Gravel Pits, Quarries, and Aggregate Crushing and Screening Plants

A rock crushing operation

Do I need an air permit for a gravel pit, quarry or aggregate crushing and screening plant? 
In most cases you will not need to obtain an air permit for small gravel pits that do not conduct any aggregate crushing operations.  Your operations are still required to take all reasonable precautions to prevent particulate matter dust from becoming airborne [VAPCR 5-231(4)].  This would include controlling dust from internal roads and traffic areas, from processing and handling of materials on-site such as a screen deck, from exposed windblown areas and by minimizing material tracked onto public roadways.  If you can see dust be emitted into the air you should be taking all reasonable measure to control it.  In the case of most new gravel pits, an Act250 permit will likely be required and the AQCD will request that the permit include a condition requiring effective dust control.

If your gravel pit or quarry will include drilling, sawing, blasting, or aggregate crushing operations then an air permit will likely be required.  In some cases, the air permit may be issued directly to the crushing plant operator rather than the gravel pit or quarry owner.  This may be the case when the gravel pit or quarry owner is separate from the crushing plant owner and the crushing operations are portable and temporary at the site and used for purposes of crushing up stockpiles before moving to another gravel pit or quarry.  The Air Permit for the crushing plant operator may then allow the plant to operate at multiple locations to crush up stockpiles.  In such a case, the gravel pit or quarry owner must take reasonable precautions to control dust from all other areas of the gravel pit or quarry.  In such cases the AQCD will request that any Act 250 permit for the gravel pit or quarry include conditions requiring effective dust control and to only utilize crushing plants that are approved by the AQCD.

What Size Crushing Plant Requires An Air Permit?
Fixed crushing plants with an initial crusher with a maximum rated capacity of greater than 25 tons per hour will require a permit.  Portable crushing plants with an initial crusher with a maximum rated capacity of greater than 150 tons per hour will require a permit.  The rated capacity is based on the manufacturer’s stated maximum rated capacity at the largest setting, not the actual anticipated operating rate for the site.  These thresholds and definitions are consistent with the federal air regulation 40 CFR Part 60 Subpart OOO Nonmetallic Mineral Processing Operations (see below).

Why Do We Regulate Gravel Pits, Quarries, and Aggregate Crushing and Processing Plants?
Gravel pits, quarries and aggregate crushing and processing operations can generate significant amounts of fine particulate matter dust, both from the aggregate processing operations as well as fugitive dust from the internal traffic areas and exposed windblown areas.  Many earthen materials and their dust also contain varying levels of crystalline silica, a hazardous air contaminant responsible for the disease silicosis.  In addition, diesel powered equipment also generates significant amounts of diesel exhaust pollution, including from on-road, off-road and stationary diesel engines that operate for extended periods of time within the confines of the site.  The Air Permit is intended to identify the applicable state and federal air pollution requirements and impose effective emission controls , monitoring and recordkeeping requirements.

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 gravel pit or quarry 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

  • Type of non-metallic mineral(s) to be processed: (e.g. sand, gravel, ledge rock, granite, marble, talc ore, etc.)
  • Will the gravel material (if applicable) be prescreened prior to crushing?
  • Method of quarrying material:
  • Include a process flow diagram depicting each piece of equipment, process flow, and anticipated processing rates (tph)
  • Number of crushers to be utilized:
  • For each Crusher
    • crusher manufacturer, model no., serial no., date of manufacture (required for determining applicability of federal NSPS Subpart OOO 40 CFR §60.670)
    • type of crusher: (e.g., jaw, cone, etc.)
    • manufacturer’s maximum rated capacity at largest possible setting (specify setting) (tph):
    • manufacturer’s maximum rated capacity at proposed setting (specify setting) (tph):
    • actual anticipated capacity at the proposed setting, include recirculation load if applicable (tph):
  • Number of screening units to be utilized:
  • For each Screen Unit
    • conveyor manufacturer, model no., conveyor serial no.,date of manufacture (required for determining applicability of federal NSPS Subpart OOO 40 CFR §60.670)
    • length and width of conveyor:
    • enclosed or not enclosed:
    • manufacturer’s rated capacity (tph):
    • actual anticipated capacity, include recirculation load if applicable (tph):
  • Non-metallic mineral moisture content (% by weight):
  • Will a fabric filter (baghouse) dust collector be used to control fugitive dust from the processing equipment?
    • If so, describe methods to be used to capture and control the fugitive dust: (e.g. location of dust collection pickup points; describe dust collection pickup points; estimate of capture efficiency at each pickup point; air flow rates at pickup points; dust collector specifications
  • Will wet suppression be utilized to control fugitive dust from the processing equipment?
    • If so, describe methods and equipment to be used to control the fugitive dust: (e.g., specify location, make and model of water spray nozzles; type of nozzles (e.g. fog, saturation, etc.); water pressure and flow rates; source of water (e.g. municipal water; dug well; artesian well; on-site surface water source such as pond, quarry or river; off-site source)
  • On an attached flow diagram of the processing equipment, please note the location of all control devices (enclosures, dust pickup points, water nozzles, pressure gauges, source of water, pump locations, etc.).

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 gravel pits, quarries 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 0.05% sulfur by weight.  Commencing July 1, 2018 the allowed sulfur content will drop to 0.0015% by weight.  This fuel is commonly referred to as Ultra Low Sulfur Diesel or Distillate (ULSD).  For many diesel engines, the allowed sulfur content is already restricted by federal regulations to 0.0015%.
  • 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.
  • 2-261 Control of Hazardous Air Contaminants.  This regulation may impose further restrictions on dust emissions that may contain hazardous air contaminates such as crystalline silica.  

Federal Regulations for Nonmetallic Mineral Processing Plants.
The US EPA regulation 40 CFR Part 60 Subpart OOO applies to nonmetallic mineral processing plants constructed or modified after August 31, 1983.  The regulation applies to fixed crushing plants with an initial crusher with a maximum rated capacity of greater than 25 tons per hour.  The regulation also applies to portable crushing plants with an initial crusher with a maximum rated capacity of greater than 150 tons per hour.  The rated capacity is based on the manufacturer’s stated maximum rated capacity at the largest setting, not the actual anticipated operating rate for the site.  This regulation limits the levels of visible dust that can be emitted from various operations. 

While the size of the initial crusher determines applicability of the entire plant, once applicable the provisions of this regulation apply to the following affected facilities in fixed or portable nonmetallic mineral processing plants: each crusher, grinding mill, screening operation, bucket elevator, belt conveyor, bagging operation, storage bin, enclosed truck or railcar loading station.  While the regulation presumes that a dust capture system venting to an emission control device will be used, wet suppression systems that either prevent the dust from being generated or that knock it down at the point of emission may also be used.  Note that for winter time or shoulder season operation wet suppression systems have freezing limitations that could prevent operation of the plant. 

This regulation also requires that each piece of applicable equipment in the nonmetallic mineral processing plant be tested by a third party testing firm to document compliance with the emission limitations.  The facility must submit the compliance test results to the AQCD and maintain records of the testing.  The AQCD permit will require the facility to maintain an inventory of all the nonmetallic mineral processing plant equipment and documentation that compliance testing has successfully been completed as applicable.  The AQCD has developed the following sample inventory template that may be used. 

For further information about this federal regulation please refer to the US EPA website.

What other permits or requirements may be applicable to my project?
The Department of Environmental Conservation Environmental Assistance Office has permit specialists that can provide assistance in determining what other state permits or programs may be applicable to your project.  You can find more information about this service at the following website:  http://dec.vermont.gov/environmental-assistance/permits