Process Engineering for Pollution Control and Waste Minimization_12 pot

material and energy balances many be found in a number of chemical engineering texts, such as Felder and Rousseau (4) and others. 3 ADDITION OF CHEMODYNAMICS In order to take LCA beyond its usual scope to assess a waste site remedy, we need not only to include the mass and energy balances for environmental compartments, but also the models and mechanisms of inter- and intramedia transport. The concepts and models of chemodynamics are provided in significant detail by Thibodeaux (5), and by Reible and Choi (6). For the purposes of this discussion, it is assumed that appropriate models of the fate and transport of contaminants for a case are known, estimated, or available in some fashion. Since the objective of the LCA in remediation is to assess the burden being placed on the environment by various remedies, the application of realistic and appropriate models is essential and found in references above (5,6) for certain cases. 4 APPLICATION With the objective being assessment of the environmental (eco- and human health) burden from various remedies in a waste site problem, we may employ, as with LCA, risk assessment in the reverse, following the methodology of Hwang (7) as extended by Constant et al. (8). The exposure is summed from different routes to get total exposure, E t , which, to have an acceptable risk, should not exceed the reference dose level (RL). Exposures are calculated as in any other assessment, based on concentration, time, body weight, etc. Key here is the concentration at the exposure point (receptor), which is a function of the concen- tration in the soil or other medium. This function is the subject of much modeling work as described above, as it is essential to have accurate representations of the fate and transport of the contaminants in and across media under investigation. Thus, one may apply the above exposure method for an acceptable risk, combined with LCA, as follows (8). First, land use or other resource needs are established, followed by assuming a chemical management or remediation scheme or treat- ment train concept. Then, incorporating regulations, laws, and liabilities, chemi- cals are traced from “cradle to grave” throughout the process as in a typical LCA. Next, risk is assessed for the scheme (7) with all material and energy balances incorporated, along with eco-risk as appropriate. With these balances completed including appropriate fate and transport models, economics of the process(es) being considered are established. If the economics are acceptable, then the technology or waste processing is appropriate for the present level of available technology considered (or assumed) in the first step. If the economics are unfavorable, another treatment, manufacturing, or remediation scheme should be Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. applied to this integrated management methodology for comparison to the first attempt. Thus, methods can be evaluated for risk-based remediation or manufac- turing as in LCA for the most economical approach. It should be noted here that technology is on a moving time line, and what is successful and economical today will need to be reassessed several times in the future as chemical fate and transport modeling, our understanding of the environment, technologies, and regulations all change. In this manner, “new” technologies such as monitored natural attenuation (MNA) can be assessed alongside and with active remedies as described in the example below. 5 EXAMPLE OF ASSESSMENT The Petro Processors, Inc. (PPI), site is one of the most significant Superfund sites in the United States. While it is not directly under Superfund, due to agreement among the parties and existing consent decree in the U.S. District Court, Middle District of LA, it provides an excellent example, via hindsight, of the utility of LCA for risk-based remediation methodology as described by Constant et al. (8). Details of the site(s), being named Brooklawn and Scenic, for the nearby roadways, may be found at EPA’s Region VI Web site (9), and are not described here. The site(s) contain approximately 400,000 tons of chlorinated hydrocarbon wastes, including hexachlorobenzene, hexachlorobutadiene, TCE, DCE, lower chlorinated products, and numerous other petrochemical wastes of similar nature. The mixture forms a dense, nonaqueous, viscous phase, which is currently covered and maintained by hydraulic containment of the groundwater and recov- ery of the organic phase (both of which are treated on-site) under strict regulatory requirements. Louisiana State University (LSU) has served as the Court’s Expert for the last 10 years regarding cleanup of this site, with the role being research into advanced technologies and assisting the court in monitoring and assessing the remediation. Just prior to LSU’s involvement, the remedy was to remove the waste, stabilize the material, and place it in a lined 1 × 10 6 yd 3 vault, with some hydraulic containment and recovery of site areas found difficult to remove due to the high water table. However, due to volatile emissions exceeding fence-line limits, the removal method was abandoned. The next remedy to be put in place was active hydraulic containment (expansion of the previous pumping layout), with several hundred wells to remove organics and contaminated water over the long term in order to protect the underlying aquifer and prevent migration. To date, only about 1% of the free-phase material has been removed, but containment appears successful, at the expense of treating millions of gallons of water containing only trace contamination levels. As this pumping method was being installed at Brooklawn, via ongoing research by LSU and site personnel for Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. augmentation of the pumping operation by both passive and active technologies, intrinsic biodegradation and hence natural attenuation was studied and then incorporated into the remedy. The addition of biodegradation, sorption, disper- sion, etc. as required within the lines of evidence of MNA as presented by EPA (10), has had a significant impact on the remedy of the PPI site. It appears at this time that active pumping of significant water volumes may be greatly reduced, while still focusing on source removal (NAPL), with the understanding that significant residuals remain bound in these systems. The MNA component is proposed to contain and reduce the size of contaminated ground- water over time, with acceptable risk. Thus, using the same receptors and risk issues, incorporation of MNA into the PPI remedy promises to reduce signifi- cantly the cost of the remedy, without increasing eco- or human health risk. In a recent comparison, starting with the same source and endpoints, in the same time frame, MNA with limited hydraulic containment (a few source removal wells) was evaluated against active hydraulic containment and recovery (many pumping wells across the site) for the Scenic site of PPI. This assessment included monitoring and other costs associated with these technologies, and a 70% cost savings was found by incorporation of MNA into the remedy. This was due mainly to the reduced number of wells to be installed and the significant reduction in treatment of produced water. While this example case of remedy comparison has occurred during the remediation of PPI, it clearly shows that we have the tools of LCA, risk-based remediation, and MNA at our disposal. When properly integrated, one can provide acceptable waste management schemes prior to initiation of a manufacturing project or site remediation. However, as technology changes, as stated earlier, this assessment must be ongoing. REFERENCES 1. T. E. Graedel, Streamlined Life-Cycle Assessment, pp. 97–98. Englewood Cliffs, NJ: Prentice Hall, 1998. 2. P. C. Schulze (ed.), Measures of Environmental Performance and Ecosystem Condi- tion. Washington, DC: National Academy Press, 1999. 3. R. J. Walter, Practical Compliance with the EPA Risk Management Program. New York: Center for Chemical Process Safety of the AIChE, 1999. 4. R. M. Felder and R. W. Rousseau, Elementary Principles of Chemical Processes, pp. 81–86. New York: Wiley, 1978. 5. L. J. Thibodeaux, Chemodynamics: Environmental Movement of Chemicals in Air, Water and Soil. New York: Wiley, 1979. 6. B. Choy and D. D. Reible, Diffusion Models of Environmental Transport. Boca Raton, FL: Lewis Pub., CRC Press, 2000. 7. S. T. Hwang. J. Environ. Sci. Health, A, vol. A27, no. 3, pp. 843–861, 1992. 8. W. D. Constant, L. J. Thibodeaux, and A. R. Machen, Environmental Chemical Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. Engineering: Part I—Fluxion; Part II—Pathways. Trends Chem. Eng., vol. 2, pp. 525–542, 1994. 9. U.S. Environmental Protection Agency (EPA) Region VI Website, Information on Superfund sites, Louisiana, Petro Processors, Inc., http://www.epa.gov/earth1r6/ 6sf/6sf-la.htm. 10. Robert S. Kerr Environmental Research Center (U.S. EPA), Natural attenuation short course materials, Ada, OK, December 2–4, 1997. Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. 17 Risk-Based Pollution Control and Waste Minimization Concepts Gilbert J. Gonzales Los Alamos National Laboratory, Los Alamos, New Mexico and New Mexico State University, Las Cruces, New Mexico 1 INTRODUCTION Ecological risk assessment is defined as “the qualitative or quantitative appraisal of impact, potential or real, of one or more stressors (such as pollution) on flora, fauna, or the encompassing ecosystem.” The underlying principles behind risk reduction and integrated decision making that are detailed in U.S. Environmental Protection Agency (EPA) strategic initiatives and guiding principles include pollution prevention (1). Pollution control (PC) and waste minimization (WM) are probably the most effective means of reducing risk to humans and the environment from hazardous and radioactive waste. Pollution control can be defined as any activity that reduces the release to the environment of substances that can cause adverse effects to humans or other biological organisms. This includes pollution prevention and waste minimization. Waste minimization is defined as pollution prevention measures that reduce Resource Conservation and Recovery Act (RCRA) hazardous waste (2). Reduced risk is one benefit of these practices, and it results most directly from lower concentrations of contaminants entering the environment from both planned and accidental releases. Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. Although it is difficult to quantify the reductions in the release of contam- inants to the environment that have resulted from reductions in waste, the reductions have most assuredly reduced risk to humans and the environment posed by toxicants. Using examples from Los Alamos National Laboratory (LANL), we will discuss the interrelatedness of pollution prevention/waste min- imization with risk reduction and how risk assessment can be generally applied to the field of pollution prevention and waste minimization. While emphasis in this chapter is on “ecological risk assessment,” the concepts and principles can also be applied to human health risk assessment. For purposes of this chapter, distinction is not made between pollution prevention, waste minimization, re- cycling or other waste management techniques, and other related terms. Rather, emphasis is on source reduction, which includes any practice that reduces the amount of contaminant entering a waste stream or the environment. It is evident that the EPA’s hierarchy of general pollution prevention and waste minimization methods is implicitly related to risk reduction (2). The preferred method, source reduction, results in the greatest reduction in human and ecological risk from contaminants. Source reduction is followed in effectiveness by recycling, treatment, and disposal. While it is possible, depending on the technology used, that recycling and treatment may increase risk to worker health because of increases in contact handling of waste, the prioritized list (source reduction → recycling → treatment → disposal) generally results in a decrease in risk to the public and the environment as one progresses from the least preferred to the most preferred method. The reason for this is simple. The preferred method results in little, if any, release of contaminants into the environ- ment compared to the less preferred methods; with the less preferred methods, not only does the quantity of contaminants potentially released into the environ- ment increase, the potential to release them increases. With this premise, it is then important to realize the magnitude of risk reduction achieved by employing pollution prevention and waste minimization at facilities such as LANL. 2 SITE DESCRIPTION AND CHARACTERIZATION LANL is located in north-central New Mexico, approximately 60 miles northwest of Santa Fe (Figure 1). LANL is a U.S. Department of Energy-owned complex managed by the University of California that was founded in 1943 as part of the Manhattan Project to create the first nuclear weapon. Since then, LANL’s mission to design, develop, and test nuclear weapons has expanded to other areas of nuclear science and energy research. The Laboratory comprises dozens of individual technical areas located on 43 square miles of land area; about 1400 major buildings and other facilities are part of the Laboratory. The Laboratory is situated on the Pajarito Plateau, which consists of a series of fingerlike mesas separated by deep east-to-west–oriented Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. RIO ARRIBA COUNTY SANTA FE COUNTY 0 0.5 1 2 mi 0 0.5 1 2 km SANTA FE COUNTY SANDO- VAL CO. SANDOVAL COUNTY LOS ALAMOS COUNTY SANDOVAL COUNTY WHITE SANTA FE NATIONAL FOREST S A N T A F E N A T I O N A L F O R E S T BANDELIER NAT. MON. SAN ILDEFONSO PUEBLO LANDS Rio Grande ★ Taos Los Alamos Grants Albuquerque Socorro Las Cruces Santa Fe NEW MEXICO To Espanola To Santa Fe LOS ALAMOS COUNTY LOS ALAMOS COUNTY RIO ARRIBA COUNTY TAOS COUNTY SANDOVAL COUNTY SANTA FE COUNTY BERNALILLO COUNTY Tierra Amarilla Taos Los Alamos Santa Fe Bernalillo Albuquerque LOS ALAMOS COUNTY Pajarito R oad East Jemez Road Los Alamos National Laboratory Technical Area boundaries County boundaries Other political boundaries Major paved roads ROCK NM CO UT AZ TX OK cARTography by A. Kron 4/5/00 BANDELIER NATIONAL MONUMENT N 4 4 30 4 502 502 502 501 4 U. S. A. LOS ALAMOS FIGURE 1 Location of the Los Alamos National Laboratory. Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. canyons cut by intermittent streams (Figure 2). Mesa tops range in elevation from approximately 7800 ft on the flanks of the Jemez Mountains to about 6200 ft at their eastern termination above the Rio Grande. Researchers at Los Alamos work on initiatives related to the Laboratory’s central mission of enhancing global security as well as on basic research in a variety of disciplines related to advanced and nuclear materials research, devel- opment, and applications; experimental science and engineering; and theory, modeling, analysis, and computation. As a fully functional institution, LANL also engages in a number of related activities including waste management; infrastruc- ture and central services; facility maintenance and refurbishment; environmental, FIGURE 2 Overhead view of the topography in and around the Los Alamos National Laboratory. Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. ecological, cultural, and natural resource management; and environmental resto- ration, including decontamination and decommissioning. As result of the scien- tific and technical work conducted at Los Alamos, the Laboratory generates, treats, and stores hazardous, mixed, and radioactive wastes. About 2120 contaminant potential release sites (PRSs) have been identified at LANL. The LANL PRSs are diverse and include past material disposal areas (landfills), canyons, drain lines, firing sites, outfalls, and other random sites such as spill locations. Categorizing contaminants into three types—organics, metals, and radionuclides—Los Alamos has all three present. The contaminants include volatile and semivolatile organics, polychlorinated biphenyls (PCBs), asbestos, pesticides, herbicides, heavy metals, beryllium, radionuclides, petroleum prod- ucts, and high explosives (3). The primary mechanisms for potential contaminant release from the site is surface-water runoff carrying potentially contaminated sediments and soil erosion exposing buried contaminants. The main pathways by which released contaminants can reach off-site residents are through infiltration into alluvial aquifers, airborne dispersion of particulate matter, and sediment migration from surface-water runoff. Like many other sites, the predominant pathway by which contaminants enter terrestrial biological systems is the inges- tion of soil, intentional or not. Diverse topography, ecology, and other factors make the consideration of issues related to contamination in the LANL environment complex. “Since 1990, LANL’s environmental restoration project has conducted over 100 cleanups. The environmental restoration project has also decommissioned over 30 structures and conducted three RCRA closure actions during this period. Schedules have been published for the planned cleanup of approximately 700 to 750 additional sites. This schedule encompasses a period of about 10 years, beginning with fiscal year 1998. The number of cleanups per year varies from approximately 100 in fiscal year 2002 to 18 in fiscal year 2008. An important and integral part of this pollution prevention technology and of identifying interim protection measures is ecological risk assessment” (3). 3 POLLUTION PREVENTION AND WASTE MINIMIZATION AT LANL The pollution prevention program at the Laboratory has been successful in reducing overall LANL wastes requiring disposal by 30% over the last 5 years. The program is site wide but has facility-specific components, especially for the larger generators of radioactive and hazardous chemical wastes. Past reductions indicate that waste generation in the future should be less than that projected. The Site Pollution Prevention Plan for Los Alamos National Laboratory (4) describes the LANL Pollution Prevention and Waste Minimization Programs, including a general program description, recently implemented actions, specific volume Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. reductions resulting from recent actions, and current development/demonstration efforts that have not yet been implemented. More specifically, LANL has achieved reductions in the generation of hazardous waste, low-level radioactive waste (LLW), and mixed LLW. These and two other waste types are defined as follows: Hazardous waste—Any substance containing waste that is regulated by RCRA, the Toxic Substances Control Act, and New Mexico as a Special Waste. Low-level radioactive waste (LLW)—Radionuclide-containing substances with a radionuclide activity (sometimes referred to as concentration) of less than 100 nCi/g. Mixed LLW—Substances containing both RCRA constituents and LLW. Transuranic radioactive (TRU) waste—Radionuclide-containing substances with a radionuclide activity (concentration) equal to or greater than 100 nCi/g. Mixed TRU waste—Substances containing both RCRA and TRU waste. Estimated reduction rates of chronically generated waste, by waste type, over a 6-year period are (D. Wilburn, personal communication, 2000) Hazardous waste: 11%/yr (65% from 1993 to 1999) LLW: 11%/yr (67% from 1993 to 1999) Mixed LLW: 12%/yr (72% from 1993 to 1999) Production of TRU and mixed TRU waste combined has increased by an average of 38%/yr (228% from 1993 to 1999). The Laboratory has dozens of pollution prevention projects ongoing and planned. Some of the efforts are pollution prevention and waste minimization in the strictest sense and some (e.g., separation of waste types or satellite treatment followed by centralized treatment) are pollution control in the broadest sense, including efforts where cost savings is the primary goal and pollution control is a secondary benefit. Three examples of pollution control/waste minimization at LANL follow. Generator Set-Aside Fee-Funded (GSAF) Plutonium Ingot Storage Cubicle Project. “An aliquot casting and blending technique is under imple- mentation at LANLs Plutonium Facility. The aliquot process allows out-of-specification plutonium to be blended with other plutonium so that the final mixed batch meets specifications and is uniform. This avoids the cost and waste generation related to reprocessing out-of-specification plutonium ingots through the nitric acid line. In addition the more uniform product will reduce the reject rate and will avoid reprocessing and remanufacturing wastes. This project will fabricate a storage system Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved. [...]... when attempting to design holistic pollution control and waste minimization programs Indices of risk used to rank contaminants that are targeted for elimination or reduction by pollution control/ waste minimization techniques can be used effectively to reduce risk to flora and fauna REFERENCES 1 CENR (Committee on Environment and Natural Resources of the National Science and Technology Council), Ecological... concentration to dose, relating food intake to soil intake, and solving for COPC- and receptor-specific ESLs, models such as Eq (3) for omnivores were used to compute ESLs for nonradionuclides: ESLij = NOAELij Ii ⋅ (fsi + fpi ⋅ TFplant,j + fii ⋅ TFinvert,j (3) where ESLij is the soil ESL for omnivore i and COPC j (mg/kg) NOAELij is the NOAEL for omnivore i and COPC j (mg/kg/day) fsi is the fraction of soil... differently for each receptor The different approaches are required because of the different ways that toxicological experiments are performed for these organisms For plants, earthworms and other soil-dwelling invertebrates, effects are based on the concentration of a COPC in soil Therefore, ESL values are directly based on effects concentrations and modeling is not required For plants and invertebrates... contributions for Aroclor-1254 by discrete location Copyright 2002 by Marcel Dekker, Inc All Rights Reserved in arriving at a cost-effective and scientifically sound risk management framework for decision making that meets performance goals and is protective of the environment) Implementing pollution controls such as those listed above is no small task at a sprawling 43-mi2 industrial site, and costs... chronic NOAELs, and knowledge of transfer coefficients including bioconcentration and bioaccumulation factors Details on this information and on the process for calculating and selecting ESLs are documented in a LANL report (11); however a summary is provided here Nonradionuclides “Although soil ESLs are based on exposure of terrestrial receptors—plants, invertebrates (earthworms), and wildlife—they... normalized daily dietary ingestion rate for omnivore i (kg/kg/day) fpi is the fraction of plants in diet for omnivore i TFplant,j is a unitless transfer factor from soil to plants for COPC j fii is the fraction of invertebrates in diet for omnivore i TFinsect,j is a unitless transfer factor from soil to insects for COPC j For any given COPC, the soil ESL used for initial screening was often the lowest... federally protected threatened and endangered species (17–19) Risk assessments of the Mexican spotted owl (Strix occidentalis lucida), the American peregrine falcon (Falco peregrinus), the bald eagle (Haliaeetus leucocephalus), and the Southwestern willow flycatcher (Empidonax traillii extimus) were performed using a custom FORTRAN model, ECORSK.5, and the geographic information system (GIS) (17–19)... resulting from soil ingestion and food consumption were compared against TRVs for nonradionuclides and radiation dose limits for radionuclides This generated hazard indices (HIs) that included a measure of additive effects from multi- Copyright 2002 by Marcel Dekker, Inc All Rights Reserved ple contaminants (radionuclides, metals, and organic chemicals) and included bioaccumulation and biomagnification factors... Laboratory is a work in progress Methods for ecorisk screening and “tier 2” assessments have been in development and implementation since approximately 1993 Most screenings and assessments completed at the Laboratory thus far are based on the U.S EPA hazard quotient method, whereby hazard quotient values are calculated for receptors for each contaminant by area and may be thought of as a ratio of a receptor’s... practical consideration is the source type of a PC/WM candidate constituent, i.e., a point source versus diffuse Obviously, point-source contaminants are subject to PC/WM and diffuse sources typically are not For example, DDT and DDE rank high in terms of toxicity as measured by its safe limit, or ESL (Table 1), and as measured in potential risk to threatened and endangered species at Los Alamos (17); however, . are pollution control in the broadest sense, including efforts where cost savings is the primary goal and pollution control is a secondary benefit. Three examples of pollution control/ waste minimization. This includes pollution prevention and waste minimization. Waste minimization is defined as pollution prevention measures that reduce Resource Conservation and Recovery Act (RCRA) hazardous waste (2) prevention projects ongoing and planned. Some of the efforts are pollution prevention and waste minimization in the strictest sense and some (e.g., separation of waste types or satellite treatment followed