County Health Department, and Manchester Township. Comments received from these entities and ATSDR's and NJDHSS' response to these comments are provided in this Health Consultation.

The Plan indicates that three zones of air monitoring, i.e., the work area, the near field area (about 100 yards away), and the site perimeter (a minimum of 300 yards away), will be established for each of seven on-site source areas. The approximately 32,000 drums in the Drum Disposal Area (DDA) will be removed during the first two years of source area remedial actions. Excavation will take place intermittently, but will be conducted, for the first two years, simultaneously at the DDA and one of the other source areas that will be excavated over a period of approximately six years.

The Plan proposes to monitor ambient air for total volatile organic chemicals (TVOCs), particulate matter, and specific site-related chemicals of concern (COCs). The COCs include nine site-wide and five source-area specific COCs that may be released during remedial activities. In each of the three zones of action, the Plan proposes "immediate" and "short-term" action levels for each COC. In addition, "long-term" action levels are proposed for the perimeter zone. Moreover, chemical-specific monitoring will be initiated using TVOC trigger levels established for each zone and , as necessary, response actions. The Plan indicates that monitoring will take place continuously in the work and near field zones during periods of excavation and drum removal. Ambient air will also be monitored continuously at six fixed and one mobile locations along the perimeter of the site property.

Based on the review of available information and the proposed Plan, ATSDR and NJDHSS conclude that:

  1. Establishment of three zones of action, i.e., work, near field, and perimeter, should be able to characterize airborne contaminants that may be emitted during remedial activities. Therefore, the proposed monitoring of COCs in these areas should adequately protect the health of workers and the public. No long-term action levels (LTALs) are necessary for the work or near field zones;


  2. Monitoring for nine site-wide and five source area-specific COCs should provide sufficient data to characterize the type and concentrations of potential airborne emissions;


  3. Installation and operation of six stationary monitoring stations (and one mobile station) along the perimeter should be sufficient to determine the potential exposure to, and thereby protect the health of, the public near the CGC property. Even though the perimeter monitoring stations will be located on CGC property (to help protect them from vandalism), they are considered to be exposure point monitors. Consequently, the continuous monitoring data that will be gathered from the stationary and mobile stations should provide sufficient information to characterize the potential exposure to the nearest off-site populations;


  4. After evaluating the action levels that are proposed in the Plan, NJDHSS and ATSDR concur that it is appropriate to utilize TVOC concentrations as the trigger levels to initiate contaminant-specific monitoring and , as necessary, response actions. Use of TVOC measurements will allow for quicker reaction and initiation of protective response actions, since identification and determination of the concentration of an individual COC requires a longer period of time than does a TVOC measurement. The use of TVOC as a trigger helps to expedite the response actions because the TVOC instruments can provide immediate readings;


  5. The Plan calls for contaminant-specific monitoring to be implemented when the TVOC trigger level is exceeded. However, in practice, contaminant-specific monitoring will be initiated before the TVOC trigger level is exceeded. Determining the identities of the individual VOCs before the TVOC trigger level is exceeded will provide an extra measure of protection for the workers and the community;


  6. NJDHSS and ATSDR have evaluated the proposed work zone and near-field action levels, and concur that they should be protective of on-site workers. These action levels should also be sufficient to determine the need to stop work and take appropriate measures to reduce the potential for COCs to exceed action levels at the perimeter;


  7. NJDHSS and ATSDR have reviewed the assumptions that were made in deriving the action levels. Most of these assumptions should be protective of public health. However, off-gassing of COCs could occur (1) during periods when excavation is not occurring, but has not been completed in a particular area, and (2) from soils brought outside for final bio-remediation. In addition, based on the proposed schedule for remediation, activities are likely to take place during essentially every available work day for two years. Therefore, the assumption of the frequency of exposure (i.e., number of days exposed) used to derive the actions levels may be exceeded;


  8. NJDHSS and ATSDR concur with the Plan that periodic confirmatory monitoring for lead and mercury will be necessary to confirm that particulate matter action levels are protective for exposure to these metals. Moreover, NJDHSS and ATSDR believe that confirmatory monitoring for lead and mercury should be conducted if any of the particulate matter action levels are exceeded. That is, confirmatory monitoring is needed to ensure that concentrations of mercury and lead do not exceed their individual action levels. If appropriate confirmatory monitoring is performed, then the proposed action levels for particulate matter should be protective of public health;


  9. While site data indicate that lead and mercury are the most likely particle-bound air contaminants, NJDHSS and ATSDR believe that it is a prudent public health measure to perform additional particle analysis for the full spectrum of potential particle-bound contaminants; and,


  10. An odor may be the first indication to nearby residents that COC's or other compounds from the source areas are in the ambient air. However, it is important to note that the presence of an odor does not necessarily indicate that there is a public health concern.

Overall, the proposed Plan and other actions that will be taken by EPA should to be protective of public health, provided that certain additional measures are taken (see Recommendations below). To adequately address community health concerns and to protect the public health during remedial activities at the on-site source areas, NJDHSS and ATSDR recommend the following:

  1. The perimeter LTALs should be re-evaluated periodically when soil excavation, bio-remediation and drum removal has begun, to determine if any of the exposure assumptions used in their development have been exceeded. If any of the assumptions are exceeded, then the LTALs should be reconsidered and lowered if warranted;


  2. If any of the action levels for particulates are exceeded while excavating the Backfill Lagoon and Filtercake Disposal Areas, particle analyses should be conducted for airborne lead and mercury, respectively;


  3. Additional analysis for the full spectrum of potential particle-bound air contaminants should be conducted. Moreover, these analyses should be conducted especially on days when the nearest receptor population is downwind of an area being excavated (e.g., analyze particles from monitors along Cardinal Drive when excavating the Filtercake Disposal Area).


  4. The Plan, and its associated response actions, should be exercised on-site, prior to the initiation of remedial activities, under different scenarios, e.g., during work and non-work hours, prior to the initiation of remedial activities to properly train monitoring and response personnel;


  5. A method for providing up-to-date information and status regarding excavation activities, as well as procedures to address inquiries from the public, should be established;


  6. Additional on-site security measures should be taken during remediation to reduce the potential for trespassers to be exposed to the on-site excavation areas and emissions and to help protect the integrity of the air monitoring equipment; and,


  7. ATSDR should evaluate the Health and Safety Plan when it becomes available.

The EPA will implement the above ATSDR and NJDHSS recommendations 1-6. The ATSDR will follow-up on recommendation number 7.


PURPOSE AND STATEMENT OF HEALTH ISSUES

The U.S. Environmental Protection Agency (EPA) Region II and the Citizen's Action Committee on the Childhood Cancer Cluster (CACCCC) requested that the Agency for Toxic Substances and Disease Registry (ATSDR) evaluate the public health implications of the proposed Air Monitoring Plan (the "Plan") that is described in Appendix A of the Preliminary Design Report for Operable Unit 2 of the Ciba-Geigy Chemical Corporation (CGC) Superfund site, located in Dover Township (Ocean County), New Jersey (Ciba, 2002a). This Health Consultation is being prepared by the New Jersey Department of Health and Senior Serivces (NJDHSS) under a cooperative agreement with ATSDR.

The Plan contains a description of the methodology and subsequent actions proposed for monitoring on-site ambient air during remedial actions that will take place on the property of the Ciba-Geigy Superfund site. Remedial actions that will be conducted during a period of approximately six years include the removal of approximately 32,000 drums of waste that contain primarily organic contaminants, and the excavation and bio-treatment of approximately 150,000 cubic yards of soil from seven contaminated on-site source areas (Ciba, 2002a).

This Health Consultation evaluates the effectiveness of the Plan in protecting the public from harmful exposure to volatile, semi-volatile, and inorganic contaminants, i.e., metals, that may be released to the ambient air during remedial activities. It examines a single exposure pathway, i.e., the potential for inhalation by site workers and the nearby public, of exposure to chemicals of concern (COCs) that may be volatilized and/or entrained in dusts that may be released to the ambient air during source area remediation activities. This pathway is the most likely source of potential exposure to the public during the planned source area remediation activities. The chemicals of concern that are considered in this Health Consultation are limited to the volatile (and semi-volatile) compounds that may be released into the ambient air during remedial actions. Inhalation of non-volatile materials, i.e., heavy metals and numerous organic dyes and associated reagents and intermediates, are not considered here, except as they may be potentially entrained in dust that is released to the atmosphere. In addition, as requested by EPA Region II, this document evaluates the action levels that have been proposed for each COC in each zone of action to determine whether they are protective of the public health. Moreover, this Health Consultation is a culmination of a review of various drafts of the Plan and numerous discussions with EPA regarding the proposed air action levels and other aspects of the air monitoring plan. During the course of these reviews and discussions, several recommendations were put forth by ATSDR and the NJDHSS that have been addressed by EPA and incorporated into the Plan. These changes are reflected in this Health Consultation. Moreover, ATSDR and NJDHSS provided a draft copy of this health consultation to the CACCCC, the Toxic Environment Affect Children's Health (TEACH) group, the Ocean County Health Department, and Manchester Township. Comments received from these entities and ATSDR's and NJDHSS' response to these comments are provided in Appendix A.


BACKGROUND

Demography and Land Use

The Ciba-Geigy Chemical Corporation (CGC) site (EPA Facility ID: NJD001502517) is located near State Route 37 in the West Dover section of Dover Township (Ocean County), New Jersey, approximately 1 mile west of the Garden State Parkway, and 3 miles west of the business district of the Toms River section of Dover Township (see Figure 1). The Toms River forms the northeastern boundary of the CGC site. Winding River Park, an outdoor recreational area located within the flood plain of the Toms River, adjoins the site on the east and northeast. To the east of the Toms River is the Coulter Street/Whitesville Road residential area. The Cardinal Drive/Oak Ridge Parkway residential area adjoins the southeast border of the site along the west bank of the Toms River. A residential area, Pine Lake Park Estates (Manchester Township), borders the northwestern boundary of the site. Additional residential and commercial properties border the site on the south and southwest along State Route 37 (NUS, 1988; Ciba, 1999). West Dover Elementary School is located adjacent to the fence line at the southeast corner of the site.

The Ciba-Geigy Chemical Corporation (formerly Toms River Chemical Company, and now renamed Ciba Specialty Chemicals, aka Ciba) owned and operated a chemical manufacturing plant (the Toms River Plant) on the property beginning in 1952. The property consists of approximately 1,402 acres, of which 320 acres had been developed. The site boundaries currently encompass 1,359 acres. Approximately 43 acres (previously known as Tract 2), located east of the main site along Oak Ridge Parkway, were donated to Dover Township in 1959, and now comprise Winding River Park. The (now demolished) former production area, wastewater treatment plant, power plant, and administrative buildings areas occupied approximately 100 acres while the plant operated. Various disposal areas and a landfill encompass approximately 220 acres. The remaining approximately 1,000 acres are undeveloped pine forest and wetlands. Except for the areas of the site that border the Toms River, the entire CGC site is fenced, with a controlled entrance from Oak Ridge Parkway on the eastern side of the site.

Site History

Beginning in 1952, the Toms River Plant produced anthraquinone-based dyes and intermediate dye products. Starting in 1959, the plant also manufactured azo dyes and their intermediates, epoxy resins, and other specialty chemicals. During peak operations, the facility had a daily production capacity of about 220,000 pounds of dyestuff and intermediates, and approximately 105,000 pounds of epoxy resins (NUS, 1988). Production of anthraquinone-based dyes ended in 1983, and azo dye production ended in 1988; epoxy resin manufacturing ended in 1990. Manufacturing operations at the plant ceased at the end of 1996 when dye standardization activities were terminated.

The manufacturing processes (estimated to be as many as 600 over more than 40 years) generated liquid and solid wastes. From about 1952 through 1977, solid and liquid process wastes were discarded in approximately twenty potential source areas located throughout CGC property. These source areas include an unlined disposal landfill containing approximately 32,000 drums, a 12-acre filtercake disposal area, a 5-acre lime sludge disposal area, a 40-acre borrow/compactor area, and numerous lagoons and basins associated with former wastewater treatment plants totaling approximately 30 acres. Several of the disposal areas were unlined. Solid wastes, including residues from manufacturing processes, were disposed of in bulk or in drums in several of the on-site source areas. Wastewater treatment sludge was stockpiled on top of a closed cell of the landfill (NUS, 1988; Ciba, 1999).

Summary of Previous Health Assessment Activity

Since 1988, ATSDR and NJDHSS have performed several public health evaluations of the Ciba-Geigy Corporation Superfund site. The most recent were conducted in conjunction with the NJDHSS/ATSDR Public Health Response Plan (PHRP) that was created to address health issues associated with the Ciba-Geigy site and other sites and issues that were related to the overall Dover Township Childhood Cancer Investigation (NJDOH and ATSDR, 1996). Based on the PHRP, a series of evaluations (see NJDHSS and ATSDR, 2001a,b,and c and references therein) were performed by the NJDHSS, under cooperative agreement with ATSDR, to evaluate the public health implications of the Ciba-Geigy site.

At the request of the Citizen's Action Committee on Childhood Cancer Cluster (CACCCC), ATSDR completed a Health Consultation (ATSDR, 2000) that evaluated the Selected Remedy that was presented in the Record of Decision (ROD) for remediating CGC on-site source areas, i.e., Operable Unit 2 (OU2) (EPA, 2000). ATSDR concluded that the Selected Remedy would be protective of public health over the long term, provided that appropriate precautions, including monitoring of ambient air, were taken to protect workers and the public from airborne contaminants that might be released during remedial activities at the source areas.

Site Visit

On May 22, 2002, a site visit was conducted at the CGC site by NJDHSS, ATSDR, and EPA Region II personnel. The CGC (now Ciba Specialty Chemicals) site is currently occupied by remedial operations personnel only. There was evidence of trespassing as a result of vandalism, specifically, sections of the perimeter fence had been cut open in several locations along the northern boundary of the site.


DISCUSSION

During more than forty years of operation, several hundred chemical compounds were used or manufactured and disposed of at the CGC site. Initially, attention was focused on characterizing and remediating contaminants that were found in the ground water beneath the site (NUS, 1988). Attention then turned to characterizing and remediating contaminated soils in on-site source areas, i.e., OU2 (CDM, 1993).

Characterization of, and the Selected Remedy for, On-site Source Areas

Figure 2 shows the locations of the approximately twenty potential on-site source areas that contain elevated concentrations of VOCs, SVOCs, and metals that are described in detail in the Feasibility Study (FS) for Operable Unit 2 (OU2) (Ciba, 1999). Through this FS process, EPA determined that seven of the twenty potential source areas would undergo remedial/removal actions that would require soil excavation or drum removal (Figure 3).

The purpose of the FS was to evaluate potential alternatives that would enable the selection of a remedy for each of the potential source areas which would be protective of human health and the environment, as well as facilitate the remedial goal of groundwater restoration. Seven alternatives for potential remedial actions were proposed for consideration. The alternatives ranged from no action to the excavation and removal of all contaminated materials. Other options that were considered included natural attenuation with monitoring, containment, ex situ thermal treatment, in/ex situ bio-remediation, and a combination of the various remedial methods. The remediation strategy that was selected by the EPA is a combination of removal and bio-remediation activities. It was determined that approximately 150,000 cubic yards of contaminated soil will be excavated and treated on site by bio-remediation, and that approximately 32,000 drums will be excavated, removed, and disposed off-site (see Table 1).

Nine site-wide and five source area-specific chemicals of concern (COCs) (see Table 1) were selected to monitor on-site contamination in the seven source areas. However, in addition to these specified COCs, several hundred organic dyes, resins, and their reagents and by-products are known to be present in the surface and subsurface soils of the source areas (CDM, 1994). Many unidentified chemicals (aka tentatively identified compounds, i.e., TICs) were also detected in samples taken from on-site soils (DS, 1997). Since most of the dyes and associated compounds that were used and manufactured by CGC are water-soluble, it is likely that they have been partitioned between the soils and ground water. However, the additional chemicals that have been identified in source areas do not have high vapor pressures, so they are not expected to volatilize when the source areas are excavated, and monitoring for these chemicals in the ambient air is not likely to be necessary. NJDHSS and ATSDR concur that the COCs that are specified in the FS and the Plan will adequately represent the compounds that may be released to the ambient air and/or included with dust that may be entrained during remedial activities.

Characterization and Monitoring of Airborne Contaminants during Remedial Activities

As indicated in the Record of Decision (ROD) for OU2 (EPA, 2000), a combination of excavation of drums and bio-treatment of contaminated soils will be utilized to remediate seven on-site source areas. Approximately 32,000 drums will be excavated (at a rate of about 225 work days per year over the course of two years, equivalent to about 70 drums per day) from the Drum Disposal Area (DDA) and disposed off-site. In addition, about 150,000 cubic yards of contaminated soil will be excavated (at a rate of about 30 days per year for six years, equivalent to about 850 cubic yards per day) from the seven source areas and subsequently bio-remediated on-site. The treated soil will be returned to on-site property after remediation. The entire OU2 remedial action is expected be completed in about eight years. Remedial activities will be conducted simultaneously at the DDA and one of the other areas until removal of the drums in the DDA is completed after about two years. Excavation and bio-remediation of the contaminated soils in the source areas will continue until remediation of the seven source areas is completed.

Since the potential exists for the release of VOCs and particulates to ambient air during remedial activities, the Plan proposes to establish three zones of action for each of the source areas (see Tables 1 and 2) that will be remediated. Under the Plan, ambient air will be monitored at: (1) the work zone; (2) the near-field zone, located approximately 300 feet from the excavation site; and (3) the site perimeter, located a minimum of about 900 feet or more from the excavation area. Stationary and mobile meteorological stations will be established to measure local weather conditions, especially wind direction and velocity, during remedial activities. The prevailing winds at the site have historically been primarily westerly, i.e., from west to east. The Plan indicates that mobile air monitoring stations will be established at the work area and at near-field zone locations. Stationary monitoring stations will also be established at six locations along the site boundary, including the two that are located on the eastern perimeter adjacent to Cardinal Drive, and one near the West Dover Elementary School adjacent to the southern corner of the CGC property (see Figure 4). An additional mobile monitoring station will also be positioned along the perimeter during each day's excavation in order to measure COC concentrations in the downwind direction.

The Plan does not propose to perform any off-site monitoring of the ambient air during remedial activities. However, even though the perimeter monitoring stations will be located on CGC property (to help protect them from vandalism), they are considered to be exposure point monitors. Consequently, the continuous monitoring data that will be gathered from the stationary and mobile stations that are adjacent to the nearby residential areas should provide sufficient information to characterize the potential exposure to these off-site populations. Therefore, ATSDR and NJDHSS believe that the placement of the monitors to be protective of public health.

The concentrations of airborne particulate matter, i.e., particulates with diameter less than 10 micrometers, i.e., PM10 (inhalable particles) , will also be monitored during excavation activities. Two of the five source area-specific COCs, namely mercury and lead, could be entrained in dust that will be released during remedial activities. Time-weighted air monitoring for lead and mercury will not be performed; however, PM10 will be monitored on a continuous basis. Based on EPA guidance, the Plan provides a rationale that indicates that if the action levels for inhalable particles are not exceeded, then the individual action levels for lead and mercury will also not be exceeded. The Plan also calls for confirmatory monitoring for lead and mercury to make sure that action levels for mercury and lead are not exceeded and that the assumption that continuous monitoring for PM will be protective of public health. ATSDR and NJDHSS concur that periodic confirmatory monitoring is indicated to determine if the assumptions stated above are correct. Moreover, ATSDR and NJDHSS believe that confirmatory monitoring for lead and mercury should be conducted if any of the particulate matter action levels are exceeded. Such confirmatory monitoring is needed to ensure that concentrations of mercury and lead do not exceed action levels. In addition, while site data indicate that lead and mercury are the most likely particle-bound air contaminants, NJDHSS and ATSDR believe that it is a prudent public health measure to perform additional particle analysis for the full spectrum of potential particle-bound contaminants.

The description of EPA's Selected Remedy in the ROD for OU2 (EPA,2000) indicates that excavated soil (about 4,000 cubic yards at a time) will initially be placed in the primary treatment area , i.e., a building which will be constructed near the Equalization Basins, where volatile organic chemicals in the soil will be biologically treated. The air in the building will be monitored while soils are inside, and air emissions from the building will be treated and be required to meet permitted standards set by the New Jersey Department of Environmental Protection (NJDEP) under the provisions of New Jersey Administrative Code (NJAC) 7:27-16 (Control and Prohibition of Air Pollution by Volatile Organic Compounds). After a period estimated to be about two months, the soil will be moved to an outdoor (secondary treatment) area, where bio-remediation will continue. However, before the soils are moved outdoors, acceptable soil concentrations of the COCs must be achieved. These levels will be set to insure that the action levels will not be exceeded in the ambient air around the secondary treatment area. To confirm that the emissions are acceptable, near-field monitoring will be conducted for several days after treated soil is brought outdoors (EPA, 2002).

Zones of Action and Exposure Duration

The Plan indicates that airborne emissions will be monitored in the three zones of action for three different potential exposure durations (see Table 2). NJDHSS and ATSDR concur that the proposed monitoring of the three zones of action for "immediate", "short-term", and "long-term" exposure should characterize the potential exposure to workers and the community due to emissions from the source areas. The exposure duration categories are defined in terms of the monitoring instrument that will be utilized to measure VOCs: (1) "immediate" exposure (ppbRae™- continuous monitoring - about 1 minute response time); (2) "short-term" exposure (ppbRae™ and SRI Instruments Gas Chromatograph-for measurement of individual VOCs-up to about 30 minutes response time); and (3) "long-term" exposure (sampling with SUMMA® canisters - 8 hours mobile, or 24 hours fixed). Confirmatory sampling for VOCs will be accomplished using SUMMA® canisters, which will take an estimated 2 to 3 days to analyze.

Source area remedial actions at CGC include about thirty separate excavation days per year at the source areas for six years (a total of about 180 excavation days), for a total of about 150,000 cubic yards. The excavations will be conducted in conjunction with about 225 drum removal events per year (a total of about 32,000 drums) that will be conducted at the DDA over a period of two years (a total of about 450 excavation days). However, off-gassing of COCs could occur during periods when excavation in a particular area is not occurring, but has not been completed, and when contaminated soils are brought outside for final bio-remediation. As a result, remedial activities are likely to take place during essentially every available work day. Therefore, emissions of COCs potentially could occur at any time while soil excavation, drum removal, and bio-remediation are occurring.

Capabilities of Air Monitoring Equipment

Several instruments will be used to monitor the ambient air in the three zones of action. Table 2 summarizes the monitoring equipment, the time duration of measurement for each type of monitoring equipment, and the Minimum Detection Level (MDL) for each instrument. VOCs will initially be monitored using the ppbRae™ portable monitor, which measures Total VOCs (TVOCs) continuously, and has a MDL of 1 ppb. The ppbRae™ utilizes a 10.6 eV photoionization source.

The SRI Instruments Gas Chromatograph (GC) will be used to determine the ambient air concentrations of individual VOCs. In order to detect all COCs, this instrument is configured with three separate detectors. The sampling/analysis will take up to 30 minutes, and the range of MDLs vary from 20 ppb to 100 ppb according to the individual compound.

SUMMA® canisters will be used to provide confirmatory measurement of the concentrations of VOCs. Ambient air will be collected in a canister for about 8 to 24 hours. Analytical results will be available in about 2 to 3 days. The MDLs for the different VOCs range from about 0.2 to 1 µg/m3.

The Plan also indicates that three different instruments will be used to measure particulates in ambient air, specifically: (1) the Casella Cel MicroDust Pro™, a semi-portable instrument that provides continuous monitoring of Total Suspended Particulates (TSP) with a MDL of 1 µg/m3; (2) the Mie DataRAM Real-Time Aerosol Monitor™, a fixed instrument with a readout every minute that is reported as a 5 minute average, that can determine both TSP and PM10 fractions, with a MDL of 0.1µg/m3; and (3) the TEOM® Series 1400a Ambient Particulate Monitor, a fixed station, confirmatory instrument that can be utilized to characterize TSP, or PM10, PM2.5, or PM1 fraction concentrations in real time. The TEOM-collected dust can also be used for confirmatory analysis for lead and mercury.

Concept of Monitoring, Action Levels, and Response Actions for VOCs

According to the Plan, the results of monitoring for TVOCs with the ppbRae™ (and TVOCs or individual VOCs with the SRI Instruments GC) will, depending on the location, measured concentration and exposure duration, trigger a variety of response actions by on- and off-site officials (including Ciba, EPA, local police, EMS, hazardous materials (hazmat), and NJDEP emergency response personnel) that range from notification of on- and off-site officials to activation and deployment of hazmat responders. Since previous sampling has shown no evidence that any pure product, i.e., non-aqueous phase liquid (NAPL), is present in identified source areas (Ciba, 1999), it does not seem likely that high concentrations of COCs will be released during excavation activities. However, if the "immediate" action level in any of the zones of action is exceeded, work will be stopped, emission control procedures will be initiated, and hazmat officials will be notified. Also, if a "short-term" action level is exceeded in any zone of action, actions will be taken to reduce emissions and upgrade worker protection. Hazmat officials will be notified after emissions are controlled. "Long-term" action levels (LTAL) have been determined for the site perimeter only, and if the LTAL is exceeded, the remediation methodology and procedures will be re-evaluated. Further details regarding emergency response actions can be found in the Draft Emergency Management Plan (Ciba, 2002b) and the Health and Safety Plan, when available.

The Plan calls for contaminant-specific air monitoring to be implemented when a TVOC trigger level (see Table 3) is exceeded. However, in practice, contaminant-specific monitoring will be initiated before the TVOC action level is exceeded (Ciba, 2002a). A possible scenario for potential exposure and prescribed response actions in the work zone is as follows. Normal TVOC background on the CGC site, as measured by the ppbRae™, was stated by Ciba personnel to be as high as about 15 ppb. If a ppbRae™ measured an increase from the background level towards the 1 ppm TVOC action level for a period of five minutes in the work zone, this would trigger use of the SRI Instruments GC in order to determine the identities of the VOCs. Identification and measurement of individual VOCs with the SRI Instruments GC would require about 20-30 minutes (possibly longer depending on the COC and its concentration). If the TVOC reading exceeded 1 ppm during that time, work would be stopped and emission control procedures would be initiated. Work would not resume until confirmation that all COCs were below their respective action levels.

Based on this anticipated scenario, NJDHSS and ATSDR concur with the Plan that the most expedient method of protecting the public health is to utilize operational trigger levels that are expressed in terms of TVOC concentration, rather than concentrations of individual COCs. As discussed in the Plan, if a ppbRae™ measurement exceeds the TVOC trigger level for a period of five minutes, response actions, e.g., work stoppage, emission controls, increasing the level of personal protection, etc., will be initiated immediately, while the identity and concentration of individual VOCs are being determined by the SRI Instruments GC. Determining the identity of the individual VOCs before the TVOC action level is exceeded will provide an extra measure of protection to the workers and the community.

Action Levels for VOCs in the Work and Near Field Zones

Action levels have been established for the work and near field zones primarily to protect site workers, but also to help determine the need to stop work and take appropriate measures to reduce the potential for the concentrations of COCs to reach levels of health concern at the perimeter and in the nearby residential areas.

Table 3 summarizes the proposed work zone and near field action levels for "immediate" and "short-term" duration exposure to each of the COCs. Nitrobenzene has the lowest published occupational exposure guidance concentration of the twelve VOCs, i.e., an eight hour duration time-weighted average of 1 ppm, so it was designated in the Plan as the short-term trigger level concentration for real time monitoring for TVOCs at the work or near field zones. As previously stated, the Plan indicates that, if this TVOC concentration is approached, compound-specific monitoring will be utilized to verify that each contaminant present is below its respective action level. For example, the proposed action level for short-term exposure to nitrobenzene in the work zone is 1 ppm. If necessary, actions will be taken to reduce emissions and upgrade worker personal protective equipment.

NJDHSS and ATSDR have evaluated the proposed work zone and near-field action levels and concur that they should be protective for on-site workers. The TVOC trigger levels should be able to determine the need to stop work and to take appropriate measures, as necessary, to reduce the potential for COCs to exceed action levels at the perimeter.

Action Levels for VOCs at the Site Perimeter

Perimeter action levels are specifically designed to protect the community from harmful exposures. As with the work and near field zones, the Plan presents proposed Action Levels for VOCs at the site perimeter. The "immediate" and"short-term" action levels for VOCs that are proposed for the site perimeter are summarized in Table 3. For example, the "immediate"action level for nitrobenzene at the perimeter is given as 20 ppm, i.e., 10% of the IDLH, and the "short-term" action level for nitrobenzene at the perimeter is given as 0.1 ppm (100 ppb), i.e., 10 % of the ACGIH Threshold Limit Value Time Weighted Average (TLV-TWA).

The proposed "long-term" action levels (LTAL) for the COCs at the site perimeter are summarized in Table 4. The LTALs were derived by modifying the EPA Reference Concentration (RfC), or Risk-Specific Dose (RSD) for carcinogens, for each of the COCs by an exposure frequency factor that is based on the expected number of days of excavation. The LTALs contain several conservative assumptions, as follow: 1) 24-hour a day exposure is assumed at the perimeter during excavation activities, 2) chemicals are assumed to be present 24-hours per day instead of just the 8-hours of excavation activities on any given day; and 3) although exposure to many of the COCs would only occur on an occasional basis, it is assumed that potential exposures are consecutive (Ciba, 2002a). NJDHSS and ATSDR have reviewed these assumptions and believe that they are protective of public health. However, the assumption of the frequency of exposure (i.e., number of days potentially exposed), a major factor in determining the long-term action levels, has the potential to be violated. Therefore, the NJDHSS and ATSDR believe that the perimeter LTALs should be re-evaluated periodically once the excavations, bio-remediation and drum removal have begun, to determine if the frequency of exposure assumption, or any of the exposure assumptions used in the development of these LTALs, should be reconsidered, and if lowering the current LTALs is warranted.

It should be noted that the odors of the VOCs that could be emitted during remediation activities may be an earlier indicator of their presence than air monitoring equipment. The human nose is, in some cases, more sensitive than available instruments, so it is possible that some people may smell the COCs at concentrations that are below the action levels. As noted in Table 5, the odor thresholds for several of the COCs are less than 1 ppm, including nitrobenzene, 2-chlorotoluene, 1,2-dichlorobenzene, and naphthalene. The odor could provide an indication to nearby residents that COC's from the source area are in the ambient air. In addition, odors from other compounds that are not COCs may also be detected during remediation. However, it is important to note that the presence of an odor does not necessarily indicate that there is a public health concern.

Action Levels for Particulates

Since dust may be generated as a result of the excavation activities, the Plan proposes to monitor the concentration of particulates in ambient air in each of the three zones of action. The concentrations of airborne particulates will be measured with several different instruments that are capable of determining the concentration (and, if desired, the size distribution) of the particles with varying detection limits. The Plan indicates that there is no "immediate" action level for particulates in any zone of action. However, "short-term" action levels have been proposed for each zone, and a "long-term" action level has been designated for the site perimeter (see Table 6). The long-term perimeter action levels are based on the National Ambient Air Quality Standards (NAAQS) of 150 µg/m3 (24- hour average) and 50 µg/m3 (annual average). The short-term action level is based on the OSHA 8-hour occupational exposure standards for particulates of 15 mg/m3 (total dust) or 5 mg/m3 (respirable fraction). The Plan proposes that work stoppage and/or dust minimization actions be initiated if any of the short-term action levels are exceeded.

Heavy metals have been designated as source area-specific contaminants in two areas, including lead in the Backfill Lagoon Area, and mercury in the Filtercake Disposal Area. As previously indicated, NJDHSS and ATSDR concur with the Plan that, if any of the particulate matter action levels are exceeded, confirmatory monitoring for lead and mercury should be conducted to determine if the particulate matter action levels are protective for exposure to these metals. That is, confirmatory monitoring is needed to ensure that the concentrations of mercury and lead do not exceed their individual action levels. If appropriate confirmatory monitoring is performed, then the proposed action levels for particulate matter should be protective of public health. In addition, while site data indicate that lead and mercury are the most likely particle-bound air contaminants, NJDHSS and ATSDR believe that it is a prudent public health measure to perform additional particle analysis for the full spectrum of potential particle-bound contaminants.

Summary of NJDHSS and ATSDR Evaluation of Proposed Action Levels

After evaluating the action levels that are proposed in the Plan, NJDHSS and ATSDR concur with the Plan that it is appropriate to utilize TVOC concentrations as the trigger levels that would initiate contaminant-specific monitoring and, as necessary, response actions. Use of TVOC measurements will allow for quicker reaction and initiation of protective response actions, since identification and determination of the concentration of an individual COC requires a longer period of time than does a TVOC measurement. Since each source area contains a mixture of COCs and other contaminants, it is probable that a mixture of chemicals will volatilize during (and after) excavation activities. A measurement of TVOC concentration will include all of the compounds that are present in ambient air. The TVOC short-term trigger levels that were proposed by Ciba are summarized in Table 3. However, as previously indicated, NJDHSS and ATSDR believe that the perimeter VOC-specific LTALs should be re-evaluated periodically when the soil excavations, bio-remediation, and drum removal have begun to determine if any of the exposure assumptions that were used to derive the perimeter LTALs are exceeded. If it is determined that any of the assumptions have been exceeded (e.g., frequency of exposure), then consideration should be given to lowering the proposed LTALs.

The use of TVOC measurements as trigger levels will simplify and help expedite response actions by relying on several key values instead of many chemical-specific ones. As the Plan is quite complex, the action levels and associated response actions should to be practiced on-site, prior to initiation of remedial activities, under different scenarios, e.g., during work and non-work hours, prior to the initiation of remedial activities to properly train monitoring and response personnel.

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