The University of Louisville Superfund Research Center (ULSRC) researchers focus on accurate measurement and monitoring of and the health impacts connected to exposure to volatile organic compounds (VOCs). The research team is therefore concerned about better understanding persistent VOCs at the Lee’s Lane Landfill and any possible human exposure pathways that could have adverse health impacts for individuals who live near or come onto the site on a regular basis. VOCs are organic chemical compounds that can volatilize under normal atmospheric conditions of temperature and pressure . There is some level of natural VOC exposure from environmental sources, but VOCs are also emitted from anthropogenic sources such as paints, cleaners, cigarette smoke, car exhaust, and industrial releases [3-6]. As such, VOCs are nearly everywhere in both indoor and outdoor environments, and background levels of VOCs may be near or above health-based exposure limits . EPA studies show that many VOCs are found at higher levels inside homes compared with levels outside regardless of whether the homes are located in urban or rural areas , creating a significant potential for exposure-related adverse health outcomes.
A number of VOCs, including 1,3-butadiene, benzene, and chloroform, have been linked to adverse health outcomes, while others have no known health effects . As with many toxic compounds, the health effects of VOC exposures depend partly upon the level and duration of the exposure. The Agency for Toxic Substance and Disease Registry (ATSDR) has ranked several VOCs on their Substance Priority List as chemicals of significant public health concern , and both the EPA  and the World Health Organization (WHO)  have recommended guidelines for indoor concentrations of specific VOCs. In the past, the Lee’s Lane Landfill site was a documented emission source of VOCs, specifically methane; these gases migrated to the adjacent Riverside Gardens neighborhood with considerable impact . The ULSRC researchers intend to offer summaries and assessments of on-going site monitoring and related decisions by KDEP and the EPA to help community members and stakeholders better understand health risks and more fully participate in determining the future of Lee’s Lane Landfill.
The EPA is the U.S. federal agency responsible for protecting the environment. Founded in 1970, the EPA conducts environmental assessments, research, and education and is responsible for issuing and enforcing regulations that establish national standards to limit human exposure to various toxins, hazardous materials, and pollutants in air, water, and soil. In 1980, Congress established the Comprehensive Environmental Response, Compensations, and Liability Act (CERCLA), more commonly known as Superfund. The Superfund program is responsible for the cleanup and remediation of contaminated sites the EPA characterizes as posing serious human health risks and environmental damage if not contained. Part of this responsibility entails ongoing monitoring of Superfund sites and performing comprehensive reviews of those sites every five years.
EPA Region 4
EPA Region 4 covers the southeast United States and serves Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, and six federally-recognized Indian tribes. Region 4’s Laboratory Services and Applied Science Division, housed in Athens, GA, is responsible for providing scientific and technical expertise and environmental data for EPA offices throughout Region 4. The laboratory conducts more than 100 field investigations and analyzes over 15,000 samples collected from Region 4 EPA sites per year .
KDEP’s mission is to protect and enhance the environment of the Commonwealth of Kentucky. As the environment plays a vital role in public health, KDEP is also indirectly responsible for protecting the health of Kentucky’s citizens. KDEP consists of six divisions: Air, Waste Management, Water, Compliance Assistance, Enforcement, and Environmental Program Support. This last division assists the other divisions and is responsible for analyzing samples collected from Superfund sites for various toxins .
MSD works to provide quality wastewater, stormwater, and flood protection services to the Louisville-Jefferson County Metro in order to maintain safe, clean waterways and to protect public health. In regard to the Lee’s Lane Landfill Superfund site, MSD is responsible for operation and maintenance (O&M) at the site, a task which includes performing quarterly air, gas, and groundwater monitoring as well as general maintenance of the site.
Pace Analytical Services
Pace Analytical is a commercial analytical testing laboratory contracted by MSD for the annual analysis of groundwater samples . Pace also performs analysis on soil and sediment samples collected from various sites throughout the city of Louisville in conjunction with other environmental consultants, although those services were not conducted as part of the 2018 FYR .
Skeo is an environmental consulting agency that frequently works with the EPA to produce documentation, websites, and other presentation tools. Consultants from Skeo helped write and produce maps for the 2018 FYR .
Smith Management Group (SMG)
SMG is an environmental consulting agency which serves to help clients address environmental risks resulting from materials, products, and waste used or generated in a given location. Throughout the early 2000s, SMG consulted with MSD to perform various O&M tasks on the Lee’s Lane Landfill Superfund site, such as requesting that abandoned groundwater monitoring wells be closed and performing an evaluation of the LFG collection system in 2010 .
Stearns, Conrad, and Schmidt (SCS) Engineers
SCS Engineers is an environmental consulting and construction firm that designs and implements sustainable environmental solutions. SCS designed and provided construction oversight of the original landfill gas (LFG) collection system and provided subsequent evaluations and remedial action recommendations for the system. In 2004, SCS performed a maintenance inspection of the LFG collection system at the behest of MSD .
Progress Since the Previous Review
The 2013 FYR posed several issues regarding ongoing site contamination and monitoring . The EPA and MSD produced subsequent reports to address many of the remaining issues before the next scheduled review in 2018. We summarize the conclusions that environmental professionals and public officials involved in the site’s cleanup provided in those reports and those documented in the 2018 FYR . In general, representatives from the EPA, KDEP, and MSD “.... agree that the cleanup and maintenance at the site has progressed as planned .” While this is a positive evaluation about the process and current status of the site, several questions and issues remain regarding monitoring processes and observed contamination levels that need to be addressed by those agencies and the responsible parties before the next FYR in 2023 and before re-use of the site moves forward.
The following tables and figures pull information from the 2013 and 2018 FYRs to highlight questions that still need resolution, ongoing gaps in monitoring data collection and analysis, and potential health risks which remain if these gaps are not resolved.
Table 1 organizes information and questions raised in the 2013 FYR  regarding the remaining contamination and potential health-related issues noted in the previous FYR. Also included are status updates for those issues based on the 2018 FYR .
Figures 3 and 4 show the locations of various monitors and contamination found via sampling.
Table 2 provides a list of the VOCs found to be present on the site between 2012 and 2015 and indicates those that exceeded the EPA screening levels. Table 3 summarizes potential sources and health risks associated with these chemicals of concern found to be present at the site.
This section summarizes data collected and resulting conclusions drawn by KDEP, MSD, and the environmental contractors after the 2013 FYR. We highlight explanations for those conclusions using a critical lens that suggests there are gaps in knowledge about the site condition and potential impacts on the surrounding residential areas.
Soil & Soil Gas
The 2013 FYR  reported that possible soil contaminants on the site had not been adequately identified. KDEP consequently performed soil sampling in 2013 and collected 31 soil samples from 28 locations across the site (see Figure 3). Of those samples, six exceeded concentrations deemed safe for occasional exposure (see Figure 3). Many of these samples showed elevated levels of benzo(a)pyrene, and some showed elevated levels of lead, dibenzo(a,h)anthracene, polychlorinated biphenyls, and bis(2-ethylhexyl) phthalate (see CSM for specific levels). A more detailed site inspection conducted in 2017 and reported in the 2018 FYR  further assessed the locations of soil contamination. Although the results indicated contamination was still present, the inspection concluded that the risk of human health was low because the locations were not deemed physically accessible to the general public.
MSD monitored levels of soil gas from both temporary and permanent gas probes on and adjacent to the site; this monitoring occurred twice a year. According to the 2016 CSM  and the 2018 FYR , several VOCs, including 1,3-butadiene, carbon tetrachloride, chloroform, methane, and tetrachloroethene, were found to be in exceedance of EPA regional screening levels between 2012 and 2015 (see Table 2). The EPA sets these standards based on the carcinogenic risk of exposure to specific compounds. They can be modified for different routes of exposure, whether by inhalation, ingestion, or dermal contact. In particular, measures of carbon tetrachloride and chloroform were above the screening levels during every sampling event between September 2012 and April 2015 at one and two wells, respectively. The exceedances in other VOC measures were more sporadic, occurring during different sampling events or at different wells. Importantly, both the 2016 CSM  and the 2018 FYR  recommend further evaluation in order to determine the source(s) of these VOCs, particularly 1,3-butadiene and carbon tetrachloride, as these VOCs exceeded screening levels at gas probes directly adjacent Riverside Gardens.
Although VOCs are found naturally in ambient air, MSD monitors ambient air levels at the site twice a year to ensure VOC levels in the area are not above background levels. Between 2013 and 2015, the reported monitoring data show that although there were elevated levels of specific VOCs, such as carbon tetrachloride and chloroform, at some monitoring stations, these levels were not sustained for extended periods. Independent measures of ambient air conducted by Russell Barnett, the director of the former Kentucky Institute for the Environment and Sustainable Development, in 2013 (unpublished data) also found elevated levels of carbon tetrachloride. However, these levels were not significantly higher than levels measured in ambient air samples collected throughout Louisville, suggesting the carbon tetrachloride was unlikely to be emanating from the landfill and indicating that it would be impossible to determine ultimate sources.
Groundwater & Groundwater Gas
The 2013 FYR  stated that groundwater on the site could be contaminated, but additional wells were needed to gather enough data to determine whether contamination existed. KDEP installed five additional groundwater wells at the site in 2014, bringing the total number of monitoring wells up to seven. Between 2013 and 2017, many of the wells routinely detected one or more of the five contaminants of concern (arsenic, manganese, iron, barium, and lead), although no increasing or decreasing trends in the concentrations of these contaminants were documented. There are missing measurements in the October 2017 well monitoring data for one or more of the five contaminants of concern that exceeded screening levels at each well in previous monitoring events. This suggests a lack of thorough testing for each of these wells. MSD installed additional groundwater wells adjacent to the site in December 2018, and updated monitoring data from these wells should provide additional information regarding potential contamination before the 2023 FYR.
Furthermore, the 2018 FYR reports that, according to the 2016 KDEP Groundwater Report , two of the groundwater monitoring wells were off-gassing VOCs at 100% of the lower explosive limit (LEL). As a result, those and subsequent years’ measurements at these wells were made using a bladder pump rather than an electronic device to prevent the possibility of an explosion. As the report does not identify which VOCs were off-gassing at these levels, it is unknown whether the levels at which they are released are hazardous to human health. The 2018 FYR identifies these VOCs as an issue that could affect future protectiveness of the site and indicates the need to determine their source(s).
In June 2013, soil gas probes along the site perimeter reported levels of seven contaminants at levels that, if found within residential homes, would pose a health risk. To ensure these contaminants were not migrating into nearby residential homes, the EPA conducted vapor intrusion sampling in 33 homes in Riverside Gardens between June 2014 and July 2015, with results reported in the 2016 CSM . The EPA collected soil samples from outside the homes in the study and air samples from the basements, sub-slabs, crawl spaces, and first floors of these homes for VOC measurements in order to identify the level and source of the VOCs. The analysis could not identify a complete vapor intrusion pathway between the site and the interior of the tested residences, and although some elevated levels of VOCs were detected, the EPA concluded that these were likely not attributable to the site because of their inability to detect a vapor intrusion pathway. The report concludes that there was “no unacceptable health risks from vapors migrating from beneath homes to indoor air .”
Landfill Gas (LFG) Collection System
In 1980, SCS Engineers, under the direction of the Jefferson County Department of Public Works, installed the landfill gas (LFG) collection system to address the potential migration of gases from the site to nearby residential areas. Engineering studies in 2004  and 2010  determined that the LFG system was inoperable and had exceeded its 25-year useful life. Gas probe data over a 22-year period (1993 to 2005) showed continuous decreases in methane levels and confirmed there had been no new releases of methane from the site. The 2016 CSM  stated that methane concentrations on the site had not exceeded the LEL (5% methane) at any probe since 2007. The CSM also reported low levels of methane from samples collected in 2013 from 18 gas probes located between the site and Riverside Gardens. The vapor intrusion study in 2014-2015 also confirmed methane was not migrating from the site to Riverside Gardens . The 2018 FYR thus noted the imminent closure of the LFG system and indicated that KDEP would continue to monitor methane levels for two years to ensure there is no increase. The shutdown of the LFG system occurred in September 2019 . No additional action is required as long as methane levels remain below the LEL.