Organizational Image Repair Tactics and Crisis Type: Implications for Crisis Response Strategy Effectiveness

Existing models of organizational crisis response effectiveness provide useful insights but are limited in terms of offering a guide for practitioners dealing with actual crisis situations. This analysis examines the relative effectiveness of image repair tactics based on differences in root causes of crisis events. Results suggest that certain image repair tactics are seen as the most and the least effective regardless of crisis type. At the same time, there were some differences across crisis types that could guide practitioner tactic choices. Limited results here and in past research raise questions about whether image repair tactic effectiveness can be usefully mapped to situational variables, such as audience or crisis type. This article concludes with discussion on this matter and suggestions for future research

Endocytic reawakening of motility in jammed epithelia.

Dynamics of epithelial monolayers has recently been interpreted in terms of a jamming or rigidity transition. How cells control such phase transitions is, however, unknown. Here we show that RAB5A, a key endocytic protein, is sufficient to induce large-scale, coordinated motility over tens of cells, and ballistic motion in otherwise kinetically arrested monolayers. This is linked to increased traction forces and to the extension of cell protrusions, which align with local velocity. Molecularly, impairing endocytosis, macropinocytosis or increasing fluid efflux abrogates RAB5A-induced collective motility. A simple model based on mechanical junctional tension and an active cell reorientation mechanism for the velocity of self-propelled cells identifies regimes of monolayer dynamics that explain endocytic reawakening of locomotion in terms of a combination of large-scale directed migration and local unjamming. These changes in multicellular dynamics enable collectives to migrate under physical constraints and may be exploited by tumours for interstitial dissemination

Eps8 is recruited to lysosomes and subjected to chaperone-mediated autophagy in cancer cells

Eps8 controls actin dynamics directly through its barbed end capping and actin-bundling activity, and indirectly by regulating Rac-activation when engaged into a trimeric complex with Eps8-Abi1-Sos1. Recently, Eps8 has been associated with promotion of various solid malignancies, but neither its mechanisms of action nor its regulation in cancer cells have been elucidated. Here, we report a novel association of Eps8 with the late endosomal/lysosomal compartment, which is independent from actin polymerization and specifically occurs in cancer cells. Endogenous Eps8 localized to large vesicular lysosomal structures in metastatic pancreatic cancer cell lines, such as AsPC-1 and Capan-1 that display high Eps8 levels. Additionally, ectopic expression of Eps8 increased the size of lysosomes. Structure-function analysis revealed that the region encompassing the amino acids 184-535 of Eps8 was sufficient to mediate lysosomal recruitment. Notably, this fragment harbors two KFERQ-like motifs required for chaperone-mediated autophagy (CMA). Furthermore, Eps8 co-immunoprecipitated with Hsc70 and LAMP-2, which are key elements for the CMA degradative pathway. Consistently, in vitro, a significant fraction of Eps8 bound to (11.9±5.1%) and was incorporated into (5.3±6.5%) lysosomes. Additionally, Eps8 binding to lysosomes was competed by other known CMA-substrates. Fluorescence recovery after photobleaching revealed that Eps8 recruitment to the lysosomal membrane was highly dynamic. Collectively, these results indicate that Eps8 in certain human cancer cells specifically localizes to lysosomes, and is directed to CMA. These results open a new field for the investigation of how Eps8 is regulated and contributes to tumor promotion in human cancers

Sos-mediated activation of rac1 by p66shc

The Son of Sevenless 1 protein (sos1) is a guanine nucleotide exchange factor (GEF) for either the ras or rac1 GTPase. We show that p66shc, an adaptor protein that promotes oxidative stress, increases the rac1-specific GEF activity of sos1, resulting in rac1 activation. P66shc decreases sos1 bound to the growth factor receptor bound protein (grb2) and increases the formation of the sos1–eps8–e3b1 tricomplex. The NH2-terminal proline-rich collagen homology 2 (CH2) domain of p66shc associates with full-length grb2 in vitro via the COOH-terminal src homology 3 (C-SH3) domain of grb2. A proline-rich motif (PPLP) in the CH2 domain mediates this association. The CH2 domain competes with the proline-rich COOH-terminal region of sos1 for the C-SH3 domain of grb2. P66shc-induced dissociation of sos1 from grb2, formation of the sos1–eps8–e3b1 complex, rac1-specific GEF activity of sos1, rac1 activation, and oxidative stress are also mediated by the PPLP motif in the CH2 domain. This relationship between p66shc, grb2, and sos1 provides a novel mechanism for the activation of rac1

Propagating Cell-Membrane Waves Driven by Curved Activators of Actin Polymerization

Cells exhibit propagating membrane waves which involve the actin cytoskeleton. One type of such membranal waves are Circular Dorsal Ruffles (CDR) which are related to endocytosis and receptor internalization. Experimentally, CDRs have been associated with membrane bound activators of actin polymerization of concave shape. We present experimental evidence for the localization of convex membrane proteins in these structures, and their insensitivity to inhibition of myosin II contractility in immortalized mouse embryo fibroblasts cell cultures. These observations lead us to propose a theoretical model which explains the formation of these waves due to the interplay between complexes that contain activators of actin polymerization and membrane-bound curved proteins of both types of curvature (concave and convex). Our model predicts that the activity of both types of curved proteins is essential for sustaining propagating waves, which are abolished when one type of curved activator is removed. Within this model waves are initiated when the level of actin polymerization induced by the curved activators is higher than some threshold value, which allows the cell to control CDR formation. We demonstrate that the model can explain many features of CDRs, and give several testable predictions. This work demonstrates the importance of curved membrane proteins in organizing the actin cytoskeleton and cell shape

LIN7 regulates the filopodia and neurite promoting activity of IRSp53

The insulin receptor substrate protein of 53\u2005kDa (IRSp53) is critically involved in the formation of filopodia and neurites through mechanisms that have only in part been clarified. Here, we investigated the role of the small scaffold protein LIN7, an interactor of IRSp53. We found that formation of actin-filled protrusions in neuronal NSC34 cells and neurites in neuroblastoma N2A depends on motifs mediating the LIN7:IRSp53 association, as both the coexpression of LIN7 with IRSp53 or the expression of the L27-IRSp53 chimera (a fusion protein between IRSp53 and the LIN7L27 domain for plasma membrane protein complexes association) prevented actin-deficient protrusions induced by overexpressed IRSp53, and enhanced the formation of actin-filled protrusions. The regulatory role of LIN7 in IRSp53-mediated extension of filopodia was demonstrated by live-cell imaging experiments in neuronal N2A cells. Moreover, LIN7 silencing prevented the extension of filopodia and neurites, induced by ectopic expression of IRSp53 or serum starvation, respectively in undifferentiated and differentiated N2A cells. The expression of full length IRSp53 or the LIN7\u394PDZ mutant lacking the domain for association with IRSp53 was unable to restore neuritogenesis in LIN7 silenced cells. Conversely, defective neuritogenesis could be rescued by the expression of RNAi-resistant full length LIN7 or chimeric L27-IRSp53. Finally, LIN7 silencing prevented the recruitment of IRSp53 in Triton X-100 insoluble complexes, otherwise occurring in differentiated cells. Collectively these data indicate that LIN7 is a novel regulator of IRSp53, and that their association is required to promote the formation of actin-dependent filopodia and neurites

The Eps8/IRSp53/VASP Network Differentially Controls Actin Capping and Bundling in Filopodia Formation

There is a body of literature that describes the geometry and the physics of filopodia using either stochastic models or partial differential equations and elasticity and coarse-grained theory. Comparatively, there is a paucity of models focusing on the regulation of the network of proteins that control the formation of different actin structures. Using a combination of in-vivo and in-vitro experiments together with a system of ordinary differential equations, we focused on a small number of well-characterized, interacting molecules involved in actin-dependent filopodia formation: the actin remodeler Eps8, whose capping and bundling activities are a function of its ligands, Abi-1 and IRSp53, respectively; VASP and Capping Protein (CP), which exert antagonistic functions in controlling filament elongation. The model emphasizes the essential role of complexes that contain the membrane deforming protein IRSp53, in the process of filopodia initiation. This model accurately accounted for all observations, including a seemingly paradoxical result whereby genetic removal of Eps8 reduced filopodia in HeLa, but increased them in hippocampal neurons, and generated quantitative predictions, which were experimentally verified. The model further permitted us to explain how filopodia are generated in different cellular contexts, depending on the dynamic interaction established by Eps8, IRSp53 and VASP with actin filaments, thus revealing an unexpected plasticity of the signaling network that governs the multifunctional activities of its components in the formation of filopodia

Cell stretching activates an ATM mechano-transduction pathway that remodels cytoskeleton and chromatin

Ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) DNA damage response (DDR) kinases contain elastic domains. ATM also responds to reactive oxygen species (ROS) and ATR to nuclear mechanical stress. Mre11 mediates ATM activation following DNA damage; ATM mutations cause ataxia telangiectasia (A-T). Here, using in vivo imaging, electron microscopy, proteomic, and mechano-biology approaches, we study how ATM responds to mechanical stress. We report that cytoskeleton and ROS, but not Mre11, mediate ATM activation following cell deformation. ATM deficiency causes hyper-stiffness, stress fiber accumulation, Yes-associated protein (YAP) nuclear enrichment, plasma and nuclear membrane alterations during interstitial migration, and H3 hyper-methylation. ATM locates to the actin cytoskeleton and, following cytoskeleton stress, promotes phosphorylation of key cytoskeleton and chromatin regulators. Our data contribute to explain some clinical features of patients with A-T and pinpoint the existence of an integrated mechano-response in which ATM and ATR have distinct roles unrelated to their canonical DDR functions

Coordination of Membrane and Actin Cytoskeleton Dynamics during Filopodia Protrusion

Leading edge protrusion of migrating cells involves tightly coordinated changes in the plasma membrane and actin cytoskeleton. It remains unclear whether polymerizing actin filaments push and deform the membrane, or membrane deformation occurs independently and is subsequently stabilized by actin filaments. To address this question, we employed an ability of the membrane-binding I-BAR domain of IRSp53 to uncouple the membrane and actin dynamics and to induce filopodia in expressing cells. Using time-lapse imaging and electron microscopy of IRSp53-I-BAR-expressing B16F1 melanoma cells, we demonstrate that cells are not able to protrude or maintain durable long extensions without actin filaments in their interior, but I-BAR-dependent membrane deformation can create a small and transient space at filopodial tips that is subsequently filled with actin filaments. Moreover, the expressed I-BAR domain forms a submembranous coat that may structurally support these transient actin-free protrusions until they are further stabilized by the actin cytoskeleton. Actin filaments in the I-BAR-induced filopodia, in contrast to normal filopodia, do not have a uniform length, are less abundant, poorly bundled, and display erratic dynamics. Such unconventional structural organization and dynamics of actin in I-BAR-induced filopodia suggests that a typical bundle of parallel actin filaments is not necessary for generation and mechanical support of the highly asymmetric filopodial geometry. Together, our data suggest that actin filaments may not directly drive the protrusion, but only stabilize the space generated by the membrane deformation; yet, such stabilization is necessary for efficient protrusion

BENEFITS ACCRUING TO THE DOE COMPLEX ATTRIBUTABLE TO THE DISPOSAL OF OFF-SITE LOW-LEVEL WASTE AT THE NEVADA TEST SITE

ABSTRACT The Nevada Test Site (NTS) has been consistently identified in national U.S. Department of Energy (DOE) reports as playing a key role in the future disposal of low-level radioactive waste (LLW) originating from waste management, site remediation, and other programs of the DOE nuclear weapons complex. This key NTS role was confirmed by the December 10, 1999 Identification of Preferred Alternatives for the Department of Energy's Waste Management Program: Low-Level Waste and Mixed Low-Level Waste Disposal Sites. (1) The findings presented in this paper represent part of a larger effort to develop information to respond to stewardship issues that have been documented by DOE stakeholders in Nevada with regard to DOE LLW disposal at the NTS. The authors identify factors that affect DOE LLW disposal options and disposal costs, including both waste generator and disposal facility costs. Based on current, national DOE analyses, cost comparisons of disposal at the NTS vs. other operational DOE disposal sites are made, as well as comparisons of anticipated facility disposal limitations. The authors' present their preliminary estimates of significant historical and projected cost savings to the DOE Complex associated with LLW disposal at the NTS. The paper concludes with a discussion of the limitations of the current, DOE volumes-based cost estimates, and a discussion of the steps currently being taken in Nevada to perform waste-steam-specific analyses. FACTORS AFFECTING DISPOSAL OPTIONS AVAILABLE TO DOE LLW GENERATORS The primary factors governing LLW disposal options available to DOE LLW generators are the availability of on-site land for LLW disposal facilities, site-specific hydrogeologic constraints on on-site LLW disposal, applicable on-site regulatory compliance restrictions, and the limited availability and high cost of alternative, off-site commercial LLW disposal options. Limited On-site Land Availability. The availability of on-site land for disposal of LLW is a threshhold issue, which must be considered in evaluating the potential option of on-site disposal of LLW at DOE sites. Some DOE Complex sites are privately-owned (e.g. ETEC, RMI, General Atomics). In such cases, DOE has no land available on-site on which to dispose of LLW. The relatively small size of other, DOE-owned sites (e.g. Grand Junction Projects Office, ITRI, SNL/CA) also limits the availability of on-site disposal. The land available for LLW disposal at some of these small sites (e.g. ITRI, SNL/CA) is further limited by on-going requirements to support DOE missions, and the need for an adequate buffer zone (the smallest area required as controlled space for monitoring and for taking mitigative measures, as may be necessary) around disposal cells. The small size of these DOE Complex sites is also an indirect measure of two other, associated characteristics important to the suitability of a site for LLW disposal: • The size and proximity of potential populations at risk (larger sites exclude population growth from ext ensive areas and provide a larger buffer); and • The likelihood contaminants in down-gradient groundwater would appear in publicly-accessible water sources (off-site population centers near small sites would tend to be located in closer proximity to these sites). On-Site Hydrogeologic Constraints on Disposal. The siting of a LLW disposal facility is the first, and arguably the most important, step for ensuring the long-term isolation of the waste. Historically, DOE and commercial disposal facilities have relied on the site hydrogeological characteristics as the principal means to mitigate nuclide migration from disposal sites (i.e., dependence on natural isolation barriers). Therefore, site-specific hydrogeological characteristics are of primary concern in determining the suitability of DOE sites for on-site disposal. DOE Orders require that disposal sites have hydrological characteristics which will protect groundwater resources. In addition, the potential for floods, erosion, earthquakes, and volcanoes must be considered in site selection (see The hydrogeologic characteristics at several DOE generator sites restrict the suitability of these sites for on-site disposal of LLW (see On-Site Regulatory Compliance Restrictions (Land Use). Several DOE sites have been placed on the U.S. Environmental Protection Agency (EPA) National Priorities List (NPL), requiring environmental remediation consistent with the regulatory requirements of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). Fernald was placed on the NPL in 1989. The Records of Decision (RODs) for environmental remediation at Fernald (developed consistent with the requirements of CERCLA) include disposal of large volumes of LLW in an on-site disposal facility (OSDF). The OSDF represents Fernald's "balanced approach" to waste management. Fernald's OSDF will contain approximately 1.9 million cubic meters of soil and debris from site remediation. An estimated 83,591 cubic meters of LLW not meeting OSDF acceptance criteria is expected to be shipped off-site to the NTS for disposal. The waste acceptance criteria for the OSDF include concentration limits on specific radionuclides and WM'00 Conference, February 27 -March 2, 2000, Tucson, AZ chemicals, and prohibited items. The criteria were developed to protect the Great Miami Aquifer to EPA's maximum contaminant levels under the Safe Drinking Water Act for a period of 1,000 years. • Small site (90 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Fernald • Location near Great Miami River. • Location atop a major sole source aquifer (State of Ohio waiver required). • Disposal limited to low concentrations to protect aquifer to maximum contaminant levels (MCLs) for 1000 years. General Atomics • Small site (120 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Grand Junction Projects Office • Small site (56.4 acres). • Location on a river and adjacent to City of Grand Junction, Colorado. • On-site facility for limited volumes would likely not be cost-effective. Kansas City Plant • Small site (141 acres). • Location in an urban setting. • On-site facility for limited volumes would likely not be cost-effective. LRRI (ITRI) • Small site (135 acres). • Location on an Air Force Base. • High seismic activity (with potential for damaging event every 100 years). • On-site facility for limited volumes would likely not be cost-effective. LLNL • Major faults in the area (San Andreas, Hayward, Calaveras, and Greenville). • Local faults have the potential for damaging earthquakes. • Potential for slope instability in Site 300. Oak Ridge • Climate is humid and relatively high precipitation (53.75 inches/yr.). • Depth to groundwater is shallow (less than 20 feet in some areas). • Groundwater is discharged to the surface in some areas. • Above-ground "tumulus" facility is expensive and long-term disposal use questionable. Mound • Small site (306 acres). • Location within City of Miamisburg near residential populations. • Location within ½ mile of Great Miami River. • Location atop a major sole source aquifer (State of Ohio waiver required). Pantex Plant • On-site facility for limited volumes would likely not be cost-effective. RMI • Small site (60 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Rocky Flats • Relatively small (384 acres) secured area inside the buffer zone. • Proximity to large (2.1 million) population and growing residential areas. Sandia/CA • Relatively small site (413 acres). • No LLW anticipated to be generated in future. Sandia/NM • Location on an Air Force Base. • Four faults (including 2 capable of major seismic activity) cut across site. • High seismic activity (with potential for damaging event every 100 years). "In 1979, [DOE] adopted a policy of disposing of its LLW at its sites to ensure the availability of reliable disposal capacity for wastes generated by its defense production mission and to limit its potential legal liability for claims by or against commercial disposal facility operators." • The commercial facility must meet applicable Federal, State, and local requirements, and have the necessary permits, licenses, and approvals; • The facility, based on DOE review, must have an adequate history of operational and regulatory performance; • Disposal of these wastes at a commercial facility must be cost-effective and in the best interests of the Department; • The waste must be sufficiently characterized and verified to meet the facility's waste acceptance criteria; • Appropriate National Environmental Policy Act (NEPA) review must be completed; and • Host states and state compacts must be consulted before the exemption is approved. Based on the results of a recent policy analysis (4), DOE has decided to continue the policy under its new DOE Order 435.1, Radioactive Waste Management, which replaced DOE Order 5820.2A effective September 1, 1999. Available options for commercial disposal of DOE LLW are currently both limited and expensive (compared to DOE disposal facility costs) for all but the lowest-activity LLW. Most DOE LLW sent to commercial facilities under the current policy has been disposed at the Envirocare facility near Clive, Utah. Envirocare is the only commercial LLW disposal facility to have opened since the Low-Level Radioactive Waste Policy Act (LLWPA) was enacted in 1980. The Envirocare facility is not a "compact facility" (as defined by 42 U.S.C. § § 2021(b)-2021(j) of the LLWPA). Hence, it can accept LLW from sites throughout the country. However, disposal at Envirocare is limited to very low-activity, NRC Class A waste. The site cannot accept LLW containing special nuclear materials in quantities sufficient to form a critical mass, as defined by 10 CFR §150.11. Large quantities of DOE LLW would not meet these restrictions. The DOE waste shipped to Envirocare has, in general, been of very low activity. In fact, most of the DOE waste disposed at Envirocare has been Section 11(e)(2) byproduct material generated during cleanups undertaken pursuant to the Formerly Utilized Sites Remedial Action Program (FUSRAP). These wastes are of such low activity that they are generally excluded from both the NRC and DOE definitions of LLW. DOE contracts with Envirocare for disposal of these low-activity wastes have experienced charges ranging from $170 -$600 per cubic meter of waste. Only two commercial LLW disposal facilities are currently licensed by the NRC to accept LLW classified as greater than NRC Class A: the facility operated by U.S. Ecology at Richland, Washington (U.S. Ecology facility) and the facility operated by Chem-Nuclear, LLC, at Barnwell, South Carolina (Barnwell facility). Only the Barnwell facility accepts LLW from generators outside of a regional compact. The U.S. Ecology facility is a "compact facility" which serves the Northwest and the Rocky Mountain Compacts. As a compact facility, the State of Washington and the Northwest Compact must approve the disposal of DOE waste at the facility. (6) The State of Washington has made approval of disposal of DOE LLW at the facility subject to certain conditions. Among the conditions are: 1) that only waste from DOE's Hanford site could be disposed at the facility; and 2) that U.S. Ecology must establish that disposal of the Hanford waste at the facility "would result in cost savings when compared to available disposal options." (7) According to available information, U.S. Ecology charges between $1,000 and$3,000 per cubic meter for the disposal of LLW. A comparison of LLW disposal cost WM'00 Conference, February 27 -March 2, 2000, Tucson, AZ ranges at commercial and DOE WM disposal sites is provided in FACTORS WHICH AFFECT THE COST OF DISPOSAL OF LLW AT DOE WM DISPOSAL SITES Within the DOE Complex, DOE maintains operational Waste Management (WM) facilities for disposal of LLW at six DOE sites: the NTS, Hanford Site, Idaho National Engineering and Environmental Laboratory (INEEL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and Savannah River Site (SRS). Three of these sites (INEEL, LANL, and ORNL) almost exclusively dispose of on-site generated LLW. Of the remaining three sites, Hanford and Savannah River have primarily accepted on-site generated waste for disposal, although they have the capability to accept off-site LLW if the waste meets site-specific acceptance criteria (stringent for Savannah River -see In addition, DOE's Environmental Restoration (ER) program operates CERCLA -regulated LLW disposal facilities at certain sites. These CERCLA facilities are limited to disposal of wastes generated from on-site environmental restoration activities, which meet facility-specific acceptance requirements. At present, there are two of these cells in operation --one at Hanford (the ERDF) and the other at Fernald (the OSDF). Two additional DOE CERCLA disposal cells dispose of waste other than LLW. These cells (at the Weldon Spring Site in Missouri and the Monticello Site in Utah) are used for disposal of Section 11(e)(2) byproduct material generated by on-site cleanup WM'00 Conference, February 27 -March 2, 2000, Tucson, AZ activities pursuant to FUSRAP. DOE is considering construction of two additional CERCLA disposal cells (at INEEL and Oak Ridge); a decision as to whether to build these cells will be made pursuant to the CERCLA process. The total cost to DOE for LLW disposal at the various DOE LLW disposal sites is affected by several factors, including the availability of disposal facility volumetric capacity and potential for expansion, the cost to operate and maintain a facility, and the cost incurred by generators to prepare and ship LLW for disposal at a facility. DOE's July 1997 Low-Level Waste Disposal Cost Comparison Report (1997 Cost Comparison Report) Only three of the WM disposal facilities (NTS, Hanford, and Savannah River) currently accept substantial amounts of LLW for disposal from off-site generators. The facilities at INEEL and ORNL are very limited in their expansion capability, and accept only on-site generated waste. At LANL, the expansion capacity is limited by the size of the mesa upon which it is located. The available expansion capacity at LANL is dedicated to supporting the LLW disposal needs of the on-site Defense Programs and National Laboratory missions. At Savannah River, the site hydrogeology permits the use of slit trenches only for slightly contaminated soil, rubble, and oversized equipment/packages. The use of engineered vaults allows disposal of a wide range of radionuclides. However, this is a much more costly method of disposal, and facility expansion costs would be much higher than for slit trench disposal. Both the NTS and Hanford have the expansion capacity and capability to dispose of large volumes of LLW with a wide range of radionuclides. Table IV provides a summary of the DOE-estimated expansion capacity at the six DOE LLW disposal facilities, and important factors restricting use of that capacity. 3 out of the total 3,572,030 m 3 of LLW projected to be disposed at Hanford over the next twenty years is anticipated to come from off-site generators. This represents less than 1 % of the total LLW projected to be disposed at Hanford during that period. Facility Disposal Costs. The DOE 1997 Cost Comparison Report found that the costs to operate and maintain a LLW disposal facility are comprised of both fixed costs and variable costs: • Fixed costs are loosely defined as those costs that are independent of waste volumes disposed. Fixed costs are recurring costs that do not vary with the rate of waste disposal activities, "such as labor and material costs to maintain the capability to receive and dispose of the first cubic meter of LLW. Examples of fixed costs are permitting, monitoring, training, and program management." • Variable costs are defined as those costs that are incurred relative to the amount of waste disposed, "such as labor, materials, and contract costs, above and beyond fixed costs necessary to dispose of LLW." The variable factor having a key impact on a facility's cost of disposal is presumed to be the volume disposed. Variable costs are considered to increase or decrease as the volume of LLW disposed increases or decreases. "Most disposal operations, maintenance, and trench development costs are a function of volume disposed and are, therefore, variable costs. For example, if each trench has a capacity of 10,000 m 3 and the facility disposes of 20,000 m 3 one year and 10,000 m 3 the next year, the facility will incur the cost of the development of two trenches the first year and the cost of one trench in the second year." The authors of this paper propose that variable costs are also highly dependent on the characteristics of the wastes being disposed, as is reflected in commercial disposal pricing schedules. The 1997 Cost Comparison Report analyzes the total disposal costs (fixed and variable) for each DOE WM facility for the years FY 1996 -FY 1998. Facility unit disposal costs are calculated by dividing the annual disposal costs by the annual volumes disposed (or anticipated to be disposed) at each facility. The 1997 Cost Comparison Report did not investigate cost impacts attributable to waste characteristics. A summary of the historical FY 1997 disposal facility unit costs is provided by Table V. • Waste Documentation for, and Acceptance or Certification by, Disposal Facilities. These activities include "verification/characterization when required for dis posal such as monitoring or assays for radioactivity, RCRA compliance sampling and analysis, visual container inspections, weight, dose rate, truck survey and vehicle release survey.&quot