# 64 FR 46476: Hazardous Waste Management System; Identification and Listing of Hazardous Waste; Chlorinated Aliphatics Production Wastes; Land Disposal Restrictions for Newly Identified Wastes; and CERCLA Hazardous Substance Designation and Reportable Quantities > Federal · Regulations · In force URL: https://www.frixlaw.com/law-library/statutes/FR_PRORULE_99-20753 ## Section - **Citation:** 64 FR 46476 - **Heading:** Hazardous Waste Management System; Identification and Listing of Hazardous Waste; Chlorinated Aliphatics Production Wastes; Land Disposal Restrictions for Newly Identified Wastes; and CERCLA Hazardous Substance Designation and Reportable Quantities - **Jurisdiction:** Federal - **Kind:** Regulations - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** Federal Register / Vol. 64 / 64 FR 46476 ## Text Part II Environmental Protection Agency _______________________________________________________________________ 40 CFR Parts 148, 261, 264, 265, 268, 271, and 302 Hazardous Waste Management System; Identification and Listing of Hazardous Waste; Chlorinated Aliphatics Production Wastes; Land Disposal Restrictions for Newly Identified Wastes; and CERCLA Hazardous Substance Designation and Reportable Quantities; Proposed Rule Proposed Rules ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 148, 261, 264, 265, 268, 271, and 302 [SWH-FRL-6413-4] RIN 2050-AD85 Hazardous Waste Management System; Identification and Listing of Hazardous Waste; Chlorinated Aliphatics Production Wastes; Land Disposal Restrictions for Newly Identified Wastes; and CERCLA Hazardous Substance Designation and Reportable Quantities AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. ----------------------------------------------------------------------- SUMMARY: The EPA is proposing to list three of six wastes from the chlorinated aliphatics industry as hazardous wastes under the Resource Conservation and Recovery Act (RCRA), which directs EPA to determine whether certain wastes from the chlorinated aliphatics industry present a hazard to human health or the environment. The effect of listing these three wastes will be to subject them to stringent management and treatment standards under RCRA and to subject them to emergency notification requirements for releases of hazardous substances to the environment. EPA is proposing a contingent-management listing approach for one of these wastes, and as one of two options for another of these wastes, such that waste generators will have the option of their waste not being listed if it is sent to a specific type of management facility. CRA and to subject them to emergency notification requirements for releases of hazardous substances to the environment. EPA is proposing a contingent-management listing approach for one of these wastes, and as one of two options for another of these wastes, such that waste generators will have the option of their waste not being listed if it is sent to a specific type of management facility. DATES: EPA will accept public comments on this proposed rule until November 23, 1999. Comments postmarked after this date will be marked ``late'' and may not be considered. Any person may request a public hearing on this proposal by filing a request by September 8, 1999. ADDRESSES: If you wish to comment on this proposed rule, you must send an original and two copies of the comments referencing docket number F- 1999-CALP-FFFFF to: RCRA Docket Information Center, Office of Solid Waste (5305G), U.S. Environmental Protection Agency Headquarters (EPA, HQ), 401 M Street, SW, Washington, D.C. 20460. Hand deliveries of comments should be made to the Arlington, VA, address listed in the fourth paragraph of SUPPLEMENTARY INFORMATION. You also may submit comments electronically by sending electronic mail through the Internet to: [email protected]. See the beginning of SUPPLEMENTARY INFORMATION for instructions on electronic submission. You should not submit electronically any confidential business information (CBI). You must submit an original and two copies of CBI under separate cover to: RCRA CBI Document Control Officer, Office of Solid Waste (5305W), U.S. EPA, 401 M Street, SW, Washington, D.C. 20460. See the beginning of SUPPLEMENTARY INFORMATION for information on viewing public comments and supporting materials. Address requests for a hearing to Mr. David Bussard at: Office of Solid Waste, Hazardous Waste Identification Division (5304W), U.S. Environmental Protection Agency, 401 M Street, SW, Washington, D.C. 20460, (703) 308-8880. ), U.S. EPA, 401 M Street, SW, Washington, D.C. 20460. See the beginning of SUPPLEMENTARY INFORMATION for information on viewing public comments and supporting materials. Address requests for a hearing to Mr. David Bussard at: Office of Solid Waste, Hazardous Waste Identification Division (5304W), U.S. Environmental Protection Agency, 401 M Street, SW, Washington, D.C. 20460, (703) 308-8880. FOR FURTHER INFORMATION CONTACT: For general information, contact the RCRA Hotline at (800) 424-9346 or TDD (800) 553-7672 (hearing impaired). In the Washington, D.C., metropolitan area, call (703) 412- 9810 or TDD (703) 412-3323. For information on specific aspects of the rule, contact Ross Elliott of the Office of Solid Waste (5304W), U.S. Environmental Protection Agency, 401 M Street, SW, Washington, D.C. 20460. [E-mail addresses and telephone numbers: [email protected], (703) 308-8748.] SUPPLEMENTARY INFORMATION: You should identify comments in electronic format with the docket number F-1999-CALP-FFFFF. You must submit all electronic comments as an ASCII (text) file, avoiding the use of special characters and any form of encryption. If you do not submit comments electronically, EPA is asking prospective commenters to voluntarily submit one additional copy of their comments on labeled personal computer diskettes in ASCII (text) format or a word processing format that can be converted to ASCII (text). It is essential to specify on the disk label the word processing software and version/ edition as well as the commenter's name. This will allow EPA to convert the comments into one of the word processing formats utilized by the Agency. Please use mailing envelopes designed to physically protect the submitted diskettes. EPA emphasizes that submission of comments on diskettes is not mandatory, nor will it result in any advantage or disadvantage to any commenter. Supporting documents in the docket for this Notice are also available in electronic format on the Internet one of the word processing formats utilized by the Agency. Please use mailing envelopes designed to physically protect the submitted diskettes. EPA emphasizes that submission of comments on diskettes is not mandatory, nor will it result in any advantage or disadvantage to any commenter. Supporting documents in the docket for this Notice are also available in electronic format on the Internet. Follow these instructions to access these documents. WWW: http://www.epa.gov/epaoswer/hazwaste/id FTP: ftp.epa/gov Login: anonymous Password: your Internet address Files are located in /pub/gopher/OSWRCRA. EPA will keep the official record for this action in paper form. Accordingly, we will transfer all comments received electronically into paper form and place them in the official record, which will also include all comments submitted directly in writing. The official record is the paper record maintained at the address in ADDRESSES at the beginning of this document. EPA responses to comments, whether the comments are written or electronic, will be in a notice in the Federal Register or in a response to comments document placed in the official record for this rulemaking. We will not immediately reply to commenters electronically other than to seek clarification of electronic comments that may be garbled in transmission or during conversion to paper form, as discussed above. You may view public comments and supporting materials in the RCRA Information Center (RIC), located at Crystal Gateway I, First Floor, 1235 Jefferson Davis Highway, Arlington, VA. The RIC is open from 9 a.m. to 4 p.m., Monday through Friday, excluding federal holidays. To review docket materials, we recommend that you make an appointment by calling (703) 603-9230. You may copy a maximum of 100 pages from any regulatory docket at no charge. Additional copies cost $0.15/page. For information on accessing paper and/or electronic copies of the document, see the first paragraph of the SUPPLEMENTARY INFORMATION section. hrough Friday, excluding federal holidays. To review docket materials, we recommend that you make an appointment by calling (703) 603-9230. You may copy a maximum of 100 pages from any regulatory docket at no charge. Additional copies cost $0.15/page. For information on accessing paper and/or electronic copies of the document, see the first paragraph of the SUPPLEMENTARY INFORMATION section. Customer Service How Can I Influence EPA's Thinking on This Proposed Rule? In developing this proposal, we tried to address the concerns of all our stakeholders. Your comments will help us improve this rule. We invite you to provide different views on options we propose, new approaches we haven't considered, new data, how this rule may affect you, or other relevant information. We welcome your views on all aspects of this proposed rule, but we request comments in particular on the items indicated at the end of each section. Your comments will be most effective if you follow the suggestions below: Explain your views as clearly as possible and provide a summary of the reasoning you used to arrive at your conclusions, as well as examples to illustrate your views, where possible. Provide solid technical and cost data to support your views. If you estimate potential costs, explain how you arrived at your estimate. Tell us which parts you support, as well as those with which you disagree. Offer specific alternatives. Reference your comments to specific sections of the proposal, such as the sections or page numbers of the preamble, or the regulatory citations. Remember that your comments must be submitted by the deadline in this notice. Include the name, date, and docket number with your comments. Contents of This Proposed Rule The contents of the preamble to this proposed rule are listed in the following outline: I. Overview specific sections of the proposal, such as the sections or page numbers of the preamble, or the regulatory citations. Remember that your comments must be submitted by the deadline in this notice. Include the name, date, and docket number with your comments. Contents of This Proposed Rule The contents of the preamble to this proposed rule are listed in the following outline: I. Overview A. Who Potentially Will Be Affected by This Proposed Rule? B. Why Does This Rule Read Differently From Other Listing Rules? C. What Are the Statutory Authorities for This Rule? II. Background A. Schedule Suit B. Existing Chlorinated Aliphatics Listings III. Today's Action A. Summary of Today's Action 1. Scope of the Listing Determination 2. Summary of the Proposed Listing Determinations 3. Summary of the Remainder of This Preamble B. Description of the Industry C. Overview of EPA's Information Collection Activities 1. Field Investigations and Sampling 2. RCRA Section 3007 Survey D. What Are the Risks Associated With Management of Wastewaters and Wastewater Treatment Sludges From the Production of Chlorinated Aliphatic Chemicals? 1. What Are the Risks for Potential Human Receptors? 2. What Are the Potential Risks for Ecological Receptors? 3. Did EPA Conduct a Peer Review of the Risk Assessment? E. Waste-Specific Listing Determination Rationales 1. Chlorinated Aliphatics Wastewaters 2. EDC/VCM Wastewater Treatment Sludges 3. VCM-A Wastewater Treatment Sludges 4. Methyl Chloride Wastewater Treatment Sludges 5. Allyl Chloride Wastewater Treatment Sludges F. Constituents Proposed for Addition to Appendix VIII to 40 CFR Part 261 IV. Economic Analysis Peer Review of the Risk Assessment? E. Waste-Specific Listing Determination Rationales 1. Chlorinated Aliphatics Wastewaters 2. EDC/VCM Wastewater Treatment Sludges 3. VCM-A Wastewater Treatment Sludges 4. Methyl Chloride Wastewater Treatment Sludges 5. Allyl Chloride Wastewater Treatment Sludges F. Constituents Proposed for Addition to Appendix VIII to 40 CFR Part 261 IV. Economic Analysis A. What Is the Purpose of the Economic Analysis? B. How May the Public Participate in the Economic Analysis? C. How Are Chlorinated Aliphatic Chemicals Used in the Economy? D. Where Are CAHCs Manufactured in the United States? E. Have CAHCs Been Produced Historically in Other Locations in the United States? F. What Are the Estimated Potential Industry Costs of This Listing? V. Proposed Treatment Standards Under RCRA's Land Disposal Restrictions A. What Are EPA's Land Disposal Restrictions (LDRs)? B. How Does EPA Develop LDR Treatment Standards? C. What Kind of Treatment Standards Are Proposed? D. Other LDR-Related Provisions E. What Standards Are Proposed for K173? F. What Standards Are Proposed for K174? G. What Standards Are Proposed for K175? H. What Other Land Disposal Restrictions Aspects Are There to the Proposal? I. Is There Treatment Capacity for the Proposed Wastes? VI. Compliance Dates A. Notification B. Interim Status and Permitted Facilities VII. State Authority A. Applicability of Rule in Authorized States B. Effect on State Authorizations VIII. Designation of Chlorinated Aliphatic Wastes (K173, K174 and K175) Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) s There Treatment Capacity for the Proposed Wastes? VI. Compliance Dates A. Notification B. Interim Status and Permitted Facilities VII. State Authority A. Applicability of Rule in Authorized States B. Effect on State Authorizations VIII. Designation of Chlorinated Aliphatic Wastes (K173, K174 and K175) Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) A. What Is the Relationship Between RCRA and CERCLA? B. Is EPA Proposing To Add Chlorinated Aliphatic Wastes to CERCLA? C. How Does EPA Determine Reportable Quantities? D. When Do I Need to Report a Release of K173, K174 or K175 Under CERCLA? E. What if I Know the Concentration of the Constituents in My Waste? F. How Did EPA Determine the RQs for K173, K174 and K175 and Their Hazardous Constituents? G. How Do I Report a Release? H. What Is the Statutory Authority for This Program? I. How Can I Influence EPA's Thinking on Regulating K173, K174 and K175 Under CERCLA? IX. Administrative Assessments A. Executive Order 12866 B. Regulatory Flexibility Act C. Paperwork Reduction Act D. Unfunded Mandates Reform Act E. Executive Order 12875: Enhancing the Intergovernmental Partnership F. Executive Order 13084: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Risks and Safety Risks H. National Technology Transfer and Advancement Act of 1995 I. Executive Order 12898: Environmental Justice I. Overview A. Who Potentially Will Be Affected by This Proposed Rule? cing the Intergovernmental Partnership F. Executive Order 13084: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Risks and Safety Risks H. National Technology Transfer and Advancement Act of 1995 I. Executive Order 12898: Environmental Justice I. Overview A. Who Potentially Will Be Affected by This Proposed Rule? Beginning January 1, 1999 all documents related to USEPA's regulatory, compliance and enforcement activities including rules, policies, interpretive guidance, and site-specific determinations with broad application, should properly identify the regulated entities, including descriptions that correspond to the applicable SIC codes or NAICS codes (source: 09 October 1998 USEPA memo from Peter D. Robertson, Acting Deputy Administrator of USEPA). Today's action, if finalized, could potentially affect those who handle the wastes that EPA is proposing to add to the Agency's list of hazardous wastes under the RCRA program. This action also may affect entities that may need to respond to releases of these wastes as CERCLA hazardous substances. These potentially-affected entities are described in the Economics Background Document placed in the docket in support of today's proposed rule; a summary is shown in the table below. Summary of Facilities Potentially Affected by the USEPA's 1999 Chlorinated Aliphatics Manufacturing Waste Listing Proposal According to Applicable SIC and NAICS Codes ---------------------------------------------------------------------------------------------------------------- Number of Parent U.S. Parent Item company Industry sector name relevant company NAICS SIC code CAHC mfg. code facilities* equivalent** ---------------------------------------------------------------------------------------------------------------- 1............................. 1311 Mining: Crude petroleum and natural 3 211111 gas. 2............................ ------------------------------ Number of Parent U.S. Parent Item company Industry sector name relevant company NAICS SIC code CAHC mfg. code facilities* equivalent** ---------------------------------------------------------------------------------------------------------------- 1............................. 1311 Mining: Crude petroleum and natural 3 211111 gas. 2............................. 1400 Mining: Nonmetallic minerals, except 2 212300 fuels. 3............................. 2295 Manufacturing: Coated fabrics, not 1 31332 rubberized. 4............................. 2800 Manufacturing: Chemicals & allied 3 325000 products. 5............................. 2810 Manufacturing: Chemicals & allied 1 325000 products. 6............................. 2812 Manufacturing: Alkalies & chlorine 1 325181 manufacture. 7............................. 2821 Manufacturing: Plastics materials & 8 325211 resins. 8............................. 2851 Manufacturing: Paints & allied 1 32551 products. 9............................. 2869 Manufacturing: Industrial organic 1 32511 chemicals, nec. 10............................ 2911 Manufacturing: Petroleum refining..... 1 32411 11............................ 3600 Manufacturing: Electronic & other 1 335000 electric equipment. ------------- Total Applicable Facilities....... 23 ---------------------------------------------------------------------------------------------------------------- *The number of relevant facilities is based on the (a) type of CAHC products manufactured, (b) types of wastes generated, and (c) baseline waste management practices, in relation to the terms and conditions of the proposed listing options. However, all CAHC manufacturing facilities in each industrial sector code may not be affected by the proposed listing options ------------------------------- *The number of relevant facilities is based on the (a) type of CAHC products manufactured, (b) types of wastes generated, and (c) baseline waste management practices, in relation to the terms and conditions of the proposed listing options. However, all CAHC manufacturing facilities in each industrial sector code may not be affected by the proposed listing options. **OSW-EMRAD derived the NAICS code equivalents above from the SIC-to-NAICS conversion tables provided by the US Department of Commerce, Bureau of the Census, at the following website: http://www.census.gov/epcd/www/ naicstab.htm. There is no direct match in the SIC-NAICS conversion tables for SIC codes 1400, 2800, 2810, and 3600, so a generalized six-digit NAICS code is provided above for these four cases. The list of potentially affected entities in the above table may not be exhaustive. Our aim is to provide a guide for readers regarding entities likely to be regulated by this action. This table lists those entities that EPA is aware potentially could be affected by this action. However, this action may affect other entities not listed in the table. To determine whether your facility is regulated by this action, you should examine 40 CFR 260 and 261 carefully in concert with the proposed rules amending RCRA that are found at the end of this Federal Register notice. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding section entitled FOR FURTHER INFORMATION CONTACT. B. Why Does This Rule Read Differently From Other Listing Rules? ld examine 40 CFR 260 and 261 carefully in concert with the proposed rules amending RCRA that are found at the end of this Federal Register notice. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding section entitled FOR FURTHER INFORMATION CONTACT. B. Why Does This Rule Read Differently From Other Listing Rules? Today's proposed listing determination preamble and regulations are written in ``readable regulations'' format. The authors tried to use active rather than passive voice, plain language, a question-and-answer format, the pronouns ``we'' for EPA and ``you'' for the owner/ generator, and other techniques to make the information in today's rule easier to read and understand. This new format is part of the Agency's efforts at regulatory reinvention, and it makes today's rule read differently from other listing rules. The Agency believes that this new format will increase readers' abilities to understand the regulations, which should then increase compliance, make enforcement easier, and foster better relationships between EPA and the regulated community. C. What Are the Statutory Authorities for This Rule? These regulations are being proposed under the authority of Sections 2002(a), 3001(b), 3001(e)(2) and 3007(a) of the Solid Waste Disposal Act, 42 U.S.C. 6912(a), 6921(b) and (e)(2), and 6927(a) as amended several times, most importantly by the Hazardous and Solid Waste Amendments of 1984 (HSWA). These statutes commonly are referred to as the Resource Conservation and Recovery Act (RCRA), and are codified at Volume 42 of the United States Code (U.S.C.), Sections 6901 to 6992(k) (42 U.S.C. 6901-6992(k)). Section 102(a) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), 42 U.S.C. 9602(a) is the authority under which the CERCLA aspects of this rule are being proposed. II. Background A. Schedule Suit servation and Recovery Act (RCRA), and are codified at Volume 42 of the United States Code (U.S.C.), Sections 6901 to 6992(k) (42 U.S.C. 6901-6992(k)). Section 102(a) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), 42 U.S.C. 9602(a) is the authority under which the CERCLA aspects of this rule are being proposed. II. Background A. Schedule Suit In 1989, the Environmental Defense Fund (EDF) sued the Environmental Protection Agency (EPA), in part for failing to meet the statutory deadlines of Section 3001(e)(2) of RCRA (EDF vs. Browner; Civ. No. 89-0598 D.D.C.). To resolve most of the issues in the case, EDF and EPA entered into a consent decree, which has been amended several times to revise dates. The consent decree sets out deadlines for promulgating certain RCRA rules and for completing certain studies and reports. Paragraph 1. m. of the consent decree obliges EPA to propose a hazardous waste listing determination for wastewaters and wastewater treatment sludges generated from the production of specified chlorinated aliphatic chemicals. The wastewater and wastewater treatment sludges subject to the consent decree are those from the production of chlorinated aliphatics for which other process wastes already have been designated as hazardous waste F024 in 40 CFR 261.31. According to the consent decree, EPA must propose listing determinations by July 30, 1999 and promulgate final listing determinations on or before September 30, 2000. Today EPA is proposing listing determinations for these wastes in accordance with the consent decree. B. Existing Chlorinated Aliphatics Listings ss wastes already have been designated as hazardous waste F024 in 40 CFR 261.31. According to the consent decree, EPA must propose listing determinations by July 30, 1999 and promulgate final listing determinations on or before September 30, 2000. Today EPA is proposing listing determinations for these wastes in accordance with the consent decree. B. Existing Chlorinated Aliphatics Listings Today's proposal does not affect the scope of the chlorinated aliphatics process wastes that already have been listed as hazardous in prior EPA rulemakings. These wastes include wastes designated as hazardous waste code F024 as well as a number of other chlorinated aliphatic wastes listed below in Table II-1. EPA is not soliciting comment on these existing hazardous waste listings and does not intend to respond to such comments, if received. Likewise, EPA is not soliciting comments in today's rule on the applicability of the existing chlorinated aliphatics listings to the provisions of CERCLA. Wastes listed as hazardous under RCRA are by definition hazardous substances under CERCLA, and are included in the list of hazardous substances in 40 CFR 302.4, along with their corresponding reportable quantities (``RQs''). Hazardous substance RQs are those quantities of the designated chemical or waste that trigger certain reporting requirements if released to the environment. The previously listed hazardous wastes from chlorinated aliphatics production and their corresponding RQs are listed below in Table II-1. zardous substances in 40 CFR 302.4, along with their corresponding reportable quantities (``RQs''). Hazardous substance RQs are those quantities of the designated chemical or waste that trigger certain reporting requirements if released to the environment. The previously listed hazardous wastes from chlorinated aliphatics production and their corresponding RQs are listed below in Table II-1. Table II-1.--List of Currently-Regulated Chlorinated Aliphatic Process Wastes and Corresponding Reportable Quantities as CERCLA Hazardous Substances ------------------------------------------------------------------------ Hazardous substance RQ pounds (KG) ------------------------------------------------------------------------ F024--Process wastes, including but not limited to, 1 (0.454) distillation residues, heavy ends, tars, and reactor cleanout wastes from the production of certain chlorinated aliphatic hydrocarbons, by free radical catalyzed processes. These chlorinated aliphatic hydrocarbons are those having carbon chain lengths ranging from one to and including five, with varying amounts and positions of chlorine substitution. [This listing does not include wastewaters, wastewater treatment sludges, spent catalysts, and wastes listed in 40 CFR 261.31 or 261.32.]........................... F025--Condensed light ends, spent filters and filter 1 (0.454) aids, and spent dessicant wastes from the production of certain chlorinated aliphatic hydrocarbons, by free radical catalyzed processes. These chlorinated aliphatic hydrocarbons are those having carbon chain lengths ranging from one to and including five, with varying amounts and positions of chlorine substitution. K016--Heavy ends or distillation residues from the 1 (0.454) production of carbon tetrachloride..................... K018--Heavy ends from the fractionation column in ethyl 1 (0.454) chloride production................................... phatic hydrocarbons are those having carbon chain lengths ranging from one to and including five, with varying amounts and positions of chlorine substitution. K016--Heavy ends or distillation residues from the 1 (0.454) production of carbon tetrachloride..................... K018--Heavy ends from the fractionation column in ethyl 1 (0.454) chloride production.................................... K019--Heavy ends from the distillation of ethylene 1 (0.454) dichloride in ethylene dichloride production........... K020--Heavy ends from the distillation of vinyl chloride 1 (0.454) in vinyl chloride monomer production................... K028--Spent catalyst from the hydrochlorinator reactor 1 (0.454) in the production of 1,1,1-trichloroethane............. K029--Waste from the product steam stripper in the 1 (0.454) production of 1,1,1-trichloroethane.................... K030--Column bottoms or heavy ends from the combined 1 (0.454) production of trichloroethylene and perchloroethylene.. K095--Distillation bottoms from the production of 1,1,1- 1 (0.454) trichloroethane........................................ K096--Heavy ends from the heavy ends column from the 1 (0.454) production of 1,1,1-trichloroethane.................... ------------------------------------------------------------------------ III. Today's Action A. Summary of Today's Action 1. Scope of the Listing Determination Aliphatic hydrocarbons are compounds composed of the atoms of hydrogen and carbon, where the carbon atoms are linked by covalent bonds in an open-chain (straight and branched) structure, and those cyclic compounds that resemble the open-chain compounds. Aliphatics are distinguished from aromatic hydrocarbons, which are defined as benzene and compounds that resemble benzene in chemical behavior. For an aliphatic to be chlorinated, one or more hydrogen atoms have been chemically replaced with chlorine atoms by covalent bonds in an open-chain (straight and branched) structure, and those cyclic compounds that resemble the open-chain compounds. Aliphatics are distinguished from aromatic hydrocarbons, which are defined as benzene and compounds that resemble benzene in chemical behavior. For an aliphatic to be chlorinated, one or more hydrogen atoms have been chemically replaced with chlorine atoms. The chlorinated aliphatic chemicals, the wastes of which are described in the (existing) F024 listing description, and identified in the consent decree, are those produced by free-radical catalyzed processes with carbon chain lengths ranging from one to five. EPA performed an initial review and investigation of the waste categories identified in the consent decree, as well as a review of chlorinated aliphatics production processes and the wastewaters and wastewater treatment sludges generated by these processes. The Agency decided, for the purpose of studying chlorinated aliphatic wastes, to divide the wastestreams into several distinct waste groupings. Waste groupings were defined to differentiate between unique residuals, as well as to differentiate between unique management practices (e.g., on- site land treatment) and/or particular constituents (e.g., mercury). The Agency segregated chlorinated aliphatics wastewaters into two groupings, with one group being wastewaters generated from the production of vinyl chloride monomer using mercuric chloride catalyst in an acetylene-based process. These wastewaters were evaluated as one group due to the unique nature of this production process, the fact that these wastewaters are treated in a dedicated wastewater treatment system, and the presence of mercury in the wastestream. All other chlorinated aliphatic wastewaters were included in a second group and evaluated collectively ercuric chloride catalyst in an acetylene-based process. These wastewaters were evaluated as one group due to the unique nature of this production process, the fact that these wastewaters are treated in a dedicated wastewater treatment system, and the presence of mercury in the wastestream. All other chlorinated aliphatic wastewaters were included in a second group and evaluated collectively. The Agency found that many producers of chlorinated aliphatics manufacture several different chlorinated aliphatic products at a single facility and commingle the wastewaters generated by all processes prior to treatment in a single wastewater treatment system. The Agency identified four waste groupings for wastewater treatment sludges generated by the chlorinated aliphatics industry. These waste groupings were defined based primarily upon the particular management practices used to manage the wastes, but also based on particular production processes. The Agency identified four waste groups for chlorinated aliphatics wastewater treatment sludges. These waste groups include sludges generated from the treatment of wastewaters from the production of: Ethylene dichloride and/or vinyl chloride monomer (EDC/ VCM); Vinyl chloride monomer using mercuric chloride catalyst in an acetylene-based process (VCM-A); Methyl chloride; and allyl chloride. The scope of today's notice does not include any other process residuals generated by the chlorinated aliphatics industry. In particular, the Agency is not re-evaluating previous listing determinations concerning wastes generated by chlorinated aliphatics production processes onomer using mercuric chloride catalyst in an acetylene-based process (VCM-A); Methyl chloride; and allyl chloride. The scope of today's notice does not include any other process residuals generated by the chlorinated aliphatics industry. In particular, the Agency is not re-evaluating previous listing determinations concerning wastes generated by chlorinated aliphatics production processes. The Agency also points out that the consent decree specifies that this listing determination ``shall include wastewaters and wastewater treatment sludges generated from the production of chlorinated aliphatics specified in the F024 listing'' (a listing which is limited to wastes from chlorinated aliphatic production using the ``free radical catalyzed process'' but does not include wastewaters or wastewater treatment sludges). However, for today's proposed rule the Agency did not restrict its evaluation of wastewaters and wastewater treatment sludges to only those generated from chlorinated aliphatics manufacturers using the free radical catalyzed process. In the rulemaking for the F024 listing (which includes process wastes such as distillation residues, heavy ends, and tars, but not wastewaters and wastewater treatment sludges) we found that there were distinct differences in the amount and type of chemical constituents present in these production wastes as a direct result of the production process used. For example, the free radical catalyzed reactions tended to produce unwanted organic compounds, as well as the desired chemical product, because this type of reaction is less specific (in terms of desired product) than other types of processes used. As a result, the chemical constituents that were the basis for listing F024 includes many organic compounds that are more prevalent in process wastes (again, tars, heavy ends, etc.) generated from the free radical catalyzed process mpounds, as well as the desired chemical product, because this type of reaction is less specific (in terms of desired product) than other types of processes used. As a result, the chemical constituents that were the basis for listing F024 includes many organic compounds that are more prevalent in process wastes (again, tars, heavy ends, etc.) generated from the free radical catalyzed process. However, in developing the information for today's proposed listing, EPA was concerned that limiting the scope of the investigation to free radical catalyzed processes might not be appropriate because of the different nature of wastewaters and wastewater treatment sludges as compared with the F024 process wastes. Wastewaters may be generated in different ways, including from scrubber waters, cooling waters, as well as reaction media, etc. Ultimately, our primary reason for not restricting our evaluation of wastewaters and wastewater treatment sludges to those generated by free radical catalyzed processes is that our preliminary analysis of these wastes indicated that the constituents of concern (i.e., dioxins, chloroform, arsenic) were not the same as the constituents of concern associated with the previously- listed F024 and F025 wastes. In those previous listing determinations (which did not include wastewaters or wastewater treatment sludges) the Agency was able to distinguish risk levels of concern based upon particular production processes. In the case of today's proposed listing determination, we were not able to make such a distinction. The primary constituents of concern in the wastes we are proposing to list as hazardous in today's notice are dioxins, whereas dioxins were not a basis for listing the F024 and F025 wastes s) the Agency was able to distinguish risk levels of concern based upon particular production processes. In the case of today's proposed listing determination, we were not able to make such a distinction. The primary constituents of concern in the wastes we are proposing to list as hazardous in today's notice are dioxins, whereas dioxins were not a basis for listing the F024 and F025 wastes. Data currently available to the Agency does not support a conclusion that wastewaters and wastewater treatment sludges generated by free radical catalyzed processes have significantly different concentrations of dioxins than other types of production processes used to manufacture chlorinated aliphatics. However, EPA requests comment and data addressing the issue of whether one type of manufacturing process (e.g., free radical catalyzation) versus all other potential processes (e.g., ionic catalyzed processes) would result in different levels of dioxins in the resulting wastestream. The Agency will consider modifying the listing description proposed in today's rulemaking as appropriate to account for distinctions identified in information available to EPA at the time of the final rule. 2. Summary of the Proposed Listing Determinations In today's notice, EPA is proposing to add three wastes generated by the chlorinated aliphatics industry to the list of hazardous wastes in 40 CFR 261.32. Below are the wastestreams EPA is proposing to list as hazardous with their corresponding proposed EPA Hazardous Waste Numbers. n information available to EPA at the time of the final rule. 2. Summary of the Proposed Listing Determinations In today's notice, EPA is proposing to add three wastes generated by the chlorinated aliphatics industry to the list of hazardous wastes in 40 CFR 261.32. Below are the wastestreams EPA is proposing to list as hazardous with their corresponding proposed EPA Hazardous Waste Numbers. K173 Wastewaters from the production of chlorinated aliphatic hydrocarbons, except for wastewaters generated from the production of vinyl chloride monomer using mercuric chloride catalyst in an acetylene-based process. This listing includes wastewaters from the production of chlorinated aliphatic hydrocarbons that have carbon chain lengths ranging from one to, and including five, with varying amounts and positions of chlorine substitution. K174 Wastewater treatment sludges from the production of ethylene dichloride or vinyl chloride monomer (EDC/VCM). K175 Wastewater treatment sludges from the production of vinyl chloride monomer using mercuric chloride catalyst in an acetylene- based process. EPA is proposing to list these wastes because these residuals meet the criteria set out in 40 CFR 261.11(a)(3) for listing a waste as hazardous. EPA assessed and considered these criteria for all six wastestreams through the use of risk assessments and risk modeling, as well as a consideration of other pertinent factors. Today's proposed listing determination follows the elements of the Agency's listing decision policy that was presented in the proposed listing for wastes generated by the dye and pigment industries published in the Federal Register on December 22, 1994 (see 59 FR 66073). This policy uses a ``weight-of-evidence'' approach in which calculated risk information is a key factor considered in making a listing determination determination follows the elements of the Agency's listing decision policy that was presented in the proposed listing for wastes generated by the dye and pigment industries published in the Federal Register on December 22, 1994 (see 59 FR 66073). This policy uses a ``weight-of-evidence'' approach in which calculated risk information is a key factor considered in making a listing determination. Upon promulgation of these proposed listings, wastes meeting the listing descriptions will become hazardous wastes and need to be managed in accordance with RCRA subtitle C requirements. Residuals from the treatment, storage, or disposal of the wastewater treatment sludges proposed to be listed as hazardous also will be classified as hazardous wastes pursuant to the ``derived-from'' rule (40 CFR 261.3(c)(2)(i)). 1 Also, with certain limited exceptions, any mixture of a listed hazardous waste and a solid waste is itself a RCRA hazardous waste (40 CFR 261.3(a)(2)(iv), ``the mixture rule''). --------------------------------------------------------------------------- \1\ As explained later in this notice, residuals generated from the management of wastewaters proposed to be listed as hazardous (i.e., wastewater treatment sludges) will not be subject to the derived-from rule due to the fact that EPA conducted separate investigations of these residuals and they are the subject of independent listing determinations. --------------------------------------------------------------------------- tice, residuals generated from the management of wastewaters proposed to be listed as hazardous (i.e., wastewater treatment sludges) will not be subject to the derived-from rule due to the fact that EPA conducted separate investigations of these residuals and they are the subject of independent listing determinations. --------------------------------------------------------------------------- In today's notice, the Agency is proposing an alternative approach to listing two of the wastes from chlorinated aliphatics processes as hazardous, rather than proposing to list these wastes in accordance with the Agency's traditional listing approach. The Agency is proposing a conditional listing approach for one waste, and as one of two alternative approaches for a second waste, because the Agency has evaluated the ways in which the wastes are likely to be managed and has determined that certain waste management activities would present significant risks but that others would be protective of human health and the environment. Under a contingent management approach, EPA is proposing to list particular wastes as hazardous only if the wastes are managed in a way other than the manner in which the Agency has determined is protective of human health and the environment. In implementing a conditional-listing approach, the Agency is proposing that wastes that fall outside the scope of the listing description (e.g., are destined for the appropriate type of disposal) are non- hazardous when generated. However, if it turns out that the waste actually is not handled in accordance with the conditions of the listing at any point in its management, the generators or other handlers of the waste would be subject to various enforcement actions or, depending on the violations, the waste could become a hazardous waste and may even be considered hazardous from the point of generation when generated. However, if it turns out that the waste actually is not handled in accordance with the conditions of the listing at any point in its management, the generators or other handlers of the waste would be subject to various enforcement actions or, depending on the violations, the waste could become a hazardous waste and may even be considered hazardous from the point of generation. The Agency's proposed conditional-listing approach for wastes generated from chlorinated aliphatics processes is further discussed in section III.E of today's notice. Today's action also proposes not to list as hazardous the following three wastes: Process wastewaters from the production of vinyl chloride monomer using mercuric chloride catalyst in an acetylene-based process, Wastewater treatment sludges from the production of methyl chloride, and Wastewater treatment sludges from the production of allyl chloride. 3. Summary of the Remainder of this Preamble Section III.B. describes the chlorinated aliphatics industry. Section III.C. describes how the information was gathered in support of today's proposed rule. Section III.D. is a description of the risk assessment performed for three of the wastes evaluated in today's rule, including chlorinated aliphatic wastewaters, EDC/VCM sludges, and methyl chloride sludges, and the results of these assessments. Section III.E provides the rationale for the proposed listing decisions for all six wastes analyzed in today's rule. Because full risk analyses were not necessary for VCM-A wastewaters, VCM-A wastewater treatment sludges, or allyl chloride sludges, we discuss our assessment of risks attributable to each of these wastes in the same sections where we describe our listing decisions for the wastes. Section IV contains the economic assessment of the industry and the estimated impact of today's proposed listing determinations isk analyses were not necessary for VCM-A wastewaters, VCM-A wastewater treatment sludges, or allyl chloride sludges, we discuss our assessment of risks attributable to each of these wastes in the same sections where we describe our listing decisions for the wastes. Section IV contains the economic assessment of the industry and the estimated impact of today's proposed listing determinations. Section V describes the proposed land disposal restriction requirements for those wastes we propose to list as hazardous, along with determinations of whether there is adequate treatment and disposal capacity for these wastes. Sections VI (compliance dates), VII (state authority), VIII (designating CERCLA hazardous substances) and IX (administrative assessments) discuss other analyses required by statute and various executive orders. B. Description of the Industry In 1992, when EPA began gathering information about the U.S. chlorinated aliphatics industry, it consisted of 27 facilities owned by 20 corporations. However, as a result of information updates in 1997, we determined that two chlorinated aliphatics facilities had closed and two additional facilities manufacture de minimis quantities of chlorinated aliphatics, lowering the number of facilities affected by today's proposed rulemaking to 23 and corporations to 19. Chlorinated aliphatics production facilities are located primarily in and around the petroleum/petrochemical industry which generally is located along the Gulf Coast. The majority of facility locations are fully integrated petrochemical processing facilities. A few facilities are co-located with other chemical manufacturing and/or petroleum refining facilities. These integrated facilities often manage wastes generated across different production processes within the same waste management systems. For example, these facilities often combine chlorinated aliphatic wastewaters with non-chlorinated aliphatics wastewaters prior to treatment facilities. A few facilities are co-located with other chemical manufacturing and/or petroleum refining facilities. These integrated facilities often manage wastes generated across different production processes within the same waste management systems. For example, these facilities often combine chlorinated aliphatic wastewaters with non-chlorinated aliphatics wastewaters prior to treatment. The combined wastewater treatment system generates a commingled sludge. In addition, there are facilities that manage chlorinated aliphatics wastewaters in separate or dedicated wastewater treatment systems. For the purpose of this listing determination, the Agency refers to these treatment systems, and resulting sludges, as ``dedicated'' systems and ``dedicated'' sludges. Nearly 10 million metric tons of chlorinated aliphatics were produced in 1996. More than 85 percent of the chlorinated aliphatic products manufactured in 1996 was ethylene dichloride and vinyl chloride monomer (EDC/VCM) manufactured via the ``balanced process.'' This process involves the production of EDC as an intermediate product using direct chlorination and oxyhydrochlorination of ethylene, followed by cracking to produce VCM. Other chlorinated aliphatics production includes chlorinated methanes, methyl chloride, and a variety of other products. C. Overview of EPA's Information Collection Activities EPA's investigation of the wastes generated by the chlorinated aliphatics industry can be characterized in terms of two major information collection efforts: field investigations and survey evaluation. The Agency's field investigations included engineering site visits, ``familiarization sampling'' (sample collection and analysis to gain a preliminary understanding of the nature and concentration of potential constituents of concern), and ``record sampling'' (sample collection and analysis to provide data to use in assessing the potential risks posed by the wastes) ns and survey evaluation. The Agency's field investigations included engineering site visits, ``familiarization sampling'' (sample collection and analysis to gain a preliminary understanding of the nature and concentration of potential constituents of concern), and ``record sampling'' (sample collection and analysis to provide data to use in assessing the potential risks posed by the wastes). The survey effort included the development, distribution, and assessment of an extensive industry-wide RCRA Section 3007 survey. Each of these efforts is summarized below. 1. Field Investigations and Sampling EPA initiated its work activities with a series of engineering site visits. The primary purpose of the site visits was to gather information on chlorinated aliphatic manufacturing processes and the generation, management, and characterization of the consent decree wastes. In addition, the field teams identified potential record sampling locations. The Agency conducted site visits at 16 facilities prior to record sampling; site visit facilities were selected based on a goal of obtaining first hand information from a representative sampling of all chlorinated aliphatic manufacturers as well as all relevant manufacturing and waste management processes, including an investigation of dedicated wastewater treatment units. Concurrently, the Agency initiated the analytical phase of this listing determination with the development of a Quality Assurance Project Plan (QAPjP) for sampling and analysis, followed by collection of 15 familiarization samples from three different manufacturing facilities (collected during the engineering site visits). The purpose of collecting familiarization samples is to assess the effectiveness of the analytical methods identified in the QAPjP for the analysis of the residuals of concern. Upon successful completion of the familiarization sampling and analysis effort, the Agency initiated record sampling and analysis of the consent decree wastes facilities (collected during the engineering site visits). The purpose of collecting familiarization samples is to assess the effectiveness of the analytical methods identified in the QAPjP for the analysis of the residuals of concern. Upon successful completion of the familiarization sampling and analysis effort, the Agency initiated record sampling and analysis of the consent decree wastes. The Agency sampled wastewaters and wastewater treatment sludges from twelve facilities. During a four- month period beginning in April of 1997, the Agency collected 52 samples, excluding additional blanks and matrix spike/matrix spike duplicates(MS/MSD) collected for quality assurance purposes. Of these 52 samples, 41 were wastewater samples, and 11 were wastewater treatment sludge samples. 2. RCRA Section 3007 Survey EPA developed an extensive questionnaire under the authority of Section 3007 of RCRA for distribution to the chlorinated aliphatics manufacturing industry. The purpose of the survey was to gather information about solid and hazardous waste generation and management practices in the U.S. chlorinated aliphatics manufacturing industry necessary to support the listing determination. The questionnaire covered topics such as chlorinated aliphatic product information, facility and unit process flow diagrams, process descriptions, residual generation and residual management profiles. The Agency distributed the survey in November of 1992 to 57 facilities and/or corporations identified as potential chlorinated aliphatics manufacturers from the most recent information available at the time. Of the 57 surveys distributed, completed surveys were received from 27 facilities. These facilities represent 20 companies that reported that they had manufactured chlorinated aliphatics in 1991. The remaining facilities notified EPA that they had either stopped operations or identified as potential chlorinated aliphatics manufacturers from the most recent information available at the time. Of the 57 surveys distributed, completed surveys were received from 27 facilities. These facilities represent 20 companies that reported that they had manufactured chlorinated aliphatics in 1991. The remaining facilities notified EPA that they had either stopped operations or did not manufacture chlorinated aliphatic products. We also conducted an exhaustive engineering review of the submitted surveys for accuracy and completeness. Data from the survey responses was then entered into a data base known as the Chlorinated Aliphatics Industry Studies Data Base (ISDB). We conducted quality assurance reviews of the ISDB to identify any inappropriate entries and missing data links. The exhaustive engineering review of each facility's response resulted in follow-up letters and/or telephone calls to facility representatives seeking clarifications, corrections, and additional data where needed. The responses to these requests for clarification, along with additional information gathered during engineering site visits and familiarization and record sampling activities were entered into the data base. In 1996 we conducted a review of data collected previously, and re- contacted facility representatives to verify the status of chlorinated aliphatics manufacturing operations. In June of 1997, the Agency sent requests for updated data (for calendar year 1996) regarding consent decree wastes generated to each facility. We processed the data received from this request in the same manner as the original RCRA surveys, and entered the new information into the ISDB. Between 1993 and 1996, two chlorinated aliphatics manufacturers ceased operations, resulting in a universe of 23 chlorinated aliphatics manufacturing facilities owned and operated by 19 different companies t decree wastes generated to each facility. We processed the data received from this request in the same manner as the original RCRA surveys, and entered the new information into the ISDB. Between 1993 and 1996, two chlorinated aliphatics manufacturers ceased operations, resulting in a universe of 23 chlorinated aliphatics manufacturing facilities owned and operated by 19 different companies. Each of the 23 current manufacturers of chlorinated aliphatics generate at least one wastestream identified in the consent decree. All 23 facilities generate at least one wastewater residual, while 14 facilities reported that they generate wastewater treatment sludges. D. What Are the Risks Associated With Management of Wastewaters and Wastewater Treatment Sludges From the Production of Chlorinated Aliphatic Chemicals? As discussed in Section III.A.2. of this preamble, EPA considers the Listing criteria set out in 40 CFR 261.11, as well as any other information relevant to the criteria, in making listing determinations. The criteria provided in 40 CFR 261.11 include eleven factors for determining ``substantial present or potential hazard to human health and the environment.'' Nine of these factors, as described generally below, are directly incorporated into EPA's completion of a risk assessment for the wastestreams of concern: Toxicity (Sec. 261.11(a)(3)(i)) is considered in developing the health benchmarks used in the risk assessment modeling. Constituent concentrations and waste quantities (Sec. Sec. 261.11(a)(3)(ii) and 261.11(a)(3)(viii)) are used to define the initial conditions for the risk evaluation. Potential to migrate, persistence, degradation, and bioaccumulation of the hazardous constituents and any degradation products (261.11(a)(3)(iii), 261.11(a)(3)(iv), 261.11(a)(3)(v), and 261.11(a)(3)(vi)) are all considered in the design of the fate and transport models used to determine the concentrations of the contaminants to which individuals are exposed onditions for the risk evaluation. Potential to migrate, persistence, degradation, and bioaccumulation of the hazardous constituents and any degradation products (261.11(a)(3)(iii), 261.11(a)(3)(iv), 261.11(a)(3)(v), and 261.11(a)(3)(vi)) are all considered in the design of the fate and transport models used to determine the concentrations of the contaminants to which individuals are exposed. We consider two of the remaining factors, plausible mismanagement and other regulatory actions (Sec. Sec. 261.11(a)(3)(vii) and 261.11(a)(3)(x)) in establishing the waste management scenario(s) modeled in the risk assessment. EPA conducted analyses of the risks posed by wastewaters and wastewater treatment sludges from the production of chlorinated aliphatic chemicals to assist in the determination of whether the wastes meet the criteria for listing set forth in 40 CFR 261.11(a)(3). This section (III.D.) discusses the human health risk analyses and ecological risk screening analyses EPA conducted to support our proposed listing determinations for chlorinated aliphatics wastewaters (other than VCM-A wastewaters), EDC/VCM wastewater treatment sludges, and methyl chloride wastewater treatment sludges. We consider the risk analyses in developing our listing decisions for each of the wastestreams (described in Sections III.E.1.a. for chlorinated aliphatics wastewaters, III.E.2. for EDC/VCM sludges, and III.E.4. for methyl chloride sludges). The risk analyses we describe in this section (III.D.) are presented in detail in the Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination which is located in the docket for today's proposed rule treams (described in Sections III.E.1.a. for chlorinated aliphatics wastewaters, III.E.2. for EDC/VCM sludges, and III.E.4. for methyl chloride sludges). The risk analyses we describe in this section (III.D.) are presented in detail in the Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination which is located in the docket for today's proposed rule. Because full risk analyses were not necessary for VCM-A wastewaters, VCM-A sludges, or allyl chloride sludges, we discuss our assessment of risks attributable to each of these wastes in the same sections where we describe our listing decisions for each of the wastes, that is, Sections III.E.1.b., III.E.3, III.E.5, respectively. 1. What are the Risks for Potential Human Receptors? a. What was EPA's Approach to Conducting the Human Health Risk Assessment? EPA's human health risk analyses for chlorinated aliphatics wastewaters and EDC/VCM and methyl chloride sludges provide estimates of the incremental human health risks resulting from exposure to contaminants detected in these wastes. The incremental human health risks are expressed as estimates of excess lifetime cancer risk for individuals (``receptors'') who may be exposed to carcinogenic (cancer- causing) contaminants and hazard quotients (HQs) for those contaminants that produce noncancer health effects. Excess lifetime cancer risk is the incremental probability (chance) of an individual developing cancer over a lifetime as a result of exposure to a carcinogen. A hazard quotient is the ratio of an individual's chronic daily dose of a noncarcinogen to an acceptable daily dose for chronic exposures to the noncarcinogen. EPA used two different methods of analysis to estimate risks. These methods are called ``deterministic risk analysis'' and ``probabilistic risk analysis.'' A deterministic risk analysis produces a point estimate of risk or hazard for each receptor based on using a single value for each parameter in the analysis arcinogen to an acceptable daily dose for chronic exposures to the noncarcinogen. EPA used two different methods of analysis to estimate risks. These methods are called ``deterministic risk analysis'' and ``probabilistic risk analysis.'' A deterministic risk analysis produces a point estimate of risk or hazard for each receptor based on using a single value for each parameter in the analysis. A probabilistic analysis calculates risk or hazard by allowing some of the parameters to have more than one value, consequently producing a distribution of risk or hazard for each receptor. A parameter is any one of a number of inputs or variables (such as waste volume or distance between the waste management unit and the receptor) required for the fate and transport and exposure models and equations that EPA uses to assess risk. (In some cases EPA treats multiple parameters as a single parameter for the purpose of conducting our analyses. We do this to prevent inadvertently combining parameters in our analyses in ways that are unrealistic. For example, EPA treats environmental setting [location] parameters such as climate, depth to groundwater, aquifer type as a single set of parameters. We believe that, for example, allowing the climate from one location to be paired with the depth to groundwater for another location could result in a scenario that would not occur in nature.) EPA conducts both ``central tendency'' and ``high end'' deterministic risk assessments to attempt to quantify the cancer risk or non-cancer hazard for the ``average'' receptor in the population ameters. We believe that, for example, allowing the climate from one location to be paired with the depth to groundwater for another location could result in a scenario that would not occur in nature.) EPA conducts both ``central tendency'' and ``high end'' deterministic risk assessments to attempt to quantify the cancer risk or non-cancer hazard for the ``average'' receptor in the population (the central tendency risk) and the risk or hazard for individuals in small, but definable ``high end'' segments of the population (the high end risk). For central tendency deterministic risk analyses, we set all parameters at their central tendency values. For the chlorinated aliphatics risk assessments, the central tendency values generally are either mean (average) or 50th percentile (median) values. We use high end deterministic risk analysis to predict the risks and hazards for those individuals exposed at the upper range of the distribution of exposures. EPA's Guidance For Risk Characterization (EPA 1995) 2 advises that ``conceptually, high end exposure means exposure above about the 90th percentile of the population distribution, but not higher than the individual in the population who has the highest exposure,'' and recommends that ``* * * the assessor should approach estimating high end by identifying the most sensitive variables and using high end values for a subset of these variables, leaving others at their central values.'' For the chlorinated aliphatics high end deterministic risk analyses, EPA set two parameters at their high end values (generally 90th percentile values), and set all other parameters at their central tendency values. We used a ``sensitivity analysis'' to identify the two parameters that we set at high end. A sensitivity analysis is an iterative procedure in which an analysis is performed by alternately setting different parameters at high end to identify the parameters that most influence the analysis' outcome nerally 90th percentile values), and set all other parameters at their central tendency values. We used a ``sensitivity analysis'' to identify the two parameters that we set at high end. A sensitivity analysis is an iterative procedure in which an analysis is performed by alternately setting different parameters at high end to identify the parameters that most influence the analysis' outcome. EPA compares the different results generated by the sensitivity analysis and selects the two high end parameters to which the analysis was ``most sensitive,'' that is, the two parameters that are expected to generate the greatest estimate of risk or hazard. --------------------------------------------------------------------------- \2\ EPA. 1995. Guidance for Risk Characterization. U.S. Environmental Protection Agency Science Policy Council. February. --------------------------------------------------------------------------- EPA used probabilistic risk assessment to support the results of the deterministic risk analyses and to allow EPA to quantify individual risk at selected percentiles of the risk distribution (for example, 50th percentile, 90th percentile, 95th percentile). EPA conducted probabilistic risk analyses for those combinations of receptor, contaminant, and pathway for which risk or hazard estimated using a deterministic analysis exceeded the following criteria: a cancer risk of 1 x 10 -6 or a hazard quotient of 1. In a probabilistic analysis, each parameter may have more than one value. EPA develops ``probability density functions'' (PDFs), distributions that describe the full range of values that the various input parameters may have nant, and pathway for which risk or hazard estimated using a deterministic analysis exceeded the following criteria: a cancer risk of 1 x 10 -6 or a hazard quotient of 1. In a probabilistic analysis, each parameter may have more than one value. EPA develops ``probability density functions'' (PDFs), distributions that describe the full range of values that the various input parameters may have. Some of the parameters in the probabilistic analysis are set as constant values because (1) there are insufficient data to develop a PDF; (2) EPA made assumptions to simplify the analysis in cases where such simplifications would improve the efficiency of the analysis without significantly affecting the results; (3) site-specific constants are available; or (4) the analysis has not been shown to be sensitive to the value of the parameter, that is, even if the parameter varies, the resulting risk estimate does not vary significantly. The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination describes the input parameters used in the probabilistic analysis. In the probabilistic analysis, risk is approximated through repetitive calculation of the fate and transport and exposure equations and models using input parameters randomly selected from the PDFs. The result of the probabilistic analysis is a distribution of the risks or hazards for each of the receptors isting Determination describes the input parameters used in the probabilistic analysis. In the probabilistic analysis, risk is approximated through repetitive calculation of the fate and transport and exposure equations and models using input parameters randomly selected from the PDFs. The result of the probabilistic analysis is a distribution of the risks or hazards for each of the receptors. The human health risk assessments that EPA conducted to support the chlorinated aliphatics listing determination included four primary tasks: (1) establishing that there are constituents in the wastes that are of concern to the Agency and that warrant analysis to determine their risk to human health; (2) establishing a scenario under which contaminants are released from a waste management unit and subsequently are transported in the environment to a human receptor; (3) estimating the concentrations of contaminants to which the receptor might be exposed; (4) quantifying the receptor's exposure to contaminants and the contaminants' toxicity to the receptor; and (5) describing the receptor's predicted risk. The following sections discuss how EPA completed each of these tasks for the risk assessments conducted to support the chlorinated aliphatics listing determination. b. How Did EPA Determine Which Waste Constituents and Waste Volumes Would Be Evaluated in the Risk Assessments? To support the chlorinated aliphatics listing determination, EPA collected and analyzed samples of wastewaters from the production of chlorinated aliphatic chemicals, wastewater treatment sludges from the production of EDC/VCM, and wastewater treatment sludges from the production of methyl chloride (see Section III.E of today's preamble, as well as the Background Document for Identification and Listing of Chlorinated Aliphatics Production Wastes, for further discussion of EPA's waste characterization efforts) production of chlorinated aliphatic chemicals, wastewater treatment sludges from the production of EDC/VCM, and wastewater treatment sludges from the production of methyl chloride (see Section III.E of today's preamble, as well as the Background Document for Identification and Listing of Chlorinated Aliphatics Production Wastes, for further discussion of EPA's waste characterization efforts). We used the results of these waste analyses to establish the ``constituents of potential concern'' (COPCs) in the wastes. We derived waste volume information from data provided by facilities in their RCRA Section 3007 questionnaire responses. EPA collected and analyzed 41 samples of wastewaters generated from the production of chlorinated aliphatic chemicals. EPA collected six of these samples at the influent (or ``headworks'') of wastewater treatment systems that manage only wastewaters derived from the production of chlorinated aliphatic chemicals. We call these samples ``dedicated'' chlorinated aliphatics wastewater samples,3 and we chose to use these samples in our assessment of the risks and hazards attributable to the management of chlorinated aliphatic wastewaters. (The assessment of dedicated sample data allows us to evaluate without question what risks are attributable to the wastes of concern to the Agency.) Because we used analytical data for dedicated chlorinated aliphatics wastewater samples in our analysis, we also used dedicated chlorinated aliphatic wastewater volumes in our analysis. We identified eight wastewater volumes that represent the volumes of dedicated chlorinated aliphatics wastewaters discharged to the headworks of chlorinated aliphatics facility wastewater treatment systems. --------------------------------------------------------------------------- ewater samples in our analysis, we also used dedicated chlorinated aliphatic wastewater volumes in our analysis. We identified eight wastewater volumes that represent the volumes of dedicated chlorinated aliphatics wastewaters discharged to the headworks of chlorinated aliphatics facility wastewater treatment systems. --------------------------------------------------------------------------- \3\ ``Dedicated'' chlorinated aliphatic wastewaters are those that are comprised only of chlorinated aliphatics process wastewaters, that is, wastewaters generated from the production of the chlorinated aliphatic chemicals of concern to this listing determination. --------------------------------------------------------------------------- EPA collected and analyzed seven samples of nonhazardous EDC/VCM sludge. (Some sludges generated by this industry already are designated as hazardous because they include material derived from wastes that EPA previously listed as hazardous waste.) Four were samples of sludges that were derived from wastewater treatment systems that manage only EDC/VCM process wastewaters. These samples are ``dedicated'' EDC/VCM sludge samples. Three were samples of sludges that result from the treatment of EDC/VCM process wastewaters combined with wastewaters from non-EDC/VCM processes and sources. EPA chose to use only the dedicated EDC/VCM sample data in our analysis. Because we used were derived from wastewater treatment systems that manage only EDC/VCM process wastewaters. These samples are ``dedicated'' EDC/VCM sludge samples. Three were samples of sludges that result from the treatment of EDC/VCM process wastewaters combined with wastewaters from non-EDC/VCM processes and sources. EPA chose to use only the dedicated EDC/VCM sample data in our analysis. Because we used analytical data for dedicated EDC/VCM sludge samples in our analysis, we also used ``dedicated'' EDC/VCM sludge volumes. EPA divided the volume of wastewater attributable to EDC/VCM processes by the total volume of wastewater influent, and applied the resultant ratio to the total sludge volumes to obtain the volume of wastewater treatment sludge attributable to EDC/VCM processes (that is, the ``dedicated `` EDC/VCM sludge volume). The methyl chloride sludge, generated by only one facility, results from treatment of the combined wastewaters from the facility's methyl chloride production process and other facility processes and sources. The facility reports that approximately 18 percent of the wastewater that generates the sludge is from the methyl chloride process. The remainder of the wastewater is from other processes. Because the sludge, as generated, is not dedicated, and there is no means to obtain a dedicated sample of the methyl chloride sludge, we conducted our risk assessment using the sample data for the nondedicated methyl chloride sludge sample, and, comparably, the nondedicated (total) methyl chloride sludge volume. Using the results of the analysis of the waste samples, EPA developed a list of ``chemicals of potential concern'' (COPCs) for the chlorinated aliphatics wastewaters, EDC/VCM sludges, and methyl chloride sludges. The COPCs are the constituents which were the subject of EPA's risk assessment thyl chloride sludge sample, and, comparably, the nondedicated (total) methyl chloride sludge volume. Using the results of the analysis of the waste samples, EPA developed a list of ``chemicals of potential concern'' (COPCs) for the chlorinated aliphatics wastewaters, EDC/VCM sludges, and methyl chloride sludges. The COPCs are the constituents which were the subject of EPA's risk assessment. EPA developed the COPC lists by taking the complete list of detected constituents in the wastes and eliminating constituents from the list that occurred at concentrations clearly below levels of concern, based on screening analyses developed to maximize risk estimates. For chlorinated aliphatics wastewaters and EDC/VCM sludges, EPA also eliminated constituents when a constituent was detected in only one of the samples and the concentration of the constituent in the one sample was qualified with the ``J'' qualifier, indicating that the constituent was detected below the quantitation limit and the reported value was estimated. Specifically, the laboratory detected 69 constituents in chlorinated aliphatics wastewater samples of which we eliminated 28; 53 constituents in EDC/ VCM sludges of which we eliminated 16; and 19 constituents in methyl chloride sludges of which we eliminated 11. Six polychlorinated dibenzodioxin (``dioxin'') congeners and ten polychlorinated dibenzofuran (``furan'') congeners were among the constituents detected in samples of the chlorinated aliphatics wastewaters, EDC/VCM sludges, and methyl chloride sludges and evaluated in the risk assessment. EPA classifies the furan congeners and certain polychlorinated biphenyl (PCB) congeners as ``dioxin-like compounds'' because of their structural similarity to the dioxins (EPA 1994a 4). In today's preamble we use the term ``dioxins'' to represent both the dioxin and furan congeners ated aliphatics wastewaters, EDC/VCM sludges, and methyl chloride sludges and evaluated in the risk assessment. EPA classifies the furan congeners and certain polychlorinated biphenyl (PCB) congeners as ``dioxin-like compounds'' because of their structural similarity to the dioxins (EPA 1994a 4). In today's preamble we use the term ``dioxins'' to represent both the dioxin and furan congeners. Our use of the term ``dioxins'' does not refer to dioxin-like PCBs because we did not analyze for PCBs in our waste samples from the chlorinated aliphatics industry since we do not expect PCBs to be constituents of the chlorinated aliphatics wastes that are the subject of today's listing determination. --------------------------------------------------------------------------- \4\ EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds, Volume I: Executive Summary. Review Draft. EPA/600/6-88/005Ca. Office of Research and Development. June. --------------------------------------------------------------------------- c. What Exposure Scenarios Did EPA Evaluate? Prior to conducting the risk assessments, EPA had to establish that there is a plausible scenario under which a receptor might be exposed to contaminants in the wastewaters and sludges. Establishing this scenario required that EPA determine: How the waste is managed or is likely to be managed; How contaminants could be released from the waste management unit; How contaminants could be transported in the environment to a point of contact with a receptor; and How a receptor could be exposed to the contaminants. One respondent to EPA's Sec. 3007 questionnaire reported that they discharge a portion of their nonhazardous chlorinated aliphatics wastewaters to nonhazardous underground injection wells. Section III.E.1.a.i. discusses EPA's evaluation of the underground injection waste management scenario. Twenty-three respondents reported that they manage their nonhazardous or exempt chlorinated aliphatics wastewaters in tanks s Sec. 3007 questionnaire reported that they discharge a portion of their nonhazardous chlorinated aliphatics wastewaters to nonhazardous underground injection wells. Section III.E.1.a.i. discusses EPA's evaluation of the underground injection waste management scenario. Twenty-three respondents reported that they manage their nonhazardous or exempt chlorinated aliphatics wastewaters in tanks. Because management of wastewaters in tanks is the dominant wastewater management practice in the chlorinated aliphatics industry, EPA chose to evaluate tanks in our risk assessment for chlorinated aliphatics wastewaters. For reasons discussed in III.E.1.a.i., EPA chose to evaluate risks attributable to management of chlorinated aliphatics wastewaters in uncovered aerated biological treatment tanks. One respondent to EPA's Sec. 3007 questionnaire reported that they manage their EDC/VCM wastewater treatment sludges in an onsite land treatment unit. All other respondents reported that nonhazardous EDC/ VCM sludges are managed in landfills. Eight facilities send EDC/VCM sludges to offsite nonhazardous waste landfills, two facilities manage EDC/VCM sludge in onsite nonhazardous industrial waste landfills, and one facility manages their nonhazardous EDC/VCM sludge in an onsite hazardous waste landfill (see section III.E.2.a. in today's preamble for a description of current methods for managing EDC/VCM sludges). For this assessment, EPA evaluated the risks associated with management of EDC/VCM sludges in unlined municipal landfills and in a land treatment unit. Because the only facility that generates methyl chloride sludges manages them in an onsite nonhazardous industrial waste landfill, EPA evaluated this management scenario in our risk assessment for methyl chloride sludges. The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination provides a complete discussion of the parameters that define the characteristics of the waste management units methyl chloride sludges manages them in an onsite nonhazardous industrial waste landfill, EPA evaluated this management scenario in our risk assessment for methyl chloride sludges. The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination provides a complete discussion of the parameters that define the characteristics of the waste management units. EPA determined that releases from all of the waste management units (tank, land treatment unit, and landfill) could occur through release of vapor emissions to the air. In addition, for the land treatment unit and the landfill, EPA determined that releases could occur through leaching of the waste into the subsurface. We assumed that the chlorinated aliphatics industry's tanks retain sufficient structural integrity to prevent wastewater releases to the subsurface (and therefore to groundwater), and that overflow and spill controls prevent wastewater releases to the ground surface. For the land treatment unit, releases also could occur through release of particulate emissions to the air and runoff and erosion of waste from the unit. EPA assumed that wastewater would entrain any particulate matter such that particulates would not be released from the tanks. EPA did not evaluate particulate emissions from the landfills because the moisture content of the sludges (41 to 74 percent moisture) would prevent generation and release of particulates to the air in the time between placement of the waste in the landfill and application of daily cover or a new day's waste addition. EPA also assumed that runon/runoff controls would prevent releases from the landfills due to erosion and runoff. EPA also evaluated the mechanisms and pathways by which contaminants (41 to 74 percent moisture) would prevent generation and release of particulates to the air in the time between placement of the waste in the landfill and application of daily cover or a new day's waste addition. EPA also assumed that runon/runoff controls would prevent releases from the landfills due to erosion and runoff. EPA also evaluated the mechanisms and pathways by which contaminants might be transported to the points where receptors are exposed. The mechanisms and pathways we evaluated are as follows: Eroded waste can be transported by runoff and deposited onto the soil and into surface water bodies. Leachate can migrate through the unsaturated 5 zone to the saturated 6 zone, where contaminants are transported in groundwater to drinking water wells and to points of discharge to surface water bodies. --------------------------------------------------------------------------- \5\ The unsaturated (vadose) zone is a subsurface zone in which the pore spaces contain both water and air. \6\ The saturated zone is a subsurface zone in which all pore spaces are full of water. --------------------------------------------------------------------------- Vapor emissions can remain dispersed in the air, or can be deposited through wet and dry deposition. Specifically, EPA models: The concentration of vapor phase contaminants in air, The diffusion of vapor phase contaminants into plants, The diffusion of vapor phase contaminants into surface water, Wet deposition of vapors onto soils and surface water (for example, due to wash-out [scavenging] by precipitation). Dry deposition of vapors onto soils (for example, due to density). Although we do not evaluate wet and dry deposition of vapors onto plants, we do assume that wet and dry deposition of vapors onto soils increase the contaminant concentrations in the soil and result in additional uptake of contaminants into plants via soil-to- plant uptake mple, due to wash-out [scavenging] by precipitation). Dry deposition of vapors onto soils (for example, due to density). Although we do not evaluate wet and dry deposition of vapors onto plants, we do assume that wet and dry deposition of vapors onto soils increase the contaminant concentrations in the soil and result in additional uptake of contaminants into plants via soil-to- plant uptake. Particulate emissions can remain dispersed in the air or be deposited through wet deposition (in precipitation) or dry deposition (particle settling). We assume that particulates may be deposited onto soil and surface water through both wet and dry deposition, and onto plants through dry deposition. Human receptors indirectly may come into contact with vapors that diffuse into vegetation, particulates that are deposited on vegetation, or contaminants that are taken up by vegetation from the soil through exposure to contaminated home-grown fruits and vegetables, as well as exposure to contaminated beef and dairy products derived from cattle which have ingested contaminated forage, silage, grain, and surface soil. Receptors that ingest fish also indirectly may come into contact with contaminants in air-borne vapors and particulates (through vapor diffusion into surface water, vapor deposition onto surface water, and particulate deposition onto surface water), contaminated groundwater (through groundwater discharge into surface water), and runoff and eroded soil that enter surface water. EPA determined that the following receptors reasonably represent the types of individuals that could be exposed to contaminants in chlorinated aliphatics wastes, and were the receptors evaluated in our risk analyses: an adult resident the child of a resident a home gardener a farmer the child of a farmer a fisher into surface water), and runoff and eroded soil that enter surface water. EPA determined that the following receptors reasonably represent the types of individuals that could be exposed to contaminants in chlorinated aliphatics wastes, and were the receptors evaluated in our risk analyses: an adult resident the child of a resident a home gardener a farmer the child of a farmer a fisher The following sections describe briefly EPA's primary assumptions regarding the characteristics and activities of each of the receptor types, and the routes by which each receptor is exposed. Adult Resident and Child of Resident--We assume that an adult and child reside near the waste management unit. The residential receptors inhale vapors and particulate matter that are dispersed in the ambient air. EPA assumes that household water is supplied to the residential receptors by a domestic groundwater well that is located near their home. The adult resident and child of the resident drink water that comes from the well. We assume that the adult resident inhales vapors that are emitted from the water that they use in their house (for example, during showering), and that the adult resident's skin also is exposed to groundwater when he/she bathes. The residential receptors do not ingest foods that are grown in the vicinity of their home, however they do incidentally ingest surface soil from their yard. Home Gardener--We assume that the residential receptor may have a home garden. The home gardener grows fruit, exposed vegetables (vegetables with edible parts that are exposed at land surface), and root vegetables. Approximately 23 percent of the exposed vegetables, 11 percent of the root vegetables, and 12 percent of the fruits eaten by the gardener are grown in his/her garden (EPA 1997a, Table 13-71) 7. The gardener's other characteristics and activities are the same as those of the adult resident. --------------------------------------------------------------------------- rface), and root vegetables. Approximately 23 percent of the exposed vegetables, 11 percent of the root vegetables, and 12 percent of the fruits eaten by the gardener are grown in his/her garden (EPA 1997a, Table 13-71) 7. The gardener's other characteristics and activities are the same as those of the adult resident. --------------------------------------------------------------------------- \7\ EPA. 1997a. Exposure Factors Handbook, Volumes I, II, and III. Office of Research and Development, Washington, D.C., EPA/600/ P-95/002Fa, b, c. August 1997; www.epa.gov/ordntrnt/ord/webpubs/ exposure/index.html. --------------------------------------------------------------------------- Fisher--We assume that the residential receptor may be a recreational angler. Approximately 32 percent of the fish eaten by the fisher are from a stream located near the waste management unit (EPA 1997a, Table 13-71). The fisher's other characteristics and activities are the same as those of the adult resident. Adult Farmer and Child of Farmer--We assume that a farmer raises fruits, exposed vegetables, root vegetables, beef cattle, and dairy cattle in an agricultural field located near the waste management unit. Approximately 42 percent of the exposed vegetables, 17 percent of the root vegetables, 33 percent of the fruits, 49 percent of the beef, and 25 percent of the dairy products eaten by the farmer and the child of the farmer are grown/raised on the farmer's agricultural field (EPA 1997a, Table 13-71). We assume that the farmer incidentally ingests soil from the agricultural field, and that the child of the farmer incidentally ingests soil from his/her yard. The farmer's and child's exposure to groundwater via ingestion, inhalation, and dermal contact are the same as that for the adult resident and child of the resident. EPA establishes the locations of receptors relative to waste management units based on information obtained from national surveys e agricultural field, and that the child of the farmer incidentally ingests soil from his/her yard. The farmer's and child's exposure to groundwater via ingestion, inhalation, and dermal contact are the same as that for the adult resident and child of the resident. EPA establishes the locations of receptors relative to waste management units based on information obtained from national surveys. Exposure to groundwater occurs through the use of water from drinking water wells, and exposure via nongroundwater pathways occurs through runoff/erosion and releases to air. Therefore, ``distance to receptor'' for groundwater exposure pathways actually is the distance to the drinking water well that the receptor is using (the ``receptor well''). ``Distance to receptor'' for nongroundwater pathways is the distance to the residence where the receptor is inhaling air or contacting soil, the distance to the garden where the receptor is growing fruits and vegetables, or the distance to the field where the receptor is growing crops or raising livestock. Consequently, EPA uses different databases to establish ``distance to receptor,'' depending on whether we are evaluating a groundwater or a nongroundwater pathway. For analysis of the nongroundwater pathway (air pathways and erosion/runoff) risks in the deterministic analysis we assume that the receptors live either 75 meters (m) (high end) or 300 m (central tendency) from the waste management unit. The distance of 250 feet (ft) (approximately 75 m) is based on the actual measured distance to the nearest resident for the worst-case facility evaluated in the risk assessment conducted to support the ``Hazardous Waste Treatment, Storage, and Disposal Facilities--Organic Air Emissions Standards for Process Vents and Equipment Leaks Final Rule'' (55 FR endency) from the waste management unit. The distance of 250 feet (ft) (approximately 75 m) is based on the actual measured distance to the nearest resident for the worst-case facility evaluated in the risk assessment conducted to support the ``Hazardous Waste Treatment, Storage, and Disposal Facilities--Organic Air Emissions Standards for Process Vents and Equipment Leaks Final Rule'' (55 FR 25454), and was used as distance to the nearest resident for that rulemaking. In the same risk assessment, EPA identified the receptor distance of 1000 ft (approximately 300 m) as the median distance in a random sample of distances to the nearest residence. For the probabilistic analysis, we assume the receptors live either 50, 75, 100, 200, 300, 500, or 1000 m from the waste management unit. For air pathway analyses, we always assume that the receptors (including cattle) are located along the centerline of the area most greatly impacted by air releases from the waste management units. However, at distances of a few hundred meters from the waste management unit, the air concentrations within about a 100 meter lateral distance do not vary appreciably. For deterministic analyses we assume that a receptor well is located 102 m (high end) or 430 m (central tendency) from the waste management unit, and that the receptor well is located on centerline of the contaminant plume (high end) or halfway between the centerline and the edge of the contaminant plume (central tendency). The 102 m distances is the 10th percentile value in the distribution of distances derived from EPA's 1988 survey of Solid Waste (Municipal) Landfill Facilities (DPRA 1993 8). The 430 m value is the 50th percentile value in that same distribution ocated on centerline of the contaminant plume (high end) or halfway between the centerline and the edge of the contaminant plume (central tendency). The 102 m distances is the 10th percentile value in the distribution of distances derived from EPA's 1988 survey of Solid Waste (Municipal) Landfill Facilities (DPRA 1993 8). The 430 m value is the 50th percentile value in that same distribution. For the Monte Carlo analysis, the distance from the waste management unit to the receptor well is based on the complete distribution of distances to receptor well reported by the survey respondents, and ranges from 0.02 m (the location of the closest reported well was 0 m) to 1604 m (the maximum distance for which EPA requested receptor well information was 1 mile). For the Monte Carlo analysis we assume that the receptor well is located anywhere within the contaminant plume. --------------------------------------------------------------------------- \8\ DPRA. 1993. Parameter Values for Developing Nationwide Regulations with the EPA's Composite Model for Landfills (EPACML). EPA Contract Number 68-WO-0029. July. --------------------------------------------------------------------------- The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination provides a complete discussion of the values of additional parameters that define the characteristics of each receptor, such as the amounts of contaminated food and water they ingest, their inhalation rates, and how long they live near the waste management unit. d. How Did EPA Predict What Contaminant Concentrations Are at the Points Where Receptors Are Exposed? EPA conducts contaminant fate and transport modeling and indirect exposure modeling to determine what the concentrations of contaminants will be in the media (for example, groundwater, air, soil, food items) that the receptor comes into contact with they live near the waste management unit. d. How Did EPA Predict What Contaminant Concentrations Are at the Points Where Receptors Are Exposed? EPA conducts contaminant fate and transport modeling and indirect exposure modeling to determine what the concentrations of contaminants will be in the media (for example, groundwater, air, soil, food items) that the receptor comes into contact with. These concentrations are called ``exposure point concentrations'' (that is, they are the contaminant concentrations at the point where the receptor is exposed to the contaminants). There are a number of computer-based models and sets of equations that EPA uses to predict exposure point concentrations. In the following sections we briefly discuss these models and equations and their application in the risk analyses. i. Partitioning Model For the landfill and the land treatment unit, EPA uses a series of ``partitioning'' equations to determine how much contaminant mass is retained in the waste management unit and how much is released into the environment. These equations are based upon equations presented in a series of articles by Jury et al. (Jury et al. 1983, 1984, and 1990 9). EPA used the partitioning equations to estimate the mass of a contaminant that will be lost from the land treatment unit due to volatilization into the air, contaminant leaching into the subsurface, runoff from the land treatment unit, and degradation. For the landfill scenarios, EPA used the partitioning equations to determine how much of the contaminant mass would be lost due to volatilization into the air; EPA assumed that the remainder of the mass would be available to leach into the subsurface. We assumed that volatilization losses could occur prior to the landfill being covered with daily cover or daily waste addition, through the daily cover or daily waste addition, and through the cap that is placed on the landfill after closure minant mass would be lost due to volatilization into the air; EPA assumed that the remainder of the mass would be available to leach into the subsurface. We assumed that volatilization losses could occur prior to the landfill being covered with daily cover or daily waste addition, through the daily cover or daily waste addition, and through the cap that is placed on the landfill after closure. For the landfill, we used toxicity characteristic leaching procedure (TCLP) analytical results (rather than the partitioning equations) as the predictor of leachate concentration. The TCLP is an analytical procedure that ``leaches'' a waste sample in a way that mimics the leaching of waste in a municipal landfill. Thus, TCLP results are a proxy for the concentrations of contaminants that would be generated in leachate if the waste were placed in a municipal landfill. --------------------------------------------------------------------------- \9\ Jury, W.A., W.F. Spencer, and W. J. Farmer. 1983. Behavior assessment model for trace organics in soil: i. model description. J. Environ. Qual. 12(4):558-564. Jury, W.A., W. J. Farmer, and W.F. Spencer. 1984. Behavior assessment model for trace organics in soil: ii. chemical classification and parameter sensitivity. J. Environ. Qual. 13(4):567-572. Jury, W.A., D. Russo, G. Streile, and H.E. Abd. 1990. Evaluation of volatilization by organic chemicals residing below the soil surface. Water Resources Research. 26(1):13-20. --------------------------------------------------------------------------- Behavior assessment model for trace organics in soil: ii. chemical classification and parameter sensitivity. J. Environ. Qual. 13(4):567-572. Jury, W.A., D. Russo, G. Streile, and H.E. Abd. 1990. Evaluation of volatilization by organic chemicals residing below the soil surface. Water Resources Research. 26(1):13-20. --------------------------------------------------------------------------- ii. Tank Emissions Model EPA modeled emissions from aerated biological wastewater treatment tanks using the CHEMDAT8 model (EPA 1994b 10). We used the emissions estimates in conjunction with the air dispersion modeling results (see Section D.1.d.iii) to estimate constituent-specific air concentrations and deposition rates. CHEMDAT8 accounts for most of the competing removal pathways that might limit air emissions, including adsorption, biodegradation, and hydrolysis. Chemicals that sorb to solids or decompose due to either biodegradation or hydrolysis have lower potential for emission to the air. CHEMDAT8 is considered to provide reasonable to slightly high estimates of air emissions. --------------------------------------------------------------------------- \10\ EPA. 1994b. CHEMDAT8 User's Guide, EPA-453/C-94-080B. Office of Air Quality Planning and Standards, US Environmental Protection Agency, Research Triangle Park, NC, November. This model is publicly available from EPA's Web page at http://www.epa.gov/ttn/ chief/software.html. --------------------------------------------------------------------------- --------------------------------------- \10\ EPA. 1994b. CHEMDAT8 User's Guide, EPA-453/C-94-080B. Office of Air Quality Planning and Standards, US Environmental Protection Agency, Research Triangle Park, NC, November. This model is publicly available from EPA's Web page at http://www.epa.gov/ttn/ chief/software.html. --------------------------------------------------------------------------- CHEMDAT8 requires that the user specify parameters relating to tank characteristics, waste characteristics, contaminant physical and chemical properties, and location-specific meteorological conditions (for example, windspeed and temperature). The tank characterization data required by the model include both tank physical parameters (for example, tank dimensions) and tank operating parameters (for example, the number of aerators in the tank). In the absence of site-specific data, we developed tank dimensions based on facility-reported wastewater generation rates, an assumed wastewater depth in the tank of 15 feet, and a retention time in the tank of two days. We selected operating parameters that we believe represent typical operating conditions of an aerated tank. The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination provides a complete list of the parameters used in the CHEMDAT8 model. iii. Air Dispersion and Deposition Model We used EPA's Industrial Source Complex Short Term model (version 3; s. We selected operating parameters that we believe represent typical operating conditions of an aerated tank. The Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination provides a complete list of the parameters used in the CHEMDAT8 model. iii. Air Dispersion and Deposition Model We used EPA's Industrial Source Complex Short Term model (version 3; ISCST3 11) to estimate the dispersion and deposition of vapors emitted from the wastewater treatment tank, the municipal landfill, the onsite industrial landfill, and the land treatment unit. EPA also used ISCST3 to estimate the dispersion and deposition of particulate emissions from the land treatment unit. For the land treatment unit, EPA used equations documented in EPA's ``Compilation of Air Pollutant Emission Factors (AP-42)'' (EPA 1985) 12 to estimate particulate emissions resulting from wind erosion and tilling activities. Vapor emissions from the landfill and the land treatment unit were estimated using the partitioning models discussed in Section III.D.1.d.i. Vapor emissions from the wastewater treatment tank were estimated using the CHEMDAT8 model discussed in Section III.D.1.d.ii. ISCST3 was used to estimate the air concentration of vapors, wet deposition of vapors, the air concentration of particulates, wet deposition of particulates, and dry deposition of particulates. We calculate dry deposition of vapors using the air concentration of vapors and a contaminant deposition velocity. --------------------------------------------------------------------------- .D.1.d.ii. ISCST3 was used to estimate the air concentration of vapors, wet deposition of vapors, the air concentration of particulates, wet deposition of particulates, and dry deposition of particulates. We calculate dry deposition of vapors using the air concentration of vapors and a contaminant deposition velocity. --------------------------------------------------------------------------- \11\ EPA. 1995. User's Guide for the Industrial Source Complex (ISC3) Dispersion Models (Draft) (Revised). Volume I. EPA-454/B-95- 003a. Office of Air Quality Planning and Standards, Emissions, Monitoring and Analysis Division, Research Triangle Park, NC. The ISCST3 model and meteorological preprocessor, PCRAMMET, and related user's guides can be accessed and downloaded through the Internet from the Support Center for Regulatory Air Models (SCRAM) web page (http://www.epa.gov/scram001). The SCRAM is part of EPA's Office of Air Quality Planning and Standards (OAQPS) Technology Transfer Network (TTN). \12\ EPA. 1985. Compilation of Air Pollutant Emission Factors, AP-42, Fifth Edition, Volume I: Stationary Point and Area Sources. Office of Air Quality Planning and Standards, Emissions Inventory Group, Research Triangle Park, NC. AP-42 can be downloaded through the Internet at http://www.epa.gov/ttn/chief/ap42.html. --------------------------------------------------------------------------- iv. Overland Transport Model The Universal Soil Loss Equation (USLE) is an erosion model originally designed to estimate long-term average soil erosion losses to a nearby surface water body from an agricultural field having uniform slope, soil type, vegetative cover, and erosion-control practices. We used a modified form of the USLE to estimate the mass of soil lost per year per unit area from the land treatment unit and deposited directly onto the adjacent receptor site (agricultural field, residential lot, home garden) and into a nearby stream s to a nearby surface water body from an agricultural field having uniform slope, soil type, vegetative cover, and erosion-control practices. We used a modified form of the USLE to estimate the mass of soil lost per year per unit area from the land treatment unit and deposited directly onto the adjacent receptor site (agricultural field, residential lot, home garden) and into a nearby stream. Because the basic USLE equation estimates only soil erosion to surface water bodies, EPA assumes the receptor location is located between the land treatment unit and the surface water body. The area including the land treatment unit, the receptor site, and the intervening area is considered for the purposes of the analysis to be an independent, discrete drainage subbasin that is at steady-state. We estimate the soil erosion load from the subbasin to the surface water body using a distance-based sediment delivery ratio, and consider that the sediment not reaching the surface water body is deposited evenly over the area of the subbasin. Using mass balance equations, EPA estimates contaminant contributions to the surface water body and the receptor soil. ``Mass balance equations'' are equations that honor the law of conservation of mass, that is, the mass of a contaminant that is present at the beginning of the analysis (for example, the mass of a contaminant in a waste placed in a waste management unit) is equal to the mass of the contaminant present at the end of the analysis. Even though at the end of the analysis the contaminant mass may be partitioned into a number of environmental ``compartments'' (for example, the waste management unit, the soil, and the surface water body), there is in total no more or no less mass than was present at the start of the analysis. Contaminated particles are transported from the land treatment unit to receptor sites via air deposition as well as runoff/erosion alysis the contaminant mass may be partitioned into a number of environmental ``compartments'' (for example, the waste management unit, the soil, and the surface water body), there is in total no more or no less mass than was present at the start of the analysis. Contaminated particles are transported from the land treatment unit to receptor sites via air deposition as well as runoff/erosion. We applied mass balance for each area of interest (for example, buffer area between source and receptor site, receptor site, or surrounding area). Consequently, the respective air deposition value for each area of interest is included in the evaluation of the mass balance. We considered that the air deposition over the entire subbasin area is uniform and equal to the air deposition modeled for the receptor site. v. Groundwater Model We used EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP; EPA 1996a, 1996b, 1996c, 1997 13) to model the subsurface fate and transport of contaminants that leach from the waste management units (the land treatment unit or the landfill) and migrate to a residential drinking water well or discharge from groundwater to surface water. --------------------------------------------------------------------------- \13\ EPA. 1996a. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) Background Document. Office of Solid Waste, Washington, DC. EPA. 1996b. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) Background Document for the Finite Source Methodology. Office of Solid Waste, Washington, DC. EPA. 1996c. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) Background Document for Metals. Office of Solid Waste, Washington, DC. EPA. 1997. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) User's Guide. Office of Solid Waste, Washington, DC ument for the Finite Source Methodology. Office of Solid Waste, Washington, DC. EPA. 1996c. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) Background Document for Metals. Office of Solid Waste, Washington, DC. EPA. 1997. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP) User's Guide. Office of Solid Waste, Washington, DC. --------------------------------------------------------------------------- Precipitation that migrates through the waste management unit generates leachate, which infiltrates the bottom of the waste management unit and migrates into the unsaturated zone. The contaminants dissolved in the leachate subsequently are transported in the aqueous phase through the unsaturated zone to the underlying saturated zone and then downgradient to a receptor (drinking water) well or surface water body located at a specified distance from the boundary of the waste management unit. EPACMTP accounts for the following processes affecting contaminant fate and transport: advection, hydrodynamic dispersion, equilibrium linear or nonlinear sorption by the soil and aquifer solids (both in the unsaturated and saturated zones), and contaminant hydrolysis. In the event that the hydrolysis daughter products are toxic and their chemical properties are known, the model also accounts for the formation and subsequent fate and transport of the daughter products. The landfill analysis employed two simplifying assumptions. First, we assumed that contaminant leaching from the landfill does not occur until after the landfill closes (that is, after 30 years). EPA made this assumption because of complexities associated with linking the output of the landfill partitioning equations (discussed in Section III.D.1.d.i.) and the groundwater model, EPACMTP. Second, we assumed that there are no contaminant losses due to mechanisms other than leaching after the landfill has been closed (that is, after 30 years) he landfill closes (that is, after 30 years). EPA made this assumption because of complexities associated with linking the output of the landfill partitioning equations (discussed in Section III.D.1.d.i.) and the groundwater model, EPACMTP. Second, we assumed that there are no contaminant losses due to mechanisms other than leaching after the landfill has been closed (that is, after 30 years). This effectively over-estimates the total mass of volatile contaminants that would leach to groundwater because it does not allow contaminant loss due to volatilization from the landfill to deplete the total contaminant mass available for leaching from the landfill in the years after closure. EPA determined that if volatile constituents caused significant risk via the groundwater pathway, we would have to re- evaluate our methodology for conducting the landfill analysis. This situation did not occur. vi. Surface Water Model EPA assumed that fish are exposed to waste constituents in surface water. Specifically, we assumed that fish are exposed to contaminants dissolved in the water column, contaminants sorbed to suspended solids in the water column, and contaminants associated with the bed sediment in the surface water body. The method used to estimate how management of chlorinated aliphatics wastewaters and wastewater treatment sludges impacts surface water is based on the methodology presented in Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions (EPA 1993) 14 the water column, and contaminants associated with the bed sediment in the surface water body. The method used to estimate how management of chlorinated aliphatics wastewaters and wastewater treatment sludges impacts surface water is based on the methodology presented in Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions (EPA 1993) 14. The model accounts for six ways in which contaminants may enter the surface water body: (1) contaminants may be sorbed to eroded soils that enter the surface water body, (2) contaminants may be dissolved in runoff that enters the surface water body, (3) contaminants may be bound to airborne particles that are deposited on the surface water body, (4) vapor phase contaminants in air may be deposited on the surface water body in precipitation (that is, wet deposition of vapor phase contaminants), (5) vapor phase contaminants in air may enter the surface water body through direct diffusion from the air, and (6) contaminants in groundwater may discharge into the surface water body. The model also accounts for processes that remove contaminants from the surface water body. These include: (1) volatilization of contaminants that are dissolved in surface water and (2) burial of contaminants in the sediment at the bottom of the surface water body. The model assumes that the impact to the water body is uniform, which is more realistic for smaller surface water bodies than for larger ones. The model estimates the concentrations of contaminants in the water column and bed sediment. We used the water column or bed sediment concentrations and bioconcentration factors (BCFs), bioaccumulation factors (BAFs), or biota-sediment accumulation factors (BSAFs) to estimate contaminant concentrations in fish tissue. --------------------------------------------------------------------------- The model estimates the concentrations of contaminants in the water column and bed sediment. We used the water column or bed sediment concentrations and bioconcentration factors (BCFs), bioaccumulation factors (BAFs), or biota-sediment accumulation factors (BSAFs) to estimate contaminant concentrations in fish tissue. --------------------------------------------------------------------------- \14\ EPA. 1993. Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. EPA/ 600/AP-93003. Office of Health and Environmental Assessment, Washington, DC. --------------------------------------------------------------------------- vii. Indirect Exposure Equations EPA uses a series of ``indirect exposure equations'' to quantify the concentrations of contaminants that pass indirectly from contaminated environmental media to the receptor. For example, contaminants that are transported in air may be deposited on plants or onto the soil where they may accumulate in forage, grain, silage or soil that is consumed by beef cattle and dairy cattle. Individuals may then ingest contaminated beef and dairy products. Similarly, contaminants may be transported in groundwater to domestic groundwater wells where the groundwater is extracted and used for showering. The water vapor generated in the shower may be inhaled by the receptor. The indirect exposure equations allow EPA to calculate exposure point concentrations for these pathways and routes of exposure. The indirect exposure equations used by EPA to conduct the chlorinated aliphatic wastewater, EDC/VCM sludge, and methyl chloride sludge risk assessments are presented in the Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination. e. How Did EPA Quantify Contaminant Exposure and Toxicity? Exposure is the condition that occurs when a contaminant comes into contact with the outer boundary of the body, such as the skin, mouth and nostrils ater, EDC/VCM sludge, and methyl chloride sludge risk assessments are presented in the Risk Assessment Technical Background Document for the Chlorinated Aliphatics Listing Determination. e. How Did EPA Quantify Contaminant Exposure and Toxicity? Exposure is the condition that occurs when a contaminant comes into contact with the outer boundary of the body, such as the skin, mouth and nostrils. Once EPA establishes the concentrations of contaminants at the points of exposure, EPA can estimate the magnitude of each receptor's exposure, or the contaminant dose. Dose is the amount of the contaminant that crosses the outer boundary of the body and is available for absorption at internal exchange boundaries (lungs, gut, skin; EPA 1992 15). For example, for exposure to a carcinogen through ingestion of contaminated drinking water, dose is a function of the concentration of the contaminant in drinking water (the exposure point concentration), as well as certain ``exposure factors,'' such as how much drinking water the receptor consumes each day (the intake rate), the number of years the receptor is exposed to contaminated drinking water (the exposure duration), how often the receptor is exposed to contaminated drinking water (the exposure frequency), the body weight of the receptor, and the period of time over which the dose is averaged. --------------------------------------------------------------------------- \15\ 57 FR 22888. Final Guidelines for Exposure Assessment. U.S. Environmental Protection Agency, May 29, 1992. --------------------------------------------------------------------------- d drinking water (the exposure frequency), the body weight of the receptor, and the period of time over which the dose is averaged. --------------------------------------------------------------------------- \15\ 57 FR 22888. Final Guidelines for Exposure Assessment. U.S. Environmental Protection Agency, May 29, 1992. --------------------------------------------------------------------------- EPA's primary source of exposure factors is the ``Exposure Factors Handbook'' published by EPA in August 1997 (EPA 1997a 16). For probabilistic risk analyses, EPA used the distributions of exposure factor values provided in the Exposure Factors Handbook to develop PDFs for exposure factors. The one situation where EPA does not develop an expression of dose is the case where we use Reference Concentrations (RfCs) 17 to estimate noncancer hazard for the inhalation exposure route. In this situation, EPA calculates noncancer hazard from concentration of the contaminant in air and the RfC, without considering exposure factors (inhalation rate, body weight) other than those inherent in the RfC. --------------------------------------------------------------------------- \16\ EPA. 1997a. Exposure Factors Handbook, Volumes I, II, and III. Office of Research and Development, Washington, D.C., EPA/600/ P-95/002Fa, b, c. August 1997, www.epa.gov/ordntrnt/ord/webpubs/ exposure/index.html. \17\ Very simply, an RfC is EPA's acceptable concentration in air for a contaminant that causes non-cancer health effects. An RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious noncancer effects during a lifetime. --------------------------------------------------------------------------- aminant that causes non-cancer health effects. An RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious noncancer effects during a lifetime. --------------------------------------------------------------------------- We express the toxicity of contaminants as health benchmarks. Health benchmarks include cancer slope factors (CSFs, EPA's measure of cancer potency) 18 for oral exposure carcinogenic contaminants; reference doses (RfDs, EPA's acceptable contaminant dose via ingestion) 19 for oral exposure to noncarcinogenic contaminants; inhalation CSFs for inhalation exposure to carcinogenic contaminants; and RfCs for inhalation exposure to noncarcinogenic contaminants. EPA derived inhalation CSFs from Unit Risk Factors (URFs) for inhalation exposure to carcinoge [Text truncated at 120,000 characters. 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