Jump to main content.

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.

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. Photo: cement plant

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.

Top of Page

Legislative and Regulatory Timeline

Top of Page

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:

  1. Select Docket Search.
  2. Select "Environmental Protection Agency" from the Agency drop-down menu.
  3. 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.
  4. 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).

Top of Page

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:

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.

Top of Page

Local Navigation

Jump to main content.