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Asphalt Plants

Hot Mix Asphalt (HMA) is a combination of approximately 95% stone, sand or gravel bound together by asphalt cement, a product of crude oil. Asphalt cement is heated and mixed with the aggregate at an HMA facility. Some plants may also process reclaimed asphalt as well. Once mixed, the asphalt is loaded into trucks for transport to the construction site. HMA plants can be permanently located on a site or be skid mounted or portable to allow movement to meet construction project needs.

Air pollution emissions are generated by the heating of asphalt cement, along with the handling of aggregate on the site, from storage piles to loaders, and dump trucks taking away the final product. Runoff from spills and dust can create storm water contamination.

Many plants are located within a quarry to easily access the aggregate mix needed for production. Quarries and HMA plants will have separate permitting needs. The following environmental information is specific to HMA and its related activities.

Air Pollution Requirements

The DNR entered into an agreement with the hot mix asphalt industry in 2001 regarding calculating air pollution emissions for hot mix asphalt (HMA) plants. This agreement lays out how plants are set up in the Air Reporting System, how air emissions are to be calculated and what processes must be included in the emissions calculations.

Along with calculating and reporting emissions, a HMA plant must apply for an air pollution permit and properly manage fugitive dust emissions. The following documents cover the emissions calculations and permitting requirements:

Example recordkeeping documents were created by the Small Business Environmental Assistance Program (SBEAP) for those plants who request help on those requirements:

Fugitive Dust

"Fugitive dust" is a term used to describe any particulate matter (PM) emissions released through any means other than a stack or duct of some kind. Any business creating enough dust, smoke, or fumes to be a noticeable source of air pollution must control those emissions. The following are examples of activities that would create fugitive dust:

  • large trucks transporting materials along unpaved roads;
  • unpaved parking lots;
  • piles of materials stored on site, like grain; and
  • dry materials directed to equipment not collected by another device, whether by baghouse, cyclone, wet scrubber, etc.

Any business that creates fugitive dust must do as much as possible to control those emissions and keep them from escaping into the environment. The following are a few suggestions based on the type of activity. Other best management practices recommended by industry experts are provided in the fact sheet Fugitive Dust Management (AM-556).

Submitting Reports to Air Management Program

The following are reports, certifications or notifications required for GOP sources:

  • January 30th - Annual Summary of Monitoring and Annual Certification of Compliance is due
  • March 1st - Air emissions inventory reporting is due; certification now happens upon submittal
  • As needed
    • Next Day Deviation Report
    • Relocation Notification

Electronic reporting access

All reports listed above can be submitted electronically. Online reporting options streamline the process through use of the DNR Switchboard and Air Reporting System. The electronic signature for reports is only available to the facility's responsible official.

  • The facility's responsible official, air management contact and/or delegated party must obtain a Web Access Management System (WAMS) ID to access the DNR Switchboard.
  • Next, facility contacts need to request access to the compliance and air emission inventory roles in order to file reports electronically.
  • Learn about all electronic submittal options at: Air Compliance Submittal Actions Electronic Reporting.
  • Tutorials on different steps in the electronic submittal process are available as well: Tutorials.

Annual summary of monitoring and certification of compliance – due January 30

Facilities covered by a GOP must submit an annual summary of monitoring and a compliance certification to DNR for each calendar year’s operations. These reports shall include enough information to determine the compliance status of the source with each applicable permit condition.

  • DNR developed a Combined Annual Monitoring Report and Certification of Compliance form for facilities covered by a GOP. Use of form 4530-175 is not mandatory, however, any report submitted by the facility must contain the same information as the form.
  • The report can be submitted and signed electronically. If the facility uses their own format, all documents should be combined and submitted as a single report.
  • The responsible official is required to certify whether compliance was continuous or intermittent for each condition.

Air Emissions Inventory – due March 1

All facilities covered by a GOP must submit an annual Air Emissions Inventory (AEI) report if they are above the reporting thresholds in ch. NR 438, Wis. Adm. Code:

  • All emission units shall be included in the AEI, including insignificant units and fugitive dust emissions.
  • If you need an extension, submit the request through the Air Reporting System (ARS) and NOT by email.
  • Businesses with air emissions below the reporting thresholds listed on Table 1 of Chapter NR 438, can submit an Under Threshold Notification (UTN) to notify DNR their air emissions are below reporting levels. The UTN is generated and submitted electronically within the Air Reporting System (ARS).

For help with submitting the AEI or UTN review the Tutorials webpage. For direct assistance, contact DNRAMEmissionsInventory@wisconsin.gov.

Air Emissions Inventory Certification

Facilities submitting an annual Air Emissions Inventory (AEI) report must certify the report after completing the QA review of the data. This will occur upon submittal of the report.

  • New in 2023 is that the responsible official must sign the AEI certification.
  • Learn how to complete the final report certification for the AEI in AM-624.
  • This certification is not required for facilities completing the Under Threshold Notification (UTN) or facilities that completed the AEI but had emissions below reporting levels in NR 438.

Deviations from requirements

Facilities are required (s. NR 439.03(4), Wis. Adm. Code) to report any deviation from permit requirements by the next business day. Deviations may include certain malfunctions or other unscheduled events (e.g., accidental release of pollutants) at the source that were not reported in advance. Review DNR's guidance memo on how deviations must be reported.

Relocation Notification

Portable sources are required to notify the department at least 20 days prior to each relocation. The written notice should be uploaded to the DNR Switchboard following these steps:

  1. Complete Form 4500-025 or complete a similar notice and save in Portable Document Format (PDF).
  2. Login to Switchboard, select your facility and then select "Air Compliance Actions."
  3. Under the "Other Reports, Plans, and Notifications", select "Upload New Document."
  4. Choose "Notification" and then “Portable Source Relocation Notification” from the drop-down menus.
  5. Indicate the County where the portable source will be relocated.
  6. Browse for the relocation notification file (PDF only) on your computer and then select "Upload Document."

Alternatively, you can send relocation notifications directly to the assigned air compliance engineer. DNR Air Contacts assigned to the facility, including the air compliance engineer, can be found in the Air Permit Search database. Staff may be reassigned without notice, so the facility is responsible for confirming the assigned air compliance engineer for each notification.

Water Requirements

Runoff from spills and dust around an asphalt plant can create storm water contamination. Asphalt plants are under a SIC code that requires a Tier 2 permit, or No Exposure application submitted. Review the no exposure criteria and the Tier 2 industrial permit requirements. Submit the appropriate application.

You must apply for an industrial Wisconsin Pollutant Discharge Elimination System (WPDES) permit If you have any of the following water discharges: vehicle wash water, noncontact cooling water, dust suppression water, scrubber water, or other industrial process wastewater. If only some sources of wastewater are present, the plant may qualify for a general permit. Complete the General Permit applicability survey, to see if the plant activities are covered.

All water permits are submitted through the ePermits portal. Before applying for a permit, the facility contact must obtain a Wisconsin User ID. Go to DNR's Switchboard to gain access.

Spills and used oil management

To prevent oil or fuel spills or clean up after a spill, there are several regulations an agriculture business should follow.