Skip to main content

Hot Mix Asphalt Plants

A hot mix asphalt facility with a dump truck receiving asphalt mixture

Do I need a permit for a Hot Mix Asphalt (HMA) Plant?
In all cases if you plan to operate a hot mix asphalt plant in Vermont, you will need to obtain an air permit. Hot mix asphalt plants are considered stationary sources of air pollution regardless of size under [VAPCR 5-401(a)(2)].

Hot mix asphalt plants are often collocated with a quarry or crushing operation. For more information on these emission sources, please visit our Gravel Pits, Quarries, and Aggregate Crushing and Screening Plants source category page.

Why do we regulate hot mix asphalt plants?
Hot mix asphalt facilities play an essential role in infrastructure development by producing the asphalt mixtures needed in road construction, but they can also produce significant amounts of air pollution if not properly managed. 

One of the primary sources of air pollution from hot mix asphalt production is from the combustion process, where fuels are mixed with the asphalt mixture and burned to release moisture. This process results in the release of particulate matter (PM), oxides of nitrogen (NOx), carbon monoxide (CO), volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). To address this, plants often employ various strategies to minimize emissions, such as ensuring optimal combustion conditions, employing emission controls such as cyclones and baghouses, and in some cases utilizing advanced burner technologies such as low-NOx burners. In Vermont hot mix asphalt plants are required to achieve 99% combustion efficiency at all times, and to perform routine stack testing to demonstrate compliance with the PM and CO emission limits in the permit every five years. 

Another potentially significant source of VOCs and odors from a hot mix asphalt plant results from the storage and handling of the asphalt itself. To mitigate this, hot mix asphalt plants in Vermont are required to employ vapor recovery systems, such as condensers or carbon adsorbers, to capture and recover the asphalt fumes from the asphalt storage tanks. 

The transportation, handling, and storage of raw materials can also cause dust and PM issues for hot mix asphalt plants. Facilities typically address these issues by ensuring that aggregate storage piles, conveyor drop points, and haul trucks are either fully or partially enclosed, or treated with wet suppression to ensure that the dust and aggregate materials do not become airborne. An air permit for a hot mix asphalt facility will include provisions for mitigating fugitive dust from the facility. 

What do I need to do to obtain an Air Permit?
A Permit to Construct application must be submitted with the appropriate application fee  to the AQCD.  The Permit must be issued before the applicant can commence construction of the project.  This would be required before opening or expanding a hot mix asphalt plant or before adding or modifying the processing equipment operated at the site.   Please refer to our Permit to Construct Application Guidance webpage for more information. In addition to the information required to be submitted for a Permit to Construct Application, please also submit the following equipment specifications and designs.

Equipment Specifications and Designs

  • Plant Manufacturer, Model No., Date of manufacture, Date of Installation 
  • Type of HMA plant (batch or drum-mix): 
    • If batch plant, maximum batch size (tons)
    • If drum mix, where will the asphalt cement (AC) be mixed with the hot aggregate material? 
      • If material will be mixed outside the drum please indicate method and equipment. 
      • If AC will be injected into drum please indicate the location of the injection point 
  • Maximum Production Rate (tons per hour): 
  • Actual Design Production Rate (tons per hour): 
  • Rotary Dryer Dimensions: 
  • Asphalt cement type: (include Material Safety Data Sheet) 
  • Number of storage tanks and capacity for asphalt cement: 
  • Number of storage tanks and capacity for fuel: 
  • Rotary Dryer Burner Type: 
  • Fuel Type: 
    • Fuel Sulfur Content (% by weight) : 
    • Fuel Higher Heating Value: Liquid fuel (MMBtu/gallon), Gaseous fuel (Btu/cubic foot) 
  • Rotary Dryer Burner 
    • Maximum Rated Heat Input (MMBtu/hr) 
    • Rotary Dryer Burner Maximum Fuel Firing Rate: 
      • Liquid fuel (gallons/hour). Gaseous fuel (cubic feet/hour) 
  • Will a storage silo be utilized? If so, identify manufacturer, model no., serial no., capacity, and size 
  • Number of feed hoppers  
    • For each feed hopper: manufacturer, model no., serial no., material contents (e.g., 3/8" stone, sand, etc.), capacity (cubic yards), feed rate (tons per hour) 
  • Number of conveyors (including bucket elevators) ▪ 
    • For each conveyor: manufacturer, model no., serial no., transfer rate (tons/hour), enclosed or not enclosed, vented to a fabric filter? 
  • Number of weight hoppers  
    • For each weight hopper: manufacturer, model no., serial no., transfer rate, enclosed or not enclosed, vented to a fabric filter? 
  • Number of screening units 
    • For each screening unit: manufacturer, model no., serial no., production rate (tons per hour), enclosed or not enclosed, vented to a fabric filter? 
  • Baghouse fines removal procedures and method of final disposal. 
  • If an internal combustion engine will be utilized to generate electricity on-site please supply specifications in accordance with the above requirements.

State Regulations
In addition to the Permitting regulations of 5-501 (Permits to Construct) and 5-1001 (Permits to Operate), the Vermont Air Pollution Control Regulations also include the following regulations that would apply to hot mix asphalt plants and their operations.

  • 5-211 Prohibition of Visible Air Contaminants.  This regulation restricts the visible dust that may be emitted by the facility.
  • 5-221(1) Sulfur Limitations in Fuel.  This regulation restricts the sulfur content of distillate fuel oil and diesel fuel oil to no greater than 0.0015% by weight.  This fuel is commonly referred to as Ultra Low Sulfur Diesel or Distillate (ULSD).  
  • 5-231 Prohibition of Particulate Matter (Dust).  These regulations limit the amount of particulate matter (dust) that can be emitted by the processing equipment and requires that all reasonable measures be taken to prevent particulate matter from becoming airborne.
  • 5-241 Prohibition of Nuisance and Odor.  This regulation prevents a facility from causing a public nuisance, of either dust or odors, off their premises.
  • 5-253.15 Control of Volatile Organic Compounds from Cutback and Emulsified Asphalt.  This regulation limits the volatile organic compound content of cutback and emulsified asphalts to less than 5% by weight.
  • 2-261 Control of Hazardous Air Contaminants.  This regulation may impose further restrictions on hazardous air toxic emissions resulting from non-virgin fuel combustion in the dryer, and to fugitive dusts at the facility containing crystalline silica. If emissions of hazardous air contaminants are anticipated to exceed the Action Level under normal conditions, the following requirements will be included in the permit as part of HMSER:
    • PM total (Method 5 and 202): 0.04 gr/dscf
    • PM filterable (Method 5 only): 0.020 gr/dscf (0.015 gr/dscf if waste oil is used)
    • CO: 0.13 lbs/ton of HMA produced
    • NOx: 0.06 lbs/ton (drum plant) or 0.12 lb/ton (batch plant)
    • PM and CO stack tests every five years.

Federal Regulations for Hot Mix Asphalt Plants
The US EPA regulation 40 CFR Part 60 Subpart I Standards of Performance for Hot Mix Asphalt Facilities applies to each hot mix asphalt facility for which construction or modification is commenced after June 11, 1973.  For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the following: dryers; systems for screening, handling, storing, and weighing hot aggregate; systems for loading, transferring, and storing mineral filler, systems for mixing hot mix asphalt; and the loading, transfer, and storage systems associated with emission control systems. This regulation requires a performance test to demonstrate compliance with the PM emissions limit of 0.04 gr/dscf. 

What other permits or requirements may be applicable to my project?
The Department of Environmental Conservation Environmental Assistance Office provides permit assistance through the Permit Navigator tool. The Permit Navigator can help you identify what environmental permits you may need for a project on a single parcel. If you have a linear, polygon, or multi-parcel project, contact a Community Assistance Specialist to get started.