Worst Case Conditions

The documented occurrence of pesticides in surface water is indicative that mnoff is an important pathway for transport of pesticide away from the site of appHcation. An estimated 160 t of atra2ine, 71 t of sima2ine, 56 t of metolachlor, and 18 t of alachlor enter the Gulf of Mexico from the Mississippi River annually as the result of mnoff (47). Field appHcation of pesticides inevitably leads to pesticide contamination of surface mnoff water unless mnoff does not occur while pesticide residues remain on the surface of the soil. The amount of pesticides transported in a field in mnoff varies from site to site. It is controUed by the timing of mnoff events, pesticide formulation, physical—chemical properties of the pesticide, and properties of the soil surface (48). Under worst-case conditions, 10% or more of the appHed pesticide can leave the edge of the field where it was appHed. 

Shaded boxes indicate worst case conditions)... 

Tables 9 and 10 give the maximum ground level concentrations expected for worst case conditions for the 3-min. and 5-min. venting rates, respectively worst case conditions were obtained from Tables 7 and 8 (i.e., values were calculated based on the largest concentration found in Tables 7 and 8 for each distance within a stability class).

The modified FMEA approach evaluates each piece of equipment (not each device) as an independent unit, assuming worst case conditions of input and output. Separators, flowlines, heaters, compressors, etc., function in the same manner no matter the specific design of the facility. That... 

The design of the system must take into account possible variation of critical control parameters that could affect performance. The maximum performance of the process should be defined by a reasonable safety margin. In order to comply with cGMP guidelines, established validation protocols, and parameters should allow the process to achieve reproducible purity and yield under stressed conditions. This implies that the industrial SMB system must be stressed to simulate worst-case conditions for process validation. 

Specific heat of liquid, BTU/lb — °F = Height of liquid (static) above ( + ) or below ( —) the centerline of the pump on discharge side, ft = Incremental height of liquid (static) above normal D level, to establish worst case condition, ft Figure 3-38... 

A sterilization process may thus be developed without a full microbiological background to the product, instead being based on the ability to deal with a worst case condition. This is indeed the situation for official sterilization methods which must be capable of general application, and modem pharmacopoeial recommendations are derived firm a careful analysis of experimental data on bacterial spore survival following treatments with heat, ionizing radiation or gas. 

It is assumed that the moisture content of the soil has been determined to be approximately 50% under worst-case conditions. Using this information and the results from vendor tests, it has been determined that a minimum dose of one part solidification reagent to two parts soil is required for the migration control of lead. Testing has shown that the optimum solidification reagent mixture would comprise ca. 50% fly ash and ca. 50% kiln dust. Thus, ca. 7000 t (6364 T) each of fly ash and cement kiln dust would be required. The reagents would be added in situ with a backhoe. As one area of the soil is fixed, the equipment could be moved onto the fixed soil to blend the next section. It may be anticipated that the soil volume would expand by ca. 20% as a result of the fixation process. This additional volume would be used to achieve the required slope for the cap. An RCRA soil/clay cap placed over the solidified material is necessary to prevent infiltration and additional hydraulic stress on the fixed soil. It is estimated that the fixation would reduce lead migration by 40% and that the fixed soil may pass the U.S. EPA levels for lead. 

The EPA RMP regulation and the European Community s Seveso II directive both exempt covered processes from some regulatory provisions, if the facility documents the absence of catastrophic damage from process accidents under reasonable worst case conditions. The State of New Jersey is also considering similar action in its proposed revisions of the Toxic Catastrophe Prevention Act (TCPA) regulations. 

When extrapolating accelerated test results it is generally necessary to refer to typical, average or worst case conditions, unless the intended application is very specific. 

It is possible to assume that the worst case conditions will prevail at all times, but this will probably lead to an unrealistically short lifetime. For example, the design temperature can be taken as the maximum. 

The committee notes that the analysis of the cell membrane failure that occurred in the 500-hour DMMP (discussed in the next section) suggests that the cell membrane tests did not represent worst-case conditions for membrane life under actual operating conditions and that limited credence can be given to the conclusions from this test (AEA, 2001k). It also notes that in the absence of organics, parasitic oxidation of water may offset the Ag2+ attacks that were anticipated in this test. 

The conditions with the worst response value can be derived from the estimated effects. The worst-case situation is that combination of factor levels resulting in the worst result, e.g., the lowest resolution. The worst-case conditions are set using only the effects significant at... 

A second possibility consists of experimentally determining the SST limits from measurements at the worst-case conditions (n measurements with standard deviation 9,12,13 gg-p limit is defined as the lower or upper limit of the one-sided 95% confidence interval around the worst-case average result. For example, for resolution, the lower limit will be considered, while for migration time it would be the upper. The confidence intervals are defined as in Equations (16) and (17), when considering the lower or the upper limit, respectively. 

TABLE 12 Results at Worst-Case Conditions to Estimate the SST Limit for the Response MTs-t (min) of Tables 9 and 11... 

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