Managing risks and uncertainties associated with a polychlorinated biphenyl (PCB) remediation project
Environmental remediation projects are by their nature expensive, include many uncertainties, can contain considerable project risks, and expenditures for these remediation projects reduce a company's income statement. As such, environmental project managers are continually being challenged to reduce the cost of these remediation projects. This challenge can be very difficult given the risks and uncertainties involved in remediation projects, but can also be supported by new remediation technologies, combinations of remediation technologies, and the application sound project management techniques to help understand and mitigate the risks and uncertainties.
This case study summarizes a recently completed PCB remediation project at a former manufacturing facility in Maine that has undergone closure and has been sold and re-occupied by a new owner. This case study covers the approach used to apply a combination of new and existing remediation techniques and the project risk management approaches used to mitigate risks and uncertainties.
Site and Project Background
The site is a typical turn-of-the-century industrial facility located in Maine. As is the case with many of these types of older industrial facilities they have been closed regarding their original use and have been undergoing changes to accommodate other uses more in line with today's economy and market place. As an industrial facility, electrical generation was performed locally and distributed through various electrical load centers at the site. PCBs were historically used within older electrical transformers and the site cleaned up under this remediation project included electrical load centers that had older PCB-type transformers. Harding ESE was initially contracted to remove and dispose of transformers that were known to contain PCB-based fluids. In the process of these removals and associated general cleaning, a number of leaks and stains were observed that indicated the potential for PCB contamination of floor surfaces inside the load centers. As a result of these observations, a characterization and remediation program within the load centers was undertaken. Subsequently, characterization and remedial actions for PCBs that were tracked onto concrete floor surfaces outside of the load centers was also performed and is the basis for this case study. The approval for this PCB remediation project was granted by United States Environmental Protection Agency (USEPA) under the authority of Section 6(e) of the Toxic Substances Control Act (TSCA), 15 U.S.C. §2605(e), and the PCB regulations at 40 CFR Part 761.
Risk Versus Reward
Having a clean environment and sound environmental management practices are important aspects to society and business. As the economy and market place becomes increasingly competitive, not only in the United States, but also worldwide, businesses and communities are faced with ever increasing environmental management and remediation costs. Business changes and philosophies have started to change the nature of environmental spending toward prevention and environmental management. Even though this shift toward prevention and environmental management is occurring, environmental costs have and still include the cost of site characterization and remediation of past activities.
The question facing today's environmental managers and service providers is how can the cost of environmental remediation be lowered without compromising clean up objectives? One way to accomplish this objective is to use innovative technologies and approaches. While innovative technologies and approaches offer the potential for cost savings they also can become more costly when not applied and managed correctly. More traditional remediation methods and technologies will typically yield more predictable results and returns, however they may not provide the opportunity to realize cost savings. The project risk tolerance (risk versus reward) needs to be considered and measured in the context of the individual project setting. Project risk tolerance usually varies from project-to-project since most environmental remediation projects, while containing similarities, will have enough differences that site-specific circumstances should always be considered. For example, while two particular sites may have similar physical and contaminant settings that would allow for the use of an identical innovative technology, client, public, regulatory, and other stakeholder concerns may result in two significantly different remediation approaches.
Exhibit 1. Sources of Risk and Mitigation Approach
The project risk tolerance for the subject PCB remediation project was determined to be adequate for the use of innovative technology and approaches so long as client, regulatory, and other stakeholder goals and objectives were met. A summary of these goals and objectives are as follows:
Client—Cleanup of PCBs and site closure is obtained in a timely manner to achieve site closure and unrestricted use/occupancy of the remediated area and at a cost that would be equal to or less than more traditional remediation methods.
Regulatory—Innovative technologies and methods used must be demonstrated effective and able to achieve the PCB cleanup level of 1 milligram per kilogram (mg/Kg).
Other Stakeholders—Current facility owner would achieve timely and unrestricted use of the remediated area with minimal disruption of operations during remediation.
Remediation Technology Selection and Screening
Remediation of PCBs was required in areas both within and outside the electrical load centers. The technology selected for use within the load centers consisted of physical removal of concrete to below the 1mg/Kg cleanup level. This technology worked well within the load centers since the load centers were relatively small in area and confined physically with walls and a ceiling. Additional challenges were posed outside the load centers in that affected areas were larger with potentially open-ended boundaries and containment of dust from physical removal methods would be more extensive and costly. Therefore innovative technologies and methods were evaluated to assess whether different technologies and methods than those used within the load centers could remediate PCBs to cleanup levels in less time, cost, and with a greater ease of use. The end result of this technology screening yielded chemical extraction as a method to evaluate for effectiveness and applicability for the project site.
The next step taken was to identify the various risks and uncertainties associated with the use of both the physical removal and chemical extraction methods and to develop actions to mitigate the risks and uncertainties to the extent practicable. This risk evaluation supported the optimization of the combined use of the traditional physical removal process and the innovative technology of chemical extraction. Exhibit 1 shows the primary sources of risks identified, the type of risk (i.e., technical, safety, cost), and the mitigation approach used.
Innovative Technology Deployment
PCB characterization information outside the load centers showed varied sizes of areas as well as varied concentrations of PCBs detected. Based on this PCB characterization data outside the load centers, Harding ESE developed a remediation approach that used a combination of physical removal of concrete and chemical extraction. The chemical extraction process was chosen to augment the physical removal of concrete in an effort to reduce overall remediation costs. An onsite pilot study indicated the potential for project cost savings should the chemical extraction process be successful (i.e., achieve the anticipated chemical extraction efficiency). The chemical extraction efficiency anticipated was 60% to 70% based on the onsite pilot test compared to the literature estimates of 90%.
Results from the site-specific chemical extraction pilot scale test indicated that the chemical extraction methods are effective for removing PCBs from the upper one-fourth inch surface of the concrete floors. TechXtract® (acid-based extraction) was selected as the chemical extractant for the project. Results from the pilot test also indicated that chemical extraction is not as effective below the one-fourth-inch depth interval. Chemical extraction was therefore only used in areas where exceedance of the 1mg/Kg clean up standard are limited to the top one-fourth inch. It was also evident from the trial that more than one application of extractant may be required to achieve the 1mg/Kg cleanup level. Chemical extraction was then targeted for areas that had more widespread PCB contamination at relatively lower concentrations (i.e., generally not more than 2mg/Kg). The physical removal technologies included scarifying/milling and cutting/jack hammering of porous concrete surfaces.
Of the sources of risk presented in Exhibit 1, the primary controllable risks that had the most potential for negatively impacting the project goals and objectives were: the actual versus anticipated performance capability of the extraction method, the sample extraction methodology, the PCB characterization sample density (i.e., number of samples per unit area) versus cleanup confirmation sample density, and the remediation cost differentials.
Performance Capability—Determination of site-specific performance capability was important since information from the USEPA SITE Program (USEPA, 1999) indicated that the TechXtract® chemical extraction process could achieve a 60% to 90% contaminant reduction. Since site-specific circumstances (e.g., physical setting and contaminants) vary, developing site-specific performance criteria was necessary to support performance predictability and where the process should be applied. Without this information the risk that chemical extraction would be applied or continue to be applied in less than optimal areas was greater, thereby contributing to possible cost and schedule impacts.
Extraction Methodology—As part of the pilot test, a comparison of two different analytical extraction methods was performed, SW-846 Methods 3540C (Soxhlet) and 3550 (ultrasonic). The USEPA preferred the 3540C method, however this method is more time intensive and did not allow for optimization of turnaround times for laboratory samples. The most efficient turnaround time was necessary to minimize remediation down time while waiting for decision-making results. The comparison was effective and the USEPA approved the use of the alternate method.
PCB Characterization Sample Density—A recognized uncertainty and risk was the difference between the PCB characterization sampling density and the verification sampling density. Verification sampling was required at a 1.5-meter density whereas characterization sampling was performed at a 3-meter density. The cost benefit relationship of additional characterization versus managing sampling uncertainty during remediation is often debated. This relationship will vary depending on the type of contamination, media contaminated, and the unit cost of remediation and disposal/destruction. Where the unit cost of disposal and remediation is high, additional characterization may be beneficial to reduce uncertainty of material quantities that would otherwise be remediated. For this project, the characterization sampling density was considered adequate and cost beneficial. Uncertainties of PCB distribution were mitigated by the use of an observational method that included pre-determined remediation performance criteria (i.e., when to apply the appropriate remediation method), rapid turnaround of analytical results to facilitate decision-making, and ongoing cost and schedule tracking to ensure that the maximum anticipated cost was not exceeded.
Remediation Cost Differentials—While the unit cost of physical removal was higher than the chemical extraction method, physical removal represented a more fixed maximum cost whereas chemical extraction represented a more variable cost. If allowed to “run its course” without adequate performance criteria and project controls, the chemical extraction method would exceed the cost of total physical removal and the maximum target project cost. The variable aspect of the chemical extraction method was the need for reapplications where verification samples indicated that the cleanup level was not achieved. Reapplication of chemical extraction versus switching to physical removal was continually evaluated against verification results, the corresponding technical performance criteria, and cost/schedule milestones and measurements. This ongoing evaluation mitigated the risk of over-applying chemical extraction in areas where it would not achieve cost and time effective results.
Exhibit 2. Target Versus Actual Remediation Methods for Load Center J1
Exhibit 3. Target Versus Actual Remediation Methods for Load Center J2
Of the sources of risk presented in Exhibit 1, the primary uncontrollable risk was the actual PCB distribution.
PCB Distribution—Having a good conceptual model of how PCBs were distributed outside the load centers was critical in developing an adequate characterization approach. The primary mode of transport and spreading of PCBs was by foot traffic over areas where spills occurred as part of the installation, maintenance, and removal of older PCB fluid containing electrical transformers. This “trafficking” of PCBs was predictable to outline the broad areas of PCB impacted concrete floors but was subject to variability within these areas, was not readily visible in places, nor necessarily detected during the PCB characterization. This risk and uncertainty was managed by the observational method and project controls discussed above.
Innovative Technology Results
The application of innovative technology (chemical extraction) for this project yielded results that were good in some areas and less effective in others. Exhibits 2 and 3 show two of the remediation areas (J1 and J2 respectively) that typified more optimum versus less effective results. The concrete floor area west of Load Center J1 was remediated by means of chemical extraction with a small area of physical removal to a one-half-inch depth. The chemical extraction areas to the west and east indicated that the extraction process reduced the size of this remediation area by approximately 85%. This area responded well to chemical extraction given that the apparent distribution of PCBs was more uniform and less concentrated and that the physical aspects of the concrete were better (i.e., less weathered and worn, less porous, and less exposed coarse aggregate).
The concrete floor area remediated outside J2 was completed by both physical removal, directly east of the Load Center, and chemical extraction further east. The area adjacent to the Load Center was remediated by one-half-inch removal. The remainder of the floor was remediated first with chemical extraction. Initial extraction attempts reduced the area by approximately 40%. Areas that did not respond to the chemical extraction were added to the physical removal program and a one-fourth-inch was removed using a milling machine. This area did not respond as well to chemical extraction given that the apparent distribution of PCBs was less even (e.g., less obvious tracking routes) and at higher concentrations, and the physical aspects of the concrete were poor (i.e., weathered and worn, more porous, and more exposed coarse aggregate).
In conclusion, the use of innovative technologies can be a benefit to a remediation project by reducing time and cost. They can, however, end up costing more and take longer if technical performance criteria are not established in the project planning phase and adequate project controls are not set up and used throughout the project execution phase. As an example, the remediation of load center J2 could have cost more if excessive reapplications of the chemical extraction method was not controlled through adequate triggers and thresholds for technical and project performance. A project risk tolerance as well as the number of risks also needs to be considered prior to selection of innovative approaches. Some project settings have low risk tolerances and too many risks will become unmanageable.
For this particular project the use of the chemical extraction process (versus complete physical removal) did achieve less amounts of waste for offsite disposal, provided for less structural degradation of existing floors, and provided for a more conducive health and safety environment by reducing the amount of dust control measures required. This also allowed for minimal disruption to current facility owner's operations. For project schedule, the remediation effort and site closure occurred in the anticipated time frame. For project budget, the target/optimum cost was not achieve due to the PCB distribution issues identified with Load Center J2. In the end, the maximum anticipated cost was not exceeded and additional detailed site characterization costs were avoided due to the successful implementation of the observational approach discussed above that included the technical and project controls performance criteria.
USEPA. 1999. SITE Technology Profiles—Tenth Edition. Demonstration Program EPA/540/R-99/500a, February.
Proceedings of the Project Management Institute Annual Seminars & Symposium
October 3–10, 2002 · San Antonio, Texas, USA