The Hartford site is located in the northern portion of the Village of Hartford, Illinois, along the historical edges of the active Mississippi River channel. EPA established an Administrative Order on Consent (AOC) with a group of principal responsible parties (PRPs) to address environmental contamination resulting from historical petroleum refining and management practices adjacent to the village. As of 2007, activities were being carried out under the AOC to mitigate hazards from vapor intrusion identified within the village limits. From 1966 through 1990, house fires occurred intermittently in the village that may have been caused or exacerbated by petroleum vapors. More recently, homeowners had registered complaints about petroleum hydrocarbon odors that triggered the need to temporarily relocate several households. Because of these concerns, EPA Region 5 and the EPA Office of Superfund Remediation and Technology Innovation (OSRTI) identified project objectives that included implementing effective short- and long-term vapor intrusion (VI) mitigation measures and delineating free phase and vapor phase hydrocarbons to support final remediation objectives. Systematic project planning (SPP) was initiated for the site involving historical data compilation, preparation of a preliminary CSM for the site, and suggestions for optimization of further characterization and cleanup efforts. The preliminary CSM developed by EPA was continually updated and evolved by the project team as new data became available.
Multiple investigations occurred at the site using a range of innovative, high-resolution site characterization (HRSC) tools and strategies. Examples include a delineation of free petroleum product that used ROSTTM along with collaborative geological and chemical data, as well as VI migration investigations that featured active soil gas and air/vapor monitoring with portable gas chromatograph/mass spectrometers (GC/MS) and on-site laboratories. These investigations identified contaminant migration pathways and receptors of concern, allowing the PRPs to refine and target their remedial approach to address homeowner concerns.
|Site Name||Hartford Plume Site|
|Project Lead Organization||Hartford Working Group - Agglomeration of Oil Companies named in the AOC|
|Project Lead Type||PRP Lead|
|Regulatory Lead Program||RCRA Corrective Action (enforcement under emergency response)|
|Triad Project Status||Field Program Completed|
|Reuse Objective Identified||Yes|
Petroleum products have been refined, managed, and stored in the Hartford area since the early 1900s. By the early 1940s, the village was surrounded by petroleum-related industrial activities to the north, northeast, and east. Since that time, refining and pipeline activity continued to expand closer to the center of the Village of Hartford. As groundwater levels generally rose in the area through the late 1970s, extensive VI began to be reported in the village. Refineries began product removal and hydraulic control measures in attempts to reduce the number of vapor-related issues in the Village.
Many investigations have been conducted since the 1970s to establish the nature and extent of contamination beneath Hartford. Soil borings and chemical analysis were among the only tools available during early investigations to examine the nature and extent of the contamination. Wells and hydrocarbon probes were used to measure the apparent thickness of free product. Samples from such wells provided important but limited information on the extent of free or mobile product beneath the village. These data likewise provided only limited information on geologic conditions, the physical and chemical characteristics of the released petroleum, and the overall extent of the contamination released by historic refinery operations. More recent HRSC tools such as cone penetrometer testing (CPT) and the ROSTTM made it possible to collect the density and diversity of data needed to unravel the complex combination of environmental impacts to the Village of Hartford.
The use of an evolving CSM helped the project team to quickly develop consensus on what was known about the site, and what additional data were needed to reach project goals. Using the CSM and innovative HRSC tools for delineation of soil, groundwater, and indoor air contamination allowed the project team to proceed with remedial design activities quickly and efficiently, addressing urgent VI issues for homeowners.
The project team used the ROSTTM data in conjunction with other historical information from the site to install new monitoring wells, nested vapor probes, and sub-slab monitoring points across the Village of Hartford to better understand the nature of vapors emanating from hydrocarbons in the subsurface. Data from vapor probes indicate the concentration and nature of vapors in the unsaturated zone as they move upward toward the surface and residential homes.
Specially-designed product recovery wells were installed. These wells were designed to remove both product and associated vapors. Furthermore, core samples were collected and analyzed from selected recovery wells to measure the physical properties of the formation and the associated contamination to estimate the potential for vapor and product removal. Testing with mobile high-vacuum extraction systems measured the tendency of the formations to yield contaminants in the vapor as well as the fluid forms.
The project objectives were defined under the articles of an AOC for the Village of Hartford site as follows:
The refined CSM produced by the ROSTTM and other collaborative tools enabled the project team to effectively target specific areas where additional investigation and remedial action were warranted. Comparative analysis of the ROSTTM data sets and other information (such as geological data from soil cores and analytical data from laboratory methods) identified a fluorescence response range for the ROSTTM tool that could be used to efficiently screen the subsurface for the presence of free product.
Through the development of a consensus vision for the site aided by the use of CSM-related work products, the project team was able to accelerate the design and implementation of a regional soil vapor extraction system. As of 2010, targeted product removal efforts were underway and full remedial systems were in the 90 percent design stage. The CSM was continually refined throughout the duration of the project and provided guidance where additional system design modifications were warranted.
Cost and time savings have not been quantified by the project team. Team consensus, however, was that the HRSC approach using the ROSTTM in conjunction with other collaborative tools provided the high-density data collection needs for the site much more efficiently and with greater overall accuracy than would be possible with a conventional drilling and sampling program.
SPP was conducted in quarterly meetings held between the responsible parties (the Harford Working Group), their consultants, the State of Illinois, and EPA Region 5 since the signing of the AOC in 2003. During these meetings, plans for each stage of data collection and remedial systems evaluation were discussed. A preliminary CSM was developed by EPA's OSRTI using available data provided by the Hartford Working Group in early 2004. Later efforts to refine the CSM were performed by the consultants for the Hartford Working Group.
The EPA OSRTI support group further facilitated SPP activities by developing principal study questions based on the AOC objectives and on historical data review:
As planning and data gathering activities proceeded, strategies to mitigate vapors and other adverse environmental conditions at the Hartford site came to be guided by key elements of the preliminary CSM, including preferred pathways apparent from the site geology and hydrogeology, as well as the thickness and chemical properties of the free product. The project team developed CSM work products (PDF, 12.7 MB) based on the innovative and traditional methods used at the site. The work products included generalized regional cross-sections to show the approximate relationship between the glacial outwash sands that are used as a source of water in the area, overlying tighter sediments, and potential sources and receptors located on the site. The CSM was used to place sentinel wells for improving containment systems beneath the refineries, and to optimize soil vapor extraction (SVE) systems.
Investigation and cleanup activities at the Village of Hartford site are managed in accordance with the AOC by the Hartford Working Group, consisting of the Atlantic Richfield Company, Premcor Refining Group, and Shell Oil Products U.S. The technical teams supporting the group were broad and diverse consisting of multiple consultants and technology vendors. Clayton Group Services, Inc., provided the CPT for the free product investigation that employed the ROSTTM and other collaborative technologies. ENSR International served as the consultant and core team for VI migration pathways assessments that used active and passive monitoring techniques for soil gas, sewer gas, and ambient indoor/outdoor air in combination with field-based GC/MS methods. The core teams included experts in the areas of chemistry, geosciences, and remedial engineering. The core teams were supported by technology vendors with expertise in specific innovative, HRSC methods (see the Technology Vendors section).
Regulatory oversight was provided by the State of Illinois and EPA Region 5, with technical support in chemistry, geosciences, and engineering from the Region 5 Superfund Technical Assistance and Response Team (START) and the EPA OSRTI Superfund Technical Support Center.
EPA, in conjunction with the Hartford Work Group core teams, analyzed data from the ROSTTM and other sources of information on a real-time basis. The geologic conditions and the nature and extent data were discussed on an as-needed basis to make efficient use of project resources. Decision logic was developed for both the free product investigation and the dissolved phase (groundwater) investigations such that the project could proceed with limited delays between data collection efforts. From the onset of the project data was shared between the parties as it became available. Instrument readings and analytical data were posted to a website daily for review during the ROSTTM investigation.
At first, decision logic was based solely on the presence or absence of free product in the subsurface beneath the site. As more was learned, decision logic for investigation- and remedy-related activities were designed around project-specific action levels for chemicals that drove risk, such as benzene in indoor air. As the remedy and mitigation efforts matured, effectiveness monitoring plans were developed that specified actions based on engineering-related parameters such as induced pressures or measured concentrations at specific monitoring points.
The Hartford Working Group selected the ROSTTM for HRSC activities at the site. The ROSTTM tool combines the use of a CPT that can be used to delineate geologic and hydrogeologic features in the subsurface on a nearly continuous basis. The laser-induced fluorescence (LIF) sensor on the ROSTTM tool can be used to develop a nearly continuous vertical readout concerning petroleum contamination in the subsurface both above and below the water table. The ROSTTM tools have been in use at petroleum sites across the U.S. since the early 1990's.
The response of the ROSTTM to petroleum hydrocarbon contamination could be roughly correlated with the presence or absence of free product. With this in mind, the ROSTTM responses, shown as red, yellow, green and blue color bands of varying intensity were examined to help distinguish potential source areas across the site. A key to the color coding of ROSTTM responses and examples of ROSTTM product delineation maps for the Harford site are shown here (PDF, 4 MB).
The total amount of fluorescence measured at a particular location was further used to estimate the potential for the presence of free product that might be susceptible to extraction. Standard core analyses and visual observations were used to develop specific threshold intensities and characteristic ROSTTM responses for various petroleum products. Additional ranges of signal types and intensities were defined as probable indicators for when these petroleum products could be considered mobile. This data was then used to help decide where additional product removal activities should be considered. Nested vapor probe results were also used along with ROSTTM CPT results to evaluate attenuation rates in the vadose zone and decide where additional SVE actions needed to be considered.
Other real-time measurement technologies used during the investigation of the site included gas monitoring devices such as a portable GC/MS. The project team also experimented with the use of passive soil gas sampling devices but decided that active soil gas sampling methods using SummaŽ canisters was generally the preferred option for air/vapor sample collection. Larger air/vapor monitoring programs employed on-site laboratories that used transportable GC/MS instruments (modified EPA Method TO-15).
TQRS not prepared
Key to data quality and defensibility was the use of a variety of collaborative data sets and investigative tools to create high-resolution data that managed different types of uncertainty. For example, geologic logging and laboratory analytical data were used to manage uncertainties associated with the ROSTTM data. Handheld GC/MS data for vapor samples were correlated to standard air methods performed by off-site laboratories, and on-site laboratories provided a level of analytical QA/QC that was comparable to off-site fixed-base laboratories. The variety of data sets combined to give the Hartford Working Group, the regulators, and other stakeholders a high degree of confidence in the CSM, such that consensus could be attained on the remedial strategy.
A relational database was developed based on EPA Region 5's standard database structure requirements. The relational database was used to prepare site images using industry-accepted graphical information system (GIS) software. The GIS work products were used during systematic planning meetings to discuss conditions at the site and to plan follow on investigations. The project team set up a secure web portal at EPA's request to assist with the sharing of data among stakeholders.
Preliminary investigations were completed in 2003-2004 over a period of less than a year.
Design and large-scale implementation of the remedy, including soil vapor extraction and free product removal,took place in less than three years following the investigative phase.
To update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.