HWF NOTES ©
The long awaited Report to Congress on Cement Kiln Dust, dated December 1993, was finally made available on January 31, 1994. This report will significantly impact cement manufacturers, hazardous waste incinerators and the thermal treatment industry in general. It has already impacted the American public through all the tax payer dollars expended in putting this report together. At least seven years in the making, it now garners a tremendous amount of interest and attention from the various affected/interested segments of society.
It was disappointing to read in the Executive Summary to the report, that "EPA has reached no conclusions with respect to the need for more stringent regulation", particularly since in the preceding section EPA concluded that "After reviewing evidence of damage to human health and the environment, performing a risk assessment, and reviewing the results of laboratory analyses of waste samples, EPA has concluded that risks associated with CKD management are generally low". The following comments are provided in hopes of enhancing the EPA decisionmaking process as relates to CKD regulation.
Use of the phrase "soot from burning of fuels" implies that cement kilns, as a combustion device, are inefficient. There are, in fact, some hydrocarbons from wet and long dry kilns, however, for the most part, the source of these hydrocarbons is naturally occurring in the raw materials not "burning of fuels". As proof, the bypass gas in preheater kilns has virtually no hydrocarbons. Under operating conditions established under BIF compliance procedures, soot is not an issue even under worst case conditions.
There is no relevance of "gross" CKD production in this CKD report to Congress and this unfortunately demonstrates yet another EPA misunderstanding about the cement industry. Gross CKD numbers can be inflated by a number of circumstances, such as kiln turbulence or gas flow dependence for heating the raw feed. The relevant number is the wasted CKD which is why EPA found no apparent relationship between the amount of gross CKD generated and the amount of CKD wasted.
EPA's lack of understanding of the cement manufacturing process continues to be unfortunate for the regulated cement manufacturing community. It is obvious that physical process differences were not understood when comparisons between gross vs net CKD production were examined. The chemistry of the raw feed will account for some of the differences. Also, particulate size distribution of the raw feed, resulting from available raw materials, the type of mill used at the plant, or a process requirement for production of certain type or quality of product may effect CKD gross vs. net production. These are fundamental aspects of CKD generation that should have been clearly identified and explained in the report.
Text associated with this exhibit (facilities with high net CKD generation relative to clinker capacity) discusses kilns that have the highest recycle of CKD and lowest net CKD. The kilns cited did not even use hazardous waste. EPA was astute enough to identify these types of kilns as preheater/precalciners. In the vernacular of some of today's school children, "No Duh!" This phenomenon is well known in the cement industry. Maybe EPA should consult the people in the know about what they are trying to report about. (Could a large part of the problems with this report be a result of the low bid approach by EPA in choosing contractors?)
The major flaw in EPA's entire rationale concerning kiln dust "production" has to do with dependent versus independent variables, with cement chemistry being the focal point. Kiln dust wastage is directly dependent upon a given cement kiln chemistry with or without the use of hazardous waste fuels. In addition, that same particular kiln cement chemistry determines whether or not hazardous waste fuel can be used at all. These two variables are in fact dependent upon the same independent variable, cement chemistry. EPA is looking at variables that are by and large completely independent of each other and attempting to draw a conclusion of cause and effect based on a correlation.
As Dr. Bruce Ames of the University of California, Berkeley, so aptly points out: A graph showing a decline in human birthrates can be compared to a graph showing a decline in the number of storks in the same area. A mathematical correlation can then be demonstrated, but does this mean that storks bring babies?
A discussion is presented here of the "chemistry" that supposedly drives the wasting of CKD, alkalies and chlorides. This assumption clearly demonstrates EPA's continued lack of understanding of the process by leaving out sulfates entirely. Interestingly enough, this chemistry discussion is preceded by the statement made on page 3-19 that CKD is essentially "off-spec clinker". What science fiction novel spawned this "brilliant" deduction? This is completely false.
The conclusion stated in the third paragraph of the Recycling Differences section; "The influence of raw feed cannot be assessed in this analysis because appropriate raw feed characterization data are not available." is a perfect demonstration of how shallow this entire section really is. Even a first year cement chemist wouldn't discuss CKD production without including a discussion on raw feed chemistry.
EPA's statement, in the third paragraph on page 3-24, that "...full recycling...could probably be achieved for any process, if cost were not an issue." again demonstrates EPA's misunderstanding of the cement manufacturing process. It is quite untrue. In addition, the statement seems to imply that if a profit is made at the same time that a waste is produced, even as a byproduct of the process, that somehow a great injustice has been performed.
In Chapter 8, the EPA discusses a number of methods for recycling. In some cases, they point out the extraction and sale of a commodity chemical (Potassium Salts, etc.). The revenue in lbs/ton for this product would become quickly depressed if several kilns chose this option thereby rendering the return on the product to negative dollars. Also, each kiln would have a different potential to recycle, depending on its CKD chemistry. There is the resistance in the marketplace to using cement with CKD in it, or CKD and ash in block manufacturing. Or, the market area may not need to use CKD because there are no appropriate industries that can use it, no sewage treatment facilities that need it, etc. So, it may turn out that while a few kilns may be able to recycle all dust, a few more may be able to place dust in environmentally approved uses. There will always be some CKD that must be wasted.
EPA again demonstrates how little it understands cement manufacturing technology/ chemistry when "regional trends" were examined in an attempt to "infer an influence from raw feed inputs" concerning recycling rates (or more accurately, high CKD wastage). EPA continues to demonstrate their complete lack of understanding of the cement manufacturing process by stating, "The most plausible explanation for decreased recycling rates among kilns burning hazardous waste is that chloride, alkali, and/or sulfate levels in some hazardous wastes may significantly increase the loading rates of these contaminants in the dust."
In fact, sulfur levels in HWF are generally much lower than in coal, and chlorine in HWF is a more efficient method of reducing clinker alkali than sulfur.
The discussion of CKD Gross Characteristics states, "An unusual feature of CKD is that unlike typical process wastes that are substantially different [and easier to deal with from a regulatory point of view] CKD is essentially cement clinker that does not quite meet commercial specifications." This is again a demonstration of EPA's naivete when it comes to cement chemistry. Not only does CKD not meet such specifications as seven day strength, but it does not demonstrate the basic cementatious properties of cement. It takes quite the stretch of the imagination to call CKD "cement clinker that does not quite meet commercial specifications." Bottom line, EPA is welcome to use CKD on their next brick/block building project and see for themselves that it simply will not hold bricks in place. Hardly the qualities of "cement clinker that does not quite meet commercial specifications."
By making this assumption statement, EPA implies that any amount of wasted dust can be made into cement if the cement companies would just try a little harder. This implies that cement companies are not only not trying hard enough, but that somehow they are so lazy and inefficient that they would just throw away good product. A reality check seems to be in order here.
The major differences between CKD and clinker is "free lime" and K, Na, SO3, concentrations - by recycling CKD back to the kiln, these are burned out to form clinker. But, these materials must go somewhere. Kiln chemistry and equilibriums are all specific to the kiln and its raw feed. Consequently, different kilns recycle more or less and waste the optimum CKD for their process. There are dramatic rewards for kilns that waste less dust, cost savings in milling, heat, etc. It is free tonnage. But if recycling degrades the cement even a small amount, your competitor will take away your customers.
In the EEC, the cement specification is set low enough that even the more inefficient kilns can produce spec clinker. In fact, if British cement manufacturers produce too good a clinker, they will lose their "British Standard" mark. In the U.S., ASTM sets the standard at a minimum quality which many kilns, as a marketing strategy, routinely exceed. Their customers (the ready-mix plants) can use less cement to produce the same amount of concrete. Again, the ready mix plants must meet a minimum standard - generally seven day strength. In the EEC, the ready mix plants must meet a standard as well, burers produce too good a clinker, they will lose their "British Standard" mark. In the U.S., ASTM sets the standard at a minimum quality which many kilns, as a marketing strategy, routinely exceed. Their customers (the ready-mix plants) can use less cement to produce the same amount of concrete. Again, the ready mix plants must meet a minimum standard - generally seven day strength. In the EEC, the ready mix plants must meet a standard as well, but must use a minimum and maximum amount of cement to do this. The EEC justifies all this by pointing out that the buildings will have a minimum acceptable quality, but at the same time it is limiting the use of resources and, most important of all, protects jobs from being taken away by a more efficient operator who bought better cement and used less in the concrete. The EPA could work the requirements to recycle all CKD into a regulation limiting the quality of the cement.
EPA is obviously surprised at their findings that volatile metals end up in the kiln dust, as discussed in the final paragraph under the metals section on page 3-33. This phenomenon was well known when BIF was written and certainly, nothing has changed since then. It is a well understood scientific fact, not some magical thing somehow related to hazardous waste fuel use. EPA's continued misunderstanding of the cement manufacturing process shines like a beacon with such statements as, "Intuitively, one would expect a mineral production waste such as CKD to contain the same types of constituents naturally present in the parent material." What does intuition have to do with a report which stated purpose on page one of the Executive Summary, "...will serve to establish a factual [emphasis added] basis for EPA decision-making regarding the appropriate regulatory status, under RCRA, of cement kiln dust."
EPA goes on to state that CKD has arsenic and strontium at levels that are within range of naturally occurring soils, "but that exceed the average native soil concentration by a factor of two or more." From this, EPA concludes, "CKD, therefore, could be a potential contributor of these metals at higher than natural levels in the environment." This comparison of metal concentrations in CKD with metals concentrations in native soils does not seem as appropriate as would a comparison with metals concentrations in shale, a component in cement manufacturing, mined from the ground where CKD is returned. Tables 1 and 2 compare CKD total metals from the Bureau of Mine's study with shale and coal fly ash concentrations.
All total metal data from EPA analysis used SW-846 methods. Data obtained by SW-846 methods cannot be used with any validity due to previously demonstrated poor recoveries as evidenced in the report by Bruce Pedersen(1).
Knowledge of cement chemistry within the cement industry indicates that the nonvolatile metal concentrations data for cement clinker and the CKD should be quite similar. It is obvious from the significant differences in the data presented for CKD in Exhibit 3-18 (pg 3-34 & 3-35) and for clinker, in Exhibit 3-30 (pg 3-64 & 3-65), that there was a digestion problem. Differences in digestion techniques have been highlighted in previous publications such as the Pedersen publication just referenced. A chemist experienced with performing these types of analyses knows that a nitric digestion alone will simply not digest silicates, a major component in this situation. A hydrofluoric digestion is essential for reliable data. A metals fate study(2) examines the relative recoveries on kiln feed and demonstrates that the nonvolatile metals are essentially the same as CKD, contrary to what might be concluded from the questionable data presented in this report.
The EPA total metal data appears to be biased as follows:
Sb - biased high, probable ICP background interference
As - biased low, median industry wide ~9 ppm, poor digestion
Ba - biased low, ~ 30%, poor digestion
Be - looks O.K.
Cd - looks O.K.
Cr - biased low, may be twice EPA measured levels, poor digestion
Pb - biased high, ICP interference, or non-random sampling by EPA choice of plants
Hg - looks O.K.
Ni - possible low bias
Se - biased high, ICP interference
Ag - biased high, ICP interference
Tl - looks O.K.
V - looks O.K.
Data representing the PCA Report 2 appears scrambled. Mercury data is listed under nickel and vice versa.
Page 3-37/38 - Dioxins and Furans
EPA states on page 3-38, "It is worthy of note that dioxins and dibenzofurans were found in CKD samples collected from both facilities burning hazardous waste fuels and those not burning hazardous waste fuels." But a glaring omission here, and from the CKD study regarding dioxins and furans in general, is any reference to background dioxin levels, or levels from other combustion devices, coal fired power plants, wood burning fire places or diesel trucks. Overall, EPA implies that any level of PCDDs/PCDFs require control. Control of PCDDs/PCDFs to a zero level is physically impossible! Despite those whom advocate "zero discharge" the basic laws of thermodynamics demonstrates this to clearly be a politically motivated myth. It is common knowledge among analytical chemists that there is no such thing as "zero".
EPA comment concerning radionuclides is contradictory. First the EPA finds that "...the activity levels observed for the radionuclides measured in CKD are expected to be no different than, for example, those found in samples of soil and rock that are randomly selected and sampled." Based upon this statement/conclusion, it would seem logical to absolve radionuclides from any further consideration as they are no greater than background, but somehow EPA logic takes an illogical turn and EPA concludes, nevertheless, because the Agency's sampling and analytical program did reveal detectable amounts of certain radionuclide species in CKD samples, it has decided to include certain of them in the risk analysis on the basis of their presence at levels exceeding defined risk criteria. Is it EPA's intent to declare certain naturally occurring soils hazardous waste?
Perhaps EPA should use its Risk Model on other naturally occurring materials for comparative purposes with known risks prior to relying on the model for regulatory decisions. A risk analysis of wood ash from home fireplaces, which many people place in their gardens, might be enlightening regarding the common sense validity of this model.
EPA suggests that TCLP metal limits may be revised downward in the next to last paragraph on page 3-47. While EPA may very well be considering such an action, this has not undergone public comment and is completely out of place in this report. Bear in mind that if TCLP limits were lowered, many naturally occurring materials would fail. However, this would be consistent with declaring naturally occurring radionuclides as hazardous waste. By these simple changes in definition, we really would live in a toxic world and "environmentalists" could dance about gleefully. The downside to such an "environmentalist" coup is that the "earth" becomes the "toxic" source, not industry.
Comments concerning antimony data at the top of page 3-55 must be clarified. There is a major interference when using ICP to determine Sb. This has apparently been true in a number of studies. Specifically, this flaw was discovered and pointed out in the initial phase of the PCA study by Gossman Consulting, Inc. The second phase PCA study eliminated this specific interference. The second phase PCA study data is likely the only reliable data in this report.
The use of t-tests to examine the effects of burning hazardous waste requires that the compared data sets have a normal distribution. A comparison of mean vs median in practically every set of data clearly demonstrates the lack of a normal distribution. Comparisons made in this study, using the t-test, are not statistically valid.
Failure of this study to use a Pearson Correlation Coefficient based on a particular confidence level or report all confidence levels for reported correlations is a major failure of this study. Under the circumstances, the quality of any correlations has not been determined and can therefore not be trusted.
A multi-variant linear regression or, at a minimum, an examination of residuals and a more clear determination of dependent vs independent variables should have been used on data presented on pages 3-59 through 3-61.
The comment "The disposal of CKD in unlined, abandoned quarries is a common waste management practice utilized at cement plants." which is made in the last paragraph on page 5-13 is made somewhat out of context. While the statement itself may be true, it is made in association with a "damage" report, implying that this is typical. While the disposal practice may be typical, documented "damage" cases are not. A better review of those hundreds of facilities where "damage" has not occurred is notably absent from this report.
The EPA has used the "unlined" modifier repeatedly in this document. This is, of course, to point out how primitive the conditions of storage at cement plants are. However, as the many successful CKD storage scenarios at other kilns demonstrate, a liner is not necessary to achieve the goal. If it were, then EPA should give serious consideration to somehow isolating shale and other mineral deposits from ground water. Wouldn't that be an EPA clean-up contractor's dream?
EPA points out in the second paragraph under Section 5.5, on page 5-49, that "Analysis shows there is a greater potential for risk through the food chain from the ingestion of vegetables, meat, milk, and soil contamination by arsenic and dioxins through atmospheric deposition of CKD from nearby piles." This statement is somewhat misleading. The "analysis" of which EPA refers is likely hypothetical risk analysis, rather than actual documentable analysis. Reference Section 8.2.5 where there is documentable analysis of actually feeding CKD to cattle and experiencing positive results with no apparent side effects. How can hypothetically derived "analysis" carry more weight than documentable analysis? Could this point to a critical flaw in EPA's risk model?
EPA mentions metals "concentrations measured during the Agency's 1992 and 1993 sampling study...", "calculated mean concentrations for metals in the EPA sampling data", "metals data (both totals and leach extract)" and "TCLP and SPLP extract analysis" in discussing data used in the Chapter Six risk analysis, but it is not clear whether there was a hodge-podge application of this mixed data or whether specific data was used. This is an important consideration since total metal data would bring into serious question the bioavailability of the metal(s). There have been situations where lead in a given CKD sample exceeded 6,000 ppm, yet still passed the EP Toxicity testing. Process/cement chemistry again comes into play here. There are clearly some mineralogical forms of these metals that are not bioavailable. A risk assessment assumption based upon the total concentration of a given metal versus what is actually bioavailable would be totally misrepresentative and not accurate.
The fourth result and conclusion on page 6-4 concerns "modeling estimates of high end risks". The estimates concerning the two assumptions of "ingestion of vegetables grown in agricultural fields contaminated by CKD and "consumption of recreationally-caught fish" appear to be in direct conflict with the real time hard data presented in section 8.2.5, where cattle were actually fed CKD and positive effects were observed, with no apparent side effects.
The sixth result and conclusion on page 6-4 only finds potential aquatic ecological damages from high end results for the metals cadmium, chromium, lead & arsenic. TCLP results from hazardous waste fuel burning CKD would certainly not support this finding. Bioavailability appears to be the issue that has not been addressed.
The first result and conclusion on page 6-5 discusses "sensitivity analysis of hypothetical but plausible (based on conditions infrequently observed) higher risk scenarios." The risk findings for "exposed" agricultural fields [based upon modeling assumptions] would seem to be refuted by the real time hard data presented in section 8.2.5, where cattle were actually fed CKD and positive benefits were observed. The high end assumptions made for "individual toxic constituents (such as dioxins, arsenic, or heavy metals)" would not be supported by the volumes of TCLP results found at hazardous waste fuel burning cement plants. The third assumption in this section concerns "subsistence food consumption". How can this be a "plausible" situation? EPA may recall that the original health based limits assumptions for 266.112 were based upon eating two liters of CKD a day. How did those risk factors compare with the "subsistence food consumption"? EPA casts doubt on the plausibility of the assumption of "subsistence food consumption" in item four on this very same page.
"Indirect food chain pathways" are cited again in the second result and conclusion on page 6-5, yet the data demonstrating the positive effects of CKD consumption by cattle, presented in section 8.2.5 casts doubt on this assumption.
In the last result and conclusion on page 6-5, EPA states, "Utilization of CKD as an agricultural liming agent appears to pose more of a risk than other byproduct beneficial uses." EPA is urged to more closely review the information presented in 8.2.5, where there was direct consumption of CKD by cattle and a positive benefit, with no apparent side effects, was observed. This real time hard data surely supersedes any hypothetical modeling assumptions. Actual studies of metal uptakes and bioavailability of various forms of metals have not been done in this report. This data is readily available from various EPA studies on the application of sewage sludge to land.
The entire study of risk, found in chapter six, uses a linear application of risk factors for arsenic, despite the fact that arsenic is a necessary micro-nutrient in the human diet. Consequently, a level of "no effect" must necessarily be used, otherwise, EPA would have us lowering arsenic in our diet to the point of suffering negative health effects.
EPA claims, in the next to last paragraph of section 7.1.1 on page 7-9, that enforcement actions were announced on 9-28-93 "In an effort to protect the public from health risks associated with burning hazardous wastes." One really has to stretch the imagination to view EPA's enforcement actions as anything but politically motivated and staged with such fanfare as to receive the maximum amount of press coverage. An outrageous enforcement action, previously announced to the tune of $1.8 million, was announced again in the 9-28-93 announcement, but no mention was made of the fact that this was a second "advertising" or that the actual settlement was significantly lower than the amount originally announced. Not only did EPA potentially discredit an operation that was making good faith compliance efforts, but didn't even have the professional courtesy to announce that perhaps the original enforcement action announcement might have been a little overzealous and based upon misunderstanding on the part of the EPA. This is now being reported throughout the country.
In many cases, it can be shown that EPA personnel took enforcement actions based upon erroneous data or controversial interpretations of regulations that have no impact whatsoever on emissions. The vast majority of any remaining violations were generally the result of perfectly legitimate confusion over what some call, purposefully vague and/or poorly worded paper work requirements. The EPA is demonstrating that the Administrative political agenda overshadows any real concern for health or environmental protection.
It is unfortunate, that a report the magnitude of the CKD report to Congress, would contain such an obvious misunderstanding of the very process about which EPA is reporting. The first paragraph of section 8.1.1, at the bottom of page 8-2, states "Most kilns are equipped with such cool-end chain sections." The lack of even simple basic knowledge about cement kilns is evident. How long has EPA been looking at cement kilns?
The "cool-end" chains are heat transfer devices not intended as particulate capture devices. They are there to transfer heat from the hot kiln gases into the slurry (in long wet kilns) or into the dry raw feed (in a long dry kiln). Once the material starts to calcine, the chains can become a process liability.
There are kilns that have drop-out boxes between the kiln exit and the ESP entrance; these frequently have chain curtains and do serve as dust knock down devices.
Interestingly, kilns with a chain section do not experience an increase in particulate emission as the chains wear out, only a rise in kiln exit temperature.
Additionally, the suggestion that ash levels in waste fuels affects the amount of CKD generation is a clear demonstration of the lack of understanding of simple cement chemistry. This is unfortunately consistent with the basic misunderstanding of cement kilns in the beginning, when the BIF rules were based upon incinerators and not cement kilns.
The top paragraph on page 8-3 states, "...a process-oriented approach to minimizing CKD generation rates appears to have a limited potential impact in comparison to other approaches...." EPA has obviously not done their homework in a proper manner. The use of Cl (as found in HWF) instead of S (as found in coal) can reduce the amount of CKD that is wasted to produce the same reduction in alkalis in cement clinker.
The second paragraph under 8.1.2 implies highly unprofessional and borderline slanderous inferences. EPA states, "Some operators may opt for removal and disposal of CKD rather than installing return systems or monitoring quality." This statement smacks of accusations that cement kiln operators are somehow lazy or not interested in the quality of their product. Maybe EPA can get away with being "lazy" or not caring about the quality of their "product", but just let EPA try to compete in a market place where tax dollars don't pay the bills.
The second paragraph on page 8-4 ignores the fact that some kilns actually add chlorine to their process to produce saleable clinker. The benefits of adding the chlorine through waste fuels is completely ignored.
In the fourth paragraph on page 8-4, EPA candidly admits that "the reasons for these differences [wet kilns recycle less CKD than dry long kilns, and dry long kilns recycle less CKD than preheater or preheater/precalciner kilns] are not fully understood...." Unfortunately, this is another example of insufficient research and insufficient understanding of cement kilns. This phenomenon is reasonably well understood inside the industry.
The top paragraph on page 8-6 ignores the problem of organic emissions from the organics that are present in the raw kiln feed.
The examples given on page 8-29 are perfectly valid examples of the potential positive effects of CKD, when used as a livestock feed ingredient, and serves as real time hard data of effects on cattle that consume fairly large quantities of CKD. This is in direct conflict with some of the risk analysis based upon assumptions. Although we cannot advocate feeding cattle CKD, it seems imminently logical that real time hard data about animal consumption of CKD would be preferable to risk analysis based entirely upon assumptions.
The CKD reuse system described on page 9-29 does not account for the fate of volatile heavy metals, which can be problematic. Many systems that encourage the recycling of CKD, back into the system, can increase releases of volatile heavy metals to the environment through emissions into the air. It is actually environmentally more sound to put the metals back where they originally came from, the ground, in what is an essentially mineralogically inert form, similar to that found in the shale and other raw materials from whence it came.
It is interesting to note that until BIF came along, kiln operators had no reason to examine their CKD for metals content as long as the clinker produced met the specifications. There are instances when kilns considering the use of waste fuel examined their CKD for the "12 metals of concern" that they discovered excessively high levels of certain toxic metals (primarily thallium and cadmium). That is, they discovered that they must waste dust. Some of the kilns that EPA has tested that do not waste dust, once they examine their CKD, will decide they should waste dust, to prevent the unsafe buildup of some metals.
EPA has assembled cost data here that is not representative of industry situations. As a general rule of responsible data reporting, a table/exhibit should stand by itself. This exhibit is very clearly labeled "Economic Benefits from Burning Hazardous Waste Fuels", yet by EPA's own admission, the cost data "...do not reflect the permitting, engineering, administrative, or operating costs associated with installing a hazardous waste fuel burning operation at a cement plant", but nonetheless, EPA constructs this highly misrepresentative Exhibit "...for illustrative purposes only." What is the value of presenting data, in this CKD report to Congress, that is misleading to begin with, does not reflect reality and is very definitively entitled "Economic Benefits from Burning Hazardous Waste Fuels" (with no footnoted qualifiers to the actual Exhibit), if not to make some type of a misrepresentative point to Congress.
In addition, where text statements are footnoted, the footnotes are inaccurate. Cost estimates in footnote #32 on page 9-33 do not appear to be based upon reality. Most kilns currently pay for clean liquid waste fuels FOB the kiln.
In section 3.1 Decision Rationale, EPA states in Step 1: "After reviewing evidence of damage to human health and the environment, performing a risk assessment, and reviewing the results of laboratory analyses of waste samples, EPA has concluded that risks associated with CKD management are generally low...". This conclusion is supported by the results and conclusion section of chapter six briefly summarized as follows:
- of seventeen radionuclides..." those nuclides with the highest potential for adverse health effects showed negligible risk
- "...on-site CKD handling and disposal does not appear to have a high potential for adverse human health and environmental risks."
- "Of the seven potential exposure pathways examined [quantitative risk modeling] in this baseline analysis, including [emphasis added] direct contact and indirect food chain pathways, estimated increased individual cancer risks never exceeded a level of 1x10-6 (most pathway risks never exceeded 1x10-8)
- "...the central tendency results for the baseline risk modeling analysis showed no exceedance of ambient quality criteria or other aquatic ecological benchmarks..."
- "Dioxin/furans did not contribute substantially to cancer risks for either the central tendency or high end plants in the baseline case studies."
- "Off-site beneficial byproduct use of CKD as a stabilizing agent for hazardous waste, sewage sludge stabilizer, road sub-base, asphalt additive, and additive for building materials (e.g. concrete and masonry block) does not appear to pose significant risks to human health or the environment."
Unfortunately, EPA was not content with the overwhelming conclusion of their risk assessment, so the following statement is also included in Step 1: "...however, there is a potential under certain circumstances for CKD to pose a danger to human health and environment...". Those "certain circumstances" are also pointed out in the results and conclusion section of chapter six and are addressed as follows:
- The fourth result and conclusion on page 6-4 concerns "modeling estimates of high end risks". The estimates concerning the two assumptions of "ingestion of vegetables grown in agricultural fields contaminated by CKD and "consumption of recreationally-caught fish" appear to be in direct conflict with the real time hard data presented in section 8.2.5, where cattle were actually fed CKD and positive effects were observed, with no apparent side effects.
- The sixth result and conclusion on page 6-4 only finds potential aquatic ecological damages from high end results for the metals cadmium, chromium, lead & arsenic. TCLP results from hazardous waste fuel burning CKD would certainly not support this finding. How can a "high end" problem exist if CKD is passing TCLP? Apparently, total metals were used for this finding, thus ignoring the issue of bioavailability.
- The first result and conclusion on page 6-5 discusses "sensitivity analysis of hypothetical but plausible (based on conditions infrequently observed) higher risk scenarios". The risk findings for "exposed" agricultural fields [based upon modeling assumptions] would seem to be refuted by the real time hard data presented in section 8.2.5, where cattle were actually fed CKD and positive benefits were observed. The high end assumptions made for "individual toxic constituents (such as dioxins, arsenic, or heavy metals)" would not be supported by the volumes of TCLP results found at hazardous waste fuel burning cement plants. The third assumption in this section concerns "subsistence food consumption". How can this be a "plausible" situation? EPA may recall that the original health based limits assumptions for 266.112 were based upon eating two liters of CKD a day. How did those risk factors compare with the "subsistence food consumption"? EPA casts doubt on the plausibility of the assumption of "subsistence food consumption" in item four on this page.
- "indirect food chain pathways" are cited again in the second result and conclusion on page 6-5, yet the data demonstrating the positive effects of CKD consumption by cattle, presented in section 8.2.5 casts tremendous doubt on this assumption.
- In the last result and conclusion on page 6-5, EPA states, "Utilization of CKD as an agricultural liming agent appears to pose more of a risk than other byproduct beneficial uses." EPA is urged to more closely review the information presented in 8.2.5, where there was direct consumption of CKD by cattle and a positive benefit, with no apparent side effects, was observed. This real time hard data surely supersedes any hypothetical modeling assumptions.
Not only does EPA create "certain circumstances" and maintain that these are "...hypothetical, yet plausible scenarios.", but adds an ominous attention getter for Congress about not only posing a danger to human health and the environment, but "...it may do so in the future." As discussed previously EPA casts doubt on their own assumptions of the "plausible" situations in the fourth item discussed on page 6-5 and highlighted above.
Then in Step 2: of section 3.1 Decision Rationale, EPA declares, "EPA has reached no conclusions with respect to the need for more stringent regulation." Given that in Step 1:, EPA "...concluded that risks associated with CKD management are generally low....", it seems rather obvious that the conclusion concerning the need for more stringent regulation should be a resounding No! Yet even with the overwhelming data confirming the low risks associated with CKD, confirming the original Bevill assumptions, EPA apparently feels compelled to suggest the possibility of Subtitle C management anyway. Why perform a study, spend who knows how much taxpayer money and then ignore the obvious conclusions?
Clearly, if CKD is declared either a hazardous waste or even a special waste, then coal fly ash and other naturally occurring materials will also be hazardous by definition. EPA appears on the verge of declaring the very earth itself as toxic and hazardous. A soul searching reality check certainly seems to be in order.
Let us elaborate on what we see in this report. Using the risk assessment data, it is easy to point out that even under the EPA's worst fantastic scenario (I.E. - high end, etc.) the risk is very low. That is, if absolutely nothing changed, the impact on health and the environment would be negligible in comparison to the continued use of tobacco products or household radon exposures. If EPA decides to do something, such as place restrictions on off-site uses of CKD and on-site management of CKD, the EPA is in the best of all worlds. It gets more people, more money, more power. And even if the program implementation is wholly inept, the program can be declared a "success" because there was nothing to worry about in the first place. In a few years, EPA can "refine" its risk model and demonstrate that everything is O.K. and take the credit for it. This is, of course, paranoid - realistic, but still paranoid.
It is obvious that the EPA had to stretch to achieve risks of >10-5, witness the inclusion of background levels of radionuclides. It may be worthwhile to point out EPA's record with respect to risk assessment, such as the PCB/Times Beach and Asbestos - both of which they have publicly recanted on, albeit in a suitably bureaucratic way.
Out of this entire report to Congress there are only a few important points:
1. CKD from non-waste and waste burning kilns are not significantly different.
2. Only a few kilns have so badly managed their dust that there has been a problem (environmentally speaking)
3. There has been no evidence that any damage has directly affected human health.
Consequently, what course is needed to protect people and the environment from a low impact waste?
"Better dust management"
The easiest way is to define the minimum criteria based on current successful management schemes and then issue that criteria as a guidance document under existing laws. Any deviation would have to be justified. Gossman Consulting, Inc. strongly endorses option 2 although option 1 is also supported by the available data. Options 3 through 5 are not supported by any available data or facts.
Comparison of Cement Kiln Dust Metal Concentrations with Coal Ash (values in ppm)
|Bureau of Mines Study - CKD||Coal Ash - United States|
|Sb||<1.6 - 8660||N/A|
|As||1.3 - 518||0.5 - 279|
|Ba||<55||52 - 5789|
|Cd||<1.5 - 352||0.1 - 18|
|Cr||11 - 172||3.4 - 437|
|Pb||17 - 1759||57 - 769|
|Hg||<.13 - 1.0||.005 - 4.2|
|Ni||<12 - 91||1.8 - 19|
|Se||N/A||.08 - 19|
|Ag||<3 - 17||.04 - 8|
|Tl||<60 - 185||0.1 - 42|
|V||<100||12 - 570|
|Zn||32 - 8660||4 - 2300|
Comparison of Mean/Median Metal Concentration Cement Kiln Dust with Coal Ash Shales
|Bureau of Mine CKD||Shale||Eastern Coal||Midwestern Coal||Western Coal|
1. Pedersen, Bruce A., "A Microwave Digestion Technique for Trace Element Analysis of Industrial Furnace Feedstreams", Proceedings of the 1992 International Specialty Conference on New RCRA Regulations for Industrial Boilers, Furnaces & Incinerators, SP-80; Air & Waste Management Association; Pittsburgh, 1992, pp 104-112.
2. Gossman, David G., Myron Black, et al., "The Fate of Trace Metals in the Wet Process Cement Kiln", in Proceedings of the 1990 AWMA International Specialty Conference on Waste Combustion in Boilers and Industrial Furnaces, SP-72; Air & Waste Management Association; Kansas City, 1990, pp 70-93.
3. Tetra Tech, Inc., Physical-Chemical Characteristics of Utility Solid Waste, EPRI EA-3236, September 1983.
4. 2. Encyclopedia Britannica, Chemical Elements, pg. 940
5. 3. Tetra Tech Inc., Physical-Chemical Characteristics of Utility Solid Waste, EPRI EA-3236, September 1983.