5. How Was the Surface Water Pathway Evaluated? A number of facilities that generate wastes covered by today's proposed rule are located adjacent to rivers or bays. As a consequence, the potential exists for subsurface releases of chemical contaminants from on site management of the wastes to enter these river and bay systems through ground water inflow. In instances where no direct contact with ground water is likely to occur (as there would otherwise be if, for example, ground water was being used for residential drinking water), it becomes important to evaluate the potential water quality impacts of these releases on surface waters in the context of hazardous waste listings. However, we wish to emphasize that the surface water impacts considered in today's proposed rule are due to subsurface releases to ground water only. Direct discharges to surface waters are already regulated by the Clean Water Act under the NPDES permit system and are not considered further in today's proposal. 21 We conducted a screening level analysis to evaluate potential surface water impacts. In this analysis, we estimated the volume of leachate that would infiltrate into ground water and assumed that this entire volume would be intercepted by surface water. Because this is a screening analysis, we made conservative assumptions that are likely to overstate the infiltration of leachate and, therefore, the potential release to surface water. For example, for on site landfills, we assumed a soil type (sandy loam) that is likely to overstate the infiltration rate even in the absence of liners or leachate collection systems. Similarly, for surface impoundments we assumed a sludge thickness (8 inches) and soil type (sandy loam) that is likely to overstate the infiltration rate. In addition, we assumed no retardation in the migration of chemical contaminants in ground water due to sorption or other processes. Due to the nature of these releases, which are likely to occur over a wide area, we assumed that the inflow of contaminated ground water was rapidly diluted into surface water and that there was little or no mixing zone. We followed EPA's Office of Water guidance for determining the design flows for rivers as regards water quality criteria. The appropriate design flow depends on the particular water quality impact being evaluated. For assessing potential impacts on aquatic life, we used the `` 7Q10'' as the design flow. The 7Q10 is the seven day low flow with a return frequency of once every 10 years and is the recommended design flow for use with chronic water quality criteria for the protection of aquatic life. We believe that chronic water quality criteria are the appropriate criteria for evaluating the potential impact of continuing steady releases, such as those that would result from subsurface discharge of contaminated ground water. On the other hand, EPA generally uses the `` 30Q5'' as the design flow for assessing potential impacts on human health. The 30Q5 is the thirty day low flow with a return frequency of once every 5 years and is the recommended design flow for use with water quality criteria for the protection of human health as regards non cancer effects. However, a 30Q5 design flow was not available in all cases. In these instances, we estimated the 30Q5 based on the 7Q10 design flow. 22 For carcinogens (e. g., arsenic), lifetime exposures are the primary concern and a design flow that corresponds to a longer averaging time is appropriate. For this reason, EPA recommends the long term harmonic mean be used as the design flow. 23 The harmonic mean is always less than the arithmetic mean and is used in place of it because low flow conditions drive long term average water quality. However, because this flow statistic was not available, we estimated the harmonic mean flow from the arithmetic mean flow and the 7Q10. As a result of the screening level analysis, all wastes screened out for which the ground water to surface water pathway was a concern. Therefore, no additional analysis of this pathway was conducted.

6. What Are the Limitations and Uncertainties of the Assessment?

Our assessment of exposures and risks is subject to a variety of limitations and uncertainties. These are discussed in some detail in the background document for today's proposed rule. A number of these are highlighted here. We assumed our sampling and analysis data are fully representative of the range of wastes generated in the effected industries. However, our own data show that there are significant variations in waste concentrations across facilities in a given industry. Variability in waste concentration that is unaccounted for could lead to an over or under estimation of risks. However, any tendency toward underestimation is likely to be mitigated to some extent by our selection of wastes and exposure scenarios that are intended to capture the highest risks. We also assumed that our methods for measuring the leaching behavior of wastes (i. e., the TCLP and SPLP test procedures) are both representative of the range of leaching conditions that exist under real world conditions and accurately quantify the concentrations of contaminants that leach into the subsurface environment from a given waste management unit. However, we know that many metals exhibit varying (or amphoteric) behavior with respect to pH and that any one test procedure is capable of characterizing leaching behavior only under a particular set of conditions. The ground water model we used in our analysis (i. e., EPACMTP) is designed to characterize dilution and attenuation in the subsurface environment under homogeneous conditions. The model does not account for subsurface heterogeneities, nor does it account for fractured flow or colloidal transport. These conditions, if present at VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00018 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55701 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules a site, can lead to less dilution and attenuation of contaminant levels than predicted by the model, causing ground water concentrations to be under estimated. In addition, sorption of metal species onto soil and aquifer materials exhibits considerable variability depending on geochemical conditions and the total concentration of the metal present at a given location. Although our use of empirically derived Kd values captures some of this variability, the available published data are fairly limited for certain metals (e. g., antimony). We have accounted for the uncertainty associated with the small number of data points explicitly for these metals by expanding the range of Kd values used for modeling (to three orders of magnitude). Even for metals that have abundant data (e. g., arsenic), it is unlikely that the range of variability apparent in the data could exist at a given site. Uncertainty associated with the specification of Kd as noted above could lead to an over or under estimation of risk. However, a tendency toward overestimation is likely to be mitigated by the fact that under near steady state conditions (when ground water impacts are the greatest), concentrations in ground water are little influenced by Kd. Under non steady conditions, any tendency toward over or underestimation is limited by the variability inherent in the empirical distributions of Kd used in the analysis, which include both relatively high and relatively low values of Kd. Nevertheless, in general the risk estimates are sensitive to the specification of Kd and, therefore, this is an important source of uncertainty in our analysis. As indicated previously, for wastes managed on site we based our assessment of human exposures on the plausibility of ground water being used for drinking water. While some information was available on utilization of ground water for drinking water, very limited information was available from which to determine the location of exposure at a given site. For wastes managed off site we assumed that ground water is used for drinking water (or will be in the future) and we used national data on the distribution of distances to residential wells to assess human exposures and risk. Our analysis did not consider possible changes in the location of on site waste management operations in the future. These exposure assumptions (about which there is considerable uncertainty) may have an impact on the estimated risks and, therefore, the outcome of the risk assessment. Other important uncertainties include those related to the health effects of chemical contaminants in humans (hazard identification), absorption and metabolism of ingested contaminates (pharmacokinetics), and biological response (dose response relationships). These and other limitations and uncertainties are discussed in the background document, `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' (August, 2000).

F. Sector Specific Listing Determination Rationales We seek comments on all proposed listing decisions in this section, and the underlying rationales used to support our proposals.

1. Antimony Oxide a. Summary. We have evaluated antimony oxide production wastes and propose to list two wastes from this process as hazardous: (1) Baghouse filters and (2) slag that is disposed of or speculatively accumulated. We propose to list the baghouse filter waste under the criterion in 40 CFR 261.11( a)( 1) because it routinely exhibits one or more of the characteristics of hazardous waste, but the waste is not consistently managed in compliance with Subtitle C regulations. We propose to list the slag under the criteria in 40 CFR 261.11( a)( 3) because of risks associated with land disposal. K176 Baghouse filters from the production of antimony oxide. (E) K177 Slag from the production of antimony oxide that is disposed of or speculatively accumulated (T). Other wastes generated by the antimony oxide industry do not meet the criteria set out at 40 CFR 261.11( a)( 3) for listing a waste as hazardous. They do not pose a substantial present or potential threat to human health or the environment. We identified no risks of concern associated with the current management of these other wastes. b. Description of the antimony oxide industry. Antimony oxide was produced by four facilities in the United States in 1998. Antimony oxide is used as a flame retardant in plastics and textiles, a smoke suppressant, a stabilizer for plastics, an opacifier in glass, ceramics and vitreous enamels, and a coating for titanium dioxide pigments and chromate pigment. The manufacturers use two different processes to produce antimony oxide. In the first process, antimony metal is roasted in the presence of air. The antimony oxide forms as a fume, cools and condenses in a baghouse. In the second process, crude (low grade) antimony oxide is roasted in the presence of air to produce higher grade antimony oxide. The antimony oxide cools and condenses in a baghouse. The crude antimony oxide comes either from off site or is recycled from within the facility. c. How does the Bevill Exclusion apply to wastes from the antimony oxide manufacturing processes? Antimony oxide producers use a range of raw materials to produce antimony oxide, including antimony metal ingots, sodium antimonate, and antimony ore concentrate, and some facilities have claimed that wastes generated from the production of antimony oxide are Bevill exempt. Wastes generated from processes using either antimony ingots or sodium antimonate (both of which are saleable mineral products) are considered chemical manufacturing wastes rather than mineral processing wastes and are not eligible for the Bevill exemption. The September 1, 1989 Bevill final rule states at 54 FR 36620± 21 that chemical manufacturing begins if there is any further processing of mineral product. Two of the facilities also purchase an antimony ore concentrate as a raw material and place this material in kilns to produce antimony oxide. The smelting of a ore concentrate above the fusion point is defined as mineral processing (See 54 FR 36618). At these antimony oxide facilities, since mineral processing has begun, wastes from the process are not eligible for the Bevill exemption as beneficiation wastes (See 40 CFR 261.4( b)( 7)( i)). In addition, although there is a Bevill exemption for 20 specific mineral processing wastes form various mineral processing sectors, the wastes generated from antimony oxide mineral processing are not included as one of these 20 wastes and are not excluded. (See 40 CFR 261.4( b)( 7)( ii)). Thus there are no antimony oxide wastes that qualify for the Bevill exemption. d. Wastes generated by these processes. Table III± 1 summarizes our information about the wastes generated from the production of antimony oxide:

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00019 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55702 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 24 `` United States Antimony Corp. Stibnite Hill Mine Project Operating Permit 00045'', 6th review draft, January 1999. This draft permit is issued under the Metal Mine Reclamation Act, 82± 4± 301 MCA. It was prepared by the facility, approved by the State of Montana on August 12, 1999 (with a number of stipulations), and subsequently approved by the Forest Service. 25 `` Above Ground Land Emplacement Facilities, N. J. Law, '' Letter to Honorable James J. Florio, Chairman, Subcommittee on Commerce, Transportation, and Tourism, Committee on Energy and Commerce, House of Representatives, from J. Winston Porter, Administrator, EPA, dated March 26, 1986. TABLE III± 1.Ð ANTIMONY OXIDE PRODUCTION WASTES Waste category Number of reported generators 1998 volume (MT) Reported waste hazard codes Management practices Antimony slag not recycled in process ........ 3 113 D008 ......................... Sent to lead smelters for lead and/ or antimony recovery; or on site drum storage prior to future on site land disposal. Baghouse filters ........................................... 4 9 No code reported ..... In process antimony recovery; off site antimony recovery; industrial Subtitle D landfill; or non hazardous waste incinerator Empty supersacks ........................................ 1 15 No code reported ..... Disposal in off site Subtitle D landfill or recycled

In addition to these wastes, there are other materials produced that are reused in the antimony oxide production process. Antimony oxide and antimony slag are captured at various points in the facility and reinserted into a furnace to produce antimony oxide, either on site or off site. Because these materials are managed prior to reuse in ways that present low potential for release, and because we evaluated process waste generated after the secondary materials are reinserted into the process, we do not believe that these secondary materials present significant risks. e. Agency evaluation. (1) Antimony slag not recycled in antimony oxide process.

How Are These Wastes Currently Managed?

Three facilities produced antimony slag that is not recycled in the antimony oxide process. Two of these facilities send the slag to lead smelters. One of the two facilities reported its slag to be TC hazardous because of its lead content (D008). The third facility, however, has historically stored a portion of its slag on site in drums, reporting that they plan to reclaim antimony when antimony prices are more favorable. Recent revisions to the facility's Operating Permit, 24 however, require that the slag be placed in an on site engineered `` slag storage pit'' to be constructed in the next two to three years. We assessed the on site disposal scenario, reflecting the projected management practice for this waste. For a number of years, the facility has been placing approximately 20 MT/ yr in steel drums on pallets on the ground. The facility reported that they intend to reclaim the antimony from this slag when antimony prices are favorable. We consider storage on site for more than one year to be speculative accumulation and consider these materials to be solid wastes. We believe that the length of time secondary materials are accumulated before being recycled is an important indicator of whether or not they are wastes. This is supported by the large number of recycling damage cases where secondary materials that were overaccumulated over time caused extensive harm. (See 50 FR 614) `` Under RCRA and the implementing regulations, permanent placement of hazardous waste, including perpetual `` storage'' falls into the regulatory category of land disposal. '' 25 (See also American Petroleum Institute v. EPA, 216 F. 3d 50 (D. C. Cir. 2000).) Since the Operating Permit requires the facility to build and use an on site, land based unit for this waste, we assessed the onsite landfill scenario for this waste.

How Was This Waste Category Characterized?

We selected two of the three facilities for sampling and analysis. At the site which stores the slag indefinitely, we collected one sample of `` reduction furnace slag'' that was designated as containing less than 5 percent antimony (AC± 1± AO± 01) and one sample of `` reduction furnace slag'' that was designated as containing between 5 and 10 percent antimony (AC± 1± AO± 06). Based on characterization information provided by the facility in its RCRA Section 3007 Survey response, we believe these samples are representative of all of the slags generated at the facility. We conducted total, TCLP and SPLP analyses of these slags. The analytical results for the constituents found to be present in the leachates at levels exceeding the HBLs are presented in Table III± 2. We collected a third sample (LI± 1± AO± 01) at a facility that reclaims its slag for lead. This sample failed the TC for lead, as the facility reported in its RCRA Section 3007 Survey response. The results are available in `` Waste Characterization Report, Laurel Industries Inc., La Porte, Texas'' in the docket for today's proposal.

TABLE III± 2.Ð CHARACTERIZATION OF SPECULATIVELY ACCUMULATED ANTIMONY SLAG Constituent of concern AC± 1± AC± 01 AC± 1± AO± 06 HBL mg/ L Total mg/ kg TCLP mg/ L SPLP mg/ L Total mg/ kg TCLP mg/ L SPLP mg/ L Antimony .......................................... 11,500 55.8 114 127,000 110 211 0.006 Arsenic ............................................. 301 2.0 2.9 478 3.1 3. 8 0.0007 Boron ................................................ <500 9.8 9.3 <2,500 8.5 8. 1 1.4 Selenium .......................................... <50 0.6 0.6 <250 0.6 0. 3 0.08 Vanadium ......................................... <50 1.3 1.1 <250 0.6 1. 0 0.14 VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00020 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55703 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules How Was the Groundwater Ingestion Risk Assessment Established?

We modeled the annual volume reported to be stored on site indefinitely (20 MT). (The facility reports that it processes sodium antimonate from two facilities and returns the resultant slag to the process for further processing. We did not include these recycled slag volumes in our modeling.) We used the total and SPLP results as model inputs, reflecting the industrial nature of the on site unit. We used only the analytical results for the facility that stores the slag indefinitely. Both of the samples for this facility are relevant because they represent the material stored on site and destined for the onsite slag pit. We did not model the sample from the other sampled facility because they acknowledged that their waste exhibited the TC. Both this facility and the facility that was not sampled reclaim these wastes in a manner that is excluded from regulation under Subtitle C. We believe that it is reasonable to assume that they will continue to manage their slags in ways that do not violate Subtitle C regulations. Also, in this case, the SPLP results are higher than the TCLP results, making the industrial landfill the worst case scenario. We examined records available from the State where the slag is stored to determine the appropriate distance towell to model. We identified four residential wells within several miles of the facility. These data demonstrate that groundwater is a viable and actively used resource in this area. One well is located 1.4 miles directly downgradient. Based on local topography and groundwater information, we do not believe the other identified wells could be affected by releases to groundwater from the facility. We modeled potential releases to a downgradient residential well. Given that our groundwater model is not configured at this time to model releases further than one mile, we did not assess the full distance to the known well. In our probabilistic analysis, we varied the well distance from the closest property boundary that appeared to be potentially downgradient to the limit of the model (one mile). Our results therefore are conservative with respect to this particular well, but otherwise reflect the fact that future residences and wells may be placed closer to the facility and any potential groundwater plumes associated with its operation. Specifically, we modeled potential distances to wells from the facility's southern boundary to one mile. We used a regional site based approach in modeling this unit, as described in section III. E. 4. We modified this to enable us to use available depth to groundwater information at this particular site.

What Is EPA's Listing Rationale for This Waste?

Where these slags are reused and present no exposure route of concern, we did not evaluate these secondary materials further. The results of the risk assessment for the on site disposal scenario for boron, selenium, and vanadium were very low. In the 90th to the 95th percentile range, the highest hazard quotient for these three constituents was in the range of 0.001. For this reason, the full results for these three constituents are not presented here. The results of the risk assessment for the on site disposal scenario for antimony and arsenic are presented in Table III± 3:

TABLE III± 3.Ð PROBABILISTIC RISK ASSESSMENT RESULTS FOR SPECULATIVELY ACCUMULATED ANTIMONY SLAG Percentile Adult risk Child risk Adult risk Child risk 1 Antimony hazard quotient 1 ArsenicÐ cancer risk 90 th % ............................................................................................................................ 2.2 4.6 4 E± 07 3 E± 07 95 th % ............................................................................................................................ 4.5 9.4 1 E± 06 9 E± 07 For a more complete description of this analysis, see `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' (August 2000) in the docket for today's proposal. In our modeling results, the dilution and attenuation factors (DAFs) were relatively high. For example, high end antimony DAFs were as high as 8,000. This is the result of the hydrogeological setting of the site evaluated. Due to the high hydraulic conductivity we used in modeling, the landfill leachate is readily diluted into a large volume of groundwater. Given the uncertainty about the actual ultimate management practice and the site specific nature of the modeling, DAFs could be considerably lower in other disposal scenarios, resulting in much higher hazard quotients and, therefore, higher potential risks. Our modeling approach assumes that the slag will be placed in an unlined unit. Information from the facility, however, indicates that they plan to place the waste in an on site lined storage pit, upon completion of construction, that will be governed by a state mining permit. We considered whether our decisionmaking should account for the added protection provided by a liner system. Our first consideration is the current uncertainty regarding this waste's disposition. While the facility has stated its intended placement of this waste in a lined unit, our most recent information indicates that construction had not yet begun. The facility may in fact choose to place this waste in an off site commercial landfill that would not necessarily be lined. This uncertainty is greater than in most waste management scenarios that we have assessed in this rulemaking, where there is a long term history of management in a particular type of management unit (e. g., an operating onsite landfill, a local off site landfill). Because of this uncertainty, we are hesitant to give much weight to a liner system that may be constructed in the future. More generally, we considered the efficacy of landfills (and any liners) over the modeled risk assessment period, which covers 10,000 years. Landfills are used actively until their capacity is reached (our models assume an active life of 30 years), and at the end of their active life, we assume landfills are closed and the wastes remain in the unit indefinitely. The effectiveness of liner systems depends on how they are designed. Composite and double liners that combine two or more layers of liner material with leachate collection and leak detection will no doubt minimize leakage to the subsurface during the period when the leachate collection system is actively managed. However, depending on the regulatory controls relevant for a particular unit, monitoring would continue for a limited postclosure period. There is also uncertainty associated with liner performance, in the near term as well as in the long term. There are a variety of factors that may influence longevity and performance, such as poor construction, installation VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00021 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55704 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 26 A material is not accumulatively speculatively, however, if the person accumulating it can show that the material is potentially recyclable and has a feasible means of being recycled and thatÐ during the calendar year (commencing on January 1)Ð the amount of material that is recycled or transferred to a different site for recycling equals at least 75 percent by weight or volume of the amount of that material accumulated at the beginning of the period. (40 CFR 261.1( c)( 8)) or facility operation, or geologic movement below the liner that can cause holes, tears or larger failures. Some defects may have a significant effect. Because of our uncertainty regarding the efficacy of the liner system over long periods of time, and the uncertainty over the ultimate disposal for this waste, we believe our use of the modeling results for an unlined landfill is appropriate. In deciding whether to list this waste as hazardous, we also considered other factors in addition to the risk results noted above. First, we considered the very high levels of toxic constituents present in the waste and in test leachate (which is one of the criterion cited in 261.11( a)( 3)( ii)). The levels of antimony and arsenic are quite high. The antimony level exceeds 10% in the waste (up to 127,000 mg/ kg), and the SPLP antimony concentration exceeds the drinking water HBL by a factor of >35,000. Another key factor is the lack of any appreciable degradation expected for these metals (a constituent's degradation or persistence is also a criterion for listing given in 261.11( a)( 3)). Unlike some organic compounds, metals such as antimony will not degrade over time. Thus, even if the loss in effectiveness of a liner system only occurs over the very long term, the metals would still be present for leaching. It is difficult to assess the impact of the long term effectiveness of the liner system in question for today's proposal. However, we note that the effectiveness of the liner system would have to be sufficient to reduce the antimony concentration at the well by close to 90% in order to keep the risks below an HQ of 1. Therefore, given the reasons cited above, we propose to list these slags as hazardous: K177 Slag from the production of antimony oxide that is disposed of or speculatively accumulated. It is important to note that this listing has been developed to capture only those wastes that are not recycled. Thus, this listing, as proposed, would not apply to generators that recycle or reclaim this material as long as it is not speculatively accumulated. If slags have been speculatively accumulated (i. e., held for more than a calendar year without recycling) at the time of the effective date of this final rule, these slags would meet the listing immediately. 26 We also propose to add antimony to Appendix VII to Part 261, which designates the hazardous constituents for which K177 would be listed. (2) Baghouse filters.

How Are These Wastes Currently Managed?

These filters capture product or offspecification product. Two facilities place antimony laden baghouse filters in their on site production furnaces. One of these facilities also sends a portion of its baghouse filters to Mexico for antimony recovery. Two other facilities dispose of these wastes in a nonhazardous waste incinerator and an industrial Subtitle D landfill. None of these wastes are handled as hazardous, although our sampling efforts showed this waste to exhibit the toxicity characteristic for lead and arsenic.

How Was This Waste Category Characterized?

We collected a total of three samples of this waste category from two facilities. At one facility we collected one sample of the `` oxidation furnace'' baghouse filters (AC± 1± AO± 03) and one sample of the `` reduction furnace'' baghouse filters (AC± 1± AO± 07). At the other facility, we collected a sample of the baghouse associated with its kiln (LI± 1± AO± 03). Because the facilities sampled represented the range of production practices within the industry, we believe these samples are representative of all of the baghouse filters generated by this industry. We conducted total, TCLP and SPLP analyses of these baghouse filters. The analytical results for the constituents found to be present in the leachates at levels exceeding the HBLs are presented in Table III± 4. Two of the three samples of the waste, one from each facility that generate this waste, exceed the toxicity characteristic for either lead or arsenic. (The third sample exhibits TCLP lead levels close to the TC standard).

TABLE III± 4.Ð CHARACTERIZATION OF BAGHOUSE FILTERS FROM ANTIMONY OXIDE PRODUCTION (MG/ KG OR MG/ L)

Constituent of Concern LI± 1± AO± 03 AC± 1± AC± 03 AC± 1± AO± 07 HBL TC Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP Limit Antimony ..................................................... 91,400 9.3 6.2 150,000 9.9 4.3 145,000 68.7 287 0.006 .............. Arsenic ........................................................ 114 <0.5 0.6 <250 <0.5 0.09 <250 1 6.9 6.9 0.0007 5.0 Boron ........................................................... 24.0 6.5 1.0 <2500 <2 0.2 <2500 <2 0.7 1.4 .............. Cadmium ..................................................... 5.3 0.3 0.5 <250 0.3 0.3 411 <0.05 0.9 0.0078 1.0 Lead ............................................................ 3.1 1 8.5 16.9 <2500 2.8 1.0 <250 <0.5 <0.05 0.015 5.0 Mercury ....................................................... 0.9 <0.002 0.001 0.1 <0.002 <0.0002 95.2 0.03 0.4 0.0047 0.2 Thallium ....................................................... <2 <2 0.06 <1000 <2 0.06 <1000 <2 0.1 0.0013 ..............

1 Exceeds Toxicity Characteristic level.

What Is EPA's Listing Rationale for This Waste?

We propose to list the baghouse filters waste because our data show it routinely exhibits one or more of the characteristics of hazardous waste (i. e., TC lead or arsenic), yet the generators do not identify their wastes as exhibiting the toxicity characteristic and the generators that dispose of this waste do not comply with Subtitle C regulations. We propose to list this waste under the 261.11( a)( 1) criteria:

K176 Baghouse filters from the production of antimony oxide (E).

Because we believe we have sufficient reason to list this waste under 261.11( a)( 1) based on the TC exceedences and lack of compliance with hazardous waste regulation, we chose to conserve our time and resources and did not conduct formal risk assessment modeling of the off site landfill scenario, as we would traditionally do to support a 261.11( a)( 3) listing. Such modeling would reflect reported management practices. Antimony is not a TC constituent and, therefore, was not considered in the 261.11( a)( 1) listing decision. However, antimony levels are high and would likely result in risk if modeled. Leach results for the waste exceed the HBLs by VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00022 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55705 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 27 As noted above, these filters capture product materials. EPA does not regulate reclamation of these products. See 50 FR 14216, April 11, 1985: `` Under the final rules, commercial chemical products and intermediates, off specification variants, spill residues, and container residues listed in 40 CFR 261.33 are not considered solid wastes when recycled except when they are recycled in ways that differ from their normal useÐ namely, when they are burned for energy recovery or used to produce a fuel'' 28 Since, as explained below, we find no significant risks from the larger volume wastes we assessed, we conclude that any low volume wastes from this third facility also would not pose any risks warranting listing. a wide margin, e. g., the SPLP results for antimony are up to 48,000 times the HBL. The high levels of antimony in the waste (up to 15%) would provide a long term source of the metal for leaching into the groundwater. Thus, we expect that modeling an off site Subtitle D scenario would yield significant drinking water risk. Note that, when facilities process the antimony oxide product captured in these filters by reinserting the productcontaining filters back into the furnace where the antimony oxide originated, without reclamation, these materials would not be solid wastes. 27 We also propose to add arsenic and lead to Appendix VII to Part 261, which designates the hazardous constituents for which K176 would be listed. The `` mixture'' rule for listed wastes currently provides an exemption for wastes listed solely because they exhibit characteristics (see 40 CFR 261.3( a)( 2)( iii)). Mixtures of such listed wastes lose their listed waste status when they cease to exhibit characteristics for which they were listed. (However, they would still need to comply with Land Disposal Restriction requirements.) In the both of the last two Hazardous Waste Identification Rule (HWIR) proposals (60 FR 66344, December 21, 1995) and (64 FR 63382, November 19, 1999), we proposed to narrow the exemption to only include wastes listed for ignitability, corrosivity, and reactivity. This narrowing would make any waste listed for the toxicity characteristic (TC) (including the waste proposed today for listing under the (a)( 1) criteria) ineligible for the current exemption. In other words, under current mixture rule regulations, mixtures containing these baghouse filters would become nonhazardous wastes once they ceased exhibiting the characteristic. Under the HWIR proposal, however, such mixtures would remain hazardous wastes even after they cease to exhibit the TC. As we state in the TC rule, chemicals can still pose hazardous at levels below the TC (see 55 FR 11799, March 29, 1990). Under an amended consent decree (Environmental Technology Council v. Browner, C. A. No. 94± 2119 (TFH), April 11, 1997), EPA is required to sign a notice taking final action with respect to the proposed revisions to the mixture rule by April 30, 2001. (3) Empty supersacks. One facility ships crude antimony oxide in supersacks and then reuses them to store intermediate materials until they wear out. The facility then sends these empty supersacks either to an off site industrial Subtitle D landfill or to an offsite plastic recycler. The facility claims that the supersacks are empty and would meet the standard in 40 CFR 261.7 (which exempts `` empty'' containers formerly used to manage hazardous waste). Although 40 CFR 261.7 does not literally apply to these sacks, we think it is reasonable to take a similar approach here. We believe that the levels of crude antimony oxide in worn out supersacks would be low because the material is the primary feedstock (raw material) used in this process. We do not believe it follows that these supersacks should be regulated, when other similarly empty containers would be exempt. Therefore, we propose not to list this waste as hazardous.

2. Barium Carbonate a. Summary. We have evaluated the wastes, waste management practices, and potential risk exposure pathways associated with the barium carbonate production processes and propose not to list any wastes from this industry as hazardous under Subtitle C of RCRA. Some wastes in this industry are D002 or D005 characteristic hazardous wastes, which are both currently subject to RCRA Subtitle C regulation and managed in compliance with those regulations. For other wastes, not identified as characteristic hazardous wastes, we have identified no risks of concern associated with the current management of these wastes that would warrant listing. These wastes do not meet the criteria listed under 40 CFR 261.11( a)( 3) for listing a waste as hazardous. b. How is barium carbonate produced? There are two facilities in the United States that produce significant quantities of barium carbonate. A Georgia facility produces barium carbonate for commercial sale. A Pennsylvania facility produces barium carbonate only for use as a feedstock in its own internal manufacturing processes. A third facility is a specialty manufacturer that produces extremely small amounts of barium carbonate (approximately 10 kg in 1998). 28 For more detailed information concerning this industry, see `` Barium Carbonate Listing Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal. Barium carbonate (BaCO3) has a wide range of uses, including feedstock for production of other barium chemicals, an additive in various glasses, ceramics, bricks, and other construction materials, an additive in oil drilling suspensions, and a brine purification chemical in the chlor alkali industry. The two primary barium carbonate production facilities use different manufacturing processes to make barium carbonate. The Georgia facility uses locally mined barite ore, containing barium in the form of barium sulfate, as the primary feedstock. The ore is crushed and milled, thermally reduced in a roasting kiln, and leached with water to dissolve the barium. The resulting barium sulfide solution is filtered and reacted with carbon dioxide gas to produce a barium carbonate precipitate. This precipitate is then dried, and sized for sale. The Pennsylvania facility uses a commercially purchased high purity barium chloride solid as the primary feedstock. The facility dissolves the barium chloride in water, heats and filters the resulting solution, and precipitates barium carbonate by reacting the barium chloride solution with ammonium bicarbonate. The resulting barium carbonate precipitate is washed, filtered, dried and sized before the facility utilizes it as a feedstock in other manufacturing processes on site. c. What wastes are generated? Table III± 5 below briefly lists the facilityreported residuals from the barium carbonate manufacturing processes, residual volumes generated in 1998, reported RCRA hazard codes, and residual management practices.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00023 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55706 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 29 Note that primary barite ore has wide use in drilling muds for the petroleum industry and numerous other industrial uses, including use as feedstock for barium chemicals; see `` Barite'' U. S. Geological SurveyÐ Minerals Information, 1997, http:// minerals. usgs. gov/ minerals/ pubs/ commodity/ barite/ index. htm. TABLE III± 5.Ð BARIUM CARBONATE PRODUCTION WASTES Waste category 1998 volume (MT) Reported RCRA hazard codes Sequential residual management practices Barite Ore Feedstock ProcessÐ Georgia Facility Treated barium wastes (D005 barium wastes include barite ore leaching waste, barium sulfide filtration sludge, and barium carbonate production area cleaning and maintenance wastes). 18,300 ................... None (D005 prior to treatment). Disposal in local, captive, industrial Subtitle D landfill (after treatment of D005 wastes in onsite Subtitle C treatment unit).

Wastewater from BaCO 3 precipitate dewatering .. 313,000 ................. None ...................... Treatment in on site, tank based WWTP prior to NPDES discharge to Etowah River. WWTP sludge ....................................................... 11,000 ................... None ...................... (1) Dewatered; (2) Treated on site; (3) Disposal in local, captive, industrial Subtitle D landfill. Spent polypropylene and nylon filter media and baghouse dust collector bags. 3 (filter media) ....... ~1.5 (baghouse bags). None ...................... (1) Washed and washwaters re inserted to barium carbonate production process. Solids managed as barium carbonate production area cleaning and maintenance wastes. (2) Treated materials disposed in off site municipal Subtitle D landfill.

High Purity Barium Chloride Feedstock ProcessÐ Pennsylvania Facility Ammonia vapor scrubber water and ammonia reclamation unit wastewaters. Not reported .......... D002 ...................... Treatment in on site, tank based WWTP.

Barium carbonate precipitate washwater .............. 1,600 ..................... None ...................... Treatment in on site, tank based WWTP prior to NPDES discharge to Susquehanna River. WWTP sludge ....................................................... 8,200 ..................... None ...................... (1) Stored in roll off bin; (2) Disposal in off site municipal Subtitle D landfill Ammoniated spent process solution storage tank solids. 1 ............................ None ...................... Disposal in off site municipal Subtitle D landfill.

Sludge and spent filter media from filtration of barium chloride solution and BaCO3 drying and sizing unit dusts. <1.23 ..................... D005 ...................... (1) Stored in closed container; (2) Sent to off site Subtitle C facility for treatment and disposal.

In addition to these wastes, the two barium carbonate manufacturing facilities also produce other materials which are either piped directly back to the production process or are used for other purposes. Residues from the barite ore feedstock production process, ore crusher/ grinder, kiln, barium carbonate drier, granulation and packaging processes are directly returned to their unit of origin with no significant pathways for exposure of these materials to the environment prior to reuse. Barium carbonate production area cleaning and maintenance wastewaters are also re inserted to the barium carbonate production process with no significant pathways for exposure of these materials to the environment prior to reuse. Because these materials are managed prior to reuse in ways that present low potential for release, and because we evaluated all wastes generated after they are reinserted into the process, we do not believe that these secondary materials present significant threats. The barite ore feedstock facility also produces molten sulfur or sodium hyposulfate from hydrogen sulfide gas piped from the barium carbonate manufacturing process. Because the material is a gas from a production unit, rather than from a waste management unit, and is conveyed to its destination through piping, the gas is not a solid waste. RCRA Section 1004( 27) excludes non contained gases from the definition of solid waste, and therefore they cannot be considered a hazardous waste (see 54 FR 50973). The facility using barium chloride as its feedstock reclaims ammonia in the form of ammonium hydroxide from barium carbonate production wastes and uses this material throughout the facility as a feedstock and reagent. Spent ammoniated process solution is piped from the process unit where it forms to a storage tank where it is commingled with ammoniated spent process solutions from several other on site manufacturing processes. The ammoniated spent process solutions from these other manufacturing processes are beyond the scope of this listing determination. From the storage tank, the facility pipes the commingled ammoniated spent process solutions to an ammonia reclamation unit which reclaims the ammonia in the form of ammonium hydroxide. Ammonium hydroxide is used on site in various manufacturing processes, including the production of ammonium bicarbonate solution for use in the barium carbonate production process. Because the spent solution is piped to the reclamation unit with no significant potential for exposure to the environment, we did not evaluate the solution further. Both facilities produce barium carbonate from a saleable mineral product. 29 Under the Bevill exemption (54 FR 36620± 21), chemical manufacturing begins if there is any further processing of a saleable mineral product. Since these facilities use saleable mineral products as feedstock, their processes are chemical manufacturing, and are not classified as mineral processing. Therefore none of the wastestreams generated by these facilities during the production of barium carbonate are Bevill exempt. See the `` Barium Carbonate Listing Background Document for the Inorganic Chemical Listing Determination'' for more details on these residuals.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00024 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55707 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules d. Waste characterization and Agency evaluation. Barium is the primary constituent of potential concern in the wastes from both facilities. Barium occurs in several production wastes at high levels, in some cases exceeding the TC level (100 mg/ L) in TCLP leachate samples. These TC wastes are coded and treated as hazardous (D005). The Georgia facility holds a hazardous waste treatment permit to allow on site stabilization of barium, and the Pennsylvania facility sends all of their D005 wastes off site for treatment and disposal at a hazardous waste treatment and disposal facility. We decided not to do characterization sampling for wastes from either facility because both facilities submitted information to us on the nature of their wastes. We also received some additional analytical data from the State of Georgia for the Georgia facility. These data provided information on the concentrations (or absence) of the metal constituents of potential concern in the wastes and in test leachates from the wastes. We believe the available information is sufficient to adequately characterize the wastes and to allow us to evaluate their risk potential for the purposes of a listing decision. `` Barium Carbonate Listing Background Document for the Inorganic Chemical Listing Determination'' summarizes the analytical data and other information available for these wastes. We propose not to list any of the wastes from the barium carbonate manufacturing industry. Many wastes from this industry are characteristically hazardous and managed as hazardous wastes either on site or at permitted Subtitle C treatment facilities off site. Other wastes did not exhibit constituents at levels of concern for purposes of a listing given the nature of their management and disposal. Several groups of wastes from each of the facilities are disposed of in a treated form, rather than an as generated form. In general, therefore, we focused our evaluation on the treated form of the wastes. The paragraphs below describe how the wastes are generated and managed for the two processes and our rationale for proposing not to list the wastes. We solicit comments on the proposed listing decisions described below. (1) Wastes from the production of barium carbonate from barite ore feedstock. (a) Treated barium wastes. The waste category, `` treated barium wastes, '' is the treatment residue from the commingling and treatment of several barium wastes in an on site hazardous waste treatment unit. The barium wastes, which are consistently characteristically hazardous for barium (D005) before treatment (or are consistently assumed by the facility to be D005 wastes), include: ÐBarite ore leaching waste, which is solids from the filtration of the liquid product stream from the barite ore roasting and leaching units, ÐBarium sulfide sludge, which is from polishing filtration of liquid barium sulfide, and, ÐWastes from cleaning and maintenance of the barium carbonate production area. A RCRA Subtitle C hazardous waste treatment facility permit governs the onsite treatment process for these barium wastes. The three wastes are sent directly to the treatment unit, or they are stored prior to treatment for short time periods in Subtitle C closed containers. The treatment process is a stabilization process for barium using gypsum (primarily calcium sulfate) to precipitate soluble barium as less soluble barium sulfate. According to RCRA Subtitle C regulations, the treated barium waste must meet the LDR UTS. Treatment takes place in concrete mixer type trucks. Once treatment is complete, the treatment trucks immediately transport the waste to the facility's captive Subtitle D landfill for disposal, located approximately 2 miles from the production facility on facilityowned property. State and facility information indicate that the treated barium wastes no longer exceed the TC level for barium (100 mg/ L from TCLP analysis) and typically leach less than 1 mg/ L barium, according to both SPLP and TCLP analyses. In addition, according to data the facility and the state of Georgia submitted to EPA from sampling events conducted during the past two years at the facility, the waste meets the LDR UTS for all regulated constituents. The treated barium wastes are disposed of in the landfill without daily cover. However, the waste has a relatively high moisture content (approximately 50%) when placed in the landfill and, according to the facility, hardens over time and does not create dust. In addition, the waste does not contain any known volatile constituents of concern. To assess the potential for groundwater releases from the captive, industrial landfill, we compared the SPLP leaching data from the facility and the state of Georgia to existing HBLs for ingestion of groundwater. SPLP data are appropriate for evaluating this waste because it is placed in a Subtitle D industrial landfill. We did not find any constituents in the available SPLP data that exceeded the health based levels by more than a factor of 2 (see section III. E. 3 for a discussion of this riskscreening criterion). See the `` Barium Carbonate Listing Background Document for the Inorganic Chemical Listing Determination'' for further details on the available data. In addition, we found only one exceedence of AWQC standards among the SPLP leaching data for treated barium wastes. Selenium was found at a level of 0.04± 0.06 mg/ L, which exceeds the AWQC standard (0.0050 mg/ L) by a factor of 8 to 12. However, the landfill in which the treated barium wastes are placed is 1,700 feet from the nearest downgradient water body, the Etowah River, and also lies beyond the river's 100 year flood plain. In recent years, the Etowah River in the vicinity of the landfill has had a flow rate varying between 9.9 to 230 m 3 per second on a daily basis. Given the distance over which leachate from the treated barium wastes would need to travel before reaching the river, dilution and attenuation during transport in local groundwater, and further dilution in the Etowah River, we believe the levels of selenium in the leachate would decrease to a level which would no longer pose a risk to the environment. We do not believe it is necessary to assess other management practices for the treated barium wastes. The facility has treated and disposed of their treatment residues in a similar manner for over 15 years. The production facility itself relies on a local source of barite ore, has operated from its current location since 1942 and is therefore not likely to change its location in the near future. The dedicated landfill has a remaining life of nearly 20 years and is located approximately 2 miles from the production facility. Given the dedicated nature of the landfill, its proximity to the production facility, and the significant remaining capacity, we believe it is unlikely that the Georgia facility will dispose of their wastes in any other unit in the near future. Thus there is no need to assess additional management scenarios for this wastestream. Given the facility's Subtitle C waste treatment permit, we believe that the facility's untreated D005 wastes are adequately managed with respect to this rulemaking. In addition, we have found no potential for releases to air, groundwater, or surface water at levels of concern from the treated wastes. Therefore we propose not to list these wastes. (b) Wastewater from barium carbonate precipitate dewatering. The facility filters barium carbonate precipitate from VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00025 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55708 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules residual process solutions and sends this filtrate to the facility's tank based wastewater treatment plant (WWTP) for treatment. According to the facility's RCRA Section 3007 Survey response, the wastewater does not exceed the TC level for any constituent. Wastewater from the barium carbonate production process commingle in the WWTP with wastewaters from other facility processes beyond the scope of this rulemaking and comprise approximately 17% of the total WWTP flow through. The wastewater treatment is an oxidation process. Treatment of the wastewaters occurs in tanks equipped with secondary containment. Given the controlled manner in which the wastewater is managed in tanks, the lack of any volatile constituents of concern, and NPDES regulation of the WWTP effluent, we propose not to list this wastewater. (c) Treated wastewater treatment plant sludge. The facility's WWTP generates a treatment sludge from the commingling and treatment of wastewaters discussed above in the preceding section. The resulting sludge is dewatered to 25% solids content in an uncovered tank. None of the information the facility provided on this waste indicates the presence of volatile constituents of concern. The facility places the dewatered WWTP sludge directly from the WWTP unit into a treatment unit consisting of a concrete mixer type truck containing gypsum (primarily calcium sulfate). The truck mixes the wastewater treatment sludge with the gypsum to convert soluble barium to a less soluble barium sulfate prior to transporting the waste to the facility's off site, captive, Subtitle D landfill. We found low potential for releases from either the dewatering tank or the treatment unit. Analytical data from the state shows that the treatment process reduced leachable barium in the sludge, according to SPLP analysis, from 53 mg/ L to 0.03 mg/ L. SPLP analytical data from the State also show no potential constituents of concern in treated WWTP sludge samples at concentrations above HBLs or above AWQCs. Therefore, this waste screened out from any further risk evaluation for groundwater or surface water. The SPLP data are appropriate for evaluating this waste because it is placed in a Subtitle D industrial landfill. Similar to the treated barium wastes described above in section (a), the waste has a high moisture content when placed in the landfill and is reported by the facility to harden over time. Therefore, we do not believe this waste poses a significant risk through releases of airborne dust. In addition, the waste does not contain any known volatile constituents of concern. We do not believe it is necessary to assess other management practices for this waste. The facility has treated and disposed of their wastewater treatment plant sludge in a similar manner for over 15 years. Given the dedicated nature of the landfill, its proximity to the production facility, and the significant remaining capacity, we believe it is unlikely that the facility will dispose of their wastes in any other facility in the foreseeable future. Based on our knowledge of the current nature of the management of the treated wastewater treatment plant sludge and of the low level of constituents of concern it contains, including volatile constituents, we propose not to list the treated wastewater treatment plant sludge. (d) Spent polypropylene and nylon filter media and baghouse dust collector bags. Baghouse dust collector bags and polypropylene and nylon filter media fabric at the Georgia facility deteriorate over time and must be replaced periodically. The facility washes the bags and filters with water and then soaks them in sulfate solution to stabilize any remaining barium. The facility then disposes of the bags and filter fabric in a local municipal Subtitle D landfill. Wastewaters from the washing of the filters and bags are returned to the production process. Solids from the washing of the filters and bags become part of the cleaning and maintenance wastes that are treated as discussed above in section (a). The facility did not provide chemical composition analyses for these wastes. However, we do not expect either baghouse bags or nylon and polypropylene filter fabrics, which are used primarily for physical separation of solids from liquids in the barium carbonate production process, to contain notable levels of any potential constituent of concern besides barium. According to the facility, neither the bags nor the filters exceed the TC level for any constituent. In addition, the facility treats the materials to stabilize any remaining barium before disposing of them in a Subtitle D municipal solid waste landfill. The facility does not produce a large volume of these wastes; approximately 3 metric tons per year of filters and approximately 1.5 metric tons per year of baghouse bags. Because barium is not volatile, and because we do not expect the filter media and bags to contain any other volatile constituents, we do not believe these residuals pose any risk through airborne pathways. Given the relatively small volume of these wastes, the inert nature of the filters and bags themselves, and the facility's washing and stabilization of barium prior to disposal, we believe these treated bag wastes do not warrant listing as hazardous wastes. (2) Wastes from the production of barium carbonate from high purity barium chloride feedstock. (a) Barium carbonate production wastewaters and wastewater treatment plant sludge. The Pennsylvania facility commingles and treats wastewaters from several manufacturing processes at their facility in an on site, tank based WWTP. Wastewaters from the barium carbonate production process are piped directly to the WWTP and comprise less than 1% of total WWTP flow through; the remainder of the wastewaters entering the WWTP are from manufacturing processes not within the scope of this listing determination. Wastewaters from the barium carbonate production process include: ÐAmmonia vapor scrubber waters and ammonia reclamation unit wastewater. ÐBarium carbonate precipitate washwater. A scrubber captures ammonia vapor from the mixing of ammonium bicarbonate solution with the barium chloride solution to precipitate barium carbonate. Water, sodium hydroxide, and emissions from other manufacturing processes in the facility mix with the ammonia vapor in the scrubber to produce this wastestream. An ammonia reclamation unit recovers ammonia from ammoniated spent process solutions from multiple manufacturing processes, including the barium carbonate manufacturing process, in the form of 28% ammonium hydroxide solution. The unit also produces a wastewater. Approximately 1% of the total ammonia reclamation unit inflow derives from the barium carbonate production process. Therefore, a small percentage of the unit's wastewater derives from barium carbonate production. The facility also produces a wastewater from the washing of barium carbonate precipitate with deionized water in order to remove any process solution remaining on the precipitate. The only possible release route of concern from the tank based system for the wastewaters would be through air releases. This pathway is highly unlikely for the nonvolatile metals that are the potential constituents of concern in these wastes. Given the controlled manner in which the wastewaters are managed and the regulation of the VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00026 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55709 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 30 The Agency has previously evaluated the Bevill status of wastestreams at the Searles Lake facility; see memos dated February 14, 1992 and June 30, 1993 in Appendix E of the `` Boric Acid Background Continued treatment unit's discharge under the NPDES program, we propose not to list these wastewaters. Treatment of the commingled wastewaters consists of neutralization followed by filtration. The treatment generates a sludge. According to the facility's RCRA Section 3007 Survey response, the sludge does not exceed the TC level for any constituent. The facility disposes of the sludge in a local Subtitle D municipal solid waste landfill. We do note the presence of some potential constituents of concern in the WWTP sludge. These constituents include vanadium, nickel, and antimony. However, we do not believe that these constituents derive from the barium carbonate manufacturing process. Because the barium carbonate production process wastewaters contribute less than 1% of the total input to the on site WWTP, any constituents in the barium carbonate production wastewaters sent to the WWTP also make a minimal contribution to the total level of constituents in the combined wastewater in the WWTP and the resulting sludge. In addition, the process uses high purity barium chloride dissolved in deionized water as its primary feedstock and reclaims much of the residual ammonia from its ammonium bicarbonate feedstock. Therefore, the likelihood that the constituents of concern in the sludge might arise from the barium carbonate production process is very low. Moreover, the facility has provided information to us indicating that the barium carbonate process is not the source of these potential constituents of concern and that they derive instead from on site manufacturing processes beyond the scope of today's listing proposal (see `` Barium Carbonate Listing Background Document for the Inorganic Chemical Listing Determination'' for further details). Given the minimal potential for contribution of constituents of concern by the barium carbonate process wastewaters to the WWTP sludge, we propose not to list this sludge under this rulemaking effort. (b) Ammoniated spent process solution storage tank solids. The facility pipes residual process solution containing ammonia directly from the barium carbonate precipitate settling unit to covered storage tanks prior to routing it through an on site ammonia reclamation unit. The barium carbonate process wastewater is one of many ammoniated residual process solutions the facility routes to the storage tanks and constitutes approximately 1% of the unit's total input. The ammoniated spent process solution storage tank accumulates solids which the facility removes and disposes of in a local Subtitle D municipal solid waste landfill on a yearly basis. The tank solids are a small volume waste of 1 MT/ yr. According to analytical data provided by the facility, the solids do not exceed the TC level for any constituent, though they do contain vanadium, nickel, and antimony at levels of potential concern. However, as noted for the wastewater treatment plant sludge, the constituents of concern in the solids are unlikely to arise from the barium carbonate production process because the barium carbonate production process contributes only 1% of the total wastewaters in the storage tanks. In addition, information the facility provided indicates that the nickel, vanadium and antimony found in the sludge derive from other manufacturing processes that are beyond the scope of this listing determination. Thus, given the solids' small volume and the low likelihood that the barium carbonate process wastewater contributes any constituents of concern, we propose not to list the ammoniated spent process solution tank solids in this listing determination. (c) Sludge and spent filter media from filtration of barium chloride solution and barium carbonate drying and sizing unit air pollution control residues. Both the air pollution control dusts from the barium carbonate drying and sizing unit and sludge and the spent filter materials from barium chloride solution filtration exceed the TC regulatory level for barium (100 mg/ L). The facility codes the waste as characteristic hazardous waste (D005). The facility stores these small volume wastes in closed containers on site before sending them to a RCRA Subtitle C hazardous waste treatment and disposal facility for treatment and disposal. We believe that the containers present no significant potential for release to the environment. We believe that regulations applying to characteristic wastes adequately protect against mismanagement. Furthermore, these wastes comprise a very small volume (< 1.23 metric tons per year). Thus, we propose not to list these wastes.

3. Boric Acid a. Summary. We have evaluated the wastes from the production of boric acid and propose not to list any wastes from this process as hazardous under RCRA. These wastes do not meet the criteria set out at 40 CFR 261.11( a)( 3) for listing wastes as hazardous. They do not pose a substantial present or potential threat to human health or the environment. We have identified no risks of concern associated with the current management of the wastes. b. Description of the boric acid industry. Boric acid was produced by two facilities in the United States in 1998. These two facilities are both located in the Mojave Desert in California, one of the few areas where borate minerals can be mined in the United States. The two facilities mine borates from different sources to produce boric acid. The first recovers borate from brines pumped from beneath Searles Dry Lake, California. The second facility mines sodium borate ores near Boron, California. The first facility extracts highly mineralized brine and uses a liquidliquid extraction process to remove the borates from the brine. During the first production step, called the `` loading section, '' the facility mixes the brine with a chelating agent in a kerosene solution that causes most of the boron and some of the sodium and potassium compounds in the brine to bind to the extractant. The loaded extractant is sent through strippers where it is mixed with dilute sulfuric acid to strip the boron, sodium and potassium from the extractant to form boric acid, sodium sulfate and potassium sulfate. The solution is then sent to a solution settler from which the liquor goes to boric acid recovery using crystallization and evaporation techniques. The second facility mines sodium borate kernite ore to produce boric acid through a process of dissolution, classification, thickening, filtration and crystallization. Because the facilities use such different sources and production processes, their resulting wastes are very different and are discussed separately. For more detailed information concerning this industry, see the `` Boric Acid Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal. c. Agency evaluation of wastes generated by the brine recovery process.

Are There Any Wastes in This Process That Fall Under the Bevill Exemption?

The depleted brine from the loading section of the brine recovery process is exempt as a mineral processing beneficiation waste under 40 CFR 261.4( b)( 7)( i). 30 This waste from the VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00027 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55710 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules Document for the Inorganic Chemical Listing Determination'' in the docket. extraction/ beneficiation of ores and minerals is thus outside the scope of the consent decree. The facility reported generating 4,600,000 MT in 1998. This Bevill exempt waste is commingled with wastes which do not qualify for the Bevill exclusion later in the process. The portion of the waste which does not qualify for the Bevill exclusion is within the scope of the consent decree and is discussed below. As discussed in the Agency's prior Bevill evaluations for this facility, mineral processing begins at the liquidliquid extraction step where sulfuric acid is added to the loaded extractant to produce sodium sulfate and boric acid. Wastes generated before this step, including spent brine, are beneficiation wastes and retain their Bevill exemption. All wastes generated after the beginning of mineral processing are non exempt solid wastes. Therefore, all of the wastes at this facility which are generated from the liquid extraction step to the end of the process are all non'exempt solid wastes. See the `` Boric Acid Background Document for the Inorganic Chemical Listing Determination'' in the docket for more information on the Bevill exemption for wastes at this facility.

What Kinds of Wastes Are Generated by the Brine Recovery Process?

The Bevill exempt depleted brine from the loading section is sent through an API settler and Wemco floatation cells designed to separate organic compounds from the brine. The organic emulsions generated in these units and in the process settlers are sent to an onsite `` crud'' treatment facility which breaks down the emulsion into aqueous and organic components. This treatment process generates a non exempt hydrocarbon waste (fuel oil) that is sent off site to a used oil refinery. The Bevill exempt brine is sent to the `` Trona skimmer'' where it is combined with other non exempt wastewaters generated during the process. The Trona skimmer acts as a settling pond promoting phase separation of remaining organic materials in the brine. The Bevill exempt brine is then returned to the dry lake for recharging as required by the facility's Bureau of Land Management permit. Because the non exempt wastewaters are commingled with the Bevill exempt brine in the Trona skimmer, the nonexempt wastewaters are also returned to the dry lake as a small percentage of the overall volume. The non exempt organic waste removed at the Trona skimmer is stored on site in a tank until it is shipped off site to a commercial blender and subsequently burned for energy recovery.

Additional wastes generated by the brine recovery process that are not Bevill exempt include: ÐPetroleum contaminated sludges from containment areas around the API settler, Wemco floatation cells, loading section and liquid liquid extraction (LLX) strippers ÐSpent activated carbon collected from the carbon filter system used to purify the borate liquor before it goes into the crystallization units In addition to the above wastes, the facility also produces other materials during the production of boric acid that are either piped directly back to the production process or used for other purposes. These materials include aqueous residuals and kerosene recovered from the crud treatment process, off specification product, scrubber water and condensate that are returned to on site production units for use. Because these materials are reused on site in production units and there is no significant potential for exposure of these materials to the environment prior to reuse, we found that they present no significant threat. Also, off specification product, when reinserted without reclamation into the process where it originated, is not a solid waste.

How Are the Wastes From the Brine Recovery Process Currently Managed?

Table III± 6 summarizes our information about the wastes from this process:

TABLE III.± 6.Ð BORIC ACID: BRINE RECOVERY PROCESS WASTES Waste category 1998 volume (MT) Sequential management practices Fuel oil from crud treatment facility .................... 690 ................................................................... (1) Stored in covered tank; (2) Sent off site to a Subtitle C permitted used oil refinery. Miscellaneous wastewaters ................................ 194,040 (The Bevill exempt partially depleted brine volume is 4.6 million MT). (1) Combined wastewaters; discharged to Trona skimmer with the Bevill exempt partially depleted brine; (2) Removal of organics in skimmer unit; (3) Commingled partially depleted brine and process wastewaters are returned to Searles Dry Lake for recharging. Organics from Trona skimmer ............................ 10 ..................................................................... (1) Stored in covered tank; (2) Sent to off site Subtitle C blender; (3) Burned for energy recovery. Sludges from containment areas ....................... 20 ..................................................................... (1) Drum storage; (2) 20 cubic yard roll off bins; (3) Transported with manifest off site to Subtitle C landfill as California only hazardous waste. Spent activated carbon ...................................... 43 ..................................................................... (1) Washed; (2) Reclaimed in an on site furnace; (3) Reused in the process.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00028 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55711 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 31 Based on the RfD in IRIS (2E± 1 mg/ kg day) and a 90th percentile drinking water intake rate in children (64 mL/ Kg/ day). What Is EPA's Decision About Whether to List These Wastes as Hazardous?

We propose not to list any wastes from the brine recovery process for the production of boric acid. Our rationale for each waste is presented below. (1) Fuel oil from the crud treatment facility. We propose not to list the fuel oil generated at the crud treatment facility. The facility characterized the fuel oil as 100 percent hydrocarbons. The fuel oil is stored on site in a covered tank prior to being shipped offsite to a Subtitle C permitted used oil refinery. For those scenarios where wastes are managed in a tank, the impervious nature of the construction materials (concrete, fiberglass, or steel) of tanks is unlikely to result in releases to groundwater in all but the most catastrophic scenarios. We also are not concerned with potential air releases because the tank is covered. The subsequent treatment at the permitted used oil refinery is already regulated under Subtitle C and the used oil regulations. Therefore, we propose not to list this waste. (2) Miscellaneous wastewaters. We propose not to list the miscellaneous wastewaters. We evaluated the potential for an exposure pathway via groundwater ingestion and determined that no such pathway exists. The facility producing boric acid by recovering borates mined from Searles Dry Lake is located in California's Mojave Desert. The process and associated wastewaters are tied to the Mojave Desert location because it is the source of the borate rich brine. The environment is arid with only 4 inches of precipitation annually. The groundwater under the facility has total dissolved solids (TDS) levels as high as 450,000 ppm. All wastewaters, including the Bevill exempt depleted brine, are co managed and ultimately returned to the dry lake resource. Due to the extremely high TDS levels in the area, the water is non potable. The surrounding communities have drinking water piped in from 25 miles away. Therefore, no groundwater exposure pathway exists. Furthermore, the total volume of the miscellaneous wastewaters is 4 percent of the volume of the depleted brine; any contaminants in these wastewaters would therefore be diluted by a factor of 25 prior to return to the dry lakebed. Most of the miscellaneous wastewaters are generated in the later part of the process and thus we do not expect they will contain constituents of concern at significant levels. There is one wastewater that contains organic constituents not found in the influent brine (formaldehyde and fuel hydrocarbons). This wastewater is generated at the carbon column. However, it only represents 0.03 percent of the total volume that is returned to the dry lake. Also, the reported level of formaldehyde in the waste would be well below the HBL for this chemical (3 mg/ L) 31 after mixing with other wastewaters. We are not concerned with potential air releases because the Trona skimmer, where the wastes are mixed, is covered. The facility also mixes a characteristic (D002) HCl acid waste stream with the Bevill exempt depleted brine prior to reaching the Trona skimmer. The resultant mixture is not characteristic and the mixing takes place within a pipeline where there is no opportunity for exposure to the characteristic waste before or during the mixing. Given the factors listed above, particularly the lack of an exposure pathway, we propose not to list the miscellaneous wastewaters. (3) Organics from the Trona skimmer. We propose not to list the organics (chlorinated hydrocarbons) recovered from the Trona skimmer. The organics are stored in a covered tank before being shipped off site. For those scenarios where wastes are managed in a tank, the impervious nature of the construction materials (concrete, fiberglass, or steel) of tanks is unlikely to result in releases to groundwater in all but the most catastrophic scenarios. We also are not concerned with potential air releases because both the Trona skimmer and tank are covered. The waste is shipped off site to a Subtitle C permitted blender prior to being burned for energy recovery in cement kilns. Burning by cement kilns is regulated under MACT standards for cement kilns (64 FR 31989, June 14, 1999 and 64 FR 52827, September 30, 1999). Therefore, we did not further evaluate potential risks from burning the organics under this listing. The facility reported a California only hazardous waste code CA343 (organic liquids, unspecified) for the waste but did not report any federal characteristic codes. The facility manifests the waste using the California code when they send it to the blender. Because this waste has significant BTU value and also carries a state hazardous waste code, we expect this management practice to continue; we do not believe there would be any significant benefit to the environment by listing this waste. (4) Sludges from containment areas. We propose not to list the sludges collected from containment areas around the process tanks, the loading section, LLX strippers, Wemco flotation cells and API settlers. The facility reported a California only hazardous waste code CA611 (petroleum contaminated soils) for the waste but did not report any federal characteristic codes. The facility stores the waste onsite in drums, transfers to it to 20 cubic yard roll off bins and mixes the sludge with soil, and then ships the waste offsite with a manifest as a California only hazardous waste to a Subtitle C landfill. The facility is tied to its location in California so we believe it is plausible that the waste will always be treated as a California only hazardous waste. We do not believe there would be any significant benefit to the environment by listing this waste. (5) Spent activated carbon. We propose not to list the carbon that is regenerated on site. The carbon is regenerated in an on site furnace. The carbon filtration process occurs later in the process after much of the organic additives have settled out of the borate liquor. Consequently, we expect that the filters will not collect high concentrations of constituents of concern, except perhaps kerosene related organics. We expect any such constituents that are filtered out using carbon adsorption to be combustible. There is no potential for exposure prior to the regeneration process or during the return of the activated carbon to the carbon filter. The furnace is permitted by the State of California Air Control Board. Although the permit does not contain any requirements for emission controls, it does require annual reporting. We reviewed the emissions data and do not believe that the emissions from the furnace are of concern. The reported emission levels are significantly below the MACT standards for permitted hazardous waste incinerators (64 FR 52827, September 30, 1999). We expect the use of this furnace to continue because it is expedient to regenerate the carbon onsite and the facility is unlikely to relocate given the proximity of the mineralized brine source. Therefore, we propose not to list this waste. d. Agency evaluation of wastes generated by the kernite ore process.

What Kinds of Wastes Are Generated by the Kernite ore Process? The facility generates two primary wastestreams: Tailings and gangue. The tailings include the wastewaters and fine insolubles from ore processing and boric acid production. The tailings are managed in tanks and then pumped to on site evaporation ponds/ surface impoundments. The boric acid gangue which includes clay, sand and other VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00029 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55712 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 32 California Water Quality Control Plan for the Lathontan Regions, revised 1991 (p. 4.6± 1) 33 Source: California Regional Water Quality Control Board permit, board order 6± 93± 17. course insolubles, is produced during the separation of solids from the borate liquor, a step the facility calls `` classification. '' The gangue is placed on a slab for drainage and then managed in on site waste piles with gangue produced from the other production process at the facility. The drainage from the slab is sent to the tailings ponds. The remaining wastestream is comprised of the filters from the filtration of the borate liquor to remove any remaining insoluble ore material prior to crystallization. The filter aid is washed off weekly and managed with the tailings. The spent filters are transferred to a solid waste bin in preparation for on site disposal in a industrial Subtitle D landfill. In addition to the above wastes, the facility also produces off specification product that is put directly back to the production process. Because the material is reused on site in production units in ways that present low potential for release, and because we evaluated process waste generated after the secondary material is reinserted into the process, we do not believe that the offspecification product presents significant risks. Note that, when facilities process off specification product by reinserting the offspecification product back into the process where it originated, without reclamation, the off specification product would not be a solid waste. The facility made beneficiation exemption claims under the Bevill amendments for the tailings and gangue wastes. Because we propose not to list these wastes, we did not review the facility's Bevill exemption claims.

How Are the Wastes From the Kernite Ore Process Currently Managed?

Table III± 7 summarizes our information about these wastes:

TABLE III± 7.Ð BORIC ACID: KERNITE ORE PROCESS WASTES Waste category 1998 volume Sequential management practices Tailings ............................................................... Up to 750,000 gallons/ day 1 ............................. (1) Stored in tank; (2) Pumped to evaporation ponds/ surface impoundments Gangue ............................................................... Portion of 900,000 MT 2 .................................... (1) Placed on slab for drainage; (2) Trucked to on site waste piles. Spent filters ........................................................ 3 ....................................................................... (1) Stored in solid waste bin; (2) On site industrial Subtitle D landfill.

1 Capacity volume for boric acid surface impoundments. Current daily quantity is lower. Source: California Regional Water Quality Control Board permit, board order 6± 93± 17. 2 The boric acid coarse gangue is co mingled with gangue from the other production process at the facility. That process is outside the scope of the consent decree. The boric acid gangue represents only a minor proportion of the total 900,000 tons of gangue typically deposited annually on the waste piles. Source: California Regional Water Quality Control Board permit, board order 6± 93± 17.

What Is EPA's Decision About Whether To List These Wastes as Hazardous?

For the reasons set out below, we propose not to list any wastes from the kernite ore process for the production of boric acid. (1) Tailings. We propose not to list the tailings from boric acid production. The tailings are managed in a tank and then pumped to evaporation ponds. The facility provided TCLP data for the tailings. Those data show waste contains arsenic and antimony above health based drinking water levels. The Agency also assumed that boron was present in significant levels due to the nature of the ore. The facility provided total levels for the boron concentration in the waste. We conducted an in depth review of the groundwater conditions at the site and have concluded that a groundwater exposure pathway does not exist. No one is currently living near the facility boundary closest to the waste management unit areas and it is unlikely that future development will occur. The closest existing drinking water well is two miles away from the waste management units. It is a community well and is subject to all applicable drinking water standards. In addition, there are several factors described below which make contamination of this well from a potential release from the facility's evaporation ponds unlikely. The groundwater under the off site area of land closest to the waste management units is not suitable for use as drinking water. The ore body, which is the raw material for the process, has a localized impact on the groundwater in its vicinity. Monitoring wells in the area show that the groundwater in the geologic strata underneath the off site area adjacent to the waste management units has total dissolved solids (TDS) levels in excess of three times the maximum level for an aquifer to be considered a drinking water source in California. 32 Additional factors such as low flow rate and high treatment cost make the potential for a private well in that area highly unlikely. Municipalities can tap into an alternative water source through a regional pipeline and need not rely on groundwater. The geology of the area has several characteristics that reduce the potential for releases from the impoundments from reaching known drinking water sources. The transport time to groundwater for the constituents of concern appears to be significant given the depth to groundwater under the waste management units (170± 220 feet) and the affinity of these constituents to bind with soil. 33 The area under the facility has several geologic faults that act as groundwater barriers. The South Borax fault is likely to prevent any potential release from the waste management units from reaching the drinking water source for the existing community well. The fault is located just south of the waste management units, between the units and the well. In addition, the groundwater underlying the waste management units is contained in the tertiary soil layer whereas the community well draws from the quaternary layer. We believe that migration between these two layers would be limited. (The facility submitted a detailed summary of the geologic conditions at the site. This information has been placed in the docket for this rulemaking. See `` Summary of Boron Operations Hydrogeology, Potential Groundwater Receptors and BAP Waste Management Parameters''). Finally, we note that the impoundments in question are designed with a triple liner and leachate collection system, making any significant release less likely over the active life of the units. Based on these factors, we do not believe there is a VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00030 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55713 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules groundwater exposure pathway from the tailings. We also assessed the potential for air releases from the tailings ponds. Because the constituents of concern from this process are nonvolatile metals, we are not concerned with releases through volatilization. Although the surface impoundments are evaporation ponds, the facility claims that there is still some level of moisture in the ponds at all times, thereby minimizing release of particulates to the air. The particulates would not likely be subject to wind blown erosion due to the moisture level of the waste. Furthermore, the closest off site receptors are at least two miles away from the unit. Due to dispersion, it is unlikely that any particulate releases would reach such receptors at significant levels. The facility also provided a risk assessment which assessed the air risks from the tailings ponds. Their assessment did not show any air risks from the tailings ponds even when they assumed a conservative dry down process for the unit. (The facility's air risk assessment is available in the RCRA docket for today's proposal). In summary, there are several site specific factors that need to be taken into account when evaluating risks from this waste. This is the only facility in the country producing boric acid from ore. The facility is tied to its location because it is the source of the ore. The hydrogeology of the site is such that local groundwater is not suitable for drinking water use, and any potential releases from the unit would be unlikely to migrate to any drinking water source. Furthermore, the facility is remote with the nearest receptors two miles away. Based on all of these facts, we propose not to list the tailings from the kernite ore process for the production of boric acid. (2) Gangue. We propose not to list the gangue generated during the boric acid process. Initially, the gangue is placed on a slab to drain. The drainage from the gangue is collected and managed with the tailings (we assessed the drainage as part of the tailings wastestream; see section (1) above for our listing recommendation). The drained gangue is trucked to on site waste piles. The gangue is wet when transported to the waste pile but most of the moisture evaporates quickly in the dry desert environment. The same geological conditions apply to the gangue waste unit as described above for the tailings waste unit. The gangue is ultimately managed as a dry waste pile and there is virtually no precipitation to cause leaching. We assumed a greater risk to groundwater would come from the tailings because there is any liquid associated with the gangue would evaporate before leaching into the subsurface. Based on our decision regarding the tailings, we did not further evaluate the risks to groundwater from the gangue. We did assess in more detail the potential for air releases from the waste pile. We do not expect releases of the nonvolatile metals from this waste. The moist gangue solids are trucked to onsite waste piles. The gangue contains enough sodium sulfate to cause the gangue piles to set up like cement when it dries, helping prevent erosion and air release of particulates from the pile. As a further check of potential air releases, we examined the potential for release of the constituent of most concern, arsenic. According to data provided by the facility, the total levels of arsenic in the gangue vary between 25 and 78 mg/ kg. We compared these total concentrations to one of the levels calculated as part of the EPA's Air Characteristic Study (530± R± 99± 019b, Aug 1999, Table 4± 3). The Study evaluated different waste management and receptor scenarios to determine waste concentrations that would remain below a specific target risk. Using the waste pile scenario at a receptor distance of 150 meters, the study showed that arsenic levels of 6,000 ppm did not cause exceedences of the target risk levels. The concentration levels in the gangue are well below this number. In addition, the location of the facility is remote with the closest residence two miles away, which is significantly beyond the 150 meter range. The Air Characteristics Study only evaluated direct risks from inhalation, not indirect risks. However, due to the desert environment where the facility is located, risks related to consumption of soil, plants or animals are highly unlikely to arise. Based on these factors, we believe that the arsenic levels in the gangue do not present unacceptable risks via the air pathway. In addition to arsenic, boron and antimony are the two other constituents of concern present in the gangue. Based on data provided by the facility, antimony is found at total concentrations ranging from 36 mg/ kg to 84 mg/ kg in the gangue. The facility estimated the boron total concentration levels to be 25,000 ppm based on average daily sampling of the gangue. Arsenic is the most toxic of the three constituents. Because the particulate releases and exposure scenario would likely be the same for all three constituents and because, as discussed above, we do not believe arsenic poses a concern, we also believe there are no unacceptable levels of risk from the antimony and boron in the gangue. After assessing possible risks from arsenic, we compared the ratios of the waste concentrations for the three constituents to the ingestion health based level for each constituent. This ratio for arsenic was an order of magnitude higher than the ratios for antimony and boron, indicating that the highest potential risk from ingestion would arise from the arsenic. Thus, based on the lack of significant risk for arsenic in this waste, the Agency concluded that neither antimony nor boron pose a significant air risk at this site. In addition, as mentioned above in the tailings section, the facility has conducted an air risk assessment. The document shows no significant risk from the management practices for the gangue waste pile. The facility's risk assessment is available in the docket for today's proposal. Therefore, based on all of these factors, we propose not to list the gangue from the production of boric acid using the kernite ore process. (3) Spent filters. We propose not to list the spent filters generated during the filtration step of the boric acid production process. The spent filters are stored in a solid waste bin and then managed in an on site industrial Subtitle D landfill. The filtration step occurs late in the process, so we expect minimal contamination. In addition, because the filters are washed weekly, the vast majority of any contaminants filtered out at this stage would be captured by the wash process and managed with the tailings (see section (1) above for listing determination on the tailings). The facility applies a daily cover at the landfill which protects against residual particulates from being released into the air. Furthermore, the quantity of spent filters is relatively small (3 MT), making it unlikely to present a significant risk in the landfill. Finally, the location of the facility is remote with the closest residence being two miles away. Therefore, we propose not to list the spent filters from the kernite ore process for the production of boric acid.

4. Cadmium Pigments a. Summary. We propose not to list any wastes from the production of cadmium pigments. All of the nonwastewater residuals consistently exhibit the toxicity characteristic for barium, cadmium, and selenium. There is only one producer, and over the past seven years the producer has drummed and shipped with manifests all its nonwastewater residuals to an off site Subtitle C facility for treatment to applicable LDR standards. The VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00031 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55714 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 34 USGS Minerals Information, Mineral Commodity Summary, 1996 (see http:// minerals. usgs. gov/ minerals/ pubs/ commodity/ cadmium/ 140396. txt) wastewaters are pretreated on site in closed tanks prior to discharge to a POTW, which is regulated under the Clean Water Act. We conclude that the existing regulatory controls adequately reduce risks, and there are no exposure pathways of concern. These wastes do not pose a substantial present or potential hazard, and thus do not meet the criteria for listing set out in 40 CFR 261.11( a)( 3). b. Description of the cadmium pigments industry. One facility produced cadmium pigments in the United States in 1998 and 1999. Cadmium pigments are cadmium sulfides of variable composition, usually produced as powders but also available in other forms such as pastes and liquids. Cadmium pigments are used to provide shades of bright yellow, orange, red, and maroon. The shades depend on the ratio of cadmium and zinc to sulfides and selenium. Current uses of cadmium pigments include decorative and protective coatings for plastics, glass, ceramics, rubber and other materials. The coatings provide heat resistance to surfaces and a barrier to chemical and sunlight exposures. Cadmium pigments are produced by digesting cadmium metal in sulfuric acid, nitric acid, and water to produce a cadmium sulfate solution (liquor). Chemical reagents are added to the liquor to selectively precipitate out metals which are present as impurities. Sodium sulfide and metals (e. g., zinc, selenium) are added to the purified liquor to yield a slurry which, after filtration, is the `` greencake'', the first intermediate product from the cadmium pigments production. The greencakes are then washed, sized, and calcined. The calcined materials are ground, rewashed, filtered, dried, milled, and blended to make different shades. The use of cadmium pigments is declining. 34 Growth in the overall demand for cadmium pigments is limited to the manufacturing areas requiring use of cadmium pigments, such as the plastics industry, where no substitute is adequate. Our RCRA Section 3007 Survey results show that six out of seven facilities ceased production of cadmium pigments in recent years. The domestic demand for cadmium pigments in the next few years is likely to remain stable. A more complete discussion of this process and the industry is provided in the `` Cadmium Pigments Listing Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal. b. What kinds of wastes are generated by this process?. Using the facility's survey response, we divided the wastes into two broad categories: Wastewaters and non wastewaters. Table III± 8 summarizes the types of wastes in each category, the characteristics of each waste, waste volume, and current management practices:

TABLE III± 8.Ð CADMIUM PIGMENT PRODUCTION WASTES Waste category Reported waste codes 1998 waste volume (MT) Management practice Non wastewaters Miscellaneous solid wastes, including materials from dust collectors, plant cleanup, filtered pigments from the presses, and from the on site wastewater pretreatment process. D005 D006 D010 33.5 .................. Each waste is drummed (separately or sometimes combined) and shipped to a commercial off site hazardous waste treatment facility to be treated and decharacterized before placing in a Subtitle D landfill Note: D005Ð barium D006Ð cadmium D010Ð selenium Contaminated paper and cloth, including filter bags, filter cloths, filter cartridges, and dust collector bags. D005 D006 D010 9.3 Contaminated gaskets generated from the red and yellow calciners. D005 D006 D010 0.3 Iron press residue generated from digestion of cadmium metal. D005 D006 D010 4.5 Wastewaters Gas scrubber wastewater (spent caustic from scrubbing vapors generated from calcination process). Not reported ..... pH adjusted, treated to remove zinc and cadmium The resulting sludge is a part of the miscellaneous solid wastes. All these wastewaters are then combined and further treated in on site closed tanks for pH adjustment 2 step filtration monitoring for turbidity prior to discharge to a POTW. Process wastewater from filtering the greencake ........ Not reported ..... pH adjusted, treated to recover cadmium. Process wastewaters from wet washing system ......... Not reported.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00032 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55715 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 35 Quarterly leachate monitoring data from March 95 to September 98, provided by Michigan's Department of Environment, Wayne County District Office and Local Office. c. Agency evaluation. After evaluating the characteristics and current management practices of all the waste residuals, we determined that: (1) all the non wastewater wastes are being properly treated and managed as hazardous wastes under RCRA regulations, and (2) all the wastewaters are being treated on site in closed tanks and discharged to a permitted POTW, where they are subject to the Clean Water Act. Therefore, we did not pursue risk assessment modeling for any of these wastes. The following are the details of our evaluation: (1) Non wastewaters. In its RCRA Section 3007 Survey, the facility classified all four wastes of this category as characteristic hazardous, as generated, for barium, cadmium, and selenium. The facility also provided data characterizing each non wastewater residual for total and TCLP concentrations of eight TC metals. Except for chromium (which was detected in the TCLP leachate of one waste below its health based level), no other hazardous constituents were reported. The total volume of these four wastes was 47.6 metric tons in 1998. Over the past seven years the generator has managed all its nonwastewater wastes generated from the production of cadmium pigments as TC hazardous wastes. These wastes are drummed and shipped with manifests to a commercial off site Subtitle C facility for treatment. The off site treatment includes mixing and treating the wastes with other solid wastes and the addition of lime and fly ash to meet the current LDR treatment standards (via stabilization). The resultant mixture forms a concrete like residue, which no longer exhibits a characteristic and is managed in a Subtitle D landfill. We believe this management, which complies with existing Subtitle C regulations, adequately protects human health and the environment. Although we generally believe that Subtitle C regulations for characteristic wastes adequately prevent mismanagement, we have additional data that help confirm our conclusion for this waste. The landfill information and leachate data provided by the local and state governments (per our request) indicate that the landfill has a liner with a leachate collection system. The landfill leachate data 35 we have to date demonstrate that constituents detected in the landfill leachates are not attributable to the cadmium pigments production wastes. The landfill information and leachate data are provided in the `` Cadmium Pigments Listing Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal. We recognize that the residues from commercial treatment facilities represent the commingling of wastes from a variety of facilities and wastes. Therefore, information on the landfill leachate from treated material is of limited use. However, the data available indicate that the cadmium pigment wastes do not present a substantial hazard when disposed. Given that the generating facility has followed the reported management practice for seven years, we believe use of this or comparable treatment and disposal will continue.

What Is EPA's Listing Rationale for These Wastes? We propose not to list any of the four wastes in this category as hazardous because they are already managed in compliance with existing hazardous waste regulations, including full compliance with the BDAT requirements for treatment prior to land disposal. We conclude that available data on the specific cadmium pigment manufacturing wastes do not support a decision to list the wastes as hazardous. (2) Wastewaters. We propose not to list the wastewaters as hazardous because the gas scrubber and the process wastewaters are pretreated onsite in closed tanks prior to discharge to a POTW. The wastewater treatment tanks provide sufficient structural integrity to minimize potential releases to groundwater. We are unlikely to find potential air releases from these tanks as neither volatile contaminants nor airborne particulates are likely to be present in these wastewaters. During treatment, the closed tanks present no significant threat of release to the environment. After treatment, the wastewaters are subject to the Clean Water Act program. We conclude that the wastewaters do not warrant listing. We assessed solids from the on site treatment as miscellaneous wastes discussed above in section (1).

5. Inorganic Hydrogen Cyanide a. Summary. We propose not to list any wastes from the production of inorganic hydrogen cyanide (HCN) as hazardous under Subtitle C of RCRA. These wastes are managed in on site wastewater treatment processes, industrial landfills, municipal landfills, hazardous waste incinerators, hazardous waste landfills, and hazardous waste injection wells. After analysis of these waste management practices and potential exposure pathways, we concluded that there are no risk pathways of concern. These wastes do not meet the criteria set out at 40 CFR 261.11( a)( 3) for listing as hazardous. They do not pose a substantial present or potential hazard to human health or the environment. b. Description of the inorganic hydrogen cyanide industry. Hydrogen cyanide (HCN) is used in the manufacture of a number of important chemicals including: adiponitrile to produce nylon, methyl methacrylate to produce clear acrylic plastics, sodium cyanide for the recovery of gold, triazines for agricultural herbicides, methionine for animal food supplements, and chelating agents for water treatment. HCN is manufactured via two primary inorganic synthesis processes: Andrussow and Blausa ¨ ure MethanAmmoniak (BMA). The Andrussow process involves the reaction of ammonia, methane (natural gas) and air over a platinum catalyst; the BMA process is similar except the reaction occurs in the absence of air. The reaction products are quenched with water. Excess ammonia reactant is recovered for reuse in the reaction or converted to an ammonium salt. The aqueous HCN product is purified and concentrated for use as a liquid feedstock for manufacturing of one or more of the final products mentioned above. Two of the Andrussow process manufacturers do not produce a liquid hydrogen cyanide intermediate product but immediately convert the hydrogen cyanide in the reactor gases in a sodium hydroxide contactor to produce liquid sodium cyanide. There are ten manufacturers of hydrogen cyanide in the United States who use the Andrussow or the BMA process. Of these ten manufacturers, only one uses the BMA process. Two of the nine Andrussow manufacturers use an abbreviated version of the Andrussow process to produce sodium cyanide. Manufacture of sodium cyanide as a final product results in fewer wastes and significantly lower wastewater volumes. The inorganic hydrogen cyanide industry subject to this rulemaking is composed only of the facilities that produce hydrogen cyanide as an intermediate product or feedstock to manufacture a variety of commercial chemicals using the Andrussow and BMA processes. This proposal specifically does not cover wastes from the manufacturing of HCN as a byproduct in the manufacture of acrylonitrile by the ammoxidation of VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00033 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55716 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules propylene (Sohio process). The Sohio process is inherently an organic chemical manufacturing process, and is not within the scope of the inorganic chemicals manufacturing industry or the consent decree. Furthermore, we have already evaluated wastes for acrylonitrile manufacturing, and the cyanide wastes associated with the Sohio process (K011, K013, and K014) are subject to Subtitle C regulation. c. What kinds of wastes are generated by this process?

How Did We Categorize the Wastes?

Wastes generated from the production of hydrogen cyanide consist of various types of wastewater, various types of spent filter media, spent catalyst, biological solids from wastewater treatment, and ammonium salts. Based on an assessment of the wastes reported in the survey, the wastes were categorized as follows: ÐCommingled wastewaters. This waste includes continuously generated wastewaters such as HCN purification wastewater and ammonia purification wastewater. ÐAmmonia recycle cartridge and spent carbon filters. This waste consists of spent filter material and filter solids that are generated during the filtration of the recycled unreacted ammonia stream prior to being reused as process feedstock. ÐBiological wastewater treatment solids. The biosolids are generated from the biological treatment of process and non process wastewaters to remove residual cyanide and organonitrile contaminants. ÐFeed gas cartridge and spent carbon filters. This waste consists of spent filter material and filter solids that are generated during the filtration of natural gas prior to being used as process feedstock. ÐProcess air cartridge filters. This waste consists of spent filter material and filter solids that are generated during the filtration of ambient air that is used in the reaction. ÐAcid spray cartridge filters. The waste consists of spent filter cartridges and filter solids from acid spray filters used in the hydrogen cyanide stripper. ÐSpent catalyst. This waste consists of metal gauze panels that contain the precious metal catalyst used to catalyze the synthesis reaction. The catalyst activity diminishes with time and needs to be replaced with fresh catalyst periodically. ÐAmmonium sulfate and ammonium phosphate. The ammonium wastes are generated from the neutralization of excess ammonia in the process using sulfuric or phosphoric acid. ÐMiscellaneous wastewaters. These numerous wastewaters are generated during plant upsets or shutdowns for maintenance and are reported in detail in the `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemical Listing Determination. '' ÐHCN polymer and sump wastes. These wastes are generated in process vessels, tanks, and wastewater collection sumps and removed during periodic plant maintenance operations. ÐSludge from wastewater collection tank. This waste is generated from the settling of suspended solids in wastewater tanks and removed during periodic plant maintenance operations. ÐHCN storage tank solids. These solids settle out of the HCN product. The solids are generated during manual tank cleaning after thorough washing. ÐWastewater filters. These are generated from the filtration of process wastewater prior to deep well injection. ÐAmmonium sulfate filters. This waste is from the filtration of the ammonium sulfate solution from the neutralization of excess ammonia by sulfuric acid. The filtered ammonium sulfate solution is then crystallized into solid form prior to sale as fertilizer. ÐSpent ammonium phosphate. Ammonium phosphate solution is used to scrub the off gas from the reactor to assist in ammonium recovery. ÐOrganic layer from wastewater collection tank. This is generated from the treatment of commingled HCN wastewater and predominantly nonHCN process wastewater. In addition to these wastes, other residuals are produced by some of the facilities that are recycled back to the production process. These materials consist of process water and recovered ammonia. These residuals are reused on site via enclosed piping systems and tanks, minimizing the potential for environmental releases. Also, we evaluated all wastes generated after these secondary materials are reinserted or reused; we do not believe that these secondary materials present significant risks. Consequently, we did not evaluate them further.

How Are These Wastes Currently Being Managed?

Table III± 9 summarizes the major waste categories, waste characteristics, waste volumes, and their current management practices:

TABLE III± 9.Ð INORGANIC HYDROGEN CYANIDE PRODUCTION WASTES Waste Category (Number of facilities) Reported Waste Codes 1 1998 volume (MT) Management practices Commingled wastewaters (8) ............................................................................ D002 ........ 5,600,000 On site wastewater treatment in tanks or surface impoundments, discharge to NPDES outfall or POTW. Ammonia recycle cartridge and spent carbon filters (5) ................................... none ......... 73 Off site municipal D landfill; off site industrial D landfill; on site Subtitle C landfill; on site Subtitle C incineration Biological wastewater treatment solids (4) ........................................................ none; F039 3 . 45,397 Off site industrial Subtitle D landfill; off site municipal Subtitle D landfill; on site Subtitle C landfill. Feed gas cartridge and spent carbon filters (9) ................................................ none ........ 9.7 Off site municipal D landfill; off site industrial D landfill; on site Subtitle C landfill as non hazardous waste; offsite recycle/ reuse via return to manufacturer Process air cartridge filters (8) .......................................................................... none ........ 7.5 Off site municipal D landfill; off site industrial D landfill; reclamation.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00034 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55717 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules TABLE III± 9.Ð INORGANIC HYDROGEN CYANIDE PRODUCTION WASTESÐ Continued Waste Category (Number of facilities) Reported Waste Codes 1 1998 volume (MT) Management practices Acid spray cartridge filters (1) ........................................................................... none ......... 1.1 On site Subtitle C landfill as nonhazardous waste. Spent catalyst (10) ............................................................................................. none ........ 4.06 Off site reclamation. Ammonium sulfate and ammonium phosphate (3) ........................................... none ........ 27,425 Off site use as fertilizer. Miscellaneous wastewaters (4) ......................................................................... none ......... 209,000 Managed with commingled wastewaters described above. HCN polymer and sump wastes (1) .................................................................. none ........ 0.7 Off site industrial D landfill Sludge from wastewater collection tank (2) ...................................................... D001; D018 2 3.9 Stabilization/ off site Subtitle C landfill; off site Subtitle C incineration. HCN storage tank solids (1) .............................................................................. none ........ 0.3 Off site municipal D landfill Wastewater filters (1) ......................................................................................... none ........ 450 Captive off site Subtitle C incineration. Ammonium sulfate filters (1) .............................................................................. none ........ 1.1 Off site industrial D landfill Spent Ammonium Phosphate (1) ...................................................................... none ........ 230 On site reuse as biological treatment system nutrient source or on site nonhazardous waste incineration Organic layer from wastewater collection tank (1) ............................................ D001 ........ 43.3 (1993) Off site Subtitle C incineration 1 D001 (ignitability), D002 (corrosivity), D018 (benzene). 2 Includes 2.1 MT reported for 1993. 3 One facility commingles wastewater to generate a hazardous waste derived from F039 wastewater.

d. Agency evaluation. We selected three facilities in Alabama, Tennessee, and Texas to collect record samples of wastes for the listing determination. These facilities were selected based on the survey information for the entire industry sector and collectively represent all the wastes generated and all of the waste management practices used by the manufacturing sector. (1) Commingled wastewaters.

How Many Facilities Generate This Waste Category and How Is It Managed?

Eight of the ten facilities generated commingled wastewaters from the inorganic hydrogen cyanide process. The total volume of commingled wastewaters reported by these facilities was 5.5 million MT in 1998. Six of these eight facilities treat the commingled wastewaters using one or more of the following operations in their on site wastewater treatment processes: (a) steam stripping to remove cyanide and ammonia, with off gasses vented to flares, scrubbers or incinerators; (b) pH adjustment; (c) aerated or non aerated biological treatment in tanks or lined/ unlined surface impoundments; (d) ozone treatment in tanks; (e) oxychlorination in surface impoundments; (f) settling in surface impoundments; and NPDES outfalls, or POTWs. In addition to commingling of the hydrogen cyanide process wastewaters, some facilities also commingle these wastewaters with wastewaters from other non HCN processes generated in the same chemical manufacturing complex. The remaining two facilities manage their commingled wastewaters by filtration and disposal via deepwell injection.

What Management Scenarios Were Assessed? Based on the reported management practices, we assessed the potential for releases from tanks and surface impoundments. We decided that risks from the ultimate discharges to NPDES outfalls and POTWs are adequately controlled by the Clean Water Act. Risks from discharges to Class I injection wells with RCRA `` no migration'' variances are adequately regulated under the Safe Drinking Water Act and RCRA (see section III. D. 3). Potential releases to groundwater. We assessed both the tank and surface impoundment scenarios for potential releases to groundwater and determined that the unlined surface impoundment scenario poses a more significant potential risk to groundwater than the tank scenario. We focused on the surface impoundment pathway because several of the reported surface impoundments are unlined, posing a potential direct release pathway to groundwater. We take the position that tanks, by the impervious nature of the construction materials (concrete, fiberglass, or steel) are not likely to result in significant releases to groundwater. We conducted sampling and analysis of these wastewaters at the three facilities located in Alabama, Tennessee, and Texas currently using surface impoundment based wastewater treatment systems. We assessed each site individually, because we believe it is reasonable to assume that large volume wastewaters managed in impoundments in question would not be moved off site or to different locations. Our decision on what scenario to assess was based on review of our analytical data and the characteristics of the surface impoundments used at the three facilities. We evaluated the potential for groundwater releases to drinking water wells at the Alabama site, and potential surface water impacts at the Tennessee facility. The analytical data for the wastewater managed in the surface impoundment at the Texas facility showed that all levels of the toxicants of concern are below healthbased levels, or are associated with other commingled on site production processes and are not due to HCN production. The Alabama facility manages wastewater in a series of surface impoundments and tanks that provide equalization, oxidation, maturation, rock reed filtration, and mixing. In addition, the facility has an emergency holding basin which has also been used for HCN process wastewaters. The surface impoundments are equipped with double synthetic liners with leachate detection and collection systems. The oxidation basin is a concrete lined structure with an additional synthetic liner. Our analytical data indicates that concentrations at the inlet to the impoundments would exceed the HBLs for one constituent of concern (acetonitrile). A study of existing wells near the facility indicates the presence of private water wells within a one mile radius of the property boundary. We VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00035 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55718 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 36 The `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemical Listing Determination, '' available in the docket for today's proposal, provides all analytical data we developed, as well as split samples collected by industry, where available. therefore assessed these units further for potential releases to groundwater. The Tennessee facility manages the wastewater in unlined surface impoundments and some of the toxicants of concern were above the health based levels and water quality criteria, thus, we assessed this facility's impoundments for potential releases to groundwater. As described below, the Tennessee facility and its surface impoundments are sited on the banks of the Loosahatchie River, with no off site downgradient wells. However, we did assess the impact from potential releases to groundwater to the nearby river at this site. Potential releases to air. We also examined the air exposure pathway for the wastewater treatment impoundments and tanks because of the potential release of volatile organic compounds and hydrogen cyanide from the wastewater treatment units. EPA is developing maximum achievable control technology (MACT) standards for cyanide manufacturing under the Clean Air Act (CAA), which may address these emissions. Although this rule will be technology based, the CAA ultimately requires EPA to regulate significant risks remaining after the imposition of technology based controls. EPA has also proposed regulations under the CAA for volatile organic compound (VOC) emissions from wastewater at Synthetic Organic Chemical Manufacturing Industry (SOCMI) facilities, which would cover the HCN manufacturers (see proposal at 60 FR 46780, September 12, 1994). Therefore, we are deferring control of any air releases to the MACT and SOCMI standards and did not assess this pathway further in today's proposal.

How Was This Waste Category Characterized?