 1 5/ 07/ 97 REVISED INTERIM WTI METALS LIMITS REFLECTING THE DETAILED RISK ASSESSMENT ( corrected version)

A. METHOD OF ESTABLISHING LIMITS The risk assessment looked at two different routes of exposure: direct exposure ( i. e., inhalation), and indirect exposure ( i. e., exposure such as might occur through food chain uptake). Both of these involve the study of long term " chronic" effects, but indirect exposure tends to be a longer term effect than direct exposure.

Even though the type of chronic effects evaluated when looking at direct exposure are associated with long term exposure to air contaminants, the EPA has historically protected communities from direct exposure to emissions from hazardous waste combustion facilities by conservatively setting maximum hourly ( i. e., relatively short term) limits on the emissions of the toxic and carcinogenic metals. Part of the reason for doing this is to help ensure that there will be no short term, or " acute," effects from fluctuations in the normal emissions.

Indirect exposure routes, on the other hand, are generally associated with the slow buildup of contaminants in the soil and plants. Because of this, it is quite possible that a particular hourly emission rate might be quite safe from the standpoint of direct route exposure, but that continuous emission at this same rate over several years might eventually create an unacceptable indirect route exposure. Because of this, both hourly and annual limits might be appropriate in some cases. In this exercise, hourly limits will be established, and the need for annual limits will be evaluated for each metal.

In this exercise, hourly limits will be calculated as prescribed in the BIF Rule at 40 CFR 266.106, using the most appropriate reference air concentrations (" RACs") and risk specific doses (" RSDs"). Potential annual limits will also be calculated. In most cases, this will be done by taking the annual emissions assumed in the " Maximum Permit Limit Emission" scenarios of the risk assessment, and reducing those annual values linearly as necessary to bring the resulting hazard index (" HI") down to 1.0 for ecological effects and 0.25 for human health effects. For example, if a maximum emission of a particular metal was hypothetically assumed to be 1000 lbs/ yr, and the resulting human health HI from that emission was found to be 0.75, this exercise would conclude that the annual emission would need to be reduced by a factor of 3, resulting in an annual emission limit of 333 lbs.  2 Table 1 summarizes the HI values calculated in the WTI risk assessment for the " Maximum Permit Limit Emission" scenarios, and the suggested annual reduction factors. Table 2 summarizes various emission data and converts these suggested annual reduction factors into suggested annual emission limits.

The HI values shown in Table 1 represent the total HI from both the direct routes and indirect routes of exposure, excerpted from the WTI risk assessment. The HI information in the risk assessment was not presented in such a way as to specify what fraction of the total HI value was a result of direct routes and what fraction was a result of indirect routes, we have concluded that restricting emission per the technique contained in the BIF Rule ( but using the more conservative RACs used the risk assessment) should properly address inhalation exposure ( because the BIF Rule calculations are essentially a direct inhalation route risk assessment), and that restricting annual emissions ( where warranted) based on total HI as described above should ensure that indirect routes are also properly addressed.

Because the BIF Rule prescribes that metals feed rates, as opposed to emission rates, be set in RCRA permits, it is anticipated that the following analysis will largely be used to establish feed limits. However, the emission limit information can be used for setting emission limits should continuous in stack monitoring be judged appropriate for verifying compliance. At the time of this writing, WTI has applied for a permit modification to install and operate a continuous emission monitor which would capture a sample stream of combustion gas from the stack and automatically analyze the stream for all regulated metals via ICP.

In this exercise, emissions and feed rates are routinely given both in units of pounds per hour (" lbs/ hr") and grams per second (" g/ sec"). However, because the BIF Rule of 40 CFR 266.106 prescribes that metals feed limits should normally be established on a 60 minute rolling average basis or equivalent, it should be noted that any values given in g/ sec should actually be implemented as a lb/ hr value on a 60 minute rolling average basis ( or similar as deemed appropriate) and not on a minute by minute or second by second basis.

B. ESTIMATION OF SYSTEM REMOVAL EFFICIENCIES (" SREs") FOR METALS:

The following is the approach that Region 5 and the Ohio EPA have developed regarding the setting certain INTERIM metals feed limits for WTI, should the State of Ohio decide to renew the RCRA permit.

1. When evaluating the impacts of metals emissions, the WTI risk assessment evaluated two different metals emission scenarios: ( 1) estimated actual emissions, aThe thermodynamic modeling was also used to evaluate whether SREs might be predicted to diminish at the significantly lower feed rates assumed in the " estimated actual emissions" scenario. EPA felt this was an important issue in light of the common finding that SREs are frequently lower at lower metal feed rates This investigation concluded that within the ranges of feed rates evaluated, no significant decreases in SRE were predicted.

bIt should be noted that, in this exercise and in the risk assessment, the BIF allowable was calculated using a new, lower, dispersion factor ( DF) developed as part of the risk assessment. Because this new DF is lower than the one used to set the present permit limits, the risk assessment actually assumed higher than present emission limits.

 3 and ( 2) full maximum permit limit emissions ( for 8760 hours of operation per year). The first emission scenario used estimates of actual emissions, considering the profiles and projected quantities of wastes expected to be received at WTI, along with measured SREs ( for metals tested during the trial burn) and estimated SREs ( for metals not tested during the trial burn). The estimated SREs were conservatively developed based on detailed thermodynamic modelinga of the combustion train, and included comparisons of SRE predictions to the known SREs from the trial burn. In this way, SREs were estimated for barium, silver, thallium, nickel, and selenium. Details of the modeling are contained in Volume III of the WTI risk assessment.

The second emission scenario, maximum permit limit emissions, was evaluated in order to determine whether additional permit conditions might be appropriate. It is not expected that WTI would ever emit at these rates. This exercise assumed that all " adjusted tier 1" metals were emitted at full BIF allowableb, and that all " tier 3" metals were emitted at the emission rates actually recorded during the trial burn ( i. e., the high temperature metals runs). Again, this maximum permit limit scenario projected these emissions out to 8760 hours per year operation.

It was understood from the beginning that using this technique would project artificially high hazard indices and/ or risks when plugged into the risk assessment, but it was decided that it was more appropriate to generate these high HI values and then adjust emission limits downward rather than using the alternate technique of calculating more realistic emissions and hazard indices, and then setting emission limits by adjusting these upward.

2. For the permit limit emissions scenario, the risk assessment has demonstrated that the artificially high " adjusted tier 1" emission rates for Ba, Ag, Tl, Ni, and Se, because they assume absolutely no SRE, would result in projected impacts where hazard indices could range as high as 4250 ( See Table 1). Although these are not real emissions, Region 5 and Ohio EPA presently believe it is appropriate to use cLimits being considered would be set depending on whether the HI exceedance is due to direct, indirect, or ecological exposure. A high HI associated with a direct exposure would result in reduced hourly emission rates, and a high HI associated with an indirect or ecological effect would result in annual limits being imposed in addition to hourly limit ( e. g., " Emissions shall be restricted to no more than 2 lb/ hr and no more than 500 lb/ yr"). Rather that generating separate HI values for direct and indirect routes, direct routes will be addressed in this exercise via " BIF Rule calculations" and indirect routes will be addressed by using the " total" HI values given in the risk assessment.

 4 this information to calculate emission/ feedc restrictions such that no metal emission would result in a HI greater than 0.25 for human health effects, or 1.0 for ecological effects, per USEPA guidelines. Because there has been no trial burn to establish SREs for these metals, a typical approach would be to simply assume that all Ba, Ag, Tl, Ni, and Se fed to the incinerator will be emitted out the stack. However, such an approach would require that extremely low feed limits be imposed in this case.

3. Because of the extensive thermodynamic modeling conducted in this case, Region 5 and Ohio developed the following interim approach to be used in the permits until a new metals trial burn can be conducted ( perhaps 1 year) to establish actual SREs for Ba, Ag, Tl, Se, and Ni, at appropriate feed rates:

a. For Ba, Ag, Ni, and Tl, apply a safety factor of 10 to the conservative SREs developed via thermodynamic modeling in the WTI risk assessment for these four metals. Thus, a safety factor of 10 would be applied to the SRE of 99.977% estimated for these metals in the risk assessment, resulting in a very conservative interim SRE of 99.77%. Note that the risk assessment SRE value was largely based on the measured SRE for arsenic ( the lowest demonstrated SRE for any metal in its category, and one of the lowest feed rate metals during the trial burn) after mechanistic comparisons to Ba, Ag, Ni, and Tl.

Additional information relative to this issue was collected during a 1996 performance test. Nickel SREs were evaluated during three of the four runs. SREs demonstrated during two runs, with nickel feed rates of 3.3 and 14.8 lbs/ hr, were 99.96 % and 99.997 %, respectively. These feed rates are considered to be typical. During a third test run, feed rates were reduced 4 orders of magnitude to .003 lb/ hr, and the SRE fell, as would be expected. During this low feed run, the SRE was approximately 72 %.

b. For Se, the SRE predicted by the thermodynamic modeling was 99.7%, based on comparison to SO2 ( determined in the modeling to be a good surrogate for Se because it is a similarly volatile compound which forms a  5 water soluble vapor). However, the peer review pointed out a potential weakness in using SO2 as a surrogate for selenium, and we recognize that subsequent stack testing for selenium would help validate this estimate.

Stack testing for Se was later conducted during the four run 1996 performance test, and that testing demonstrated the following:

SRE = 99.5 % @ 26.6 lb/ hr Se feed SRE = 99.994 % @ 0.32 lb/ hr Se feed SRE = 99.9998 % @ 21.3 lb/ hr Se feed SRE = 99.5 % @ 31.6 lb/ hr Se feed Although there was a lot of variation in the results, the results do seem to validate the assumption used in the risk assessment. The average of these four runs was 99.75, which tends to match the model results. Even though this testing was not an official trial burn, we believe this combined data can be used on an interim basis until a subsequent selenium trial burn can be conducted. The suggested interim SRE for selenium would be 99.7 %.

c. At the present time, mercury will continue to be handled as an " adjusted tier 1" metal, i. e., it will be assumed that there is no SRE. This is discussed further below.

C. CALCULATION OF LIMITS FOR INDIVIDUAL METALS:

Barium:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed. In most cases, only the maximum hourly metals feed limit will need to be set in the permit. Annual limits might be necessary in some cases if the risk assessment predicted greater problems with indirect exposure than with direct exposure.

1) Maximum Hourly Emissions of Barium:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. Although the BIF Rule prescribes an RAC for Barium of 50 µ g/ m3, the USEPA risk assessment concluded that a better RAC value based on more recent data would be 0.13 µ g/ m3. A summary chart comparing the RACs and risk specific doses (" RSDs") of the BIF Rule to the RACs and RSDs used in the risk assessment is attached as Table 3. dSee USEPA Risk Assessment Volume I, Chapter IV, Table IV 3.

ePenetration is defined as ( 1  removal efficiency). In this case, the penetration would be calculated as ( 1  0.9977) = .0023.

 6 The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ secd. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 0.13 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 0.143 g/ sec (= 1.13 lb/ hr)

2) Maximum Hourly Feed Rate of Barium:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which would conservatively be expected to result in an emission of 0.143 g/ sec or less can be estimated as described earlier. From the analysis contained in Section B of this document, the interim SRE estimated for Barium would be 99.77%, which is the same as a penetratione of .0023. Per the BIF Rule, feed rates are generally to be calculated and implemented as hourly rolling averages. Feed rate would be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 0.143 g/ sec) / (. 0023)

= 62.2 g/ sec (= 473 lb/ hr)  7 3) Annual Maximum Emission Rate of Barium In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 682 lbs/ yr 4) Interim Annual Maximum Feed Rate of Barium Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which results in an emission of 682 lbs/ yr or less can be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 682 lbs/ yr ) / (. 0023)

= 296,000 lbs/ yr Mercury:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Mercury:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. Although the BIF Rule prescribes an RAC for Mercury of .08 µ g/ m3, the USEPA risk assessment concluded that a better value based on more recent data would be .075 µ g/ m3.  8 The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From these, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 0.075 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= .0824 g/ sec (= 0.65 lb/ hr)

2) Maximum Hourly Feed Rate of Mercury:

During the 1993 trial burn, WTI demonstrated virtually no SRE for mercury. More recent test data has demonstrated that WTI can achieve a mercury SRE of approximately 95%. However, at the time of this writing, the U. S. EPA and the Ohio EPA have not made a final decision as to whether the quantity and quality of new test data is sufficient to allow WTI to use this new demonstrated SRE value. Therefore, the very conservative assumption is made in this analysis that all mercury fed to the incinerator is emitted out the stack. If and when subsequent data is judged sufficient to allow a higher SRE in these calculations, the U. S. EPA and/ or Ohio EPA will make the appropriate changes in the feed limits.

Maximum Feed Rate = Maximum Emission Rate = .0824 g/ sec ( = 0.65 lb/ hr)

3) Annual Maximum Emission Rate of Mercury In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 355 lbs/ yr  9 4) Interim Annual Maximum Feed Rate of Mercury:

Because a new mercury SRE has not been approved as of this writing, the very conservative assumption is made here that all mercury fed to the incinerator is emitted out the stack.

Maximum Annual Feed Rate = Maximum Annual Emission Rate = 355 lbs/ yr Silver:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Silver:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. The BIF Rule prescribes an RAC for silver of 3 µ g/ m3 ( note that the USEPA risk assessment used a more current RAC value of 4.4 µ g/ m3 based on more recent data, but for the purposes of this analysis, the more conservative BIF value will be used). A summary chart comparing the RACs and risk specific doses (" RSDs") of the BIF Rule to the RACs and RSDs used in the risk assessment is attached as Table 3.

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 3.0 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 3.3 g/ sec ( = 26 lb/ hr)  10 2) Maximum Hourly Feed Rate of Silver:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which would conservatively be expected to result in an emission of 3.3 g/ sec or less can be estimated as described earlier. From the analysis contained in Section B of this document, the interim SRE estimated for silver would be 99.77%, which is the same as a penetration of .0023. Per the BIF Rule, feed rates are generally to be calculated and implemented as hourly rolling averages. Feed rate would be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 3.3 g/ sec) / (. 0023)

= 1435 g/ sec ( = 11,370 lb/ hr)

3) Annual Maximum Emission Rate of Silver In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 954 lbs/ yr 4) Interim Annual Maximum Feed Rate of Silver Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which results in an emission of 954 lbs/ yr or less can be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)  11 Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 954 lbs/ yr ) / (. 0023)

= 415,000 lbs/ yr Thallium:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Thallium:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. Although the BIF Rule prescribes an RAC for thallium of 0.50 µ g/ m3, the USEPA risk assessment concluded that a better RAC value based on more recent data would be 0.061 µ g/ m3. A summary chart comparing the RACs and risk specific doses (" RSDs") of the BIF Rule to the RACs and RSDs used in the risk assessment is attached as Table 3.

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 0.061 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= .067 g/ sec (= 0.53 lb/ hr)  12 2) Maximum Hourly Feed Rate of Thallium:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which would conservatively be expected to result in an emission of .067 g/ sec or less can be estimated as described earlier. From the analysis contained in Section B of this document, the interim SRE estimated for thallium would be 99.77%, which is the same as a penetration of .0023. Per the BIF Rule, feed rates are generally to be calculated and implemented as hourly rolling averages. Feed rate would be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = (. 067 g/ sec) / (. 0023)

= 29.1 g/ sec (= 231 lb/ hr)

3) Annual Maximum Emission Rate of Thallium:

In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 6.6 lbs/ yr 4) Interim Annual Maximum Feed Rate of Thallium:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which results in an emission of 6.6 lbs/ yr or less can be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)  13 Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 6.6 lbs/ yr ) / (. 0023)

= 2870 lbs/ yr Nickel:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Nickel:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. Although the BIF Rule prescribes an RAC for nickel of 20 µ g/ m3, the USEPA risk assessment concluded that a better RAC value based on more recent data would be 18 µ g/ m3.

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 18 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 19.8 g/ sec (= 156 lb/ hr)  14 2) Maximum Hourly Feed Rate of Nickel:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which would conservatively be expected to result in an emission of 19.8 g/ sec or less can be estimated as described earlier. From the analysis contained in Section B of this document, the interim SRE estimated for nickel would be 99.77%, which is the same as a penetration of .0023. Per the BIF Rule, feed rates are generally to be calculated and implemented as hourly rolling averages. Feed rate would be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 19.8 g/ sec) / (. 0023)

= 8610 g/ sec ( = 68,260 lb/ hr)

3) Annual Maximum Emission Rate of Nickel:

In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 4170 lbs/ yr 4) Interim Annual Maximum Feed Rate of Nickel:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which results in an emission of 4170 lbs/ yr or less can be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)  15 Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 4170 lbs/ yr ) / (. 0023)

= 1.8 E+ 6 lbs/ yr Selenium:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Selenium:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. The BIF Rule prescribes an RAC for selenium of 4.0 µ g/ m3 ( note that the USEPA risk assessment used a more current RAC value of 4.4 µ g/ m3 based on more recent data, but for the purposes of this analysis, the more conservative BIF value will be used).

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 4.0 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 4.4 g/ sec (= 34.9 lb/ hr)  16 2) Maximum Hourly Feed Rate of Selenium:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which would conservatively be expected to result in an emission of 4.4 g/ sec or less can be estimated as described earlier. From the analysis contained in Section B of this document, the interim SRE estimated for selenium would be 99.7%, which is the same as a penetration of .003. Per the BIF Rule, feed rates are generally to be calculated and implemented as hourly rolling averages. Feed rate would be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)

Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 4.4 g/ sec) / (. 005)

= 1467 g/ sec ( = 11,630 lb/ hr)

3) Annual Maximum Emission Rate of Selenium:

In addition to hourly maximum metal emission/ feed limits, annual emission limits might be warranted. From attached Table 2, the maximum annual emission rate has been calculated as:

Suggested Annual Emission Limit = ( Max Permit Limit Emission) / ( Suggested Reduction)

Suggested Annual Emission Limit = 102 lbs/ yr 4) Interim Annual Maximum Feed Rate of Selenium:

Until further testing can be performed to precisely establish the system removal efficiency for this metal, an interim feed rate which results in an emission of 102 lbs/ yr or less can be calculated as follows:

( Feed Rate) X ( Penetration) = ( Emission Rate)

( Feed Rate) = ( Emission Rate) / ( Penetration)  17 Maximum Feed Rate = ( Maximum Emission Rate) / ( Penetration)

Maximum Feed Rate = ( 102 lbs/ yr ) / (. 003)

= 3.4 E+ 4 lbs/ yr Antimony:

For each metal, limiting values should be evaluated for ( 1) maximum hourly emissions, ( 2) maximum hourly metal feed, ( 3) maximum annual emissions, and ( 4) maximum annual metal feed.

1) Maximum Hourly Emissions of Antimony:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. The BIF Rule prescribes an RAC for antimony of 0.30 µ g/ m3 ( note that the USEPA risk assessment used a more current RAC value of .35 µ g/ m3 based on more recent data, but for the purposes of this analysis, the more conservative BIF value of 0.30 µ g/ m3 will be used).

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this and the above, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 0.30 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 0.33 g/ sec ( = 2.6 lb/ hr) fTable 2 of Attachment VII 1 to Volume VIII of the risk assessment indicates that the trial burn emission rate for antimony, if projected out to 8760 hours of operation per year, would only result in a predicted HI of .0016 at the point of maximum concentration. Therefore, it appears that this emission limit could be increased by several orders of magnitude without having a significant risk impact. This issue is still being considered.

 18 2) Maximum Hourly Feed Rate of Antimony:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded during the trial burn ( which resulted in an antimony emission of 1.6 E 4 g/ sec, or 1.27 E 3 lb/ hr) should remain as the regulatory feed rate limit.

Feed Rate Limit = 1.18 g/ sec ( = 9.4 lbs/ hr)

3) Annual Maximum Emission Rate of Antimony:

In addition to the hourly maximum metal emission/ feed limit, an annual emission limit might be warranted. From attached Table 2, no maximum annual emission rate was found to be necessary for antimony. However, this was based on a trial burn emission rate of 1.6 E 4 g/ sec projected to 8760 hours/ year operation. Therefore, the risk assessment at this time only shows that this specific annual emission rate would be protectivef. This value can be used as an annual emission limit ( although further risk assessment calculation might demonstrate that higher values are also fully protective).

Annual Emission Limit = ( Trial Burn Emission Rate) X ( 8760 hours/ yr)

Annual Emission Limit = ( 1.6 E 4 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Emission Limit = 5046 g/ yr ( = 11.1 lb/ yr)  19 4) Interim Annual Maximum Feed Rate of Antimony:

At this time, there is no information indicating that an annual restriction on antimony feed rate would be needed in addition to the hourly value given above.

Annual Feed Limit = ( 9.4 lb/ hr) X 8760 hrs/ yr = 82,300 lbs/ yr Arsenic:

1) Maximum Hourly Emissions of Arsenic:

For a carcinogen such as arsenic, the emission rate would normally be calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference specific dose (" RSD"). This approach considers direct exposure cancer risks from this carcinogenic metal. The RSD used in the WTI risk assessment was the same as the RSD prescribed in the BIF Rule, i. e., .0023 µ g/ m3. However, in the BIF Rule calculations, the TOTAL cancer risk associated with arsenic, beryllium, cadmium, and hexavalent chromium together must be equal to or less than 10 5. A common way to implement this is to divide the RSD by 4, which ascribes one quarter of the allowable theoretical cancer risk to each of the four metals. This technique will be used in the calculations below. However, it must be noted that the permittee has the right to apportion these differently depending on the specific wastes received at the facility, so that any emission or feed values calculated below for the four carcinogenic metals will remain tentative until accepted by the permittee.

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From the above information, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF) gThe BIF Rule calculations of emission limit base the limit on a simple risk assessment which only considers direct inhalation exposure. The BIF calculations do not consider indirect routes of exposure, which in some cases may be the more sensitive pathways. The calculations in this document are designed to consider both direct and indirect routes of exposure, because they are based on the detailed risk assessment.

 20 (" BIF" Max Emission Rate) = ( RSD/ 4) / ( DF)

(" BIF" Max Emission Rate) = ( 0.0023 µ g/ m3) / ( 4) X ( 0.91 µ g/ m3/ g/ sec)

= 6.3 E 4 g/ sec ( = 5 E 3 lb/ hr)

2) Maximum Hourly Feed Rate for Arsenic:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded during the trial burn ( which resulted in an emission of 1.6 E 4 g/ sec) should remain as the regulatory feed rate limit. Therefore, based on the trial burn feed rate:

Feed Rate Limit = 0.479 g/ sec ( = 3.8 lbs/ hr)

3) Annual Maximum Emission Rate for Arsenic:

Per Table 1, there is no suggested annual limit. This was verified against " Table 2" of the Appendix VII to Volume VIII of the risk assessment. In that table, which evaluates cancer risks and human health His at the maximum permitted emission rates, all HI values are well below 0.25 and all cancer risk factors are well below the regulatory value of 10 5.

The human health portion of the risk assessment demonstrated that the metals emissions demonstrated during the trial burn add up to a total calculated cancer risk of 10 6, as shown in Table 4, when both direct and indirect exposure routes are considered. Therefore, any annual permit limits calculated below per the BIF Rule should be evaluated against the trial burn emission values, and the actual annual permit limits imposed should be restricted to no more than a factor of 10 times that recorded during the trial burn. Per this analysis, if the " BIF calculated" emission limit value is less than 10 times the measured trial burn emission rate, the conclusion would be that the BIF calculated value is fully protective for both directg and indirect routes of exposure.  21 The average trial burn emission for arsenic was recorded as 1.6 E 4 g/ sec. As a risk check, ten times this value would be 1.6 E 3 g/ sec, which is higher than the " BIF calculated" value. Therefore, the " BIF calculated" value of 6.3 E 4 is less that 10 times the trial burn value and therefore is appropriate and protective on both an hourly and annual basis.

( Annual Emission Limit) = ( 5 E 3 lb/ hr) X ( 8760 hrs/ yr)

= 43.8 lbs/ yr 4) Interim Annual Maximum Feed Rate of Arsenic For the reasons cited in the above paragraph, no annual maximum feed rate would be required.

( Annual Feed Limit) = ( 3.8 lbs/ hr) X ( 8760 hrs/ yr)

= 3.33 E+ 4 lbs/ yr Beryllium:

1) Maximum Hourly Emissions of Beryllium:

For a carcinogen such as beryllium, the emission rate would normally be calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference specific dose (" RSD"). This approach considers direct exposure cancer risks from this carcinogenic metal. The RSD used in the WTI risk assessment was the same as the RSD prescribed in the BIF Rule, i. e., .0042 µ g/ m3. However, in the BIF Rule calculations, the TOTAL cancer risk associated with arsenic, beryllium, cadmium, and hexavalent chromium together must be equal to or less than 10 5. A common way to implement this is to divide the RSD by 4, which ascribes one quarter of the allowable theoretical cancer risk to each of the four metals. This technique will be used in the calculations below. However, it must be noted that the permittee has the right to apportion these differently depending on the specific wastes received at the facility, so that any emission or feed values calculated below for the four carcinogenic metals will remain tentative until accepted by the permittee.  22 The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From the above information, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

(" BIF" Max Emission Rate) = ( RSD/ 4) / ( DF)

(" BIF" Max Emission Rate) = ( 0.00105 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 1.1 E 3 g/ sec ( = 9.1 E 3 lb/ hr)

2) Maximum Hourly Feed Rate of Beryllium:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded during the trial burn ( which resulted in an average emission of < 3.6 E 6 g/ sec) should remain as the regulatory feed rate limit.

Feed Rate Limit = .0378 g/ sec ( = 0.30 lbs/ hr)

3) Annual Maximum Emission Rate of Beryllium:

Per Table 1, there is no suggested annual limit from the risk assessment. However, this was based on a trial burn emission rate of 3.6 E 6 g/ sec.

The human health portion of the risk assessment demonstrated that continuous emission of heavy metals at the rates measured during the trial burn add up to a total calculated cancer risk of 10 6, as shown in Table 4, when both direct and indirect routes of exposure are considered. Any permit emission limits representing higher emissions, such as BIF calculated allowable hourly emissions, need to also consider the trial burn emission values used in the risk assessment. Annual emissions should be restricted to no more than a factor of 10 times that recorded during the trial burn ( because the trial burn emissions demonstrated a 10 6 cancer risk, which is one tenth of the normal standard of 10 5) to ensure longterm protectiveness from indirect exposure effects.

The average trial burn emission for beryllium was recorded as < 3.6 E 6 g/ sec. As a risk check, ten times this value would be 3.6 E 5 g/ sec, which is lower ( i. e., more  23 restrictive) than the " BIF calculated" value. This means that the hourly BIF value might not be fully protective when projected out to the long term. This value of 3.6 E 5 g/ sec, projected out to an annual emission, would be an appropriate protective annual emission limit.

Recommended Annual Emission Limit = ( 3.6 E 5 g/ sec) X ( 3.15 sec/ yr)

= 1135 g/ yr ( = 2.5 lbs/ yr)

4) Interim Annual Maximum Feed Rate of Beryllium Until new trial burn testing indicates that a different feed rate is appropriate, the hourly feed rate recorded during the trial burn should remain as the regulatory feed rate limit. The annual feed limit would simply be this same value projected out to 8760 hours per year:

Annual Feed Limit = ( Hourly Feed Limit) X ( 8760 hours/ yr)

Annual Feed Limit = (. 0378 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Feed Limit = 1190 kg/ yr ( = 2630 lb/ yr)

Cadmium:

1) Maximum Hourly Emissions of Cadmium:

For a carcinogen such as cadmium, the emission rate would normally be calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference specific dose (" RSD"). This approach considers direct exposure cancer risks from this carcinogenic metal. The RSD used in the WTI risk assessment was the same as the RSD prescribed in the BIF Rule, i. e., .0056 µ g/ m3. However, in the BIF Rule calculations, the TOTAL cancer risk associated with arsenic, beryllium, cadmium, and hexavalent chromium together must be equal to or less than 10 5. A common way to implement this is to divide the RSD by 4, which ascribes one quarter of the allowable theoretical cancer risk to each of the four metals. This technique is used in the calculations below, but it must be noted that the permittee has the right to apportion these differently depending on the specific wastes received at the facility, so that any emission or feed values calculated below for the four carcinogenic metals will remain tentative until accepted by the permittee.  24 The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From the above information, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

(" BIF" Max Emission Rate) = ( RSD/ 4) / ( DF)

(" BIF" Max Emission Rate) = ( 0.0014 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 1.54 E 3 g/ sec ( = 1.22 E 2 lb/ hr)

2) Maximum Hourly Feed Rate of Cadmium:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded for cadmium during the trial burn ( which resulted in an average emission of 1.9 E 4 g/ sec) should remain as the regulatory feed rate limit.

Feed Rate Limit = 1.47 g/ sec ( = 11.7 lbs/ hr)

3) Annual Maximum Emission Rate of Cadmium:

Per Table 1, there is no suggested annual limit from the risk assessment. However, this was based on a trial burn emission rate for cadmium of 1.9 E 4 g/ sec, so the following further analysis is appropriate:

The potential cancer and toxicity effects of cadmium were verified against " Table 2" of the Appendix VII to Volume VIII of the risk assessment. In that table, which evaluates cancer risks and human health HI values at the maximum permitted emission rates, all HI values are well below 0.25 and all cancer risk factors are well below the regulatory value of 10 5.

The human health portion of the risk assessment demonstrated that the metals emissions during the trial burn add up to a total calculated cancer risk of 10 6, as shown in Table 4. Therefore, any permit limits calculated per the BIF Rule should be evaluated against the trial burn emission values, and the annual permit limits  25 imposed should be restricted to no more than a factor of 10 times the emission rate recorded during the trial burn.

The average trial burn emission for cadmium was recorded as 1.9 E 4 g/ sec. As a risk check, ten times this value ( based on the fact that the emission rates used in the permit limit scenario of the risk assessment resulted in cancer risks of 10% of the regulatory limit, as described above) would be 1.9 E 3 g/ sec, which is higher than the " BIF calculated" value. Therefore, the BIF value is fully protective even when both direct and indirect routes of exposure are considered. Therefore, the annual limit can be the same as the hourly limit projected out to 8760 hours.

Annual Emission Limit = ( Hourly Emission Limit) X ( 8760 hrs/ yr)

Annual Emission Limit = ( 1.54 E 3 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Emission Limit = 48.6 kg/ yr ( = 107 lb/ yr)

4) Interim Annual Maximum Feed Rate for Cadmium:

Until new trial burn testing indicates that a different feed rate is appropriate, the hourly feed rate recorded during the trial burn should remain as the regulatory feed rate limit. The annual feed limit would simply be this same value projected out to 8760 hours per year:

Annual Feed Limit = ( Hourly Feed Limit) X ( 8760 hours/ yr)

Annual Feed Limit = ( 1.47 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Feed Limit = 46,360 kg/ yr ( = 102,100 lb/ yr)

Chromium:

1) Maximum Hourly Emissions of Chromium:

For a carcinogen such as chromium, the emission rate would normally be calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference specific dose (" RSD"). This approach considers direct exposure cancer risks from this carcinogenic metal. The RSD used in the WTI risk assessment was the same as the RSD prescribed in the BIF Rule, i. e., .00083 µ g/ m3. However, in the BIF Rule calculations, the TOTAL cancer risk associated with arsenic, beryllium, cadmium, and hexavalent chromium together  26 must be equal to or less than 10 5. A common way to implement this is to divide the RSD by 4, which ascribes one quarter of the allowable theoretical cancer risk to each of the four metals. This technique will be used in the calculations below, but it must be noted that the permittee has the right to apportion these differently depending on the specific wastes received at the facility, so that any emission or feed values calculated below for the four carcinogenic metals will remain tentative until accepted by the permittee.

This analysis of chromium emissions assumes that all chromium emitted out the stack is in the most carcinogenic form, i. e., hexavalent chromium.

The refined modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From the above information, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

(" BIF" Max Emission Rate) = ( RSD/ 4) / ( DF)

(" BIF" Max Emission Rate) = ( 2.075 E 4 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 2.28 E 4 g/ sec ( = 1.81 E 3 lb/ hr)

2) Maximum Hourly Feed Rate of Chromium:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded during the trial burn ( which resulted in an average emission of 1.5 E 4 g/ sec) should remain as the regulatory feed rate limit.

Feed Rate Limit = 22.4 g/ sec ( = 178 lbs/ hr)

3) Annual Maximum Emission Rate of Chromium:

Per Table 1, there is no suggested annual limit from the risk assessment. However, this was based on a trial burn chromium emission rate of 1.5 E 4 g/ sec, so the following further analysis is appropriate to verify that the slightly higher " BIF calculated" emission limit value of 2.28 E 4 g/ sec is fully protective.  27 The potential cancer and toxicity effects were verified against " Table 2" of the Appendix VII to Volume VIII of the risk assessment. In that table, which evaluates cancer risks and human health HI values at the maximum permitted emission rates, all HI values are well below 0.25 and all cancer risk factors are well below the regulatory value of 10 5.

The human health portion of the risk assessment demonstrated that the metals emissions recorded during the trial burn add up to a total calculated cancer risk of 10 6, as shown in Table 4. Therefore, any permit limits calculated per the BIF Rule should be evaluated against the trial burn emission values, and the actual permit limits imposed should be restricted to no more than a factor of 10 times the trial burn emission values.

The average trial burn emission for chromium was recorded as 1.5 E 4 g/ sec. As a risk check, ten times this value ( this 10X factor is based on the fact that the emission rates used in the permit limit scenario of the risk assessment resulted in cancer risks of 10% of the 10 5 regulatory value, as described above) would be 1.5 E 3 g/ sec, which is higher than the " BIF calculated" value. Therefore, the BIF value is fully protective even when both direct and indirect routes of exposure are considered. Even at an emission rate 10 times the trial burn emission rate, all values would be below these thresholds. Because the " BIF calculated" emission limit is less than 10 times the trial burn emission rate, no additional annual limits appear to be warranted as long as the hourly limit is complied with. The annual emission limit would simply be the same as the hourly limit projected out to 8760 hours per year.

Annual Emission Limit = ( Hourly Emission Limit) X ( 8760 hrs/ yr)

Annual Emission Limit = ( 2.28 E 4 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Emission Limit = 7190 g/ yr ( = 15.8 lb/ yr)

4) Interim Annual Maximum Feed Rate of Chromium:

Until new trial burn testing indicates that a different feed rate is appropriate, the hourly chromium feed rate recorded during the trial burn should remain as the regulatory feed rate limit. The annual feed limit would simply be this same value projected out to 8760 hours per year:

Annual Feed Limit = ( Hourly Feed Limit) X ( 8760 hours/ yr)  28 Annual Feed Limit = ( 22.4 g/ sec) X ( 3600 sec/ hr) X ( 8760 hrs/ yr)

Annual Feed Limit = 7.06 E+ 5 kg/ yr ( = 1.56 E+ 6 lb/ yr)

Lead:

1) Maximum Hourly Emissions of Lead:

This is calculated as described in the BIF Rule at 40 CFR 266.106, using the dispersion factor (" DF") and the reference air concentration (" RAC"). This approach considers direct exposure risks. The BIF Rule prescribes an RAC for lead of .09 µ g/ m3. The USEPA risk assessment used a different technique for evaluating lead toxicity, known as the Uptake/ Biokenetic Model. This technique cannot be readily compared to the BIF calculation technique, so additional evaluation might be warranted to verify any significant changes in the emission limit.

The refined air dispersion modeling used in the risk assessment resulted in a DF of 0.91 µ g/ m3/ g/ sec. From this information, the calculated hourly max emission rate would be:

( Emission Rate) X ( DF) = ( Ground Level Concentration)

( Emission Rate) = ( Ground Level Concentration) / ( DF)

( Max Emission Rate) = ( RAC) / ( DF)

Max Emission Rate = ( 0.09 µ g/ m3) / ( 0.91 µ g/ m3/ g/ sec)

= 0.10 g/ sec (= 0.78 lb/ hr)

The human health impact of this " BIF calculated" emission limit is presently being re evaluated because it is considerably greater than what was evaluated in the risk assessment. In the interim, it is recommended that the emissions of Pb be restricted to no more than 2 3 times the average of the actual measured values from the 1993 trial burns. Therefore, it is recommended that until further analysis is completed, the following emission limit be imposed:

Maximum Emission Rate = 3 X (. 0012 g/ sec)

= .0036 g/ sec ( = .029 lb/ hr)  29 2) Maximum Hourly Feed Rate of Lead:

Until new trial burn testing indicates that a different feed rate is appropriate, the feed rate recorded during the trial burn ( which resulted in an emission of 1.2 E 3 g/ sec) should remain as the regulatory feed rate limit.

Feed Rate Limit = 12.6 g/ sec ( = 100 lbs/ hr)

3) Annual Maximum Emission Rate of Lead:

At this time, there is no information indicating that an annual restriction on lead emission rate is needed in addition to the hourly value given above.

Annual Emission Limit = (. 029 lb/ hr) X 8760 hrs/ yr = 254 lb/ yr 4) Interim Annual Maximum Feed Rate of Lead:

At this time, there is no information indicating that an annual restriction on lead feed rate would be needed in addition to the hourly value given above.

Annual Feed Limit = ( 100 lb/ hr) X 8760 hrs/ yr = 8.7 E+ 5 lbs/ yr aBased on projected annual emissions at " maximum permit limit" hourly maximum emission rates only. See USEPA Risk Assessment Volume VIII, Attachment VII 1 for complete listing of predicted human health HI and cancer risk values at full permit limit metals emission rates.

bSee Volume VI, Chapter VII, Section E. 1. a., p. VII 12. HI effects potentially above the value of 1 shown in chart are associated with food chain impacts to either the short tailed shrew or the American robin.

cThis HI is largely caused by direct exposure, due to a much lower barium RAC used in the risk assessment.

dThis ascribes only 25% of the available Human Health HI for toxicological effects from this pollutant to this one emission source, per USEPA guidance. This factors in the fact that there might be other pollution sources also impacting the area.

eThis is the greater of the HI or Cancer Risk suggested reduction. The Cancer risk of 1.5 E 3 would require a reduction by 150x to bring the risk down to 1.0 E 5.

 30 Table 1 Potential reductions in annual emissiona rates at WTI:

Metal Ecob HHRA HHRA Sugg'd HI> 1 HI> 1 Cancer> 10 5 Reduction ______________________________________________________________________

Ba 416 1400c NA 1400 x 4d = 5600x Hg 4.1 4.3c NA 4.3 x 4 = 17.2x Ag 5.2 60 NA 60 x 4 = 240x Tl 4250 650 NA 4250x Ni 367 14 1.5 E 3 367xe Se 3000 30 NA 3000x Sb ok ok ok none As ok ok ok none  31 Metal Eco HHRA HHRA Sugg'd Annual HI> 1 HI> 1 Cancer> 10 5 Reduction ______________________________________________________________________ Be ok ok ok none Cd ok ok ok none Cr ok ok ok none Pb ok no RfD/ slope fctr. NA none Al ok not evaluated NA none Cu ok not evaluated NA none Zn ok not evaluated NA none aEstimated Actual emission values are those developed by MRI based on averaging of waste profile information from WTI, and represent the emissions thought to reflect reality much more closely than does extrapolating the hourly permit limits out to annual emission values.

bMax possible emissions based on continuous emission at the hourly " permit limit" values in the risk assessment were based on the following: ( 1) Actual trial burn emission values from 3/ 93 trial burn where that metal was tested, or ( 2) " BIF Adjusted Tier 1" calculated allowable values for metals which were not tested during the 3/ 93 trial burn ( except for Copper, Zinc, and Aluminum, which are not presently regulated under RCRA). These Adjusted Tier 1 values were based on possible future permit use of newest Dispersion Factor (" DF") of 0.92 ( used in the R/ A) instead of older DF = 1.50 ( which was used to set the present permit limits). This new lower DF was used here and in the risk assessment because it was assumed that the permittee might request approval of these higher hourly emission rates reflecting the updated modeling.

cThese values are calculated based on the g/ sec emission values for ( 1) actual predicted and ( 2) possible maximum used in the risk assessment, multiplied by 69462 pound per year per gram per second.  32 TABLE 2 Metal MRI Possible Max Emissions: Present R/ A Projected Suggested Suggested Estimated Actuala Rsk Assmntb Present Limit Feed Annual Emissionc Annual Annual Annual Avg. Limit Estd. Actual Possible Max Reduc. Factor Limit Ba 1.5 E 4 g/ sec 55 g/ sec 33.4 g/ s 33.4 g/ s 10 lb/ yr 3.82E+ 6 lb/ y 5600x 682 lb/ y ( 436 lbs/ hr) ( 265 lbs/ hr) ( 265 lbs/ hr)

Hg 1.4 E 3 g/ sec .088 g/ sec .053 g/ s .0184 g/ s 97 lb/ yr 6110 lb/ y 17.2x 355 lb/ y ( 0.7 lb/ hr) ( 0.42 lbs/ hr) ( 0.146 lbs/ hr)

Ag 1.5 E 5 g/ sec 3.3 g/ sec 2.0 g/ s 2.0 g/ s 1.0 lb/ yr 2.29E+ 5 lb/ y 240x 954 lb/ y ( 26 lbs/ hr) ( 15.9 lbs/ hr) ( 15.9 lbs/ hr)

Tl 3.4 E 5 g/ sec 0.55 g/ sec 0.333 g/ s 0.333 g/ s 2.4 lbs/ yr 3.82 E+ 4 lb/ yr 4250x 6.6 lb/ y ( 4.4 lbs/ hr) ( 2.65 lbs/ hr) ( 2.65 lb/ hr)  33

Metal MRI Possible Max Emissions Present R/ A Projected Suggested Suggested Estimated Actual Rsk Assmnt Present Limit Feed Annual Emission Annual Annual Annual Avg. Limit Estd. Actual Possible Max Reduct. Factor Limit Ni 5.0 E 6 g/ sec 22 g/ sec None None 0.35 lb/ yr 1.53E+ 6 lbs/ yr 367x 4170 lbs/ y ( 174 lbs/ hr)

Se 4.7 E 4 g/ sec 4.4 g/ sec None None 33 lbs/ yr 3.06E+ 5 lbs/ yr 3000x 102 lbs/ y ( 35 lbs/ hr)

Sb 4.2 E 6 g/ sec 1.6 E 4 g/ sec 0.20 g/ s 1.18 g/ s 0.3 lb/ yr 11.1 lbs/ yr none ( 1.27 E 3 lb/ hr) ( 1.59 lb/ hr) ( 9.4 lbs/ hr)

As 3.7 E 5 g/ sec 1.1 E 4 g/ sec .0015 g/ s 0.479 g/ s 2.6 lbs/ yr 7.64 lbs/ yr none ( 8.7 E 4 lb/ hr) (. 0121 lb/ hr) ( 3.8 lb/ hr)

Be 3.3 E 8 g/ sec < 3.6 E 6 g/ sec .0028 g/ s .0378 g/ s .0023 lb/ yr 0.25 lb/ yr none (< 2.85 E 5 lb/ hr) (. 0222 lb/ hr) ( 0.3 lb/ hr)

Cd 1.6 E 5 g/ sec 1.9 E 4 g/ sec .00373 g/ s 1.47 g/ s 1.1 lb/ yr 13.2 lbs/ yr none ( 1.5 E 3 lb/ hr) (. 0296 lb/ hr) ( 11.7 lb/ hr) dAlthough the value for Cr6+ measured during the trial burn was 1.7 E 6 g/ sec, only a fraction of the chrome in the waste feed was Cr6+ during the trial burn. For regulatory purposes, all chromium exiting the stack is presently being considered to be Cr6+, since it is possible that the chromium in the waste feed could potentially be 100% Cr6+ at any time after the trial burn. Therefore, the total chromium emission of 1.5 E 4 g/ sec is being considered Cr6+.

eChromium feed limit is a limit on total chromium.  34

Cr6+ 7.1 E 7 g/ sec 1.5 E 4 g/ secd 5.5E 4g/ se 22.4 g/ s .05 lb/ yr 10.4 lbs/ yr none ( 1.2 E 3 lb/ hr) (. 00439 lb/ hr) ( 178 lb/ hr)

Pb 4.3 E 5 g/ sec 1.2 E 3 g/ sec .060 g/ s 12.6 g/ s 3.0 lbs/ yr 83.4 lbs/ yr none ( 9.5 E 3 lb/ hr) ( 0.47 lb/ h) ( 100 lb/ h)

Metal MRI Possible Max Emissions Present R/ A Projected Suggested Suggested Estimated Actual Rsk Assmnt Present Limit Feed Annual Emission Annual Annual Annual Avg. Limit Estd. Actual Possible Max Reduct. Factor Limit Al 1.2 E 4 g/ sec n/ a None None 8.34 lbs/ yr n/ a none Cu 9.4 E 5 g/ sec n/ a None None 6.5 lbs/ yr n/ a none Zn 1.2 E 4 g/ sec n/ a None None 8.34 lbs/ yr n/ a none  35 Table 3 Comparison of RACs and RSDs from BIF Rule and WTI RA BIF WTI R/ A BIF WTI RA Metal TB Emiss. RAC RAC RSD RSD ( g/ s) ( µ g/ m3) ( µ g/ m3) ( µ g/ m3) ( µ g/ m3) _________________________________________________________________________________________

Ba 50 0.13 Hg .08 .075 Ag 3.0 4.4 Tl 0.50 .061 Ni 20 18 Se 4 4.4 Sb 1.6 E 4 0.30 0.35 As 1.1 E 4 .0023 .0023 Be 3.6 E 6 .0042 .0042 Cd 1.9 E 4 .0056 .0056 Cr 1.5 E 4 .00083 .00083 Pb 1.2 E 3 .09 Not Applic  36 Table 4 Maximum Potential Cancer Risks from Arsenic, Beryllium, Cadmium, and Chromium Calculated in Risk Assessment Under " Permit Limit" Emission Scenario:

As 4.5 E 7 Be 2.6 E 9 Cd 9.3 E 8 Cr 4.9 E 7 TOTAL 1.0 E  6  37 TABLE 5 Possible New1 Metals Feed and Emission Limits Present Hourly Present Hourly New Hourly New Hourly New Annual New Annual ESTIMATED3 Emission Feed Emission Feed Emission Feed ANNUAL Metal Limit Limit Limit Limits Limit Limit EMISSION Ba 265 lbs/ hr 265 lbs/ hr 1.13 lb/ hr 493 lbs/ hr 682 lbs/ yr 2.96 E+ 5 lbs/ yr 10 lbs/ yr Hg 0.42 lb/ hr 0.146 lb/ hr 0.65 lb/ hr 0.65 lb/ hr 355 lbs/ yr 355 lbs/ yr 97 lbs/ yr Ag 15.9 lbs/ hr 15.9 lbs/ hr 26 lbs/ hr 11,370 lbs/ hr 954 lbs/ yr 4.15 E+ 5 lbs/ yr 1 lb/ yr Tl 2.65 lbs/ hr 2.65 lbs/ hr 0.53 lb/ hr 231 lbs/ hr 6.6 lbs/ yr 2870 lbs/ yr 2.4 lb/ yr Ni None None 156 lbs/ hr 68,260 lb/ hr 4170 lbs/ yr 1.8 E+ 6 lbs/ yr 0.34 lb/ yr Se None None 34.9 lbs/ hr 11,630 lbs/ hr 102 lbs/ yr 3.4 E+ 4 lbs/ yr 33 lb/ yr Sb 1.59 lb/ hr 9.4 lbs/ hr 2.6 lbs/ hr 9.4 lbs/ hr 11.1 lbs/ yr ( 82,300 lbs/ yr) 0.3 lb/ yr As .0121 lb/ hr 3.8 lbs/ hr .005 lbs/ hr 3.8 lbs/ hr ( 43.8 lbs/ yr) ( 3.3 E+ 4 lbs/ yr) 2.6 lb/ yr  38

TABLE 5 Continued Possible New Metals Feed and Emission Limits Present Present New Hourly New Hourly Annual Annual ESTIMATED Emission Feed Emission Feed Emission Feed ANNUAL Metal Limit Limit Limit Limits Limit Limit EMISSION Be .0222 lb/ hr 0.3 lb/ hr .0091 lb/ hr 0.30 lb/ hr 2.50 lbs/ yr ( 2630 lbs/ yr) .0023 lb/ yr Cd .0296 lb/ hr 11.7 lb/ hr .0122 lb/ hr 11.7 lbs/ hr ( 107 lbs/ yr) ( 1.0 E+ 5 lbs/ yr) 1.1 lb/ yr Cr+ .00439 lb/ hr 178 lb/ hr .0018 lb/ hr 178 lbs/ hr ( 15.8 lbs/ yr) ( 1.56 E+ 6 lbs/ yr) .05 lb/ yr Pb 0.47 lb/ hr 100 lb/ hr 0.029 lb/ hr4 100 lbs/ hr ( 254 lbs/ yr) ( 8.7 E+ 5 lbs/ yr) 3.0 lb/ yr 1. Note that these values listed as " New" or " Annual" represent maximum values; Actual permit limits can be set at lower levels that given in chart, if appropriate. These reflect USEPA limits; State limits might be more restrictive.

2. Parentheses indicate annual limits which are the same as the hourly multiplied by 8760 hours/ yr.

3. ESTIMATED ANNUAL lists the emission values used in the risk assessment, based on actual WTI waste profiles, operation at full thermal capacity 365 days per year, and the most precise available estimates of metals removal efficiencies.

4. These new emission limits for lead are conservative interim limits, subject to change upon further evaluation.