Superfund Program Proposed Plan Chemical Leaman Tank Lines Superfund Site July 2009 U.S. Environmental Protection Agency, Region 2 .^DS7^ Si \ CD EPA ANNOUNCES PROPOSED PLAN This Proposed Plan identifies the Preferred Alternative to address source areas to ground-water contamination at the Chemical Leaman Tank Lines Superfund Site (Site) in Logan Township, Gloucester County, New Jersey, and provides the rationale for this preference. These alternatives have been developed to address source areas contaminated with Non-Aqueous Phase Liquid (NAPL), volatile organic compounds (VOCs), including cis-1,2- dichloroethene, trichloroethene, and tetrachloroethene; semivolatile organic compounds (SVOCs), including naphthalene and bis(2-ethylhexyl)phthalate; and arsenic. The U.S. Environmental Protection Agency's (EPA's) Preferred Alternative to address source areas to groundwater contamination is Alternative 2A, which includes a combination of Non-Aqueous Phase Liquid recovery, in situ thermal treatment with soil vapor extraction, and extraction and treatment of groundwater. EPA is addressing the cleanup of the Site in three phases, called Operable Units. This Proposed Plan addresses Operable Unit 2 (OU2), which includes the final cleanup of contaminated source areas related to the Site which are contributing to groundwater contamination. The Operable Unit One (OU1) remedy, which consists of groundwater extraction and treatment, will serve to restore the contaminated groundwater plume to beneficial use and will meet the maximum contaminant levels for drinking water. The OU1 groundwater treatment plant has been constructed and is currently in the startup phase. The OU3 remedy addressed wetlands contamination at the site. Remediation and restoration activities for the wetlands have been completed. This Proposed Plan includes summaries of all cleanup alternatives evaluated for OU2 at the Site. This document is issued by EPA, the lead agency for Site activities, and the New Jersey Department of Environmental Protection (NJDEP), the support agency. EPA, in consultation with NJDEP, will select the final remedy for OU2 after reviewing and considering all information submitted during a 30-day public comment period. EPA, in consultation with NJDEP, may modify the preferred alternative or select another response action presented in this Proposed Plan based on new information or public comments. Therefore, the public is encouraged to review and comment on all the alternatives presented in this document. EPA is issuing this Proposed Plan as part of its community relations program under Section 117(a) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA, or Superfund). This Proposed Plan summarizes information that can be found in greater detail in the Remedial Investigation and Feasibility Study (RI/FS) reports and other documents contained in the Administrative Record for the Site. MARK YOUR CALENDAR PUBLIC COMMENT PERIOD: July 6, 2009 - August 5, 2009 EPA will accept written comments on the Proposed Plan during the public comment period. PUBLIC MEETING: Monday, July 20, 2009, at 7 P.M. EPA will hold a public meeting to explain the Proposed Plan and all of the alternatives presented in the Feasibility Study. Oral and written comments will also be accepted at the meeting. The meeting will be held in the Logan Township Municipal Building, Municipal Courtroom, located at 125 Main Street, Bridgeport, New Jersey 08014 For more information, see the Administrative Record at the following locations: U.S. EPA Records Center, Region 2 290 Broadway, 18th Floor. New York, New York 10007-1866 (212)637-4308 Hours: Monday-Friday - 9 am to 5 p.m., by appointment. Township Municipal Clerk's Office Logan Township Municipal Building 125 Main Street, Bridgeport, NJ 08014 (856)467-3424 Ext. 9 Summer Hours (Memorial Dav - Labor SITE DESCRIPTION The Site is located in a predominantly rural area of Logan Township, Gloucester County, New Jersey. The Site consists of a 38.5-acre active tanker truck washing terminal area, as well as surrounding property that remains unused, and is bordered to the north by a Conrail rail line, to the east by Cedar Swamp, to the south by Moss Branch Creek and adjacent wetlands, and to the west by Pierson Materials, Inc. sand pits. ------- The Site is zoned Light Industrial with designated principal uses including: warehousing, freight terminals, fabrication of processed materials, office buildings, and other low impact industrial uses. Most of the northern and western portions of the Site consist of unpaved (sand and gravel) parking and driveway areas. Wetlands occupy the eastern and southern portions of the Site. The Site property west of Oak Grove Road is undeveloped. Land use in the immediate vicinity of the Site is predominately residential, industrial and agricultural. The groundwater in the vicinity of the Site is a potable water supply; however, residential properties located in the vicinity of the Site are connected to the public water supply. SITE HISTORY Facility operations at the Site began in 1961. Historically, wastewaters from washing and rinsing of the tanker trucks were contained on-site in seven unlined settling and aeration lagoons before ultimately being discharged to the Cedar Swamp and Moss Branch Creek via adjacent wetlands. Three of these lagoons were the Primary Settling Lagoons located just east of the Terminal Building and four lagoons were the Secondary Aeration and Settling Lagoons located south of the Terminal Building. An oil slick was present on all of the lagoons during a July 7, 1972 NJDEP inspection. In response to NJDEP requirements, the facility installed a rinse-water containment system for its tanker washing operation in August 1975, and by 1977, the facility ceased using the wastewater lagoons. The liquid that remained in the lagoons was reportedly drained and the sludge that had accumulated at the bottom of the Primary Settling Lagoons was removed by vacuum truck. The settling and aeration lagoons were then backfilled with clean fill and construction debris; however, sludge that had accumulated in the aeration lagoons was not removed prior to backfilling. In 1980 and 1981, the NJDEP found carbon tetrachloride and other organic compounds in the groundwater on the Site, as well as in neighboring private supply wells. The presence of these compounds in the groundwater of the area apparently resulted from former wastewater handling and disposal practices at the Site. Contamination was also found in Site soils and the adjacent wetland area. Specifically, VOCs, base-neutral extractable compounds, and inorganic compounds (metals) were detected in Site soils and in wetlands adjacent to the Site. VOCs were the principal contaminants of concerns associated with groundwater and were found in soils associated with the former settling and aeration lagoons and other historic operational release areas. In addition to VOCs, several SVOCs and arsenic were detected at elevated levels in both unsaturated and saturated soils on-site. In 1982, the sump beneath the 3,000-gallon stainless steel settling tank (located in the waste accumulation building) was found to be leaking and was repaired. Visible sludge and contaminated soil in the former Primary Settling Lagoons and around the settling tank were excavated to a depth of approximately 12 feet below ground surface (bgs), under the supervision of the State of NJ. These excavations were then backfilled with clean sand. Investigation findings indicated that contaminated groundwater affected areas beyond the truck washing facility and nearby residences. Therefore, the Site was placed on the National Priorities List (NPL) of Superfund Sites on September 21, 1984. The remedial investigation/feasibility study (RI/FS) process at the Site was initiated in 1985. Based on the complexity of the contamination, EPA divided the Site into the following three OUs for the purpose of Site cleanup: OU1 addresses the remediation of contaminated groundwater underlying the Site; OU2 addresses the remediation of contaminated source areas to groundwater contamination; and OUS addresses the remediation of contaminated wetlands at the Site. A Record of Decision (ROD) for OU1 was issued by EPA on September 28, 1990 that selected groundwater extraction and treatment as the groundwater remedy. Significant investigations were performed as part of the Remedial Design (RD) phase for OU1 and construction of the groundwater treatment plant for OU1 was completed in January 2007. The groundwater extraction and treatment system consists of 20 recovery wells with a total pumping rate of 230 gallons per minute (gpm) from the shallow and intermediate aquifer zones and is currently in the startup phase. EPA issued a ROD for OUS on October 5, 1993 that selected excavation and off-site disposal of contaminated wetland soils and sediments along with wetland restoration activities. Remediation and restoration activities in wetland areas of the Site were completed in July 2007. The objective of the OU2 Remedial Investigation (RI) for the Site was to identify and delineate both unsaturated and saturated areas of soil contamination serving as sources of groundwater contamination, also known as "principal threat" waste. At this Site, principal threat waste consists of source material which is defined as material that included or contains hazardous substances, pollutants or contaminants that act as a reservoir for migration of contamination to groundwater. Four separate phases of investigations were conducted for OU2 between 1985 and ------- 2008 to characterize the nature and extent of the contaminated soil source areas. WHAT IS A "PRINCIPAL THREAT"? The NCP establishes an expectation that EPA will use treatment to address the principal threats posed by a site wherever practicable (NCP Section 300.430(a)(l)(iii)(A)). The "principal threat" concept is applied to the characterization of "source materials" at a Superfund site. A source material is material that includes or contains hazardous substances, pollutants or contaminants that act as a reservoir for migration of contamination to ground water, surface water or air, or acts as a source for direct exposure. Contaminated ground water generally is not considered to be a source material; however, Non-Aqueous Phase Liquids (NAPLs) in ground water may be viewed as source material. Principal threat wastes are those source materials considered to be highly toxic or highly mobile that generally cannot be reliably contained, or would present a significant risk to human health or the environment should exposure occur. The decision to treat these wastes is made on a site-specific basis through a detailed analysis of the alternatives using the nine remedy selection criteria This analysis provides a basis for making a statutory finding that the remedy employs treatment as a principal element. The final 2009 RI Report for OU2 presents the data from all four phases of the OU2 investigation. The 1999 NJDEP Impact to Groundwater Standards and the Non- Residential Direct Contact Soil Cleanup Criteria were used as a basis of comparison for the analytical results. Elevated concentrations of VOCs, including cis-1,2- dichloroethene (DCE), trichloroethene (TCE), tetrachloroethene (PCE); SVOCs, including naphthalene, bis(2-ethylhexyl)phthalate; and arsenic were observed, and source areas or areas of concern (AOCs) warranting remedial action were identified. Driver chemicals of potential concern (COPCs) were selected for each AOC based on the relatively high concentrations of these COPCs detected in the soil and the prevalence of these chemicals detected in groundwater, which suggests a high degree of mobility. The driver COPCs were used to delineate the AOCs. In June 2009, EPA completed the Feasibility Study (FS) for OU2 at the Site. The purpose of the FS is to identify, develop, screen, and evaluate a range of remedial alternatives for the AOCs identified in the RI and to provide the regulatory agencies with data sufficient to select a feasible and cost-effective remedial alternative that protects public health and the environment from potential risks at the Site. SITE CHARACTERISTICS OU2 encompasses approximately 13 acres and is generally defined as the active facility operations area of the Site. Undeveloped land and a quarry are located directly west of the site. A Conrail railroad borders the Site to the north and separates it from several private residences along Route 44. North of Route 44 is Cooper Lake, an abandoned sand and gravel pit that was filled with water for use as a recreational lake. Three residences on the southern edge of the lake are occupied year-round, while four structures on the western and northeastern edges of the lake are believed to be occupied seasonally. Residents in the vicinity of the Site are connected to a public water supply. There are no surface water bodies within OU2; however, forested wetlands in the southern and eastern portions of the Site constitute OU3. These wetlands are part of the Great Cedar Swamp, a tidal wetland within the Delaware River drainage basin. Several slow moving streams are present in the wetland. Moss Branch drains the southern portion of the Site and flows north but is impeded by Routes 130 and 44. Unnamed streams north of the Site drain the wetlands and flow into the Delaware River which is located approximately 1% miles north of the Site. The topography in the area around the Site is flat and gently slopes toward the southeast. Surface elevations across the property range from approximately five feet above mean sea level in the wetlands (OU3) to 12 feet above mean sea level in the parking lot. Five geologic units underlie the Site. The undifferentiated sediments at depths less than 150 feet at the Site are composed of sands, silts and clays. A review of geologic boring logs reveals that the shallow subzone consists primarily of fine to coarse-grained, tan to light brown quartz sand and fine - grained quartz gravel with trace amounts of sand-sized feldspar, very fine-grained lignite and unidentified heavy minerals, intermixed with varying amounts of brown to orange, fine to medium-grained quartz silt. There are three potentially significant water-bearing subzones within the undifferentiated upper zone in the vicinity of the Site. The subzones are separated by discontinuous clay units of variable thickness and were interpreted to occur as: (1) a shallow subzone occurring from ground surface to approximately 30 feet bgs; (2) an intermediate subzone occurring from 30 to 100 feet bgs; and (3) a deep subzone from 100 to approximately 150 feet bgs. The average depth to shallow groundwater at the Site is approximately 7 feet bgs. Logan Township, which encompasses 22.8 square miles, has a population of approximately 6,032, according to the United States 2000 Census. Bridgeport has a population of approximately 635. Source Area Contamination OU2 was originally defined as the surficial (unsaturated) soils primarily located around the former settling and aeration lagoons; however, the scope of the operable unit ------- was expanded to include additional potential source areas to groundwater contamination, including unsaturated and saturated soils and areas containing Non-Aqueous Phase Liquid (NAPL). Four phases of investigations were conducted for OU2, with each subsequent investigation building upon the data of previous RI activities to characterize the nature and extent of source areas within the OU2 boundaries. Over 200 soil borings were installed and over 200 subsurface soil samples were collected around the former aeration and settling lagoon areas and in the vicinity of the terminal building. For the purposes of consistency in evaluating the data from the four phases of the remedial investigation, the 1999 NJDEP Impact to Groundwater and Non-Residential Direct Contact Soil Cleanup Criteria were used as a basis of comparison. Soil zones which contain relatively high levels of contamination are referred to as "source areas" or "Areas of Concern." These AOCs were defined in terms of relative concentrations of Chemicals of Potential Concern that "drive" potential groundwater contamination at the Site and in terms of COPCs that indicate the presence of NAPL. "Driver COPCs" denote the most prevalent of the toxic and mobile chemicals found on-site. Driver COPCs were selected for each AOC based on the relatively high concentrations of these COPCs detected in soil and the prevalence of these constituents detected in groundwater, which suggests a high degree of mobility. Based on the data from the RI investigations, eight Areas (AOCs) were initially identified along with six additional Spill Areas which occurred as a result of operational spills between 2007 and 2008 (See Figure 2). Spill Areas 1, 3, 4 and 6 did not pose a human health risk and were addressed by spill response actions during the course of the RI; therefore, no further action is required for these Spill Areas. Area 5 did not pose a human health risk and sampling results indicated that no further action is required for this Area. The Baseline Human Health Risk Assessment determined that the unsaturated soils in Spill Areas 2 and 5 and Areas 7B, 7C and 8 pose a potential human health threat. Since these areas were limited in size (totaling approximately 330 cubic yards) and extent of contamination, they are being addressed by the Potentially Responsible Party (PRP), with EPA oversight, in a separate removal action. Soils in these areas will be excavated and appropriately disposed of off-site and therefore were not carried through the Feasibility Study. Accordingly, the following AOCs remain and warrant a remedial action because they are source areas to groundwater contamination: Areas 1, 2, 3, 4, 6 and the area beneath the Waste Accumulation Building (WAB) (See Figure 1). Driver COPCs were identified for each of these areas and were used to delineate the extent of contamination for each AOC (See Table 1). For Area 1, the driver COPCs include trichloroethene (TCE) (0.14 milligrams per kilograms (mg/kg) - 10,000 mg/kg), cis- 1,2-dichloroethene (DCE) (0.59 mg/kg - 160 mg/kg), bis(2-ethylhexyl)phthalate (27 mg/kg - 2,600 mg/kg), butylbenzylphthalate (0.66 mg/kg - 3,000 mg/kg), naphthalene (1.6 mg/kg - 2,500 mg/kg) and n- nitrosodiphenylamine (9.5 mg/kg - 450 mg/kg). For Areas 2, 3 and 4, the driver COPCs include DCE (0.001 mg/kg - 410 mg/kg) and TCE (0.001 mg/kg - 53,000 mg/kg). Area 6 COPCs include DCE (0.001 mg/kg - 25,000 mg/kg), TCE (0.0007 mg/kg - 27,000 mg/kg), bis(2-ethylhexyl)phthalate (0.22 mg/kg - 14,000 mg/kg), butylbenzylphthalate (0.07 mg/kg - 26,000 mg/kg), 1,2- dichlorobenzene (0.0015 mg/kg - 450,000 mg/kg) and naphthalene (0.06 mg/kg - 29,000 mg/kg). The WAB COPCs include DCE (0.26 mg/kg - 110 mg/kg), tetrachloroethene (PCE) (0.26 mg/kg - 250 mg/kg), TCE (0.26 mg/kg - 740 mg/kg), 1,2-dichlorobenzene (0.16 mg/kg - 77 mg/kg), bis(2-ethylhexyl)phthalate (14 mg/kg - 260 mg/kg), butylbenzylphthalate (4.6 mg/kg - 460 mg/kg), naphthalene (92 mg/kg - 530 mg/kg), n- nitrosophenylamine (23 mg/kg - 20,000 mg/kg), and arsenic (35 mg/kg - 440 mg/kg). These six contaminated soil areas are acting as sources to groundwater contamination. The contamination in these six AOCs falls within one or more of the following categories: 1) unsaturated soils (located 0 ft to 7 ft bgs); 2) Non-Aqueous Phase Liquid (NAPL) and associated saturated soils (located 2 ft to 20 ft bgs); and 3) highly contaminated saturated soils in the intermediate groundwater zone (located 25 ft to 95 ft bgs). Remediation of OU2 source areas will augment the OU1 groundwater remedy and provide for a more timely restoration of the aquifer to drinking water standards, which is the primary objective of the OU1 remedy. SCOPE AND ROLE OF THE ACTION EPA has addressed the cleanup of this Site by implementing immediate actions to address situations which present an imminent threat to human health, and a long-term cleanup. With respect to immediate actions taken, activated carbon treatment units were placed in four homes with contaminated drinking water. The four homes were later connected to a permanent water line from a nearby town in 1987. Three more homes threatened by site-related groundwater contamination were connected to the municipal water line in March 1993 and August 1995. The long-term cleanup will be conducted in three discrete phases, or Operable Units. ------- • Operable Unit (OU) 1, which was the subject of a 1990 ROD, provides for the implementation of a groundwater remedy which consists of the construction of groundwater extraction and treatment plant. Construction of the plant was completed in January 2007. The groundwater treatment plant is currently in the startup phase. • OU2, which is the subject of this Proposed Plan, will provide for implementation of a remedy to address source areas to groundwater contamination at the Site. By addressing source areas, OU2 will address principal threat waste at the Site, effectively augment the OU1 groundwater remedy, and provide for a more timely restoration of the aquifer to drinking water standards. The OU2 ROD is expected to be the final remedy selected for this Site. • OU3 addresses the remediation of contaminated wetlands at the Site. EPA issued a ROD for OU3 on October 5, 1993 and excavation, off-site disposal and restoration activities were completed in July 2007. SUMMARY OF OPERABLE UNIT 2 RISKS Summary of Site Risks The purpose of the risk assessment is to identify potential cancer risks and non-cancer health hazards at the Site assuming that no further remedial action is taken. A baseline human health risk assessment (HHRA) was performed to evaluate current and future cancer risks and non-cancer health hazards based on the results of the Remedial Investigation (RI). A screening- level ecological risk assessment (SLERA) was also conducted to assess the risk posed to ecological receptors due to site-related contamination. As part of the RI/FS, EPA conducted a baseline risk assessment to estimate the current and future effects of contaminants on human health and the environment. A baseline risk assessment is an analysis of the potential adverse human health and ecological effects of releases of hazardous substances from a site in the absence of any actions or controls to mitigate contamination, under current and future land uses. The baseline risk assessment includes a human health risk assessment (FfHRA) and an ecological risk assessment (SLERA) and can be found in the RI Report in the Administrative Record. The cancer risk and non-cancer health hazard estimates in the HHRA are based on current reasonable maximum exposure (RME) scenarios which portray the highest level of human exposure that could reasonably be expected to occur. RME scenarios were developed by taking into account various health protective estimates about the frequency and duration of an individual's exposure to chemicals selected as chemicals of potential concern (COPCs), as well as the toxicity of these contaminants. In addition, cancer risks and non-cancer health hazard indices (His) to the average exposed individual, referred to as the Central Tendency Exposure (CTE), are also provided. CTEs are based on less conservative (lower) exposure frequencies than those used to calculate the RME individual. CTEs serve to show a range of risks to different exposed individuals other than the RME individual. However, consistent with the NCP and Superfund law, remedial decisions are based on the RME. (Please see the text box on the following page for an explanation of these terms). Human Health Risk Assessment The Site property is currently zoned industrial and the future land use is expected to remain the same. The baseline risk assessment began by selecting COPCs in the soil that would be representative of site risks. The OU2 data were grouped into exposure units and the potential for adverse health effects following exposure from direct contact to COPCs and inhalation of volatiles and particulates was evaluated separately for each exposure unit. The composition of each exposure unit was based on the area targeted for investigation or geographic proximity and similar nature of chemical contamination of the representative samples. The exposure units for which risk was evaluated included the following: former primary settling lagoons (Areas 1 and 5); former secondary aeration lagoons (Area 3); Area 4 (i.e., Southwest NAPL areas); Area 6 (near borings W8/W9); Area 7 (including Spill Areas 2, 3, and 5); Area 8; the Terminal Parking Areas; and Spill Area 4. The COPCs for the Site risk assessment were trichloroethene (TCE), naphthalene, arsenic, and manganese in soil. Note that the risk assessment only evaluated unsaturated soils from 0-10 feet below ground surface (bgs) because construction and other activities are not anticipated below the water table. The OU2 RI investigated unsaturated soils as well as saturated soils and NAPL. The contamination detected in saturated soils and NAPL is not included in this risk ------- WHAT IS RISK AND HOW IS IT CALCULATED? Human Health Risk Assessment: A Superfund baseline human health risk assessment is an analysis of the potential adverse health effects caused by hazardous substance releases from a site in the absence of any actions to control or mitigate these under current- and future-land uses. A four-step process is utilized for assessing site-related human health risks for reasonable maximum exposure scenarios. Hazard Identification: In this step, the chemicals of potential concern (COPCs) at the site in various media (i.e., soil, groundwater, surface water, and air) are identified based on such factors as toxicity, frequency of occurrence, and fate and transport of the contaminants in the environment, concentrations of the contaminants in specific media, mobility, persistence, and bioaccumulation. Exposure Assessment: In this step, the different exposure pathways through which people might be exposed to the contaminants in air, water, soil, etc. identified in the previous step are evaluated. Examples of exposure pathways include incidental ingestion of and dermal contact with contaminated soil and ingestion of and dermal contact with contaminated groundwater. Factors relating to the exposure assessment include, but are not limited to, the concentrations in specific media that people might be exposed to and the frequency and duration of that exposure. Using these factors, a "reasonable maximum exposure" scenario, which portrays the highest level of human exposure that could reasonably be expected to occur, is calculated. Toxicity Assessment: In this step, the types of adverse health effects associated with chemical exposures, and the relationship between magnitude of exposure and severity of adverse effects are determined. Potential health effects are chemical-specific and may include the risk of developing cancer over a lifetime or other non-cancer health hazards, such as changes in the normal functions of organs within the body (e.g., changes in the effectiveness of the immune system). Some chemicals are capable of causing both cancer and non-cancer health hazards. Risk Characterization: This step summarizes and combines outputs of the exposure and toxicity assessments to provide a quantitative assessment of site risks for all COPCs. Exposures are evaluated based on the potential risk of developing cancer and the potential for non-cancer health hazards. The likelihood of an individual developing cancer is expressed as a probability. For example, a 10"4 cancer risk means a "one in ten thousand excess cancer risk"; or one additional cancer may be seen in a population of 10,000 people as a result of exposure to site contaminants under the conditions identified in the Exposure Assessment. Current Superfund regulations for exposures identify the range for determining whether remedial action is necessary as an individual excess lifetime cancer risk of 10"4 to 10"6, corresponding to a one in ten thousand to a one in a million excess cancer risk. The State of New Jersey has set the acceptable cancer risk at 10"6. For non-cancer health effects, a "hazard index" (HI) is calculated. The key concept for a non-cancer HI is that a "threshold" (measured as an HI of less than or equal to 1) exists below which non-cancer health hazards are not expected to occur. assessment as it does not pose a direct human health risk based on its location. Based on the current zoning and anticipated future land use, the risk assessment focused on a variety of possible receptors. The baseline risk assessment evaluated health effects that could result from exposure to contaminated soil though ingestion, dermal exposures, and inhalation. Based on the current and most likely future land use of the Site and surrounding area, the following potential human receptor populations were identified: outdoor site workers, trespassers, off-site residents, and construction/utility workers. Human receptor populations evaluated under a hypothetical, future site redevelopment scenario include construction workers and off-site residents. The potential for exposure via incidental ingestion, dermal contact, and inhalation of volatiles and particulates was evaluated for all of the receptors, with the exception of off-site residents, who were assumed to be exposed via inhalation of volatiles and windblown particulates from the Site only. The risk assessment determined that there were no unacceptable risks posed to the current/future off-Site residents and trespassers. Elevated risks were identified for the current/future outdoor site worker (in portions of Area 7), current/future construction/utility worker (in Area 8 and Spill Area 2) and future construction worker under the hypothetical, future site redevelopment scenario (in portions of Area 7, Area 8 and Spill Area 2). A complete discussion of the exposure pathways and estimates of risk can be found in the Remedial Investigation Report for OU2, Appendix C, entitled Baseline Human Health and Screening Level Ecological Risk Assessment, which is available in the Administrative Record for the Site and located in the information repository. Vapor Intrusion The potential for exposure of off-site residents via inhalation of volatile chemicals that may migrate from groundwater to soil to indoor air was evaluated under OU1. As part of the OU1 activities, EPA conducted soil vapor and indoor air evaluations at the neighboring residences. The study concluded that for off-site residents, the concentrations of VOCs in indoor air (or subslab) were less than the concentrations that would require remedial action. The results of the analysis were reviewed by the EPA and documented in correspondence to the PRP and the individual residents. Documentation of the analysis is available in the Administrative Record for the Site. Further evaluation of this pathway was not conducted under OU2, which addresses potential soil exposures only. Screening Level Ecological Risk Assessment A Screening Level Ecological Risk Assessment (SLERA) was conducted to identify potential environmental risks ------- associated with the Site. Information regarding the environmental setting and chemical contamination at the Site was compiled. Based on the relatively small area (one acre) of the former secondary aeration lagoons, low quality habitat it affords, proximity to higher quality habitat located in OU3, conservative nature of the toxicity reference values (TRVs), and the relatively limited samples that exceed the TRVs, the HQs that were greater than 1.0 are not deemed significant. Therefore, the SLERA concluded that a more thorough ecological risk assessment is not warranted and no further action regarding ecological risk is necessary for OU2. Summary of Human Health and Ecological Risks A baseline Human Health Risk Assessment (HHRA) was conducted and risks were evaluated using data from all of the areas of the site identified during the RI. These areas include Areas 1 through 8 and Spill Areas 1 through 6. The full HHRA is presented in Appendix C of the RI Report which is available in the Administrative Record. The HHRA found that human health risks were above the acceptable risk range for cancer and non- cancer risks based on potential exposure to soils in Spill Area 2 and Areas 7 and 8. Given that these areas were very limited in size and extent of contamination, they are being addressed by the PRP, with EPA oversight, in a separate removal action. Approximately 330 cubic yards of contaminated shallow soils from these areas will be excavated and appropriately disposed of off-site by the PRPs and further action for these areas is not required. While the remaining areas are not posing a direct human health risk, they contain highly elevated levels of contaminants which are principal threat wastes and are significant sources of groundwater contamination. Unacceptable risks are posed by groundwater and are being addressed as part of ongoing OU1 cleanup activities. A Screening Level Ecological Risk Assessment was conducted to identify potential environmental risks associated with the Site. The SLERA concluded that a more thorough ecological risk assessment is not warranted and no further action regarding ecological risk is necessary for OU2. Based upon the results of the RI and the risk assessment, EPA has determined that actual or threatened releases of hazardous substances from the Site, if not addressed by the preferred remedy or one of the other active measures considered, may present a current or potential threat to human health and the environment. REMEDIAL ACTION OBJECTIVES Remedial action objectives (RAOs) are specific goals to protect human health and the environment. These objectives are based on available information and standards, such as applicable or relevant and appropriate requirements (ARARs), to-be-considered guidance, and site-specific risk-based levels. The following RAOs have been identified for unsaturated and saturated zone soils containing NAPL and COPCs at the Site: • Reduce contaminant levels present in source areas of groundwater contamination to the maximum extent practicable. • Improve the efficiency and effectiveness of the OU1 groundwater pump and treat remedy. The RAOs for OU2 are not quantitative due to the fact that there are no elevated direct human health risks posed by Site soils addressed in this FS; however, highly contaminated unsaturated and saturated soils have been identified as sources to groundwater contamination. The OU1 risk assessment concluded that groundwater contamination was posing a potential human health risk. Therefore, a remedial action to address source material contributing to the groundwater contamination is warranted. The OU2 remedial action would reduce contaminant levels and remove product in the unsaturated and saturated soils to the maximum extent practicable. OU2 remedial measures will support the OU1 remedial action objective of restoring groundwater to drinking water standards. This action should serve to shorten the time necessary to achieve the drinking water standards. SUMMARY OF TREATMENT TECHNOLOGIES Potential remedial technologies and process options were identified and screened using effectiveness, implementability and cost as the criteria, with the most emphasis on the effectiveness of the remedial technology. The technologies that passed this initial screening are described below and include thermal treatment, enhanced bioremediation, in situ chemical oxidation, NAPL recovery, and pump and treat. Note that these treatment technologies will not all work in each of the areas warranting remediation; therefore, the remedial alternatives presented in the next section consist of a combination of these technologies to treat all of the areas that require remediation. A number of technologies were evaluated in the FS and screened out including, but not limited to, excavation. Excavation was not determined to be cost effective due to associated disposal and dewatering costs. Thermal Treatment Many different methods and combinations of techniques ------- can be used to apply heat to contaminated soil in situ. The heat can destroy or volatilize organic chemicals. As the chemicals change into gases, their mobility increases, and the gases can be extracted via collection wells for capture and cleanup in an ex situ treatment unit, such as a Soil Vapor Extraction system (SVE). Thermal methods can be particularly useful for non-aqueous phase liquids (NAPLs). Heat can be introduced to the subsurface via several methods such as by electrical resistance heating, thermal conduction, or injection of steam. These heating methods will be further evaluated during the remedial design (RD) phase; however, for this Site, electrical resistance heating may be the most cost- effective method. Electrical Resistance Heating (ERH) uses arrays of electrodes installed around a central neutral electrode to create a concentrated flow of current toward the central point. Resistance to flow in the soils generates heat greater than 100°C, producing steam and readily mobile contaminants that are collected, via SVE, and treated at the surface. A SVE system applies a vacuum to the soil to induce the controlled flow of air and removes volatile and some semivolatile organic contaminants from the soil. Once the emitted vapors are collected from the soil, they are treated prior to discharge to the atmosphere. This technology was considered for treatment of Areas 1, 4, and 6. Enhanced Bioremediation Bioremediation uses microorganisms to degrade organic contaminants in soil, sludge, and solids. The microorganisms break down contaminants by using them as a food source or co-metabolizing them with a food source. Aerobic processes require an oxygen source, and the end products typically are carbon dioxide and water. Anaerobic processes are conducted in the absence of oxygen, and the end products can include methane, hydrogen gas, sulfide, elemental sulfur, and dinitrogen gas. In situ bioremediation is bioremediation in place, rather than ex situ or above ground. In situ techniques stimulate and create a favorable environment for microorganisms to grow and use contaminants as a food and energy source. Generally, this means injecting some combination of nutrients and moisture into the soil (via borings), and controlling the temperature and pH. Sometimes, microorganisms that have been adapted for degradation of specific contaminants are applied to enhance the process. The injection points may be refined during the RD phase. Contaminant concentrations in soil and groundwater would be monitored in the treatment areas before, during, and after treatment for baseline characterization, progress assessment, and post-treatment sampling, respectively. This treatment was considered for Areas 1, 2, 3, 4 and 6. In Situ Chemical Oxidation Chemical oxidation typically involves reduction/oxidation (redox) reactions that chemically convert hazardous contaminants to nonhazardous or less toxic compounds that are more stable, less mobile, or inert. Redox reactions involve the transfer of electrons from one compound to another. Specifically, one reactant is oxidized (loses electrons) and one is reduced (gains electrons). The oxidizing agents most commonly used for treatment of hazardous contaminants in soil are ozone, hydrogen peroxide, hypochlorites, chlorine, chlorine dioxide, potassium permanganate, and Fentons reagent (hydrogen peroxide and iron). For in situ chemical oxidation, injectors would be installed in a grid pattern to the desired treatment depth interval, which would be determined during the RD phase, and the oxidizing agent would be injected into the desired area. This technology was considered for treatment of Areas 1, 4, and 6. NAPL Recovery A NAPL recovery system is designed to remove free phase product that exists in either the saturated or unsaturated zone soils. In areas where recoverable NAPL exists, recovery wells are installed and the NAPL is pumped into a storage tank. The NAPL is then disposed of appropriately. A pump-down test would need to be performed to determine the optimal design for the system; however, the system would operate under the same parameters as those established for the NAPL recovery system that has been operating in Area 1. This technology could be applied to Area 6 as well as Area 4 if recoverable NAPL is observed in Area 4 during RD activities. Note that the NAPL recovery system would not be effective at removing residual NAPL (NAPL bound to the soil matrices); therefore, an additional treatment technology could be used to address residual NAPL and any other identified contaminants. Pump and Treat Pump and treat is a common method for cleaning up groundwater. Pumps are used to bring contaminated groundwater to the surface where it can be cleaned up (treated) more easily. Groundwater is the water that has collected underground in the spaces between dirt particles and crack within rocks. Groundwater flows underground and may empty into rivers or lakes. To remove polluted groundwater, an extraction system was built. This system consists of 20 extraction wells with a pumping rate of 230 gpm. When the pumps are turned on, they pull the contaminated groundwater into the wells and up to the surface. At the surface, the water goes to a treatment system where metals and VOCs are removed through a series of process treatment steps including filtration and air stripping. A pump and treat system at the Site was constructed as ------- part of the OU1 remedy. For the purposes of OU2, additional pumping wells may be placed into groundwater source areas and set at low pumping rates or in pulse mode to address highly contaminated groundwater in these source areas to improve the removal of contaminant mass from the soil/aquifer matrix. This technology would help to reduce the potential spread of contamination throughout the groundwater plume area. This technology is considered for treatment of Areas 2 and 3. The number of extraction wells and flow rates needed to achieve source area treatment in Areas 2 and 3 would be determined during the RD phase. SUMMARY OF REMEDIAL ALTERNATIVES The remedial action alternatives for the treatment of source areas of groundwater contamination at the Site will require a combination of treatment technologies. This is primarily due to the fact that the contamination is present at different depths, varying volumes and in some cases, consists of recoverable NAPL. Please see Figure 1 for source area identification. Six remedial alternatives, which compare different treatment technologies, have been developed and are presented below. Since all of the alternatives may not result in unrestricted use and unlimited exposure, a deed restriction may be required for the Site in the future. Remedial Alternatives Alternative 1 - No Action The No Action alternative was retained, as required by the National Oil and Hazardous Substance Pollution Contingency Plan (NCP), and provides a baseline for comparison with other alternatives. No remedial actions would be implemented as part of the No Action Alternative. Furthermore, institutional and engineering controls would not be implemented. Total Capital Cost $0 Operation and Maintenance $0 Total Present Net Worth$0 Timeframe 0 years Alternative 2A - NAPL Recovery Plus in situ Thermal Treatment with SVE in Areas 1, 4, 6 and the WAB; and Pump and Treat in Areas 2 and 3 Alternative 2A involves the installation of a NAPL recovery system, similar to the system that already exists in Area 1 (installed in 2003). The NAPL recovery system would be installed to remove recoverable product from Area 6, which is estimated to have approximately 400 cubic yards (cu yds) of saturated soils containing NAPL, and will continue to operate as long as it is effectively removing product. A NAPL recovery system could potentially be installed in additional areas (such as Area 4 and beneath the WAB) should NAPL be discovered during the RD phase. Areas 1, 4, 6 and the WAB would undergo in situ thermal treatment for approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in the unsaturated and/or saturated zone soils. Details of the treatment for these areas will be developed during the design phase. For Areas 2 and 3, a pump and treat system technology would be installed to treat highly contaminated groundwater in the intermediate zone. Vertical extraction wells, pumps, power source and conveyance piping would need to be installed in each area; however, the pump and treat technology for Areas 2 and 3 could be tied into the OU1 groundwater treatment system to utilize the existing infrastructure. The number of extraction wells and flow rates needed to achieve source area treatment in Areas 2 and 3 would be determined during the RD phase; however, treatment will likely be limited to one double- screened well per area pumping at approximately 20 gpm each. Total Capital Cost $2,850,000 Operation and Maintenance $1,850,000 Total Present Net Worth$5,030,000 Timeframe 2 years plus 30 years for Pump and Treat Alternative 2B - NAPL Recovery Plus in situ Thermal Treatment with SVE in Areas 1, 4, 6 and the WAB; and Enhanced Bioremediation in Areas 2 and 3 Alternative 2B employs the same remedial technologies as Alternative 2A for Areas 1, 4, 6 and WAB, including NAPL recovery and in situ thermal treatment with SVE. These areas consist of approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in both the unsaturated and/or saturated zone soils. However, enhanced bioremediation would be implemented in Areas 2 and 3. Total Capital Cost $6,230,000 Operation and Maintenance $3,280,000 Total Present Net Worth$ 10,400,000 Timeframe 5 years Alternative 3 - NAPL Recovery Plus in situ Chemical Oxidation (ISCO) in Areas 1, 4, 6 and the WAB; and Pump and Treat in Areas 2 and 3 Alternative 3 involves the installation of a NAPL recovery system to address free phase product in Area 6 and potentially Area 4, as was describe in Alternative 2A. Alternative 3 also includes the treatment of contamination ------- in Areas 1, 4, 6 and the WAB through the implementation of ISCO. These areas include a total of approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in the unsaturated and/or saturated zone soils. Details of the treatment for these areas would be developed during the design phase. The Pump and Treat technology would be applied to Areas 2 and 3, as described in Alternative 2A. Enhanced bioremediation was not considered for treatment of Areas 2 and 3 in combination with ISCO in Areas 1, 4, 6 and the WAB because these treatment technologies are not compatible with each other. They require opposite chemical conditions in the environment to work properly. Total Capital Cost $3,490,000 Operation and Maintenance $1,390,000 Total Present Net Worth$5,240,000 Timeframe 3 years plus 30 years for Pump and Treat Alternative 4A - NAPL Recovery and Enhanced Bioremediation in Areas 1, 2, 3, 4, 6 and the WAB Alternative 4A employs the same remedial technology as Alternative 2A for NAPL Recovery; however, this alternative would implement enhanced bioremediation at Areas 1, 2, 3, 4, 6 and the WAB. Areas 1, 4, 6 and the WAB include approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in the unsaturated and/or saturated zone soils which are located in the shallow subzone (less than 30 feet below ground surface (bgs)). Details of the treatment for these areas would be developed during the design phase. The enhanced bioremediation technology would also be applied to treat contaminated groundwater in the soil/aquifer matrix of the intermediate zone (30- 100 ft bgs) in Areas 2 and 3. Total Capital Cost $7,220,000 Operation and Maintenance $3,980,000 Total Present Net Worth$ 12,300,000 Timeframe 5 years Alternative 4B - NAPL Recovery Plus Enhanced Bioremediation at Areas 1, 4, 6 and the WAB; and Pump and Treat at Areas 2 and 3 Alternative 4B involves the installation of a NAPL recovery system to address free phase product in Area 6 and potentially Area 4, as was describe in Alternative 2A. Enhanced Bioremediation would be applied to address Areas 1, 4, 6 and the WAB which contain a total of approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in the unsaturated and/or saturated zone soils. Pump and Treat technology would be applied to Areas 2 and 3, as described in Alternative 2A. Total Capital Cost $3,840,000 Operation and Maintenance $2,580,000 Total Present Net Worth$6,910,000 Timeframe 5 years plus 30 years for Pump and Treat Evaluation of Remedial Alternatives Nine criteria are used to evaluate the different remedial alternatives individually and against each other in order to select the best alternative. This section of the Proposed Plan profiles the relative performance of each alternative against the nine criteria, noting how it compares to the other options under consideration. The nine evaluation criteria are discussed below. A more detailed analysis can be found in the FS report. Overall Protection of Human Health and the Environment While source areas to groundwater contamination do not pose a direct risk to human health or the environment, they contribute to groundwater contamination at the Site which poses risks to human health. Under Alternative 1, No Action, source areas will remain untreated on Site and will continue to contribute to groundwater contamination. Alternatives 2A, 2B, 3, 4A and 4B are protective because hazardous constituents are removed from soil and groundwater and converted into non-toxic by-products. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) The three broad categories of ARARs include chemical- specific, location-specific and action-specific ARARs. 10 ------- THE NINE SUPERFUND EVALUATION CRITERIA 1. Overall Protectiveness of Human Health and the Environment evaluates whether and how an alternative eliminates, reduces, or controls threats to public health and the environment through institutional controls, engineering controls, or treatment. 2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) evaluates whether the alternative meets federal and state environmental statutes, regulations, and other requirements that pertain to the site, or whether a waiver is justified. 3. Long-term Effectiveness and Permanence considers the ability of an alternative to maintain protection of human health and the environment overtime. 4. Reduction of Toxicity, Mobility, or Volume (TMV) of Contaminants through Treatment evaluates an alternative's use of treatment to reduce the harmful effects of principal contaminants, their ability to move in the environment, and the amount of contamination present. 5. Short-term Effectiveness considers the length of time needed to implement an alternative and the risks the alternative poses to workers, the community, and the environment during implementation. 6. Implementability considers the technical and administrative feasibility of implementing the alternative, including factors such as the relative availability of goods and services. 7. Cost includes estimated capital and annual operations and maintenance costs, as well as present worth cost. Present worth cost is the total cost of an alternative over time in terms of today's dollar value. Cost estimates are expected to be accurate within a range of +50 to -30 percent. 8. State/Support Agency Acceptance considers whether the State agrees with the EPA's analyses and recommendations, as described in the RI/FS and Proposed Plan. 9. Community Acceptance considers whether the local community agrees with EPA's analyses and preferred alternative. Comments received on the Proposed Plan are an important indicator of community acceptance. There are no chemical-specific ARARs for OU2 because there are no direct human health risks associated with the source areas that are the subject of this proposed plan. However, ARARs have been established for groundwater as part of the OU1 remedial action objective to restore the aquifer to drinking water standards. OU2 will actively address source areas to further support the ARARs established under OU1. Location and action-specific ARARs, such as wetland mitigation regulations and hazardous waste disposal regulations may also apply to OU2 and the selected remedy will be designed to ensure compliance with all applicable ARARs. A complete listing of ARARs for the Site can be viewed in the Feasibility Study Report in the Administrative Record. Alternative 1, No Action, would not comply with ARARs since is does not include treatment of source areas known to contain recoverable and/or residual NAPL. Alternatives 2A, 2B, 3, 4A and 4B are all expected to comply with the applicable ARARS and are further expected to comply with groundwater ARARs established in the OU1 Record of Decision for groundwater. Long-Term Effectiveness and Permanence The highest degree of permanence and long-term effectiveness is achieved for those alternatives that result in the greatest removal of contaminants from the Site. Alternative 1, No Action, will not result in any mass reduction. Alternatives 2A, 2B, 3, 4A, and 4B include NAPL recovery, which is effective for removal of the bulk of the source material (free phase product), but does not effectively mitigate long-term risks from residual NAPL and other identified contaminants in the unsaturated and saturated zone soils. In comparing thermal treatment, enhanced bioremediation and in situ chemical oxidation (ISCO), thermal treatment (Alternative 2A & 2B) has the highest overall estimated degree of permanence (greater than 90% mass reductions), followed by ISCO (Alternative 3, 80-90% mass reduction) and enhanced bioremediation (Alternatives 2B, 4A & 4B, 50% to over 90% mass reductions). ISCO is more effective at treating media containing both VOCs and SVOCs; however, VOCs are the primary COPCs at the Site. Of these technologies, it is important to note that "rebound" can be a factor to consider with respect to long-term effectiveness and permanence in the treatment of groundwater in the intermediate zone. Rebound is the term applied to contaminant concentrations measured near a source area which decrease following initiation of source treatment operations but increase once the treatment has ended. Both pump and treat (Alternatives 2A, 3 and 4B) and enhanced bioremediation (Alternatives 2B and 4A) are susceptible to rebound effects after active treatment stops; however, long-term pump and treat would likely have less rebound, primarily due to the extensive period of time that the pumping will occur. Reduction of Toxicity, Mobility, or Volume Through Treatment The greatest reduction in toxicity, mobility, and volume of COPCs will be achieved by those technologies that result in the greatest mass removals from the Site. Alternative 1 provides no reduction in toxicity, mobility and volume. All of the other alternatives are expected to achieve a high degree of reduction in toxicity, mobility and volume of COPCs at the Site; however, thermal treatment 11 ------- (Alternative 2A & 2B) and ISCO (Alternative 3) are expected to be able to achieve the greatest mass reduction in the unsaturated and saturated zone soils with mass reductions of greater than 90% for thermal treatment and 80-90% mass reductions for ISCO. Groundwater pump and treat (Alternatives 2A, 3 and 4B) is expected to reduce the toxicity and volume of contaminants in the vicinity of the source areas overtime through active treatment. The alternatives with the pump and treat component would also reduce the potential spread of contamination throughout the identified groundwater plume area. Short-Term Effectiveness With the exception of Alternative 1, which has no impact on short-term effectiveness, all of the Alternatives (2A, 2B, 3, 4A and 4B) are expected to have minimal impacts on Site workers (including remedial construction workers and workers from the truck washing facility) and nearby residents during remedy implementation. The potential risks to Site workers and area residents during remedy implementation will be addressed by adherence to protective worker practices, safety standards, and equipment. A site-specific health and safety plan will be prepared for EPA's approval and trained personnel will perform remedial activities. Appropriate personnel monitoring and emission controls and monitoring will be provided, as needed, during remedy implementation. Implementation of enhanced bioremediation (Alternatives 2B, 4A and 4B) is expected to take much longer than for thermal treatment (Alternatives 2A and 2B) and ISCO (Alternative 3) which can be implemented in relatively short timeframes of approximately 1 to 3 years. The longer implementation timeframe associated with enhanced bioremediation is due to uncertainties associated with the establishment of microbial populations and site-specific biodegradation rates. The pump and treat component of the alternatives (Alternatives 2A, 3, and 4B) may operate as long as the groundwater treatment system is running for OU1 (up to 30 years); however, this timeframe may be less based on monitoring results. Implementability All of the alternatives are technically and administratively feasible, have been implemented at other sites, and make use of standard engineering practices. Alternative 1 requires the least effort to implement; however it would not meet the RAOs for OU2. Alternatives 2A, 2B, 3, 4A and 4B, is technically feasible, as demonstrated by the Area 1 NAPL recovery system which has been operating since 2003. The pump and treat component of Alternatives 2A, 3 and 4B would be relatively easy to implement given that the infrastructure for pump and treat system already exists at the Site. ISCO and enhanced bioremediation may be more difficult to implement than all other alternatives. With ISCO (Alternative 3), it may be difficult to pump the oxidants to the right spots and ensure sufficient mixing. With enhanced bioremediation (Alternatives 2B, 4A and 4B), the following challenges exist: 1) it may be difficult to maintain the proper conditions underground to support bioremediation; 2) it will likely take longer to implement as compared with thermal treatment or ISCO due to uncertainties associated with the amount of time needed to establish microbial populations and site-specific biodegradation rates; and 3) it would be hard to control the amount of biomass generated from this technology, which may be drawn into the OU1 groundwater pump and treat system, thereby potentially fouling operations. Thermal treatment (Alternatives 2A and 2B) is easier to implement than ISCO (Alternative 3) and enhanced bioremediation (Alternatives 2B, 4A and 4B) due to the distribution of contaminants at the Site and the Site geology. The availability of service and materials required for the implementation of all alternatives is adequate. Alternatives 2A and 2B involve thermal treatment which requires large amounts of energy. The energy demands for these alternatives are not expected to be a roadblock to implementation since there is an active facility on-site that is connected to the local electrical power utility. All alternatives, other than Alternative 1, require services and materials that are currently readily available from technology vendors, and are therefore, not expected to present a challenge to remedy implementation. Cost Alternative 1 has no cost, but does not meet RAOs. The total estimated costs for the remaining alternatives, from lowest to highest cost, are as follows: Alternative 2A ($5,030,000), Alternative 3 ($5,240,000), Alternative 4B ($6,910,000), Alternative 2B ($10,400,000) and Alternative 4A ($12,300,000). Alternatives 2B and 4A are significantly more costly than the other alternatives due to the technology implementation and monitoring costs associated with enhanced bioremediation in Areas 2 and 3. Alternative 4B is more costly than Alternatives 2A and 3 due to performance monitoring costs associated with the enhanced bioremediation component of Alternative 4B in Areas 1, 4, and 6. The NAPL recovery system, which is a component of State/Support Agency Acceptance 12 ------- The State of New Jersey agrees with the preferred alternative in this Proposed Plan. Community Acceptance Community acceptance of the preferred alternative will be evaluated after the public comment period ends and will be described in the Responsiveness Summary of the OU2 Record of Decision for this Site. The Record of Decision is the document that formalizes the selection of the remedy for a site. SUMMARY OF ALTERNATIVE THE PREFERRED The Preferred Alternative for the cleanup of source areas to groundwater contamination at the Site is Alternative 2A - NAPL Recovery Plus in situ Thermal Treatment with SVE at Areas 1, 4, 6 and the WAB; and Pump and Treat at Areas 2 and 3. Alternative 2A involves a combination of technologies to remove as much principal threat waste/contaminant source material as practicable. A NAPL recovery system already exists in Area 1 and will continue to pump in that Area until NAPL is no longer recovered. To date, the Area 1 system has recovered approximately 3,500 gallons of free product. Modifications may be made to the NAPL recovery system as part of this remedy, during the RD phase, to increase its effectiveness. A similar NAPL recovery system will be installed in Area 6, which has approximately 400 cu yds of saturated soils containing recoverable NAPL, and possibly Area 4 and beneath the WAB if recoverable NAPL is observed during RD activities. Once NAPL is pumped out of the ground, it will be held in a storage tank until it can be appropriately disposed of off-site. One recovery well is expected to be sufficient to pump recoverable NAPL out of each Area; however, the number of wells required will be determined in the RD phase. In situ thermal treatment with SVE will be applied to Areas 1, 4, 6 and the WAB which contain a total of approximately 6,200 cu yds of residual NAPL (NAPL bound within the soil matrix) and other contaminants resulting from facility operations in the unsaturated and/or saturated zone soils. Details of the treatment for this area will be developed during the design phase. While a variety of heating options may be explored in the RD phase, it appears the electrical resistance heating may be the most cost effective thermal treatment for the site. Using this method, arrays of electrodes would be installed to create a flow of current in the subsurface soils. Resistance to the flow in the soils would generate heat which will produce steam and volatilize (convert to gas) contaminants. As the contaminants change into gases, their mobility increases, and the gases can be extracted via a Soil Vapor Extraction system (SVE). A SVE system applies a vacuum to the soil to induce the controlled flow of air and removes volatile and some semi volatile organic contaminants from the soil. Once the emitted vapors are collected from the soil, they will be treated using granular activated carbon adsorption units prior to discharge to the atmosphere. Thermal treatment may also have a synergistic effect on NAPL recovery in Areas 1, 4 and 6 due to the fact that the heat generated by this technology may alter the viscosity (thickness) of the NAPL making it easier to pump out of the ground. Furthermore, thermal treatment can also increase the amount of available organic carbon, thereby stimulating microbial activities that may potentially further degrade contaminants. Since all of the alternatives may not result in unlimited use/unrestricted exposure, a deed restriction may be required for the Site in the future. A pump and treat system already exists at the Site and was constructed as part of the OU1 remedy. As part of Alternative 2A, additional pumping wells will be placed in the groundwater in Areas 2 and 3 which comprise approximately 143,000 cu yds within the intermediate zone (30-100 ft below ground surface). The extraction wells may be set at low pumping rates or in pulse mode to improve the removal of contaminant mass from the soil/aquifer matrix, albeit at diffusion-limited rates. These additional wells will primarily serve to assist in achieving the OU1 RAOs by aiding in the removal of mass from highly contaminated groundwater in the vicinity of source areas. This technology will further help to reduce the potential spread of contamination throughout the groundwater plume area. The number of extraction wells and flow rates needed to achieve source zone treatment in each area would be determined during the RD phase, but it is likely that one or two double-screened wells per area would be needed. These extraction wells and the associated well pumps will be consistent with those already installed in other areas of the Site for the OU1 remedy. The current groundwater treatment system for OU1 will need to be evaluated to determine if significant design or operational modifications will be necessary to adequately handle the increased flow and treatment requirements. However, this is not expected as the contaminants are similar to those of OU1 and the treatment plant was designed with sufficient capacity to handle additional groundwater flow. Alternative 2A provides the best balance of the nine criteria used to evaluate the remedial alternatives presented in this proposed plan. Alternative 2A has the ability to reduce the toxicity, mobility and volume of 13 ------- principal threat wastes to a greater degree than the other alternatives, has the shortest timeframe for implementation, provides a greater degree of long-term effectiveness and permanence and is cost effective. Consistent with EPA Region 2's Clean and Green policy, EPA will evaluate the use of sustainable technologies and practices with respect to any remedial alternative selected for the Site. As is EPA's policy, Five-Year Reviews will be conducted until remediation goals are achieved and the Site is available for unrestricted use and unlimited exposure. COMMUNITY PARTICIPATION EPA provided information regarding the cleanup of the Chemical Leaman Tank Lines Superfund Site to the public through public meetings, the Administrative Record file for the Site and announcements published in the Courier Post newspaper. EPA encourages the public to gain a more comprehensive understanding of the Site and the Superfund activities that have been conducted there. For further information on EPA's preferred alternative for the Chemical Leaman Tank Lines Superfund Site: Theresa Hwilka Natalie Loney Remedial Project Manager Community Relations (212) 637-4409 (212) 637-3639 U.S. EPA oadway 19* New York, New York 10007-1866 290 Broadway 19th Floor The dates for the public comment period; the date, the location and time of the public meeting; and the locations of the Administrative Record files, are provided on the front page of this Proposed Plan. 14 ------- GLOSSARY ARARs: Applicable or Relevant and Appropriate Requirements. These are Federal or State environmental rules and regulations that may pertain to the Site or a particular alternative. Carcinogenic Risk: Cancer risks are expressed as a number reflecting the increased chance that a person will develop cancer if exposed to chemicals or substances. For example, EPA's acceptable risk range for Superfund hazardous waste sites is 1 x 10~4 to 1 x 10~6, meaning there is 1 additional chance in 10,000 (1 x 10"4) to 1 additional chance in 1 million (1 x 10"6) that a person will develop cancer if exposed to a Site contaminant that is not remediated. CERCLA: Comprehensive Environmental Response, Compensation and Liability Act. A Federal law, commonly referred to as the "Superfund" Program, passed in 1980 that provides for response actions at sites found to be contaminated with hazardous substances, pollutants or contaminants that endanger public health and safety or the environment. COPC: Chemicals of Potential Concern. SLERA: Screening Level Ecological Risk Assessment. An evaluation of the potential risk posed to the environment if remedial activities are not performed at the Site. FS: Feasibility Study. Analysis of the practicability of multiple remedial action options for the Site. Groundwater: Subsurface water that occurs in soils and geologic formations that are fully saturated. HHRA: Human Health Risk Assessment. An evaluation of the risk posed to human health should remedial activities not be implemented. HI: Hazard Index. A number indicative of noncarcinogenic health effects that is the ratio of the existing level of exposure to an acceptable level of exposure. A value equal to or less than one indicates that the human population is not likely to experience adverse effects. HQ: Hazard Quotient. HQs are used to evaluate noncarcinogenic health effects and ecological risks. A value equal to or less than one indicates that the human or ecological population are not likely to experience adverse effects. ICs: Institutional Controls. Administrative methods to prevent human exposure to contaminants, such as by restricting the use of groundwater for drinking water purposes. Nine Evaluation Criteria: See text box on Page 7. Noncarcinogenic Risk: Noncancer Hazards (or risk) are expressed as a quotient that compares the existing level of exposure to the acceptable level of exposure. There is a level of exposure (the reference dose) below which it is unlikely for even a sensitive population to experience adverse health effects. USEPA's threshold level for noncarcinogenic risk at Superfund sites is 1, meaning that if the exposure exceeds the threshold; there may be a concern for potential noncancer effects. NPL: National Priorities List. A list developed by USEPA of uncontrolled hazardous substance release sites in the United States that are considered priorities for long-term remedial evaluation and response. Operable Unit (OU): a discrete action that comprises an incremental step toward comprehensively addressing site problems. This discrete portion of a remedial response manages migration, or eliminates or mitigates a release, threat of a release, or pathway of exposure. The cleanup of a site can be divided into a number of operable units, depending on the complexity of the problems associated with the site. Present-Worth Cost: Total cost, in current dollars, of the remedial action. The present-worth cost includes capital costs required to implement the remedial action, as well as the cost of long-term operations, maintenance, and monitoring. Proposed Plan: A document that presents the preferred remedial alternative and requests public input regarding the proposed cleanup alternative. Public Comment Period: The time allowed for the members of a potentially affected community to express views and concerns regarding USEPA's preferred remedial alternative. RAOs: Remedial Action Objectives. Objectives of remedial actions that are developed based on contaminated media, contaminants of concern, potential receptors and exposure scenarios, human health and ecological risk assessment, and attainment of regulatory cleanup levels. Record of Decision (ROD): A legal document that describes the cleanup action or remedy selected for a site, the basis for choosing that remedy, and public comments on the selected remedy. Remedial Action: A cleanup to address hazardous substances at a site. RI: Remedial Investigation. A study of a facility that supports the selection of a remedy where hazardous substances have been disposed or released. The RI identifies the nature and extent of contamination at the facility and analyzes risk associated with COPCs. TBCs: "To-be-considereds," consists of non-promulgated advisories and/or guidance that were developed by EPA, other federal agencies, or states that may be useful in developing CERCLA remedies. USEPA: United States Environmental Protection Agency. The Federal agency responsible for administration and enforcement of CERCLA (and other environmental statutes and regulations), and final approval authority for the selected ROD. VOC: Volatile Organic Compound. Type of chemical that readily vaporizes, often producing a distinguishable odor. 15 ------- Figure 1: Areas Warranting Remediation Chemical Leaman Tank Lines Superfund Site, Operable Unit 2, Logan Township, Gloucester County, New Jersey AND 2 16 ------- Table 1 - Concentration Ranges for Driver Chemicals of Potential Concern ARIA 1 Driver COPCs tndJoroetlieae (TCE) cis-ljS-didJoioetben* (DCE) bisO-ethylhesylplitttalate) Butylbeuzylphthalate Naphthalene N-uilresodipkeaylamine Minimum Concentration (mg.-'kg) 0.14U 0.59J ""7 0.66 J 1.6 J 9.5 Maximum Concentration (rag/kg) 10.000 160 J 2600 3000 2500 450 AREA 2 Driver COPCs tricbloroetfaene (TCE) ci3-l,2-dicHoTOetheiia (DCE) Minimum Concentration (mg/kg) 0.001U 0.0044J Maximum Concentration (nag/kg) 2.6 •7 3 AREAS Driver COPCs trichloroetlieEis (TCE) eii-1.2-didiloi-0etheae (DCE) Minimum Concentration (mg/kg) 0.12 J 0.12 J Maximum Concentration (mg/kgj 0.9.5 0.2 J AREA 4 Driver COPCs (ricklaroetheae (TCE) cii-l,2-dLcHoix>ethen* (DCE) Miaimum C'oacentration (mg/kg) 0.016 0.001 J Maximum Concentration (ing/kg) 5J;OCO 410 J AREA 6 Driver COPCs tticbJoroethene (TCE) cii-1.2-dicHoroetheas (DCE) 1 . 2 -Dichlojofaeuzeae bis(2-ethylliex>ipiithalata) Bunibeiizylphthalate 2CapktS£JE3ie Mraimum Concentration (mg/kg) 0.0007 O.OC1 0.0015 J 0.22 J 0.07 J 0.06 J Maximum Concentration (nag/kg) 27,000 25.000 450,000 14.000 26.000 29.000 WASTE ACCUMULATION BUILDING (WAB) Driver COPCs tridJoroetheae (TCE) ek-l^-dicKbioetheae (DCE) TetracliloroetlieEie (PC E) 1,2-Dichlorobenzeae bisQ-ethylhexylphthalate) Butvlbeuzvlphtbakte Xaphtisleoe n-mtroiodiphenylamise Ai'isidc Miaimum C'©ncentrati®n (mg/kg) 0.26U 0.26U 0.26U 0.16 J 14 4.61 92 21 35 Maximum Concentration (ing/kg) 740 110 250 ~~> 260 460 530 20.000 440 J - The concentration given i; an approximate value U - The compound was not datected at the uxhcated coDcetittation 11 ------- |