We conducted sampling and analysis of these wastewaters at the three facilities currently using surface impoundment based wastewater treatment systems. We collected samples at various places in the process, including prior to commingling, so that we could assess the risks of the wastestream at issue here. Today's proposal is based primarily on samples of the commingled wastewaters collected in the wastewater treatment plants. 36 For assessing the groundwaterto drinking water pathway at the Alabama facility, we used the sample collected at the HCN wastewater collection tank where the HCN wastewaters are collected prior to mixing with other non HCN wastewaters in the equalization impoundment. We estimated the concentration of the constituents of concern in the equalization impoundment by applying the dilution factor in the impoundment (e. g., 36 to 1 total wastewaters to HCN wastewaters), and we assessed these concentrations in our modeling for this pathway. For the groundwater tosurface water pathway at the Tennessee facility, we used the sample collected at the exit from the surface impoundments. We used the sample from wastewater exiting the unit, rather than at the inlet, because treatment occurs in the impoundment. However, the inlet data are similar, and even using the inlet data would not significantly increase the surface water screening results. We analyzed the waste for both amenable and total cyanide, as well as a number of volatile organics and metals. We used the amenable cyanide results as our cyanide risk assessment inputs because we believe that amenable cyanide most closely represents the fraction of cyanide likely to be mobile in a groundwater scenario and the `` free cyanide'' assessed in our health based level (HBL). However, this had no impact on our risk results, because our data show that amenable and total cyanide results for this waste are the same. We sampled the wastewater at the Alabama facility in August, 1999. The analytical data for the commingled HCN wastewaters (DG± 1± HC± 07) represent waste concentrations prior to commingling with other non HCN wastewaters. Our results for a key chemical, acetonitrile, are qualified as `` estimated'' for this sample as a result of problems during sampling and analyses at this site as described further in Waste Characterization Report, Degussa Huls; February 25, 2000, available in the docket for today's proposal. The facility's split samples were more problematic, because the analytical instruments were not calibrated for key constituents being analyzed; thus, the split sample results appear even more uncertain. Despite the estimated nature of the results for acetonitrile in this waste sample, the data clearly indicate that acetonitrile is likely to be present in the waste. Acetonitrile, also commonly referred to as methyl cyanide, is a likely by product from the main reaction between methane and ammonia to form hydrogen cyanide. In addition, samples we collected at the Tennessee facility show that significant levels of acetonitrile are present in the wastewater, albeit at somewhat lower levels than we found at the Alabama site.

We initially sampled at the Tennessee facility in August of 1999 (sample DM± 1± HC± 08). We used the analytical results for this sample as input to the risk assessment (described further below). However, because our analytical results for amenable cyanide were qualified due to holding time exceedences, we sampled at this facility a second time in October of 1999 to better understand the potential impact of this waste on the environment (DM± 2± HC± 08). All of the analytical data for these samples are available in `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemicals Listing Determination'' in the docket for today's proposal. The second round of sampling showed lower levels of the key constituent of potential concern than found in the first round of sampling. Due to time constraints, we did not re run the risk assessment model for this pathway to incorporate the second round of analytical data. However, this would result in somewhat lower risks, and thus would have had not impacted our proposed decision.

The critical analytical results for the commingled wastewaters for the Tennessee and Alabama surface impoundments are presented below in Table III± 10. These represent the constituents found to be present in the wastewaters at level exceeding the HBLs or AWQC. (Several other constituents were marginally above the AWQC and were not important in the surface water screening.)

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00036 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55719 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 37 The facility reported that the cover on the equalization unit was installed to ensure compliance with expected new regulations to control volatile organic carbon emissions from wastewater sources for the Synthetic Organic Chemical Manufacturing Industry (SOCMI) (proposal, 59 FR 46780, September 9, 1994). 38 U. S. EPA Phase II RFI Workplan, Potentiometric Surface Plan, March 3 & 4, 1999. TABLE III± 10.Ð CHARACTERIZATION OF COMMINGLED WASTEWATERS FROM INORGANIC HCN PRODUCTION (MG/ L)

Constituent of concern Sample DM± 1± HC± 08 Sample DM± 2± HC± 08 2nd Rnd Sample DG± 1± HC± 07 1 HBL AWQC Amenable CN .............................................................................. 0.638 <0.01 0.509 0.3 0.005 Nitrite as N .................................................................................. 11.5 no analysis <2.5 2 1 Vinyl chloride ............................................................................... 0.029 3 0.0066 L <0.001 0.0009 (0.1) 0.002 Acetonitrile ................................................................................... 4 50 K 28 L 190 0.09 (0.045) 2 N/ A Acrylonitrile .................................................................................. 0.013 <0.001 <0.0005 0.002 (0.03) 5.9E± 05 1 HBL in parenthesis based on inhalation pathway from residential use of water ( e. g., showering). 2 N/ A: Not Applicable. 3 L: Qualified result with a low bias for positive result. 4 K: Qualified result with a high bias for positive result.

How Was the Groundwater To Drinking Water Risk Assessment Established? The Alabama facility's surface impoundments are located in the center of an industrial park on the west side of Mobile Bay. The wastewater treatment impoundments are located near the eastern property boundary of the facility and approximately 4,000 feet south of the State of Alabama barge canal. We chose to assess surface water risks at the Tennessee facility, which is closer to a surface water body. However, given the use of groundwater in the area around the Alabama facility, we assessed the possible impact on drinking water wells. We selected the equalization basin as the unit for quantitative modeling. This is the first surface impoundment in the series and is likely to hold the highest level of constituents of concern. We elected not to assess the emergency holding pond, which is used primarily during high stormwater events. Due to the intermittent use of the holding pond, we expect the potential for significant groundwater releases to be greater for the equalization pond. In addition, the equalization pond is covered with a floating synthetic membrane, while the holding pond is not. 37 Our modeling of the covered equalization pond did not assume any loss of the volatile constituents of concern, thus allowing more of the constituents to infiltrate to the groundwater rather than volatilize to the air. Based on information available in a corrective action plan related to a product spill on site (Risk Based Corrective Action Plan for the Sodium Cyanide Production Unit at Degussa Corporation Alabama Facility, Theodore, Alabama; March 19, 1998), the most likely direction of groundwater flow is to the low lying areas to the north northeast of the surface impoundments. We found there are drinking water wells located due east of the equalization surface impoundment. Although the wells are located east of the surface impoundment instead of the estimated north northeast groundwater flow direction, they are at somewhat lower ground elevation than the surface impoundment. Given the uncertainty in the direction of the groundwater flow, we assumed that contaminated groundwater from the surface impoundment could migrate to the east and reach these wells. Based on the available land use and groundwater use information for this area, we performed risk modeling for potential releases to drinking water wells located between 3,100 and 5,280 feet east of the surface impoundment. The minimum distance of 3,100 feet is based on the distance from the impoundment to the eastern boundary of the industrial area controlled by the facility. The maximum distance of 5,280 is the distance east from the impoundment to the closest known well. This drinking water well appears to be located just inside the eastern boundary of the state property, which lies to the east of the industrial park where the facility is located. We also assumed that a future well may be placed in the same State property directly east of the facility's undeveloped tract at approximately 3,100 feet from the surface impoundment. The details of this assessment are presented in the `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in the docket for today's proposal. The results of the risk modeling for the only drinking water constituent of concern are presented in Table III± 11 below. TABLE III± 11.Ð GROUNDWATER RISK RESULTS FOR COMMINGLED WASTEWATERS FROM THE PRODUCTION OF INORGANIC HYDROGEN CYANIDE Percentile Acetonitrile hazard quotient (HQ) 1 90th % ...................................... 0.3 95th % ...................................... 0.5 1 Risk from inhalation scenario during showering included exposure factors for both adult and child in the analysis.

How Was The Groundwater To Surface Water Risk Assessment Established? The Tennessee facility and its surface impoundments are sited on the banks of the Loosahatchie River. The surface impoundments are located approximately 800 feet from the river. Based on information available in the Remedial Facility Investigation (RFI), 38 the direction of the groundwater flow is documented to be south towards the Loosahatchie River. The possibility of a public water supply well or private well being located downgradient of the Tennessee surface impoundments is unlikely because the facility boundary extends to the river to the south. Hence, based on the geologic setting of the facility as detailed above, we believe it is highly unlikely that these impoundments could impact drinking water wells via migration of a contaminated groundwater plume. Based on these facts we did not assess the groundwater to drinking water well pathway further at this site. We did, however, conduct a screening analysis of potential releases of groundwater to surface water and subsequent exposure via ingestion because of the proximity of the unit to the river. We calculated the concentrations in the river that would result from discharge of contaminated VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00037 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55720 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules groundwater by estimating the infiltration rate for the unlined impoundment and diluting the resulting leachate volume into the river under various flow conditions. The results of this screening level analysis suggest that concentrations of the constituents of concern in the river would be well below the aquatic life AWQC and HBLs for drinking water. The details of the screening analysis are presented in `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in the docket for today's proposal.

What Is EPA's Listing Rationale for This Waste?

Our risk assessment results for the surface impoundment scenario, summarized above for drinking water in Table III± 11, suggest that the only constituent of concern that required modeling (acetonitrile) does not pose a substantial present or potential hazard to human health and the environment. The HQ was below one at both the 90th and 95th percentile in the probabilistic risk distribution. The results of our risk analysis also show that hypothetical releases to the adjacent river would not result in exceedences of risk thresholds. Our analysis was conducted at a screening level and thus is based on a number of conservative assumptions that may overstate actual risk. We did not account for dilution of the potential plume in groundwater flowing under the surface impoundment that would result in yet lower river concentrations. We did not account for the likelihood that river water would be pretreated prior to use for drinking and showering. We did not account for volatilization, biodegradation, or hydrolysis of the cyanide and other constituents prior to exposure. Even if we used the surface impoundment influent concentrations, rather than the exit concentrations, as input to the analysis, this waste would not exceed risk thresholds in the adjacent river. For these reasons, we propose not to list this waste category as hazardous. For a more complete description of this analysis, see `` Risk Assessment for the Listing Determination for Inorganic Chemical Manufacturing Wastes'' in the docket for this proposal. (2) Ammonia recycle cartridge and spent carbon filters.

How Many Facilities Generate This Waste Category and How Is It Managed? Five facilities reported generating 73 MT/ year of filter media and waste solids in 1998 from the removal of organonitrile polymers from the ammonia recycle stream. The management methods reported by the industry were off site municipal Subtitle D landfill, off site industrial Subtitle D landfill, on site Subtitle C incineration, and on site Subtitle C landfill.

What Management Scenarios Were Assessed? We conducted risk assessment modeling for off site disposal in both a municipal and an industrial landfill, using only those two waste volumes reported to be managed in off site Subtitle D landfills; volumes managed as hazardous wastes were not included in this array. No significant volatile constituents were detected in this waste (only non volatile metals were detected; see following section), thus volatilization from landfills to the air was not a pathway of concern. We did not conduct risk assessment of the voluntary Subtitle C landfill and incineration practices because we assumed that listing would not significantly increase regulatory control for these wastes. Note that these on site captive units have sufficient capacity and flexibility to accept these relatively small volume non hazardous wastes.

How Was This Waste Category Characterized?

Two samples were collected at different facilities. We sampled again at both facilities because of problems with the cyanide analyses for the first set of analyses and elevated detection limits for certain metals in the Tennessee sample. Due to the schedule constraints of this determination, we initiated the risk analyses using the first round of samples. The risk analysis and second round of sampling and analysis were conducted in parallel. HBLs are shown in Table III± 12.

TABLE III± 12.Ð CHARACTERIZATION OF AMMONIA RECYCLE FILTERS [mg/ L]

Parameter RH± 1± HC± 05 (1st data set) RH± 2± HC± 05 (2nd data set) DM± 1± HC± 04 (1st data set) DM± 02± HC± 04 (2nd data set) HBL TCLP SPLP TCLP SPLP TCLP SPLP TCLP SPLP Antimony ...................................... 1 0.55 J 0.59 <0.5 0.237 <0.5 <0.5 0.8 0.08 0.006 Arsenic ......................................... 2 0.045 L 0.039 <0.5 0.0137 <0.5 <0.05 <0.5 0.0112 0.0007 Nickel ........................................... 0.50 J 0.61 <0.2 0.303 <0.2 0.0654 <0.2 0.0178 0.31 Total CN ................................ N/ A 2.4 L 0.230 0.243 0.218 0.187 L 3 0.222 0.303 4 0.31 1 J: Estimated result, due to poor field duplication. 2 L: Qualified result with a low bias for positive result. 3 Average of duplicate sample results. 4 HBL for hydrogen cyanide.

How Was the Groundwater Ingestion Risk Assessment Established?

We assessed the off site landfill scenario for the ammonia recycle filter cartridges, reflecting the types of management reported for this waste. We assessed the groundwater ingestion pathway for these landfills. Our model inputs included different hydrogeologic settings reflecting the two regions where the wastes are reported to be managed. As noted in section III. C., we used the TCLP results for the municipal landfill scenario and the SPLP for the industrial landfill scenario. As described above, we had some initial concerns about our analytical data and determined that re analysis would serve to demonstrate the validity of these data. Due to the time constraints of this listing determination, we could not delay the risk assessment modeling until the validated results of the second round of analyses became available, and thus used the first round of samples for the Texas facility as model input. Subsequently, having reviewed all the analytical data, we believe that the modeled data set appropriately characterizes the risks of VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00038 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55721 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules all constituents included in the first sampling round, and that re running the model with the second round of analytical data would not increase the predicted risk. The only additional constituent of concern found in the second analysis was cadmium. We modeled this constituent using the same two scenarios and found no significant risk. What is EPA's Listing Rationale for This Waste?

The results of our probabilistic risk assessment are provided in Table III± 13 below (we also completed deterministic risk modeling and the results were comparable; see `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' for details). At the 90th and 95th percentile cumulative risk level, we found no cancer risk in excess of 1E± 07, nor did we find any hazard quotients that exceeded one. As a matter of policy, we generally do not consider listing wastes with predicted cancer risks of less than 1E± 06 or hazard quotients of less than 1.0. We see no special concerns warranting an exception to this policy. Based on these results we conclude that this waste does not pose risk to human health and the environment at levels that warrant listing. We therefore are proposing not to list ammonia recycle filters from inorganic hydrogen cyanide production.

TABLE III± 13.Ð GROUNDWATER RISK RESULTS FOR AMMONIA RECYCLE FILTERS 1 Percentile Antimony Arsenic Cadmium Adult HQ Child HQ Adult cancer risk Child cancer risk Adult HQ Child HQ Industrial Landfill: 90th ........................................................................... 7.9E± 02 1.6E± 01 3.8E± 08 2.8E± 08 3.6E± 04 7.7E± 04 95th ........................................................................... 1.9E± 01 3.9E± 01 1.6E± 07 1.2E± 07 1.6E± 03 3.4E± 03 Municipal Landfill: 90th ........................................................................... 8.7E± 02 1.8E± 01 3.9E± 08 3.1E± 08 4.0E± 04 8.5E± 04 95th ........................................................................... 2.0E± 01 4.2E± 01 1.8E± 07 1.3E± 07 1.7E± 03 3.7E± 03 1 Modeling for two other constituents (nickel and cyanide) yielded HQs that were extremely small (< 1E± 16) even at the 95th%.

(3) Biological wastewater treatment solids.

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

Four facilities reported a total volume of 45,397 MT/ year for this waste. The management methods reported are offsite municipal and industrial Subtitle D landfills, on site Subtitle C landfill, and off site use as agricultural liming agent (volume not reported).

What Management Scenarios Were Assessed?

We evaluated the Subtitle D landfill and the agricultural liming agent scenario reflecting the reported management practices. We assessed the landfill scenario using our TCLP and SPLP results for the wastes reported managed in such landfills. We assessed the agricultural use scenario by comparing total constituent concentrations to the soil screening levels (see section III. C. 3).

How Was This Waste Category Characterized?

We collected two samples of this waste at two different facilities. We conducted total and leaching analyses of these samples. To evaluate the industrial landfill disposal scenario we compared the SPLP leaching results to constituent HBLs, and for the municipal landfill scenario we compared TCLP leaching results to the HBLs. In all cases the SPLP and TCLP levels corresponding to the management practice were below the HBLs. For the agricultural liming scenario, we compared the total concentrations in the waste to the soil screening levels; no constituents exceeded these screening levels, i. e., all constituents were below background or direct soil ingestion levels. The full analyses are summarized in the `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemicals Listing Determination'' and the analytical results are reported in detail in the Waste Characterization Reports for this sector; these documents are available in the docket for today's proposal.

What Is EPA's Listing Rationale for This Waste?

We propose not to list this waste as hazardous because the levels of toxicant constituents found in the waste are below the levels of concern. (4) Feed gas cartridge and spent carbon filters.

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

Nine facilities reported a total volume of 9.7 MT/ year for this waste. The management methods reported are offsite manufacturer refurbishing for reuse, off site municipal D landfill, off site industrial D landfill, and on site C hazardous landfill. The facility using the hazardous C landfill for disposal of the filters is managing the filters as nonhazardous waste in a captive on site C landfill.

What Management Scenarios Were Assessed?

We assessed the municipal and industrial Subtitle D landfill scenarios using our TCLP and SPLP results, respectively. No volatile constituents were detected in this waste (only nonvolatile metals were detected; see following section), thus volatilization from landfills to the air was not a pathway of concern. We did not assess the voluntary Subtitle C landfill scenario because we assumed that listing would not significantly increase regulatory control. Note that the on site unit has sufficient capacity to continue to accept this small volume waste.

How Was This Waste Category Characterized?

We collected one sample of this waste. The analytical results showed that SPLP levels for all constituents are below drinking water HBLs. The TCLP results showed levels that exceeded HBLs for the constituents summarized below in Table III± 14:

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00039 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55722 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules TABLE III± 14.Ð CHARACTERIZATION OF FEED GAS FILTERS FROM INORGANIC HCN PRODUCTION [mg/ kg or mg/ L]

Constituent Total TCLP SPLP HBL Boron ............................................................................................................................... 17,900 7.4 <0.5 1.4 Lead ................................................................................................................................. 18.5 1 0.03 1 0.003 0.015 Nickel ............................................................................................................................... 91.0 0.4 <0.05 0.31 Zinc .................................................................................................................................. 1,060 13 <0.5 5 1 Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limits.

Split sample results provided by the facility were comparable. We did not find cyanide in these wastes. The full analytical results are summarized in the `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemicals Listing Determination'' and are reported in detail in the Waste Characterization Reports for this sector; these documents are available in the docket for today's proposal.

How Was the Groundwater Ingestion Risk Assessment Established? We assessed the groundwater ingestion pathway for the off site landfill scenario for this waste, reflecting the types of management reported. As noted in section III. E., we used the TCLP results for the municipal landfill scenario and the SPLP for the industrial landfill scenario. We found that the industrial Subtitle D landfill scenario screened out because all constituents in the SPLP analysis were below their respective HBLs. The constituents of concern that exceeded their respective HBLs in the TCLP results were boron, lead, nickel, and zinc. We evaluated these constituents using the de minimis volume screening analysis, as described in section III. E. 3 of today's proposal. The analysis suggests that lead, nickel and zinc are not of concern. We modeled the remaining constituent, boron, using our standard groundwater model for the municipal landfill scenario. We modeled the municipal landfill scenario, using a hydrogeologic setting reflecting the region where the waste was reported to be managed.

What Is EPA's Listing Rationale for This Waste? As noted above, the industrial landfill scenario screened out. For the municipal landfill scenario, the results in Table III± 15 show that the HQs are well below one at both the 90th and 95th% for the constituent of concern. Thus, our risk assessment results suggest that the only constituent of concern that required modeling (boron) does not pose a substantial present or potential hazard to human health and the environment. For a more complete description of this analysis, see `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes' in the docket. Thus, we propose not to list this waste as hazardous.

TABLE III± 15.Ð GROUNDWATER RISK RESULTS FOR FEED GAS FILTERS FOR BORON Percentile Adult HQ Child HQ 90th ....................................... 0.007 0.01 95th ....................................... 0.01 0.05 (5) Process air cartridge filters.

How Many Facilities Generate This Waste Category and How Is It Managed? Eight facilities reported a total volume of 7.5 MT/ year for this waste. The management methods reported are offsite industrial D landfill, off site manufacturer refurbishing for reuse, offsite municipal D landfill, and on site industrial D landfill. Most facilities reported the practice of filtering the air that they feed to the reactors. Very small volumes of spent filters are generated periodically. We did not assess these wastes beyond the characterization provided in the RCRA Section 3007 Survey results because no wastes were available to sample when we conducted our sampling. The level of toxic constituents is expected to be low because the filters are only used to remove airborne solids from the ambient air used in the process.

What Is EPA's Listing Rationale for This Waste? We propose not to list this waste as hazardous because we do not believe that the level of any toxic constituents in these small waste volumes would exceed levels of concern that would pose a risk based on management in Subtitle D landfills. (6) Acid spray cartridge filters.

How Many Facilities Generate This Waste Category and How Is It Managed? One facility reported a total volume of 1.1 MT/ year for this waste. The management method reported was onsite Subtitle C disposal as a nonhazardous waste. The cartridge type filter elements are used in the process to prevent clogging of spray nozzles used to inject the hydrogen cyanide intermediate product into the HCN stripper. The filters remove process particulates, including rust, from the hydrogen cyanide intermediate product. The waste is generated when the spent filter elements are replaced weekly. While this waste is classified as nonhazardous, the generator disposes of it in the facility's on site Subtitle C landfill.

How Was This Waste Category Characterized? No sample of this waste was collected because of unavailability during the sampling time frame and because the level of toxic constituents is expected to be low. The filters are used to remove inert impurities such as pipe scale. The facility washes the filters prior to removal of the filters from the process. We expect that any hydrogen cyanide contamination is removed during this washing. The facility reported in its RCRA Section 3007 Survey that the waste contains a total concentration of cyanide of one ppm.

What Is EPA's Listing Rationale for This Waste? We propose not to list this waste as hazardous because the level of toxic constituents found in this waste are expected to be below levels of concern. While we do not have any leaching test data, we can conservatively estimate that any leachable level of cyanide would be at least 20 fold less than the 1 ppm total level reported, i. e, less than 0.05 mg/ L. This is well below the HBL for amenable cyanide (0.3 mg/ L). Furthermore, this small volume waste is already managed in a Subtitle C landfill. (7) Spent catalyst. All ten facilities reported generation of this waste, with a combined total volume of 4.1 MT/ year. The management method reported was off site metals reclamation or regeneration. These catalysts gradually lose their effectiveness over time and are periodically reclaimed. Due to the VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00040 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55723 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 39 Note that the SPLP/ HBL groundwater screen for this scenario is likely to be a worse case screening, because the fertilizer application scenario isn ot analogous to a landfill scenario, particularly with respect to application rates. high value of these precious metal materials, generators maintain close control over these materials. The spent material is an impermeable metal gauze that undergoes thorough cleaning and decontamination to eliminate cyanide concentrations prior to removal from the reactor. We have chosen not to evaluate these materials further because management practices for these materials prior to reuse minimize the potential for environmental releases. Therefore, we propose not to list this waste as hazardous because there are no significant known exposure pathways that would present risk. (8) Ammonium sulfate and ammonium phosphate.

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

Three facilities reported a total volume of 27,425 MT/ year for this waste. The management method reported was off site use as fertilizer.

What Management Scenarios Were Assessed?

We assessed the agricultural end use of this waste by comparing the total constituent results to the soil screening levels. In this case we evaluated the material, because it is land applied.

How Was This Waste Category Characterized?

One sample of this by product was collected from the Alabama site. The analytical data results show that the detected constituents of concern in the total analyses are below the soil screening levels. In addition, we compared the SPLP leaching results to the HBLs as a screen of potential groundwater exposure. 39 The detected SPLP results are below the HBLs. The analytical results showing the level of toxic constituents are included in the `` Inorganic Hydrogen Cyanide Listing Background Document for the Inorganic Chemicals Listing Determination. ''

What Is EPA's Listing Rationale for This Waste?

We propose not to list this waste as hazardous because the levels of toxic constituents found in the waste are below levels of concern. (9) Miscellaneous wastewaters.

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

Four facilities reported a total volume of 209,000 MT/ year for this waste category; the total volume represents twenty two different miscellaneous wastestreams that are generated on an intermittent or periodic basis. The management method reported was commingling with other major process wastewater streams described above as the `` commingled wastewaters'' category.

What Management Scenarios Were Assessed? We did not assess these numerous wastewater streams individually. The wastewaters were assessed indirectly within the commingled wastewater category discussed earlier. The volume and constituents represented by these miscellaneous wastewaters are represented in the total commingled major and miscellaneous wastewater streams.

How Was This Waste Category Characterized? We did not collect samples of these miscellaneous wastewater streams. The levels of toxic contaminants in these wastewaters are reflected in the contaminant concentrations of the total commingled wastewater streams at each facility. See the commingled wastewater category discussed earlier in this section for a discussion on how the commingled major and miscellaneous wastewater streams were characterized. Two of the miscellaneous wastewaters were reported to contain potentially high concentrations of hydrogen cyanide when generated.

What Is EPA's Listing Rationale for This Waste Category? We propose not to list this waste category as hazardous. There is no direct exposure pathway into the environment from these individual wastes, because they are treated and commingled with the other wastewaters generated at each facility. Although high concentrations of hydrogen cyanide in the wastewaters are possible for some of these wastes, the risk is reduced by the high dilution that occurs when these wastewaters are mixed with other large volume wastewaters in the facility wide wastewater collection system. These miscellaneous wastewaters are generated intermittently and infrequently. Thus, any potential releases from land based management of the wastes after dilution in with other wastewaters would be short lived, and unlikely to result in any significant long term risk. In addition, the hydrogen cyanide contaminant is readily and rapidly treated in the wastewater treatment systems, so that any risk is minimized. For example, the tank farm scrubber water from the Tennessee facility is treated through oxychlorination, which rapidly destroys the hydrogen cyanide. As noted earlier, potential hydrogen cyanide releases via the air pathway would be covered by the Hydrogen Cyanide MACT rule. (10) HCN polymer and HCN sump wastes. One facility reported a total volume of 0.7 MT/ year (0.3 MT/ yr polymer and 0.4 MT/ year sump wastes) for these two wastes. The physical description of the wastes was reported as dirt, debris and inert polymer solids. The wastes are disposed of in an off site industrial Subtitle D landfill. Very small volumes of these wastes are generated periodically. We did not assess these wastes beyond the characterization provided in the RCRA Section 3007 Survey results because of the unavailability under the sample schedule and because of the low concentrations of toxic constituents expected to be present in this waste. In the RCRA Section 3007 Survey, the one generator reported that total levels of cyanide were 50 mg/ kg for the HCN polymer and 5 mg/ kg for the sump wastes. These levels are unlikely to pose a risk in a landfill scenario for these very small waste volumes. In support of this, we note here, as we did above for the acid spray filter cartridge waste category, leaching test results would be at least 20 fold less than the total levels. This would mean any leaching from sump waste would be below the HBL for cyanide. While this 20 fold factor would leave the HCN polymer somewhat above the HBL at 2.5 ppm cyanide, we note that groundwater modeling for cyanide for the ammonia recycle filters indicates similar levels of cyanide in a larger waste volume presents very low levels of risk in a landfill scenario. Therefore, we propose not to list HCN polymer and HCN sump wastes. (11) Sludge from wastewater collection tank. One facility reported a volume of 2.1 MT over a seven year period, or approximately 0.3 MT/ year for this waste. The waste was coded as hazardous (D001), stabilized on site and disposed of in an off site Subtitle C landfill. The waste is generated approximately every ten years; the volume reported was for 1993 with no generation of that waste since that date. This waste results from sedimentation in a wastewater collection tank. HCN wastewaters managed in this tank only account for ten percent of throughput; the sediment thus is only marginally associated with HCN production. One other facility reported generating 1.8 MT of this waste, and also codes it as characteristically hazardous waste (in this case as D018 for benzene). This VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00041 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55724 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules second facility sends the waste off site to a Subtitle C incinerator; the facility reported that the benzene was derived from other on site processes. We propose not to list these wastes because they are very small volume wastes that are already managed as characteristically hazardous wastes in full compliance with the Subtitle C regulations. In addition, the wastes are generated from the treatment of predominantly non HCN wastewater from unrelated petrochemical processes at the facilities. (12) HCN storage tank solids. One facility reported a volume of 0.3 MT/ year for this waste. During periodic shutdowns of this product tank for cleaning, solids are removed after rigorous washing of the tank interior to remove soluble cyanide. The waste consists of polymer and tank scale. The waste is disposed of in an off site municipal Subtitle D landfill. A sample of this waste was not collected because of unavailability during the sampling time frame. However, the waste description provided by the facility indicates the waste is similar in composition to the ammonia recycle filters, which we have proposed not to list. Given the much smaller volume here, this waste is not expected to present significant risk. Therefore, we are proposing not to list this waste as hazardous. (13) Wastewater filters. One facility reported a volume of 450 MT/ year for this waste. The waste is managed in a captive, off site Subtitle C incinerator as characteristically hazardous waste. The waste is spent filters from the filtration of commingled wastewaters from various on site processes prior to on site deepwell injection and is generated periodically. A sample of this waste was not available during the sampling time frame. However, the one generator reported that the waste is characteristically hazardous due to benzene, and the facility manages the waste as D018. The source of the benzene is the waste from other nonHCN process wastewaters at the facility. We propose not to list this waste because it is already managed as a hazardous waste in accordance with Subtitle C regulations. (14) Ammonium sulfate filters. One facility reported a volume of 1.1 MT/ year for this waste. The waste is managed in an off site industrial landfill. The waste is generated periodically. We did not assess this waste beyond the characterization provided in the RCRA Section 3007 Survey results because of the unavailability of samples under the sample schedule. However, the facility reported concentrations of cyanide (1 mg/ kg) and ammonium sulfate (5,000 mg/ kg). This concentration of cyanide is considered to be very small and is not expected to be of concern (see discussion of cyanide for acid spray cartridge filters). In addition, we collected a sample of the ammonium sulfate by product (i. e., the material being filtered to generate this waste) and did not find any constituents of concern. See discussions for ammonium sulfate and ammonium phosphate. Therefore, we propose not to list this waste as hazardous because we do not believe that there are any significant levels of toxic constituents in the waste. (15) Spent ammonium phosphate. One facility reported a volume of 230 MT/ year for this waste. The waste is reused on site as a nutrient source in the biological treatment unit or incinerated on site in a nonhazardous waste incinerator. The waste is generated in batches one or two times per year. The waste is generated from the scrubbing of the reactor off gas stream using aqueous monoammonium phosphate solution in the ammonia recovery process. The resulting diammonium phosphate solution is then purified to recover the ammonia and the resulting spent ammonium phosphate solution is stored in tanks prior to final management. We did not assess this waste beyond the characterization provided in the § 3007 Survey results because of the unavailability of samples under the sample schedule; the characterization indicates the presence of organonitrile compounds in the waste. However, the preferred management method is to reuse the waste as a nutrient source in the biotreatment system, with incineration only when this is not possible due to the solution becoming spent or when the concentrations of phosphate and ammonia are incompatible with the wastewater treatment system. We believe the levels of organonitrile compounds do not pose a risk under either management scenario. The wastewater treatment scenario results in the destruction of the compounds via biodegradation and the incineration scenario would also result in destruction of the volatile organonitriles. Additionally, emissions from the on site incinerator would be regulated under the Hydrogen Cyanide MACT standards which will be proposed in 2000. Therefore, we propose not to list this waste as hazardous. (16) Organic layer from wastewater collection tank. One facility reported a volume of 43.3 MT/ year for this waste. The waste is coded as D001 and sent offsite Subtitle C incineration. This waste is generated approximately every ten years; the volume reported was for 1993 with no generation of the waste since that date. Thus, on an annualized basis the waste quantity generated would be approximately 4 MT/ yr. We did not assess these wastes beyond the characterization provided in the RCRA Section 3007 Survey results because of the unavailability of samples under the sample schedule. We propose not to list this waste as hazardous because the waste is managed as characteristically hazardous in accordance with all applicable Subtitle C standards, which adequately protect against mismanagement. Further, the waste is generated from the treatment of predominantly non HCN wastewater from other unrelated petrochemical processes at the facility. Only ten percent of the wastewater throughput in the tank generating this waste is associated with HCN production; the percentage contribution from the HCN process to this oily layer is likely to be much lower, because other petrochemical processes on site are likely sources of the organic material.

6. Phenyl Mercuric Acetate a. Summary. We propose not to list any wastes from the production of phenyl mercuric acetate (PMA) as hazardous under Subtitle C of RCRA. PMA currently is not manufactured in the United States, and it is extremely unlikely that it will be manufactured in the United States in the future. Therefore, there are no wastes being generated that could be subject to a listing determination. b. Description of the phenyl mercuric acetate industry. PMA (C8H8Hg O2) is an organic mercury compound, a white to creamy white odorless crystalline powder or clear solution. Prior to 1990 it was the predominant fungicide used in the latex paint industry. In 1990, EPA banned the use of PMA in interior paint (55 FR 26754, June 29, 1990) and subsequently, the paint industry ceased using PMA in paint production. PMA is still used for other limited purposes (e. g., slimicide in paper mills; selective herbicide for crabgrass; fungicide for diseases of turf on golf greens and tees; fungicidal seed dressing for seed and soil borne diseases of cereals, sorghum, and groundnuts). Based on our research and the results of our RCRA Section 3007 Survey, we conclude that there is no domestic production of PMA. Any domestic demand is met by imports from other countries. See the `` Phenyl Mercuric Acetate Listing Background Document for the Inorganic Chemical Listing Determination'' for details.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00042 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55725 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 40 One facility has shut down their phosphoric acid process and reported few wastes generated in 1998. This facility's wastes therefore are not included in the following overview, but were evaluated to determine their potential threat to human health or the environment. The details of this facility's waste generation and management practices are included in the `` Phosphoric Acid Listing Background Document for the Inorganic Chemical Listing Determination''. c. Agency evaluation. PMA is not produced within the United States and is not widely used in domestic manufacturing processes. Therefore, we have no reason to believe that wastes from the production of PMA are generated within the U. S. Given the compound's limited market within the U. S., it is highly unlikely that new production of PMA will occur within the U. S. in the future. As a result of these market conditions, there are no wastes that can be assessed for this sector. Therefore, we propose not to list any PMA production wastes as hazardous.

7. Phosphoric Acid From the Dry Process a. Summary. We have evaluated the wastes from the production of phosphoric acid manufactured via the dry process, and propose not to list any wastes from this process as hazardous wastes. These wastestreams 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 these wastes. b. Description of the phosphoric acid industry. Phosphoric acid was produced by the dry process by eight facilities in the United States in 1998. The majority of phosphoric acid is consumed in the manufacture of phosphate salts. These phosphorus containing compounds are used in detergents, animal feed supplements, dentifrices, fertilizers, metal treating, water softening, leavening agents, and flame and fire retardants. In the dry process, elemental phosphorous is burned in excess air generating phosphorous pentoxide (P2O5). The resulting phosphorus pentoxide is hydrated with a spray of recycled phosphoric acid and water, forming phosphoric acid that is collected as product. Scrubbers are employed for the hydrator off gases to absorb as much phosphoric acid mist as possible from the excess air. The strong phosphoric acid stream from the hydrator is purified with hydrogen sulfide to precipitate out arsenic trisulfide. This sludge is removed by filtration. In some cases, offspecification product is filtered and recycled into the process. The product may also be filtered after it leaves the storage tank and prior to loading in truck and railcars. c. Description of wastes generated by the phosphoric acid process. We have identified fourteen waste categories from the production of phosphoric acid (via the dry process) that required assessment. These waste categories are described briefly and in more detail in the following subsections. 40 ÐArsenic filter cake is the result of filtering the phosphoric acid after the addition of sodium hydrosulfide or hydrogen sulfide gas and a filter aid. The precipitate consists of arsenic trisulfide and other heavy metal sulfides which are essentially insoluble in strong acid. ÐCombustion chamber slag (infrequently generated) is the result of residue buildup on the walls of the chamber. ÐOff specification phosphoric acid is generated when the product does not meet color or concentration specifications. ÐSpent filters (from purification) are generated from the units that are used to remove arsenic from the phosphoric acid. ÐCaustic scrubber water is generated when air used to remove hydrogen sulfide gas at the acid purification step is scrubbed. This scrubbing operation controls odor and acid mist before the air is discharged to the atmosphere. ÐPhosphoric acid spills occur around the process or storage tanks area. These materials are collected in contained areas and pumped to management units. ÐClean up and washdown water from across the units is collected in a sump and discharged to the wastewater treatment system. ÐProcess acid leaks occur when piping and coupling break, or during equipment maintenance. These materials are collected in contained areas and pumped to management units. ÐSpent mist eliminator packing (filters) are used in the scrubber system to remove gas and acid particulates from the phosphoric acid. The filter packing material is reported to consist of polyester fibers, stainless steel, steel wool or fiberglass. The filters are periodically replaced and the spent packing is washed prior to disposal. ÐRubber liners of product storage tanks are periodically replaced. ÐSpent filters for product are generated when product is filtered prior to loading into tank cars and trucks to remove settled solids. The filters are changed periodically and rinsed with water prior to disposal. ÐSpent activated carbon for offspecification product is generated when carbon is used to remove traces of contaminants from the offspecification product. ÐSpent filters for off specification product is generated when filters are used to remove solids from the offspecification product. ÐWastewater treatment sludges are generated when wastewaters from the phosphoric acid and other processes are treated. These sludges are only marginally derived from phosphoric acid wastewaters due to commingling with large volumes of other nonphosphoric acid wastewaters. The solids that are removed by filtration are landfilled or sold. Three facilities reported that they collect phosphoric acid in air pollution control devices (i. e., vent scrubbers, absorbers, mist eliminator). Each site reported that they then recycle these acids into the production process. This material is continuously reused in the production process. Based on our site visits, the material is piped from the generating unit to the production process, minimizing the potential for releases to the environment prior to reuse. We evaluated all wastes generated after the materials are reused and concluded that none merited listing. Consequently, we do not believe that these materials present significant threats. At two of the facilities, the caustic scrubber water, generated from scrubbing the air to remove hydrogen sulfide gas, is returned as makeup solution to the purification process. Based on information from one of the facilities and our site visit, the material is piped from the generating unit to the production process, and there is no significant potential for exposure. Also, process acid leaks are collected in tanks at one facility and piped back to the acid process, with no significant exposure route for this material. As stated above, we evaluated all wastes generated after the materials are reused and concluded that none merited listing. Consequently, we do not believe that these materials present significant threats. We have organized our discussion of these wastes in terms of how they are currently managed: characteristic wastes, wastewaters, and noncharacteristic solid wastes.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00043 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55726 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules d. Agency evaluation. (1) Characteristic wastes. The RCRA Section 3007 Surveys show that a number of wastes are managed as RCRA characteristic wastes at all times. These wastes are hazardous wastes because they exhibit the characteristics of corrosivity or toxicity for arsenic. We believe that these wastes are managed according to the applicable RCRA Subtitle C regulations, including LDR standards. The LDR restrictions apply prior to land disposal. Furthermore, these wastes are managed or disposed in Subtitle C management units. Table III± 16 summarizes our information regarding the generation and management of these wastes.

TABLE III± 16.Ð CHARACTERISTIC WASTES FROM PHOSPHORIC ACID PRODUCTION DISPOSED IN SUBTITLE C UNITS Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Final management practices Arsenic filter cake ........................... 7 614 D002, D004 .................................... Subtitle C landfill Combustion chamber slag .............. 1 0.1 D002 ............................................... Subtitle C incineration Off specification phosphoric acid ... 1 0.71 D002 ............................................... Subtitle C landfill Spent filters (from purification) ....... 2 4.6 D004 ............................................... Subtitle C incineration or Subtitle C landfill We propose not to list these four waste categories as hazardous wastes under RCRA. All generators of these wastes already report managing these materials as hazardous from the point of generation through disposal, because they exhibit one or more of the hazardous waste characteristics. We believe that the rules applying to characteristic wastes adequately protect against mismanagement. (2) Other characteristic waste.

TABLE III± 17.Ð OTHER CHARACTERISTIC WASTES FROM THE PRODUCTION OF PHOSPHORIC ACID Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Phosphoric acid spills ..................... 2 2.2 D002 ............................................... (1) Neutralized, (2) roll off bin, (3) Subtitle D landfill; (1) Tanks, (2) neutralized in surface impoundment, (3) NPDES We assessed the specific management practices employed for this wastestream, as summarized in Table III± 17, and determined that no exposure scenarios of concern exist. One facility reported that the wastestream is managed as hazardous (D002), neutralized, and disposed of in a Subtitle D landfill. These product spills are expected to be mostly phosphoric acid, which is hazardous because it is corrosive. The facility effectively treats and neutralizes these wastes prior to disposal. There is no significant risk expected from the disposal of the small volume (0.5 MT/ yr) of treated spills to the landfill. The second facility reported placing the untreated spills into its wastewater treatment system, which includes both tanks and impoundments. Again, we expect that this waste presents hazards because of its corrosivity, not because it contains hazardous constituents. We do not expect releases to groundwater from tanks because we assume that they function effectively. With regard to the surface impoundment, we note that the facility has estimated that these small volume spills make up less than 0.001% of the total wastewater volumes. We expect that dilution of this magnitude would effectively treat the spills rapidly. Further, the facility reported that the wastewaters in the impoundment are neutralized. Consequently, we do not anticipate that any potential releases from the surface impoundment would pose a significant threat to groundwater. Ultimately, the spills are discharged, along with the much larger volume of wastewaters generated on site, to surface waters under a NPDES permit, which provides effective control and an exemption from RCRA regulations. We also note that we expect no release of constituents of concern to the air from either the tank or the impoundments, because the waste contains no volatile constituents. (3) Wastewaters. Wastewaters are generated at various points in the process as a result of scrubbing operations, equipment cleanup, and management of leaks and spills. As reported by the facilities, the primary constituents of concern in these wastewaters are phosphoric acid and traces of hydrogen sulfide, which are readily treated and controlled via neutralization. Phosphoric acid, when neutralized, forms various phosphate salts, none of which are known to pose a significant risk to human health and the environment. Similarly, hydrogen sulfide is neutralized to form nonvolatile salts. All facilities report that these wastewaters comprise very small portions of the overall wastewater treatment throughput, which contains wastewaters from other unrelated onsite processes. Table III± 18 summarizes our information on these wastewaters.

TABLE III± 18.Ð WASTEWATERS FROM PHOSPHORIC ACID PRODUCTION Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Caustic scrubber water ................................. 1 36 none ................. (1) pretreatment in covered tanks, (2) POTW VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00044 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55727 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules TABLE III± 18.Ð WASTEWATERS FROM PHOSPHORIC ACID PRODUCTIONÐ Continued Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Cleanup water ............................................... 1 small volume (volume not reported) none ................. (1) pretreatment in covered tanks, (2) POTW Process acid leaks ........................................ 1 25 1 none ................. (1) pretreatment in covered tanks, (2) NPDES 1 The 25 tons include leaks from eight processes, of which one is phosphoric acid production. The individual volume of leaks from phosphoric acid production is unknown.

We have assessed the management practices employed for these wastes and determined that no exposure pathway of concern exists. We believe these wastewaters will continue to be managed in existing tank based treatment systems. We believe the manufacturers have made a considerable investment in wastewater treatment systems using tanks and will continue to use them. Further, we assumed that wastewater treatment tanks retain sufficient structural integrity to prevent wastewater releases to the subsurface (and therefore to groundwater), and that overflow and spill controls prevent significant wastewater releases. Thus, based on the lack of any significant likelihood of release of the constituents to groundwater, we did not project significant risks to groundwater from these wastes in the tank based wastewater treatment scenario. Furthermore, discharges to POTWs and surface waters under NPDES are regulated under the Clean Water Act and are exempt from RCRA Subtitle C regulation and thus were not assessed. We also considered the possibility of air releases from tanks. The only potential volatile constituent of concern in these wastes is hydrogen sulfide. The treatment processes employed are designed to neutralize this compound, reducing the potential for volatilization. In addition, the facilities have installed tank covers, further reducing the likelihood of release to the air. As a result, we did not model releases to air from tanks from the production of phosphoric acid. Thus, we propose not to list these wastewaters as hazardous wastes under RCRA. (4) Non characteristic solid wastes. The phosphoric acid sector reported six waste categories that do not routinely exhibit any of the hazardous waste characteristics and that are often managed in Subtitle D landfills, as summarized in Table III± 19:

TABLE III± 19.Ð NON CHARACTERISTIC SOLID WASTES Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Spent mist eliminator packing ....................... 5 28.4 None ................. (1) storage in containers, (2) treatment to control acid (washing, neutralization, or off site stabilization by one facility), (3) recycling or disposal in Subtitle C or D landfills Rubber liners ................................................. 2 19.8 None ................. (1) storage in containers, (2) Subtitle C incineration or neutralization before Subtitle D landfill. Spent filters for product ................................. 1 0.5 None ................. (1) storage in containers, (2) off site stabilization (3) Subtitle D landfill. Spent activated carbon for off specification product. 1 1 3 None ................. (1) storage in containers, (2) off site stabilization (3) Subtitle D landfill. Spent filters for off specification product ....... 1 0.5 None ................. (1) storage in containers, (2) off site stabilization (3) Subtitle D landfill. Wastewater treatment sludges ...................... 3 2 0.005 None ................. (1) storage in containers, (2) Subtitle D landfill.

1 1996 volume; none generated in 1997 or 1998. 2 Two facilities did not report volumes due to very small input of phosphoric acid production wastes to the WWT system; one facility estimated that 0.0001% of 4,640 MT sludge generated (or 0.005 MT) was from phosphoric acid production.

The spent mist filters collect phosphoric acid mist before arsenic trisulfide is precipitated out. The material which condenses in the filters is expected to be corrosive and may contain some arsenic. However, the material used for filter packing in the mist eliminators is typically polyester, fiberglass, or steel wool. The filter packing provides surface area for condensation, not absorption, and is not expected to accumulate waste or constituents. Thus, arsenic is not expected to adhere to the filters as condensate drops back into process. The generators treat the spent filters prior to disposal to remove or immobilize any low levels of constituents that may remain. The rubber liners and spent filters for product are associated with food grade products. We expect any contaminant levels to be extremely low due to purity requirements. Consequently, we believe it is unlikely that they contain any constituent at levels of concern (i. e., above health based limits for ingestion). We also note that both wastes are treated prior to disposal in landfills. Similarly, we do not expect the spent carbon or spent filters associated with off specification product to contain significant levels of constituents of concern. Product is classified as `` offspecification due to color and concentration of acid, rather than VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00045 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55728 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules because of the presence of any contaminants. We note again that these wastes undergo treatment prior to placement in landfills. In addition, both the activated carbon, which is infrequently generated, and the offspecification filters are very low volume wastes (on an annualized basis, the spent carbon totals about 1 MT and the spent off specification filters equal 0.5 MT). As stated in the wastewater rationale, the wastewater contribution from the phosphoric acid process is insignificant. Therefore, the volumes of treatment sludge (and any constituents of potential concern) attributable to the phosphoric acid process are small and unlikely to present any significant risk. We do not believe any of these materials contain significant concentrations of any contaminants of concern. Therefore, we propose not to list these wastes as listed hazardous wastes under RCRA.

8. Phosphorus Pentasulfide a. Summary. We have evaluated the wastes from the production of phosphorus pentasulfide and propose not to list any wastes from this process as hazardous. These wastestreams 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 have identified no risks of concern associated with the current management of these wastes. b. Description of the phosphorus pentasulfide industry. Phosphorus pentasulfide was produced by three facilities in the United States in 1998. Phosphorus pentasulfide is used in the manufacture of lubricating oil additives, insecticides, ore flotation agents and specialty chemicals. The production of phosphorus pentasulfide begins by feeding liquid phosphorus and liquid sulfur into a reactor. The reaction is carefully controlled because phosphorus pentasulfide reacts violently with air forming phosphorus pentoxide and sulfur dioxide and because toxic hydrogen sulfide gas forms when phosphorus pentasulfide combines with moisture on exposure to air. To reduce this hazard, the process equipment is continuously purged with nitrogen. The phosphorus pentasulfide vapors are distilled and the liquid from the process is solidified, milled and packaged. One facility operates its entire process under nitrogen blanket. The blanketed vessels, packaging area and tote bin wash systems are all vented to a caustic scrubber. A second facility vents the reactor to a caustic scrubber that removes the sulfur dioxide and hydrogen sulfide and generates a blowdown wastestream. The facility has other scrubbers that remove phosphorus pentoxide from the exhaust stream and reacts it with water to produce a dilute phosphoric acid that is routed to their acid plant. The third facility fills the reactor, condenser and packaging equipment with nitrogen to prevent oxidation. This nitrogen stream is scrubbed with recirculating water to remove phosphorus pentasulfide dust. The scrubber liquor is treated and discharged. c. Description of wastes generated by the phosphorus pentasulfide process. We have identified nine waste categories from the production of phosphorus pentasulfide that required assessment. These waste categories are described briefly and in more detail in the following subsections. ÐStill residue/ reactor waste is the result of impurities being left behind when the phosphorus pentasulfide is distilled to remove undesirables (high boilers). This residue consists of glassy phosphates, carbon, and iron sulfide compounds and is removed from the reactor during unit turnaround ÐPhosphorus pentasulfide scrap waste is occasionally generated during certain maintenance operations or equipment failure. This waste can also consist of commercial offspecification material and fugitive dust from the packaging operation. ÐAbsorbents contaminated with phosphorus pentasulfide and Therminol (benzylated ethyl benzene) are generated from cleaning up leaks during maintenance operations. The absorbent material may be in the form of floor dry (a granular material) or an absorbent pillow. ÐWaste Therminol is a spent heat transfer product used for the vessels and pipes to prevent freeze up of the liquid phosphorus pentasulfide. ÐScrubber water is generated as a result of a nitrogen stream being scrubbed to remove phosphorus pentasulfide dust. The packaging equipment is filled with nitrogen to prevent oxidation. ÐCaustic scrubber water is the result of the reactor, packing and tote bin wash system being vented to the scrubber to remove sulfur dioxide and residual hydrogen sulfide. ÐTote bin wash water results from cleaning the shipping containers that hold the product. The phosphorus pentasulfide residue is washed from the returned containers with water and caustic. ÐScrap sulfur is occasionally generated when making or breaking couplings to hoses where sulfur comes into the reaction.

One facility reported that they filter elemental phosphorus before feeding it to the reactor. The filter solids, called phosphorus impurities, are managed in tanks and then are piped to that facility's phosphoric acid production furnace for phosphorus reclamation. Because there is low potential for significant exposure from on site storage prior to entry in the furnace, we did not evaluate this material further under this sector. Note that wastes generated from the production of phosphoric acid via the dry process, including this facility's phosphoric acid furnace, are addressed in section III. F. 7 of today's proposal. We have organized our discussion of these wastes in terms of how they are currently managed: characteristic wastes, wastewaters, and scrap sulfur. d. Agency evaluation. (1) Characteristic wastes. The RCRA Section 3007 Surveys show that a number of the phosphorus pentasulfide wastes categories are managed as RCRA hazardous wastes at all times. These wastes are hazardous because they exhibit the characteristics of ignitability, reactivity or toxicity for chromium or benzene. The facility that generates the largest volume waste, phosphorus pentasulfide scrap waste, considers it to be a listed hazardous waste (U189). The surveys also show that these wastes are managed as hazardous wastes, with final disposition by incinerated in Subtitle C units. Table III± 20 summarizes our information about these wastes.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00046 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55729 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules 41 One facility discontinued production as of November 1999 and has no future plans to resume production of phosphorus trichloride. This facility's wastes therefore are not included in the following overview, but were evaluated to determine their potential threat to human health or the environment. The details of this facility's waste generation and management practices are included in the `` Phosphoric Acid Listing Background Document for the Inorganic Chemical Listing Determination. '' TABLE III± 20.Ð CHARACTERISTIC WASTES FROM PHOSPHORUS PENTASULFIDE PRODUCTION DISPOSED IN SUBTITLE C UNITS Waste category Number of reported generators 1998 volume (MT) Reported hazard codes Final management practices Still residue/ reactor waste ............................. 2 4.6 D003, D007 ...... Subtitle C incineration. Phosphorus pentasulfide scrap waste .......... 3 67.75 D001, D003, U189. Subtitle C incineration.

Contaminated absorbent ............................... 1 1.2 (1996) D003 ................. Subtitle C incineration. Waste Therminol ........................................... 1 1.4 D018 ................. Subtitle C incineration.

We propose not to list these four waste categories as hazardous wastes under RCRA. All generators of these wastes already report managing these materials as hazardous from the point of generation through incineration because they exhibited one or more of the hazardous waste characteristics. Again, the rules applying to characteristic wastes adequately protect against mismanagement. Furthermore, ninety percent of the waste are already listed as commercial chemical product (U189). Therefore, we propose not to list these wastes. (2) Wastewaters. Wastewaters are generated at various points in the process as a result of scrubbing operations and tote bin washing. As identified by the facilities, the primary constituents of concern in these wastewaters are phosphoric acid and hydrogen sulfide which are readily controlled via neutralization. The management practices for these wastewaters do not allow for the release of phosphoric acid and hydrogen sulfide to the environment in an undiluted or unneutralized state. Table III± 21 summarizes our information on these wastewaters:

TABLE III± 21.Ð WASTEWATERS FROM PHOSPHORUS PENTASULFIDE PRODUCTION Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Process scrubber water ................................ 1 77,377 none ................. (1) Sewer, (2) POTW Caustic scrubber water ................................. 2 2,177 none ................. (1) Covered tanks, (2) off site treatment, (3) NPDES; (1) Treatment in covered tanks, (2) POTW. Tote bin wash water ...................................... 2 188 (1) D003 ........... (2) none ............ (1) Covered tanks, (2) off site treatment, (3) NPDES; (1) Treatment in covered tanks, (2) POTW.

We assessed the management practices for these wastes and determined that no exposure pathway of concern exists. Thus, we propose not to list these wastes as listed hazardous wastes under RCRA. The covered tanks employed minimize potential for releases to groundwater and air. Discharges to surface waters under NPDES are exempt from RCRA regulation. Discharges to POTWs via the facility's common sewage line are excluded from RCRA (40 CFR 261.4( a)( 1)( ii)). (3) Scrap sulfur. One facility reported generation of scrap sulfur that occasionally exhibits the characteristic of TC for lead. This sulfur is managed as hazardous in a Subtitle C incinerator. The 1998 waste volume was 0.12 MT. We do not believe this material warrants listing as hazardous waste and, therefore, propose not to list this waste as hazardous under RCRA. While this waste category was reported to periodically exhibit a characteristic, the generator always manages the waste in a Subtitle C incinerator. We believe this management practice is likely to continue because the cost to treat it as hazardous is low for such a small volume wastes, and because the waste may be TC hazardous as generated. This waste is also small volume and highly unlikely to present a significant risk.

9. Phosphorus Trichloride a. Summary. We have evaluated the wastes from the production of phosphorus trichloride and propose not to list any wastes from this process as hazardous wastes. These wastes 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 have identified no risks of concern associated with the current management of these wastes. b. Description of the phosphorus trichloride industry. Six facilities in the United States reported producing phosphorus trichloride in 1997 or 1998. We are assessing wastes from the five facilities that still produce this product. 41 Phosphorus trichloride is used as an intermediate in the production of a variety of chemicals. These chemicals are used to make pesticides, herbicides, antiscaling additives, corrosion inhibitors for cooling towers and heat exchangers, surfactants, sequestrants, and textile treating agents. Phosphorus VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00047 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55730 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules trichloride is used as a raw material in the production of chemicals that are used extensively as lubricating oil additives to control corrosion and as antioxidants and flame retardants in plastics. Phosphorus trichloride (PCl3) is a clear, volatile liquid with a pungent, irritating odor. Phosphorus trichloride is produced by one basic process. Liquid phosphorus and chlorine gas are continuously introduced into a reaction vessel. The phosphorus trichloride vapor phase is purified in a packed column and then liquified in a condenser. Most raw material impurities remain in the reactor and are removed as solid waste periodically during unit turnaround. Some facilities filter the product before shipment to ensure there is no dirt or other particles in the final product. A scrubber is used to collect materials from various points in the process. For example, hydrochloric acid and phosphorus acid (H3PO3), the hydrolysis products of phosphorus trichloride vapors are vented to the scrubber from the reactor. Also, phosphorus trichloride vapor generated during transfer of the product into shipping containers is collected and vented to the same scrubber. The wastewater generated from the scrubber( s) is commingled with miscellaneous wastewaters (e. g., reactor washout, spent filter wash, process area wash water) and sent for treatment. Some facilities generate a wastewater treatment sludge from the cleanout of treatment tanks. All of these facilities produce a variety of other products that are outside the scope of today's rule, and they commingle the wastewaters from PCl3 production with wastewaters from other processes. c. What kinds of wastes are generated by this process?. We have organized our discussion of these wastes in terms of how they are currently managed: characteristic wastes, wastewaters, recycled phosphorus, and noncharacteristic non wastewaters. The wastes generated by this process include: ÐReactor cleanout sludge consists of impurities from the elemental phosphorus and chlorine raw materials, including high boiling impurities such as arsenic trichloride that are retained in the reactor. These materials are sent to Subtitle C incinerators. ÐInitial washout water from reactor is generated as a result of rinsing out the reactor after sludge removal. In one case, the reactor is cleaned with hot water only and there is no initial sludge removal step. These materials are treated and discharged to an POTW and under a NPDES permit. ÐProduct storage tank cleanout with nonreactive phosphate ester is the rinsate generated from cleaning the storage tank or equipment. When this rinse is done, the rinsate is drummed for off site disposal as a hazardous waste. ÐProduct storage tank cleanout with water is generated as a result of additional rinsing that follows phosphate ester rinsing. This potentially acidic rinse water is sent to wastewater treatment for neutralization. ÐSpent filter washwater for product is generated as the result of washing the spent filters used to remove dirt and particles from the product. This wash water is mixed with other wastewaters and sent to wastewater pretreatment. ÐProcess area wash water consists of pad washdown/ rain water and any spilled material collected in contained areas. This wash water is mixed with other wastewaters and sent to wastewater pretreatment. ÐFinal washout water from reactor is the rinsate from additional reactor washing after sludge removal. The one facility reporting this rinsate commingles it with other wastewaters prior to wastewater pretreatment. ÐCaustic scrubber water consists of small amounts of sodium salts and residual caustic. Phosphorus trichloride, acid vapors, traces of chlorine and carbon dioxide are vented from various points of the process. The vent releases mixed with air are scrubbed before the air is released to the atmosphere. The spent scrubber charge is sent along with other wastewaters to wastewater pretreatment. ÐProcess scrubber water consists of a weak acidic solution from scrubbing residual gases from distillation and from various storage tank vents. ÐSpent filters for product are generated due to filtering dirt and other particles from the product before shipment. The filters are washed and dried before disposal. ÐWastewater treatment sludges are generated when wastewaters from the phosphorus trichloride and other processes are biologically treated. These sludges are only marginally derived from phosphorus trichloride wastewaters due to commingling with large volumes of other nonphosphorus trichloride wastewaters. The solids that are removed by filtration are landfilled. One facility reported recycling three secondary materials: phosphorous storage tank sediment; phosphorous transfer water; and absorber residual. The phosphorous storage tank sediment is generated periodically when the phosphorus storage tanks are cleaned. Because the material is stored in containers prior to being sent off site for recovery of phosphorus we found low potential for significant exposure from on site storage. The phosphorous recovery process is outside the scope of the consent decree so we did not evaluate its wastes. At this same facility, raw material phosphorous is unloaded from rail cars and conveyed through the facility using a closed pressurized piping system that uses water to push the phosphorous in the piping system. To unload the phosphorous from each rail car, water is pumped into the rail car to push the phosphorous out. Because the phosphorous/ water filled rail cars are then returned to the phosphorous manufacturers, where the phosphorous is then recovered, we found no potential for significant exposure, and did not evaluate this material further. The third instance of recycling at this facility, gases vented from the product check, storage tanks, and reflux separator are collected in an absorber. The vapors from the absorber are captured in a caustic scrubber and sent to wastewater treatment (see wastewaters in section d( 2) below). According to the facility, the non vapor phosphorous trichloride residual from the absorber is collected and piped to a non consent decree production process where the phosphorous trichloride is incorporated into the non consent decree product. Because this material is piped from the phosphorous trichloride process to the non consent decree process, and there is no significant potential for exposure, we did not evaluate this residual further. d. Agency evaluation. We have organized our discussion of these wastes in terms of how they are currently managed: characteristic wastes, noncharacteristic wastewaters, and noncharacteristic solid wastes. (1) Wastes that are characteristically hazardous wastes. Many of the phosphorus trichloride producers stated that a number of their wastes exhibit RCRA characteristics. These wastes are hazardous wastes because they exhibit the characteristics of ignitability, corrosivity, reactivity or toxicity. The Toxicity Characteristic was reported for arsenic, cadmium, chromium, lead, mercury, selenium or silver. These characteristic wastes are subject to the applicable LDR standards. Furthermore, these wastes are VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00048 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55731 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules ultimately disposed in Subtitle C management units or as discharges regulated under the Clean Water Act. We believe that the applicable Subtitle C and Clean Water Act regulations adequately protect against mismanagement. Table III± 22 summarizes our information about these wastes.

TABLE III± 22.Ð CHARACTERISTIC WASTES FROM PHOSPHORUS TRICHLORIDE PRODUCTION Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Reactor cleanout sludge ............................... 4 1 66 D001± 004, D006± 009, D010, D011. (1) container (2) Subtitle C incineration Initial washout water from reactor ................. 4 1 478 (1) D002, D004, D006, D007. (2) D002, D004 (3) D004, D007 (1) off site pretreatment, (2) POTW; (1) neutralized in tanks, (2) surface impoundment, (3) biotreat in tank, (4) NPDES; (1) tank, (2) off site biotreatment, (3) NPDES Product storage tank cleanout with nonreactive phosphate ester. 1 10 D002, D003 ...... (1) container (2) Subtitle C incineration Product storage tank cleanout with water ..... 1 15 D002 ................. (1) neutralized in tanks, (2) NPDES Spent filter wash for product ......................... 1 15 D002 ................. (1) pretreatment in tanks, (2) NPDES Process area wash water .............................. 1 1,400 D002 ................. (1) tanks, (2) NPDES 1 Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in 1998.

For all but one of the wastes in the above table, the generators report managing these materials as hazardous from the point of generation through disposal (or the point at which they become discharges to surface water regulated under NPDES or POTW regulations). We believe these wastes are sufficiently regulated such that mismanagement is unlikely. Thus, we propose not to list these seven waste categories. One facility appears to treat initial washout reactor water in tanks and then pass it through a nonhazardous waste surface impoundment. (All other units used to manage this waste have RCRA permits or are exempt from permitting.) While we have no analytical data on the treated waste that enters the impoundment, we do not believe this waste is likely to pose significant risk. The waste is generated infrequently (once a year) and combined with wastewaters from other processes. Based on information supplied by the facility, we estimated that the washout water would be diluted at least a hundred fold by the daily throughput to the wastewater treatment system. Any potential releases from the impoundment after dilution with other wastewaters would be unlikely to result in any significant long term risk. Therefore, we believe that this specific waste also does not pose significant threats to human health or the environment. (2) Non characteristic wastewaters. Wastewaters are generated at various points in the process as a result of scrubbing operations, equipment cleanup, and washing the process area. According to the data submitted by the facility, the primary constituents of concern in these wastewaters are hydrochloric acid and phosphorous acid, which are readily controlled via neutralization. The management practices for these wastewaters minimize opportunities for the release of hydrochloric acid or phosphorous acid to the environment in an undiluted or unneutralized state. Table III± 23 summarizes our information on these wastewaters.

TABLE III± 23.Ð WASTEWATERS FROM PHOSPHORUS TRICHLORIDE PRODUCTION Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Sequential management practices Final washout water from reactor ................. 1 not reported none ................. (1) pretreatment in tanks, (2) POTW. Caustic scrubber water ................................. 3 4,236 1 none ................. (1) pretreatment in tanks, (2) POTW or NPDES. Process scrubber water ................................ 3 12,528 1 D002 (one facility (1) pretreatment or neutralized in tanks, (2) POTW or NPDES.

1 Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in 1998.

We have assessed the management practices employed for these wastes and determined that no exposure pathway of concern exists that warrants listing. We have determined that plausible management would be continued management in existing tank based treatment systems. We believe the manufacturers have made a VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00049 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55732 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules considerable investment in wastewater treatment systems using tanks and will continue to use them. Further, we assumed that wastewater treatment tanks retain sufficient structural integrity to prevent wastewater releases to the subsurface (and therefore to groundwater), and that overflow and spill controls prevent significant wastewater releases. Thus, based on the lack of any significant likelihood of release of the constituents to groundwater, we did not project significant risks to groundwater from these wastes in the tank based wastewater treatment scenario. Furthermore, discharges to POTWs and surface waters under NPDES are regulated under the Clean Water Act and are exempt from RCRA Subtitle C regulation and thus were not assessed. We also considered the possibility of air releases from tanks. For most wastes, the constituents of concern are nonvolatile metals, making volatilization a very unlikely pathway of release from tanks. In addition, the facilities have installed tank covers, further reducing the likelihood of release to the air. As a result, we did not model releases to air from tanks from the production of phosphorus trichloride. Thus, we propose not to list these wastewaters as hazardous wastes under RCRA. (3) Non characteristic nonwastewaters The phosphorus trichloride sector reported two waste categories that do not routinely exhibit any characteristic and that are often managed in Subtitle D landfills; these wastes are summarized in Table III± 24.

TABLE III± 24.Ð NON CHARACTERISTIC SOLID WASTES Waste category Number of reported generators 1998 Volume (MT) Reported hazard codes Management practices Spent filters for product ................................. 1 0.1 none ................. industrial Subtitle D landfill. Wastewater treatment sludges ...................... 4 1 1,100 none 2 ............... Subtitle D landfill or Subtitle C landfill.

1 Volumes from 1997 are included in the totals when the wastes were not generated by a facility in 1998. 2 One facility reported that this wastewater treatment sludge is occasionally characteristically hazardous for D028 (dichloroethane), and the waste is then sent to a Subtitle C landfill. The dichloroethane is used in a process unrelated to the phosphorus trichloride process of interest in today's proposal.

The phosphorus trichloride product is filtered to remove PCl4 and PCl5. These compounds produce a slime on the product and are more viscous than the product. The facility washes the filters before sending them to disposal. The contaminants are easily washed off because of their ready solubility in water. The spent filters are generated in very small volumes. We are proposing not to list them because we do not expect the washed filters to contain significant levels of contaminants of concern. All four of the facilities that generate wastewater treatment sludges commingle wastewaters from PCl3 production with wastewaters from other processes. The wastewater contribution from the phosphorus trichloride process is very small compared to volumes of wastewaters from the other processes. Therefore, the phosphorus trichloride process does not contribute significant amounts of constituents to this sludge. We do not believe any of these materials warrant listing as hazardous wastes from the production of phosphorus trichloride. Therefore, we propose not to list these wastes as hazardous wastes under RCRA in this rulemaking.

10. Potassium Dichromate a. Summary. We evaluated the wastes from the production of potassium dichromate and propose not to list any wastes from this process as hazardous wastes under RCRA. 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 potassium dichromate industry. Potassium dichromate, which has a wide variety of industrial uses, was produced by a single facility in the United States in 1998. The U. S. demand for this chemical is very limited and has mostly been replaced by sodium dichromate for industrial use. Any demand not met by the U. S. facility is met by imports to U. S. distributors. Potassium dichromate is produced by reacting chromium trioxide with potassium hydroxide. The reactants are mixed in a reactor along with a crystal modifier. The potassium dichromate is crystallized, sent through a centrifuge to remove any remaining mother liquor, dried and packaged for sale. The single waste is filtered out from the mother liquor. The mother liquor is recycled back into the process. c. What kinds of wastes are generated by this process? There is one waste category generated from this process: filter solids and spent filter media. According to data submitted by the facility, this waste typically contains 12.5 percent chromium. The facility reports the waste as hazardous for chromium and manages it as hazardous (D007). The reported waste volume for 1998 was 0.6 MT. The waste is stored on site in drums and is shipped off site to a commercial Subtitle C facility for stabilization to meet the land disposal restrictions (40 CFR 268.40 and 268.48) and final disposal in a Subtitle C landfill. Because the total chromium levels are so high, we believe this waste will always exhibit the toxicity characteristic. d. Agency evaluation. We propose not to list this waste as hazardous under Subtitle C of RCRA. This waste is currently managed as hazardous from the point of generation through ultimate disposal because it is characteristically hazardous. The composition of the waste is such that it is likely to always be characteristic for chromium. The rules applying to characteristic wastes adequately protect against mismanagement.

11. Sodium Chlorate a. Summary. We propose not to list any wastes from the production of sodium chlorate (NaClO3) as hazardous under Subtitle C of RCRA. Process sludges, spent filters, wastewaters and hydrogen gas are generated from the production of sodium chlorate. These wastes and materials are managed in a variety of ways. After analysis of the management practices and potential exposure pathways of these wastes and materials, we concluded that there are no risk pathways of concern. These wastes and materials 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 sodium chlorate industry. There were ten facilities producing sodium chlorate in 1999. This industry manufactures sodium chlorate crystals and solutions from electrolysis of a sodium chloride brine.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00050 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55733 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules Sodium chlorate is the raw material used for the production of chlorine dioxide, which is replacing chlorine and sodium hypochlorite to be used as an oxidizing bleaching agent by the pulp and paper industry. The replacement of elemental chlorine with chlorine dioxide reduces effluent emissions of dioxin formed in the bleaching process of paper and pulp. Approximately ninety eight percent of sodium chlorate is used to generate chlorine dioxide. The other important use of sodium chlorate is as an intermediate in the production of other chlorates, perchlorates, and chlorites. All ten facilities use a similar process in producing sodium chlorate. These facilities dissolve sodium chloride salt in water to create a liquid brine. The brine is treated to remove impurities, such as calcium carbonate and magnesium hydroxide. The treated brine is filtered and pumped into electrolytic cells. In the cells, sodium chloride is converted to chlorine and sodium hydroxide which further react to form sodium chlorate and hydrogen gas. This reaction is catalyzed by sodium dichromate. Sodium chlorate is then treated with heat and urea to remove residual sodium hypochlorite. Sodium chlorate is then processed further for crystallization, centrifuging, drying, and packaging. A more complete discussion of this process and the industry can be found in `` Sodium Chlorate Listing Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal. c. What kinds of wastes are generated by this process? Wastes generated from the production of sodium chlorate consist of process sludges, spent filters and wastewaters. Based on an evaluation of survey responses from the ten sodium chlorate producers, we divided the wastes further into six general waste categories based on the presence or absence of chromium and lead. The sodium chlorate industry in general characterizes wastes that have been in contact with chromium or lead as hazardous (D007 or D008). Chromium is introduced into the process by the addition of sodium dichromate into electrolytic cells to protect electrodes from corrosion and to improve product yields. The presence of lead in the wastes results from the deterioration of anodes that can be used in the electrolytic cells. The six waste categories are: ÐProcess sludges with chromium or lead. These include electrolytic cells sludge, product filter press sludge, and those brine treatment sludges generated from purification where brine is formed by mixing salts with chrome laden wastewaters recycled from various steps of the process. ÐProcess sludges without chromium and lead. These wastes include filter press sludge or drum sludge from treatment of brine, when recycled chrome laden wastewater is not used in the brine dissolution step. ÐSpent filters with chromium or lead. The filters are generated at several points in the production process, but most are generated after the electrolysis of the brine solution when the mother liquor is filtered to remove impurities. ÐSpent filters without chromium and lead. Examples include disposable cartridge and sock filters from treatment of brine, when recycled chrome laden wastewater is not used in the brine dissolution step. ÐWastewaters with chromium that are not recycled back to the process. ÐOther wastewaters that do not contain chromium or lead and are not recycled (condensate, cooling water, and ion exchange wastewater). In addition to these wastes, other materials are produced by all ten facilities during the production of sodium chlorate that are piped directly back to the production process. Scrubber waters and filtrates are piped to on site sodium chlorate production units for use. Because these materials are managed prior to reuse in ways that present low potential for releases to the environment, and because we evaluated process wastes generated after they are reused, we do not believe that these secondary materials present significant threats. At all ten facilities, hydrogen gas is produced by the electrolysis units and is either piped to on site boilers, vented, or in one case, piped to a compression plant where it is compressed and sold. Because the material is a gas produced from a production unit rather than a waste management unit and is conveyed to its destination via piping, the gas is not a solid waste. RCRA Section 1004( 27) excludes non contained gases from the definition of solid waste and thus they cannot be considered a hazardous waste. (See 54 FR 50973) Because the gaseous materials are not solid wastes when produced, we did not evaluate them further for purposes of listing. One facility reports generating a wastewater (sulfate solution) from brine treatment. The wastewater is transported to an off site facility and used in their black liquor pulping process. The sulfate solution is added to black liquor for use in a wood digester. The process in the digester is outside the scope of the consent decree and we have not evaluated risks from wastes that it produces. We note, however, that the reuse of black liquor is excluded from regulation (40 CFR 261.4( a)( 6)). The sulfate solution is stored in tanks prior to use in the pulping process, which minimizes the potential for releases.

How Are These Wastes Currently Being Managed?

Table III± 25 summarizes the six waste categories, waste characteristics, waste volumes, and their current management practices:

TABLE III± 25.Ð WASTE FROM SODIUM CHLORATE PRODUCTION Waste category (number of facilities) Reported Waste Codes 1 1998 Volume (MT) Management practices Process sludges with chromium or lead (10). D001, D002, D007, D008 ........................ 28,547 Nine facilities store the waste on site in containers and then send it to Subtitle C landfills or incinerators; one facility decharacterizes the waste in tanks before managing it in on site surface impoundments Two facilities did not report hazard codes.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00051 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55734 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules TABLE III± 25.Ð WASTE FROM SODIUM CHLORATE PRODUCTIONÐ Continued Waste category (number of facilities) Reported Waste Codes 1 1998 Volume (MT) Management practices Process sludges without chromium and lead (5 2 ). none reported .......................................... 1,886 Three facilities store the waste on site in containers and then send it off site to municipal Subtitle D landfills; one facility stores the waste on a concrete pad with secondary containment before applying it to an on site land farm; one facility stores the waste on site in containers and then sends it off site to an industrial Subtitle D landfill; one facility stores the waste on site in containers before sending it off site for recycling. Spent filters with chromium or lead (7) ... D001, D007, D008 .................................. 82.9 All seven facilities classify the waste as hazardous; six send the waste to Subtitle C landfills or incinerators; one facility decharacterizes the waste on site in tanks, stores it in a closed compactor then ships the waste off site to an industrial Subtitle D landfill. Spent filters without chromium and lead (4). none reported .......................................... 3.52 Three facilities store the waste on site in containers and send it off site to Subtitle D landfills. One facility stores the waste with process sludge in on site containers and then sends it off site to a Subtitle C facility for stabilization prior to disposal in a Subtitle C landfill. Wastewaters with chromium that are not recycled back to the process (2). D002, D007 ............................................. 26,736 One facility sends the wastewater to an off site Subtitle C facility for treatment and disposal. One facility combines and treats the wastewater with other process wastewaters in tanks prior to discharge to on site surface impoundments Other wastewaters that do not contain chromium or lead and are not recycled (condensate, cooling water, ion exchange wastewater). none reported .......................................... 10,744 3 Discharged via NPDES permit or to a POTW.

1 D001 (ignitability); D002 (corrosivity); D007 (chromium); D008 (lead). 2 One facility contributes more than one residuals to this waste group. 3 Two facilities did not report volumes of this wastewater.

d. Agency evaluation. We selected wastes from three facilities for sampling. As described in detail in `` Sodium Chlorate Listing Background Document for the Inorganic Chemical Listing Determination'' in the docket for today's proposal, we selected these facilities and wastes because based on the survey information collected, we believe that the wastes generated by these three facilities are fully representative of the wastes generated by this industry and their management practices. We evaluated the characteristics and current management practices of each of the six waste categories. The details of our evaluation follow. (1) Process sludge with chromium or lead.

How Is This Waste Managed?

The predominant source of process sludge with chromium or lead is from the periodic cleanout of electrolytic cells used to convert the brine solution to sodium chlorate. All ten facilities generate this waste. Seven facilities classify their wastes as characteristic and send it off site to Subtitle C landfills or incinerators. Two facilities do not classify their wastes as characteristic but nevertheless send their wastes to Subtitle C landfills. The tenth facility, located in Hamilton, Mississippi, reports this waste to be characteristic and treats it in tanks to reduce hexavalent chromium to the relatively stable trivalent state. The facility commingles this sludge with wastes from the production of titanium dioxide (TiO2) in these tanks. The treated mixture is subsequently managed in a series of four surface impoundments, three of which are lined with leachate collection systems. Today's proposal separately addresses the titanium dioxide wastes that are commingled with this sodium chlorate sludge (see section III. F. 14. c.( 14)). How Was This Waste Characterized?

We collected a total of six samples to assess this waste categories. Three samples of the sludge from electrolytic cells were collected at two facilities where the wastes were destined for Subtitle C treatment and disposal. These two facilities generate and manage this waste as characteristically hazardous. These samples were part of the record characterizing this waste category, but were not used for risk assessment. We collected another three samples from the Hamilton, Mississippi facility that classifies this waste as characteristically hazardous and treats it in tanks to remove the characteristic prior to pumping the effluent to on site surface impoundments. One sample (KM± SC± 01) reflects the untreated sodium chlorate sludge collected from a dedicated sump prior to commingling with the titanium dioxide wastewaters. The second sample (KM± SI± 01) is the treated combined wastes collected at the inlet to the surface impoundments. The VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00052 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55735 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules third sample (KM± SI± 04) is the treated commingled sludge collected from one of the on site surface impoundments. Table III± 26, below, represents the analytical results for the Hamilton, Mississippi samples for total and hexavalent chromium, the primary constituent of concern. Total constituent analyses were conducted for the untreated waste. No other toxicants in the untreated wastewater sample (KM± SC± 01) exceed the health based levels. For the treated waste and the sludge collected from the impoundment, total and leaching analyses were conducted to allow us to assess potential releases to the environment. Our analytical data shows that total hexavalent chromium level in the treated sample (KM± SI± 01) is below the HBL for hexavalent chromium, demonstrating the effectiveness of the treatment process. We assessed the treated commingled sludge settled in the impoundments and found that the chromium levels did not exceed the HBLs.

TABLE III± 26.Ð ANALYTICAL DATA FOR SODIUM CHLORATE Constituents of concern KM± SC± 01 (Untreated NaC1O3 wastes only) KM± SI± 01 (Treated commingled NaC1O3 and TiO2 wastes) KM± SI± 04 (Treated commingled NaC1O3 and TiO2 sludge in impoundment) HBL Total (mg/ 1) Total (mg/ kg) SPLP (mg/ l) Total (mg/ kg) SPLP (mg/ l)

Chromium ......................................................................... 0.99 31.1 <0.05 1,140 0.05 23 Hexavalent Chromium ..................................................... 0.85 L <0.02 <0.02 <0.8 0.03 0.05 L: Concentration reported from analysis performed outside method recommended holding time. Value should be considered biased low.

The total chromium concentration in the treated waste is higher than the untreated waste due to commingling with other wastes from the titanium dioxide production process. There are other constituents detected in the treated commingled waste sample (KM± SI± 01) that are attributable to the titanium dioxide production process; these constituents are assessed in section III. F. 14. c.( 14) of today's proposal.

What Is EPA's Listing Rationale for This Waste? We propose not to list this waste category. Seven facilities consider wastes in this category to be characteristically hazardous (for D001, D002, D007 or D008) and manage the wastes under Subtitle C regulations. We believe that these regulations adequately protect against mismanagement. Two facilities do not classify their wastes as characteristic but send them to Subtitle C landfills. We also believe that this practice adequately prevents mismanagement. The remaining facility (which does not identify its sludges as characteristic hazardous wastes) treats the sludge in tanks to reduce hexavalent chromium to trivalent chromium prior to placement in on site surface impoundments. We found that the waste did not pose risks during treatment because there are no exposure pathways of concern for the on site treatment tanks. The wastes are treated in concrete tanks with secondary containment which minimize potential releases to groundwater. We also are not concerned with potential air releases from these tanks as neither volatile contaminants nor airborne particulates are likely to be present in the wastes. As discussed above, the primary constituent of concern in this waste is hexavalent chromium, which is treated to form relatively stable trivalent chromium. The physical form of the wastes (i. e., sludge with high water content) eliminates the potential for a significant release of airborne particulates. Furthermore, our analytical data show that the waste, after treatment, does not contain any constituents of concern at levels exceeding health based levels. (2) Process sludge without chromium and lead.

How Is This Waste Managed?

This sludge is produced as part of the initial purification of the brine solution. Five facilities report generating this type of waste and managing it as nonhazardous. Four facilities manage the waste in an on site land farm, offsite municipal Subtitle D landfills, and an industrial Subtitle D landfill. One facility ships their waste off site for recycling. We collected a total of four samples of this waste category from two facilities. Two of the four samples (HT± SN± 01 and EC± SN± 03) are representative of wastes that are land disposed. The other two samples (EC± SN± 01 and EC± SN± 02) are representative of wastes that are generally recycled and occasionally also landfilled. Table III± 27 identifies the constituents of concern that we found to be present in the waste at levels exceeding their respective HBLs and/ or soil screening levels.

TABLE III± 27.Ð ANALYTICAL RESULTS FOR SODIUM CHLORATE PROCESS SLUDGE WITHOUT CHROMIUM AND LEAD (PPM)

Parameter HT± SN± 01 EC± SN± 03 EC± SN± 01 EC± SN± 02 HBL 1 SSL Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP Arsenic .............................................. 14.3 2 0.03 <0.05 <5 <0.005 <0.05 <5 <0.005 <0.05 <5 <0.005 <0.05 0.0007 5.2 Cadmium ........................................... 27.4 <0.05 <0.05 <5 <0.05 <0.05 <5 <0.05 <0.05 <5 <0.05 <0.05 0.0078 4.3 Chromium ......................................... 57.3 <0.05 <0.05 15.3 <0.05 <0.05 <5 <0.05 <0.05 10.1 <0.05 <0.05 23 37 Copper .............................................. 17.2 <0.25 <0.05 15.3 <0.05 <0.05 <5 <0.25 <0.05 5.3 <0.25 <0.05 1.3 17 Lead .................................................. 14.8 0.024 <0.03 139 <0.03 <0.03 19.3 0.12 E 0.001 34.9 0.05 E 0.002 E 0.015 400* Manganese ....................................... 69.2 0.08 <0.05 238 4.5 <0.05 125 0.5 <0.05 51.9 0.7 <0.05 0.73 330 Mercury ............................................. 0.5 L <0.002 <0.0002 <0.1 <0.002 <0.0002 <0.1 <0.002 <0.0002 <0.1 <0.002 <0.0002 0.0047 24* Nickel ................................................ 7.4 <0.2 <0.05 12.1 0.4 <0.05 <5 <0.2 <0.05 <5 <0.2 <0.05 0.31 13 Silver ................................................. 1.1 <0.1 <0.01 <1 <0.1 <0.01 <1 <0.1 <0.01 <1 <0.1 <0.01 0.078 400* Zinc ................................................... 111 <2 <0.5 279 10.6 <0.5 <50 <2 <0.5 <50 <2 <0.5 4.7 48 1 SSL: Soil Screening Level based on geometric mean background concentration (mg/ kg) in soils in conterminous U. S. or soil ingestion HBL (marked *). 2 Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limit. E: Analysis performed outside recommended holding time. Reported value should be considered as estimated.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00053 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55736 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules What Management Scenarios Did We Aassess? We evaluated wastes managed under the four identified management scenarios: on site land farm, municipal Subtitle D landfill, industrial Subtitle D landfill, and recycling. Land farm scenario. One facility reports managing 37 MT/ year of this waste in an on site permitted land farm. EPA previously assessed this same land farm as part of the chlorinated aliphatics listing determinations (see proposed rule at 64 FR 46475, August 25, 1999). Today's assessment of sodium chlorate waste placed in the same unit is based on our earlier modeling of this unit for a waste from the production of chlorinated aliphatics (EDC/ VCM sludges). In assessing this management scenario, we first compared the total constituent concentrations of all four record samples to background soil concentrations. The following metals exceeded this screening criteria: arsenic, cadmium, chromium, copper, lead, mercury, silver, and zinc. We then used the metal modeling results generated from the chlorinated aliphatics listing determination to calculate the proportional sodium chlorate risk. The calculated modeling results of arsenic, cadmium, hexavalent chromium, and zinc for the same land farm are all below a hazard quotient (HQ) of 1 and 10 ´6 risk thresholds for the land treatment scenario. Finally, we compared the total concentrations of copper, lead, mercury, and silver of all samples to the soil ingestion HBL because these constituents were not assessed in the chlorinated aliphatics risk analyses. The maximum total concentrations of lead, mercury, and silver are well below the soil ingestion HBL, and the maximum total concentration of copper in this waste (i. e., 17.2 mg/ kg) is very close to the soil ingestion HBL (i. e., 17 mg/ kg). We believe that after mixing with soil in the land application unit, the copper concentration in the unit will be even lower. We do not believe this waste poses risk via volatilization to the air pathway because it does not contain any significant toxic volatile chemicals. In addition, the comparison described above for this unit, where we determined that the detected waste constituents are present in the waste at levels below or very close to the soil ingestion levels, suggests that any wind blown dust from the unit should not pose risk at levels of concern. Based on our analysis, we conclude that the waste does not present a substantial risk to human health or the environment when land applied. Landfill scenarios. Three facilities manage their wastes in municipal Subtitle D landfills and one facility manages its waste in an industrial Subtitle D landfill. We used the SPLP results of all four relevant samples to evaluate the industrial Subtitle D landfill management scenario. We found that the waste poses no substantial present or potential hazard to human health and the environment when managed in an industrial Subtitle D landfill because the SPLP leachate concentration of all constituents of the four samples of this waste category are below their respective HBLs. We used the TCLP results of all four relevant samples to assess the municipal Subtitle D landfill scenario. We modeled all three volumes reported being sent to municipal Subtitle D landfills. We focused our assessment on the geological regions in the northwestern and southeastern areas of the country because of the locations of the facilities and the landfills currently being used. The constituents we modeled are arsenic, lead, manganese, nickel, and zinc. The details regarding our modeling inputs and assumptions are provided in `` Sodium Chlorate Listing Background Document for the Inorganic Chemical Listing Determination'' and `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes' in the docket for today's proposal. The results of our risk assessment are summarized below in Table III± 28.

TABLE III± 28.Ð GROUNDWATER PATHWAY RISK ASSESSMENT RESULTS FOR PROCESS SLUDGE WITHOUT CHROMIUM AND LEAD Percentile Arsenic Manganese Nickel Zinc Adult cancer risk Child cancer risk Adult HQ Child HQ Adult HQ Child HQ Adult HQ Child HQ 90th .................................................. 3E± 08 ...... 2E± 08 ...... 2E± 04 ...... 4E± 04 ...... 2E± 06 ...... 3E± 06 ...... 5E± 08 ...... 1E± 07 95th .................................................. 2E± 07 ...... 2E± 07 ...... 6E± 04 ...... 1E± 03 ...... 2E± 05 ...... 3E± 05 ...... 5E± 06 ...... 1E± 05 Based on these risk assessment results, we conclude that process sludge without chromium and lead does not pose a substantial present or potential hazard to human health and the environment when managed in municipal Subtitle D landfills. We calculated hazard quotients for noncarcinogenic compounds (lead, manganese, nickel, and zinc), and all of these were well below a value of one. We found no adult or child cancer risk for arsenic in excess of 1E± 06 at the 95th percentile. Based on these results we conclude that this waste does not pose risk to human health and the environment. For a more complete description of this analysis, see `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in the docket for this proposal. Recycling scenario.Ð One facility ships their wastes to an off site facility for reuse. The material is added to mined gypsum used to retard the setting of concrete. We assessed this use because it involves land placement, with higher likelihood of releases to the environment. Two samples of this waste category were collected from the facility that produces and manages this waste in such a fashion. We compared this use to a less protective landfarming scenario, which we modeled, and found no risk of concern. The volume of the waste is quite small (< 1%) when compared to the volume of mined gypsum used by the off site facility. We believe that the constituent concentrations in the final cement product would be even lower due to mixing with other materials.

What Is EPA's Listing Rationale For This Waste?

Based on our assessments of the four management scenarios (on site land farm, municipal Subtitle D landfill, industrial Subtitle D landfill, and recycling), we found that the wastes do not present a substantial risk to human health or the environment. Therefore, we propose not to list these wastes. (3) Spent filters with chromium or lead.

VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00054 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55737 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules How Is This Waste Managed?

Spent filters are generated at several points in the production process but most are generated after the electrolysis of the brine solution. Seven facilities report generating this waste. Six of the seven facilities report this waste to be characteristic and ship it to off site Subtitle C landfills or incinerators. The seventh facility generates a very small volume of D007 waste that is acidwashed and decharacterized (to meet UTS) before being landfilled at an offsite industrial Subtitle D landfill.

How Was This Waste Characterized? We collected one sample of the spent filter that was decharacterized prior to being sent to an industrial Subtitle D landfill. We did not sample any of the six facilities that already adequately managed the waste under Subtitle C regulations. Table III± 29 presents the analytical results for the total and leaching analyses of the decharacterized spent filter sample (KM± FB± 01) for arsenic, lead, total chromium, and hexavalent chromium. Chromium and lead are the two primary constituents of concern in wastes of this category. The sample was not collected from the facility that uses anodes with lead coating, thus lead was not present in this sample. Arsenic was the only constituent detected in the SPLP analysis of this sample at levels exceeding the HBL.

TABLE III± 29.Ð ANALYTICAL RESULTS FOR SPENT FILTERS WITH CHROMIUM (KM± FB± 01)

Parameter Total (mg/ kg) TCLP (mg/ l) SPLP (mg/ l) Drinking water HBLs (mg/ l)

Arsenic ............................................................................................................. <0.5 <0.5 1 0.005 0.0007 Chromium ........................................................................................................ 41.0 <0.05 <0.05 20 Hexavalent Chromium ..................................................................................... 16.8 2 NA 2 <0.022 0.05 Lead ................................................................................................................. <5 <0.5 <0.03 0.015 1 Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection. 2 NA Not applicable. Typical TCLP leaching solution is not suitable for leachable hexavalent chromium because most (or all) hexavalent chromium in TCLP waste leachates were converted to trivalent chromium. The leach test for hexavalent chromium was modified by replacing the typical (TCLP/ SPLP) solution with deionized water.

What Is EPA's Listing Rationale For This Waste?

As previously noted, six of the seven generators of this waste report managing their wastes in Subtitle C facilities as characteristically hazardous from the point of generation through ultimate disposal. We did not conduct risk assessment on wastes identified as hazardous wastes and managed in Subtitle C facilities because listing would not provide any significant incremental control of wastes already managed under Subtitle C. We evaluated the small volume waste (i. e., 2.3 MT/ yr) generated by the seventh facility that decharacterizes its waste before landfilling in an industrial Subtitle D landfill. Because the volume of this waste is relatively small, we used a screening analysis (described in section III. E. 3) to screen the potential risk to groundwater associated with landfilling this waste. We found that the SPLP data for arsenic screens out because the volume of the waste generated by the facility is insufficient to release arsenic at levels of concern. For a more complete description of this analysis, see `` Risk Assessment for the Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in the docket for this proposal. Our analytical data demonstrate that the waste is effectively decharacterized and does not pose risks warranting listing for chromium, the primary constituent of concern in this waste. The result of the screening analysis for arsenic, the only constituent present in the waste's leachate at levels exceeding the HBL, shows that the arsenic in this waste does not pose risk to human health and the environment. Therefore, we propose not to list spent filters with chromium. (4) Spent filters without chromium and lead.

How Is This Waste Managed? This residual is usually generated as part of the initial brine purification steps, where impurities are removed from the brine solution, and from filtering of product during packaging. Four facilities report generating this type of waste. Two of these four facilities manage their wastes as nonhazardous in municipal Subtitle D landfills. One facility manages its waste as nonhazardous in an industrial Subtitle D landfill. One facility sends their spent filters along with process sludge off site to a Subtitle C facility for stabilization prior to disposal in a Subtitle C landfill. These wastes are generated in very small volumes.

How Was This Waste Characterized?

We collected two samples (HT± FB± 01 and HT± FB± 02) from one facility. These two samples are representative of wastes in this category that are land disposed. We found that antimony, arsenic, boron, hexavalent chromium, and lead in the TCLP or SPLP waste leachates exceeded their HBLs. We also found that cadmium was not detected in the leachates at a detection level of six times higher than its HBL. The detection limit was high due to dilution to minimize sample matrix interferences. Information on constituents of concern is summarized in Table III± 30.

TABLE III± 30.Ð ANALYTICAL RESULTS FOR SPENT FILTERS WITHOUT CHROMIUM OR LEAD Parameter HT± FB± 01 HT± FB± 02 HBL (mg/ l) Total (mg/ kg) TCLP (mg/ l) SPLP (mg/ l) Total (mg/ kg) TCLP (mg/ l) SPLP (mg/ l)

Antimony ...................... 34.1 0.018 <0.005 <5 0.012 <0.005 0.006 Arsenic ......................... 7.3 0.014 0.003 5.3 <0.005 <0.005 0.0007 Boron ............................ <50 6.1 <0.05 <50 0.67 <0.5 1.4 Cadmium ...................... 22.5 <0.05 <0.05 <5 <0.05 <0.05 0.008 Cr, +6 ........................... <0.8 NA <0.02 2.8 L NA 0.19 L 0.05 VerDate 11< MAY> 2000 20: 03 Sep 13, 2000 Jkt 190000 PO 00000 Frm 00055 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 14SEP2. SGM pfrm12 PsN: 14SEP2 55738 Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / Proposed Rules TABLE III± 30.Ð ANALYTICAL RESULTS FOR SPENT FILTERS WITHOUT CHROMIUM OR LEADÐ Continued Parameter HT± FB± 01 HT± FB± 02 HBL (mg/ l) Total (mg/ kg) TCLP (mg/ l) SPLP (mg/ l) Total (mg/ kg) TCLP (mg/ l) SPLP (mg/ l)

Lead ............................. 8.7 0.024 0.06 7.1 0.020 0.012 0.015 L: Concentration reported from analysis performed outside required holding time. Value should be considered biased low.

What Management Scenarios Were Assessed? We modeled both the industrial (0.6 MT/ year) and municipal (2.8 MT/ year) landfill scenarios, based on the reported management practices. We used the SPLP leachate concentrations to evaluate the industrial landfill scenario. The constituents of concern that exceeded their respective HBLs in the SPLP results were arsenic, hexavalent chromium, and lead. We evaluated these constituents using the de minimis volume screening analysis, as described in section III. E. 3 of today's proposal. The analysis suggests that hexavalent chromium and lead are not of concern. We then modeled arsenic using our standard groundwater model for the industrial landfill scenario. We used the TCLP leachate concentrations to evaluate the municipal landfill scenario. Using the de minimis volume analysis, we screened out boron, hexavalent chromium, and lead. We then conducted full groundwater modeling for the municipal scenario for antimony, arsenic, and cadmium.