In the Spring of 2003, the U.S. Environmental Protection Agency (EPA) Region 8 requested assistance from the EPA Brownfields Technology Support Center (BTSC) to review a draft Field Sampling Plan (FSP) and refine the technical approach for the focused Site Inspection (SI) planned at the Ross Incinerator Site, in Colman, South Dakota (Site). The BTSC assisted Region 8 with further SPP for the project, outlining the conceptual site model (CSM), and providing suggestions regarding a high-resolution sampling strategy and the use of field test kits. Late in 2003, as the report for the focused SI was being prepared, the BTSC again collaborated with Region 8 in the statistical assessment and interpretation of the analytical results. The assessment found limited potential PCB impacts from the Site, possibly supporting a NFRAP determination under CERCLA. In 2007, a final decision of No Further Remedial Action was made.
|Site Name||Ross Incinerator|
|Site Type||Electrical Equipment Reclamation/Incinerator|
|Site Regulatory ID||CERCLIS ID# SDD34760462|
|Project Lead Organization||Superfund Technical Assessment and Response Team (START) 2, EPA Region 8. Region 8's contractor for START 2 is URS Operating Services (UOS)|
|Project Lead Type||EPA Lead|
|Regulatory Lead Program||Superfund Remedial|
|Triad Project Status||Field Program Completed|
|Reuse Objective Identified||Yes|
Ross Service Company, Inc., (Ross Incinerator) has operated as an electrical equipment reclamation facility at the Site since 1973. Originally the company burned transformer equipment, varnish, and insulation, including polychlorinated biphenyls (PCB)-based and non-PCB-based transformer oils in an open pit. A wire reclamation incinerator was added in late 1973, and by 1975 the incinerator became the company's only means of electrical equipment reclamation.
After 1973, waste PCB oil from the transformers was either used to heat the main office building located on the property, or sold as fuel oil. In 1990, Ross Incinerator replaced the original incinerator, stopped receiving transformers, and received only electrical equipment parts. Ross Incinerator used the new incinerator to burn varnishes and remnant PCB oil off of used electrical equipment and wire to reclaim the copper. Also in 1990, the company began to have incinerator ash and waste tested and disposed at approved facilities. Previously, ash waste had been disposed on-site or in local landfills. Site operations may also have impacted a ditch running along the western boundary of the property that eventually led to a local creek (0.5 miles away).
In 2002, Ross Incinerator again began receiving transformers for reclamation. The Company has a South Dakota air permit for uncontrolled potential emissions less than 100 tons per year of regulated air pollutant.
After accounting for the positive bias in the test kit data, the statistical analysis found that no on-site surface soil samples exceeded the risk-based screening level applied for the project. This screening level was the EPA Region 8 preliminary remedial goal (PRG) of 1.4 micrograms per kilogram (µg/kg) for industrial use. The lack of test kit detections in the off-site samples of soil, surface water, and sediment samples, again with corroborating CLP data, further indicated that PCBs had not significantly impacted other environmental media surrounding the Site. Therefore, the test kit data cost-effectively indicated that no further action was necessary for an industrial land use scenario, which was considered appropriate for the Site because it was anticipated to remain in the hands of Ross Services, Inc. for the foreseeable future as an electrical equipment recycling facility.
Previous evaluations, including a Preliminary Assessment (PA) performed in 1994 by the South Dakota Department of the Environment and Natural Resources (SDDENR), found evidence of PCB releases to soil, surface water, and sediment at the Site. In early 2003, EPA Region 8 assessed that a focused SI should be performed to more clearly establish whether the Site posed potential risks. The objective of the focused SI was to reassess the Site using EPA's Hazard Ranking System (HRS) along with up-to-date, high-resolution site characterization data. The focused SI, also termed a Site Reassessment (SR), was intended to support an EPA decision as to whether additional work was required under the Superfund program, or whether a NFRAP designation would be appropriate for the Site.
The use of test kits for PCB analysis reduced the need for more expensive CLP laboratory analysis, and enabled a high-density of sampling in soils across the Site. In addition to delineating PCB contamination on-site, the test kits helped delineate the distance over which PCBs were distributed to off-site soil via the air pathway, as well as in a nearby ditch and creek via surface water transport. This sampling density, in combination with high degree of correlation that was found between the test kits and collaborative laboratory data, provided EPA Region 8 with an acceptable level of confidence in its final site decision.
No cost or time savings have been quantified. However, a conventional SI approach, employing more limited judgmental ("worst case") sampling, may have resulted in the Site being unnecessarily designated for the Superfund Remedial program, which would have had significant cost and time implications.
The focused SI was designed around the principal study question that guides most PAs and SIs under the Superfund process: "Has the Site released hazardous constituents at levels that warrant ranking of the Site using the HRS?" Through review of historical information from the PA and other investigations at the Site, a limited CSM was derived that identified the primary contaminants, release mechanisms, environmental media, and exposure scenarios of interest for ranking the Site. PCBs in surface soil were identified as the primary contaminants and media of concern, although other contaminants (metals, dioxins) and media (surface water, sediment) were identified for more limited evaluation.
The initial sampling approach proposed for surface soil on and around the Site involved a combination of composite grid and judgmental sampling. However, additional SPP performed by EPA Region 8 with the support of the BTSC later revised the characterization method to a high-resolution approach using an unaligned grid with an increased number of sampling locations for analysis using field test kits. Unless staining or other evidence of potential releases were noted in a given grid element (at which point a biased sample was taken), sample locations within the grid element were to be selected randomly. Additional judgmental samples were to be collected as identified by the field team to confirm or delineate hotspots.
The project was led by the EPA Region 8 Site Assessment Manager (SAM), who was the principal decision maker for the project. The SAM was supported by other EPA Region 8 technical staff in risk assessment and quality assurance (QA). The SAM was also supported by the Superfund Technical Assistance & Response Team (START) 2 contractor, UOS, who provided the technical field team of environmental scientists and prepared the plans and reports. Upon request, the BTSC provided additional support to the SAM and to UOS in analytical chemistry, QA, and statistics. SDDENR provided input as a stakeholder, commenting on plans and reports.
The field team began with the biased unaligned grid and judgmental sampling approach outlined in the final FSP. The field team dynamically refined and augmented the sampling design in the field (see the Decision Logic discussion below). This process was limited by schedule and budget constraints (such as the number of test kits purchased), as well as by equipment problems with the kits (see "Real-Time Measurements" below). The field team communicated regularly with the SAM to relay results and discuss modifications to the sampling strategy. Final decisions regarding the regarding further action at the Site were not made in the field, instead awaiting CLP laboratory results to draw correlations with the field test kit data and comparisons to risk screening levels.
The investigation was a SR action for CERCLIS tracking, which is similar in scope to an SI. Therefore, because it was a limited initial investigation, detailed decision logic diagrams were not developed. Nevertheless, the field team modified and optimized the sampling program as possible and appropriate based on the field results. For example, additional biased locations were sampled based on visual observations at the Site ("samples of opportunity"), and other "step-out" locations were identified and sampled to delineate potential hotspots as indicated by test kit results.
The immunoassay (IA) test kits used for PCB analyses in the field were used "off the shelf" — no preliminary testing or site-specific demonstration of methods applicability (DMA) was performed. A total of 54 samples were analyzed by the test kits, including 31 on-site and 11 off-site (residential) soil samples. Five sediment, two surface water, and five background soil samples were also analyzed. On-site soil concentrations ranged from nondetect (at 0.2 to 18.9 µg/kg total PCBs), whereas other samples were essentially all nondetect. Twenty percent of the samples, representing the full range of concentrations measured by the kits, were submitted for CLP laboratory analyses using gas chromatography (GC) methods.
The spectrometer supplied with the test kits malfunctioned in the field. As a result, the analyses for some samples were delayed until the field crew demobilized. To some extent, this problem compromised the real-time, dynamic work strategy (DWS) for the sampling program; however; data quality was not compromised since holding times were met. Also, regression analyses of the field data relative to the CLP data indicated a high degree of correlation, reducing decision uncertainty.
TQRS not prepared
The statistical assessment focused on the 31 surface soil samples that were collected on-site. A clear correlation was found between the test kit and CLP results, with an r-value of 0.989. The kits displayed a consistent high bias of 10X or more over the laboratory results.
A primary goal of the data assessment was to generate an action level for the test kit data that correlated with the EPA Region 8 industrial PRG used for decision-making. When the SI began, the PRG was 2.9 µg/kg. BTSC performed a regression analysis for EPA Region 8 that incorporated that 95% confidence limit of the regression line as a safety factor. The regression analysis found that the PRG correlated with a concentration of 40 µg/kg as reported by the test kit. All field concentrations reported at the Site (max. = 18.9 µg/kg) were below this "field-based" action level, indicating that the Site did not contain concentrations of concern in surface soil based on an industrial land use scenario.
During the investigation, EPA Region 8 revised the PRG from 2.9 to 1.4 µg/kg. SDDENR requested that on-site data be re-evaluated relative to the revised PRG. Reapplication of the regression analysis by EPA Region 8 during preparation of the Final Analytical Results Report found that the new PRG correlated with a test kit concentration of 20 µg/kg. This new field-based action level remained above the highest sample concentration, still demonstrating the minimal risk associated with the Site.
The UOS project team noted that while blanks and calibrations were performed as quality control (QC) measures for the field test kits and indicated no problems, other QC checks such as field duplicates and spikes were not performed due to limited test kit materials.
Data were managed using spreadsheets and commercially available basic statistics packages.
The SI field program was completed July 14-18, 2003. Follow-on analytical work was performed during the week of July 19-23 at the UOS laboratory facility using a replacement spectrometer provided by SDI.
|Statistical Data Assessment Letter (220 KB)|
To update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.