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Cement Kiln Dust Waste
How is Cement Made?
Cement is produced by burning mixtures of limestone, minerals, and other additives at high temperatures in a special rotary kiln. Hot air mixing with the raw materials creates a chemical reaction and produces "clinker," marble-sized pellets and sand-sized particles. The clinker is removed from the kiln, cooled, finished, and ground for bagging.
This web page provides an outline of the legislative and regulatory history, and current status of the CKD exemption and proposed regulations. Links to key regulatory and technical documents are also provided.
- Legislative and Regulatory Timeline
- Public Docket for Cement Kiln Dust
- Supporting Technical Documents
You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.
Cement kiln dust (CKD) is the fine-grained, solid, highly alkaline waste removed from cement kiln exhaust gas by air pollution control devices. Because much of the CKD is actually unreacted raw materials, large amounts of it can and are, recycled back into the production process. Some CKD is reused directly, while some requires treatment prior to reuse. CKD not returned to the production process is typically disposed in land-based disposal units (i.e., landfills, waste piles, or surface impoundments), although some is also sold for beneficial reuse.
CKD is categorized by EPA as a "special waste" and has been temporarily exempted from federal hazardous waste regulations under Subtitle C of the Resource Conservation and Recovery Act (RCRA). EPA is in the process of developing standards for the management of CKD and has published a set of proposed Subtitle D (i.e., non-hazardous, solid waste) regulations to govern CKD management.
Legislative and Regulatory Timeline
- July 25, 2002 EPA publishes a notice of data availability (NODA) in the Federal Register (67 FR 48648). In addition to announcing the availability of new data to the public, the NODA explains that EPA is considering a new approach to CKD management whereby it would finalize the proposed CKD management standards as a RCRA Subtitle D (solid waste) rule and temporarily suspend the proposed RCRA Subtitle C (hazardous waste) portion of the proposed rule for 3 to 5 years to assess how CKD management practices and state regulatory programs evolve. Based upon this assessment, EPA will either formally withdraw or promulgate that portion of the 1999 proposed rule. For additional information, see:
- Additional Data Available on Wastes Studied in the Report to Congress on Cement Kiln Dust, July 25, 2002 (67 FR 48648) (PDF) (3 pp, 167K)
- Federal Register NODA: Extension of Public Comment Period - November 8, 2002 (67 FR 68130) (PDF) (2 pp, 164K)
- CKD Proposed Rule NODA Comments (PDF) (31 pp, 281K)
Summary and response to comments on the Cement Kiln Dust Notice of Data Availability.
- August 20, 1999EPA publishes "Standards for the Management of Cement Kiln Dust; Proposed Rule" (64 FR 45632). EPA's proposed approach would allow CKD to remain a non-hazardous waste provided that the specified management standards are met. CKD not managed in compliance with the standards is proposed to be a "listed waste" and would need to comply with tailored RCRA Subtitle C management standards. For additional information, see:
- Standards for the Management of Cement Kiln Dust; Proposed Rule, August 20, 1999 (64 FR 45632) (PDF) (66 pp, 533K)
- Environmental Fact Sheet: Management Standards Proposed for Cement Kiln Dust Waste (EPA530-99-F-023) | PDF Version (2 pp, 16K)
- Extension of Public Comment Period - October 28, 1999 (64 FR 58022) (PDF) (1 pg, 13K)
- CKD Proposed Rule Comments (PDF) (244 pp, 1.9MB)
Summary and response to comments on the Cement Kiln Dust Proposed Rule.
- February 7, 1995EPA issues its final regulatory determination for CKD (PDF) (12 pp, 137K) in the Federal Register (60 FR 7366). In its determination, EPA states that additional control of CKD is warranted to protect human health and the environment from damage resulting from current disposal practices.
- December 31, 1993EPA submits a Report to Congress on Cement Kiln Dust that addresses the eight study factors required by §8002(o) of RCRA for CKD.
- June 19, 1991In a consent decree, EPA agrees to complete the Report to Congress on CKD by April 30, 1993. The consent decree is later modified to extend the deadline to December 31, 1993.
- March 8, 1989The Environmental Defense Fund files suit against EPA for missing the statutory deadline. The American Petroleum Institute and the Edison Electric Institute intervene in the case.
- October 31, 1983EPA misses the statutory deadline for submitting its CKD Report to Congress.
- November 11, 1980EPA promulgates interim final amendments to the hazardous waste regulations in the Federal Register (45 FR 76618). This FR notice includes an exclusion for cement kiln dust from the definition of hazardous waste (§261.4(b)(8)).
- October 12, 1980Congress enacts the Solid Waste Disposal Act Amendments of 1980 (Public Law 96-482) which amends RCRA. Among the amendments, Section 3001(b)(3)(A)(i-iii)frequently referred to as the Bevill Amendmenttemporarily exempts three special wastes from hazardous waste regulation until further study can be completed. Cement kiln dust is one of the wastes exempted. At the same time, Section 8002(o) requires EPA to study CKD and submit a Report to Congress evaluating the status of its management and potential risk to human health and the environment by October 1983. EPA is also required to make a regulatory determination (within six months of the completing the Report to Congress) as to whether CKD warrants regulation under RCRA Subtitle C or some other set of regulations.
- December 18, 1978EPA publishes the first set of proposed hazardous waste management standards in the Federal Register (43 FR 58946). This FR notice includes a proposal to exempt six categories of "special wastes" from the RCRA Subtitle C regulations until further study can be completed. Cement kiln dust is included as one of the six special wastes.
- October 21, 1976Congress passes the Resources Conservation and Recovery Act (RCRA) (Public Law 94-580) which requires EPA to develop regulations governing the identification and management of hazardous waste.
Public Docket for Cement Kiln Dust
Dockets contain all publicly available materials used in the development of regulations, such as Federal Register notices and rules, supporting analyses, technical background documents, and comments submitted by the public on Agency reports and rulemakings. EPA dockets are available electronically at Regulations.gov.
To use Regulations.gov:
- Select Docket Search.
- Select "Environmental Protection Agency" from the Agency drop-down menu.
- In the Keyword Box, type "cement kiln dust" and then click the "Submit" button to receive your search results. Be patient; loading the documents can take several minutes.
- The docket should appear with the docket ID number (e.g., EPA-HQ-RCRA-1994-0072).
For a complete listing of all materials contained in the CKD Docket, refer to RCRA Docket Index Number F-1999-CKDP-FFFFF (Text File) (61 K).
Supporting Technical Documents
Analysis of Groundwater Monitoring Data Submitted by the American Portland Cement Alliance (PDF) (54 pp, 3.6MB)
This 2001 report contains summaries of the information gathered from the document, "Cement Kiln Dust Groundwater Monitoring Summary", produced by the American Portland Cement Alliance (APCA). The document also is available as individual, smaller PDF files:
- Part I - Introduction (PDF) (4 pp, 217K)
- Part II - Two Data Tables (PDF) (2 pp, 1.5MB)
- Part III - Section II (PDF) (48 pp, 501K)
Cement Kiln Dust Groundwater Migration Pathway Report (PDF) (92 pp, 355K)
This 1998 report is the second phase of a two phase work effort to determine migration of contaminants from CKD leachate to receptor wells under high alkalinity conditions.
Risk Assessment for Cement Kiln Dust Used as an Agricultural Soil Amendment; Draft Report (PDF) (324 pp, 1.8MB)
This 1998 report presents the risk assessment methodology used to estimate the incremental increase in individual lifetime risk from the use of CKD as an agricultural soil amendment.
Technical Background Document: Compliance Cost Estimates for the Proposed Land Management Regulation of Cement Kiln Dust (PDF) (67 pp, 282K)
This 1998 report presents EPA's compliance cost estimates for the land management of CKD generated by the Portland Cement Industry in support of the Agency's proposed regulation.
Technical Background Document on Control of Fugitive Dust at Cement Manufacturing Facilities; Draft (PDF) (54 pp, 260K)
This 1998 document summarizes the basis for EPA's proposed performance standards and technology-based standards for controlling fugitive emissions of CKD.
Technical Background Document on Ground Water Controls at CKD Landfills; Draft (PDF) (199 pp, 723K)
This 1998 document describes EPA's development of proposed performance standards and design and operating criteria for controlling releases to ground water at CKD landfill units.
Evaluation of Metals Migration from Cement Kiln Dust (CKD) Piles Using the EPACMTP Groundwater Model; Draft (PDF) (30 pp, 140K)
This 1997 report documents the results of EPA's additional groundwater analyses using the more complex groundwater model, EPACMTP, to supplement its initial screening-level groundwater modeling to determine whether constituents could leach from the CKD management units to the groundwater and then move to a receptor site.
Examination of Metals Transport under Highly Alkaline Conditions (PDF) (37 pp, 159K)
This 1997 report presents metal adsorption distribution coefficients (Kd values) for the metals barium (Ba), beryllium (Be), cadmium (Cd), chromium(III) (Cr(III)), and lead (Pb) in groundwater under the highly alkaline conditions possible with land disposal of CKD.
Technical Background Document on the Efficiency and Effectiveness of CKD Landfill Design Elements; Draft (PDF) (65 pp, 334K)
This 1997 document presents an evaluation of the landfill design elements being considered by EPA for inclusion in the proposed rule.
Technical Background Document: Population Risks from Indirect Exposure Pathways, and Population Effects from Exposure to Airborne Particles from Cement Kiln Dust Waste
This 1997 document analyzes the extent to which current practices for managing CKD onsite at cement manufacturing plants pose a health risk to nearby, offsite populations.