Water Protection Program fact sheet
Division of Environmental Quality Director: Kyra Moore

No exposure means all the materials and activities at a facility are indoors or protected from exposure to rain, snow, snowmelt and runoff. If that describes your facility, you can apply to be excluded from stormwater permitting. This guidance provides information on Missouri’s No Exposure Certification for exclusion from the permitting requirements for the discharge of stormwater regulated under the National Pollution Discharge Elimination System and the Missouri Clean Water Law. This guidance is not all-inclusive and only provides examples. There may be other industrial activities and industrial materials at your facility that are not identified in this document.

You may contact your local Department of Natural Resources’ regional office if you need assistance with the form or wish to participate in a compliance assistance visit to determine eligibility for exclusion. 


Under state regulations, an NPDES permit from the department is required for stormwater runoff from certain industrial activities that are listed among the regulated categories and meet certain requirements as outlined in 10 CSR 20-6.200 (2). An industrial activity may be excluded from a stormwater permit if the activity does not expose materials to stormwater as stated in 10 CSR 20-6.200 (1)(C)(1) through 10 CSR 20-6.200 (1)(C)(2)(C). Qualified permit holders, as well as new applicants that qualify, must submit a completed No Exposure Certification For Exclusion from NPDES Stormwater Permitting Under Missouri Clean Water Law Form MO 780-2828 to the appropriate department office.

Definition of Key Terms

Industrial Materials and Activities

These include but are not limited to material handling equipment or activities, industrial machinery, raw materials, intermediate products, by-products, final products or waste (including recyclable) products. Material handling activities include the storage, loading and unloading, transportation or conveyance of any raw materials, intermediate product, by-product, final product or waste product.

Storm-Resistant Shelters

Storm-resistant shelters include completely roofed and walled buildings or structures, as well as structures with only a top cover but no wells, provided material under the structure is not otherwise subject to any run-on and subsequent runoff of stormwater. Temporary covers (i.e., tarpaulins) may also qualify as storm-resistant shelter until permanent enclosure can be achieved.

Loading and Unloading

Loading and unloading operations include pumping of liquids or gases from tankers to storage facilities, pneumatic transfer of dry chemicals, transfer by mechanical conveyor systems or transfer of bags, boxes, drums or other containers by forklift or other material handling equipment.

Vehicle Maintenance

Vehicle maintenance includes vehicle rehabilitation, mechanical repairs, painting, fueling and lubrication associated with the facility or industrial activity.

What is No Exposure?

No exposure means that all industrial materials are stored and all industrial activities are protected by a permanent building or permanent storm resistant shelter to prevent exposure to precipitation including rain, snow, snowmelt and run-on and runoff.


The following materials and activities do not have to be stored or performed inside such a building or structure:

  • Dumpsters or other rigid containers used to contain non-hazardous solid waste or recyclables that are leak-proof and have rigid lids that keep out precipitation. Lids must be kept closed.
  • Vehicles used in material handling in normal operating condition with no residue or contamination on the external exposed surfaces. Vehicles awaiting on-site repair/maintenance are not considered to be well maintained and may pose an exposure risk only if exposing materials or pollutants to stormwater.
  • Pipe that is not deteriorated to the point that it adds pollutants to stormwater and does not leak, and that is installed for use in the transportation or conveyance of materials at or through the facility. This does not include pumps, inlet valves, or outlet valves.
  • Wash waters generated from routine exterior washing of the facility that do not contain soaps or detergents and that are absorbed into the soil and do not runoff.
  • Drums, barrels, tanks and similar containers that are tightly sealed, provided those containers are not deteriorated to the point at which it adds pollutants to stormwater and do not leak. “Sealed” means banded or otherwise secured and without operational taps or valves.

Final products that are meant to be used outdoors (e.g., automobiles, bricks) and pose little risk of stormwater contamination, i.e., the products cannot be mobilized by precipitation or runoff. Containers, racks and other transport platforms (e.g., clean wooden pallets) used for the storage or conveyance of these final products, can be stored outside, providing the containers, racks and platforms are pollutant-free.

Who May File a Request for No Exposure Certification?

Federal law at 40 CFR Part 122.26 prohibits point source discharges of stormwater associated with industrial activity to waters of the U.S. without a NPDES permit. However, NPDES permit coverage is not required for discharges of stormwater associated with industrial activities identified at 40 CFR 122.26(b)(14)(i)-(ix) and (xi) if the discharger can certify that a condition of “no exposure” exists at the industrial facility or site.

Facilities that meet the requirements outlined in 10 CSR 20-6.200 (1)(C), unless otherwise required by the department, may file a NEC.  

Stormwater discharges from construction activities identified in 40 CFR 122.26(b)(14)(x) and (b)(15) are not eligible for the no exposure exclusion.

General Requirements to Achieve No Exposure Certification

Facilities must complete and submit No Exposure Certification Request Form to the appropriate department office. Facilities that currently operate under, or are seeking exclusion from, a site specific NPDES permit will submit the form to the Water Protection Program. Facilities that currently operate under or are seeking exclusion from a general Missouri State Operating Permit will submit the form to the appropriate regional office.

The completed form and any supporting documents should be submitted to:

Central Office Regional Offices

Missouri Department of Natural Resources
Water Protection Program
ATTN: Operating Permits Section
P.O. Box 176
Jefferson City, MO  65102-0176
800-361-4827 or 573-522-4502

Please send to the appropriate regional office

There are no fees required for No Exposure Certifications. Qualifying facilities are not required to prepare a Stormwater Pollution Prevention Plan (SWPPP), conduct any routine inspections, monitor for stormwater discharges or submit monitoring reports.

The certification is available on a facility-wide basis, not for individual outfalls or drainage areas. If any exposed industrial materials or activities are found on any portion of the facility, the facility does not qualify for the certification.

The department retains the authority to inspect the facility and deny this exclusion upon determining that industrial materials or activities are exposed to stormwater.

Maintaining a Condition of No Exposure

The No Exposure Certification is non-transferrable with ownership changes. The new owner must submit a new certification request certifying the facility will operate under the No Exposure Certification conditions. The certification is issued for a period of five years. A signed certification must be submitted to the department 30 days prior to the expiration of any previous certification.

The No Exposure Certification is a conditional exclusion. If circumstances change and industrial materials or activities become exposed to precipitation, the facility is not eligible to retain the certification. A facility that anticipates changes resulting in exposure should submit the appropriate permit application and obtain a NPDES permit prior to the change of circumstance. Failure to maintain the conditions of no exposure or obtain a NPDES permit can lead to unpermitted discharges.

Ensure the facility continues to meet conditions of the certification through proper housekeeping and oversight of changes at the facility, which could result in exposure of materials or industrial activities to stormwater. If the facilities plans changes that they are unsure would meet no exposure conditions, please contact the appropriate department office for guidance or request a Compliance Assistance Visit.

Facilities that discharge stormwater through a Municipal Separate Storm Sewer System  must submit a copy of their No Exposure Certification to the system operator, as well as allow inspection and public reporting of the inspection findings by the system operator.

Industrial Materials and Activities Having Exposure

Though not intended to be an exhaustive list, nor all-inclusive, the following list provides examples of materials and activities (with exceptions) that are considered as having an element of exposure to stormwater and therefore not eligible for exclusion. There may be other industrial activities and materials at your facility that are not listed.

  • Loading platforms that extend beyond the permanent wall (except for a bladder or similar device).
  • Drums, barrels and similar containers not stored under roof in a permanent building or structure (except as allowed below).
  • Outdoor storage of industrial materials and ongoing outdoor operations including site remediation or other operations resulting from past industrial activities.
  • Industrial activities and materials loaded, unloaded, or stored on roads or railways owned or maintained by the facility.
  • Materials stored outdoors under overhangs, permanent tarp storage or in storage containers and other structures that are not permanent buildings or structures.
  • Sand and salt to be applied to access roads, parking lots or sidewalks at the facility, strictly for traction or for the melting of snow or ice, must be stored in a permanent structure or tightly sealed container during the months of April through October.
  • Outside material handing activities (except loading, unloading and transferring industrial materials into or from enclosed vehicles directly into or from a permanent structure at a loading platform that does not extend beyond the permanent wall).
  • Waste materials, including recyclables, stored outside (except wastes in closed with rigid lids, non-leaking dumpsters).
  • Poor industrial housekeeping as evidenced by traces of oil, grease or other compounds on the ground, that can be seen in spots, pools, puddles or other discoloration and odors and the overall condition of the facility (unused equipment, maintenance materials, industrial litter etc.).
  • Particulate matter, visible deposits or residue from roof stacks or vents not otherwise regulated (i.e., under an air quality control permit) and evident in the stormwater discharge.

Materials and activities that may be present at a facility certified as No Exposure are:

  • Containers and tanks sealed and not deteriorated to the point that they add pollutants to stormwater; cannot have any taps or valves, which could have the possibility of leaking product or waste.
  • Adequately maintained vehicles and their storage, such as forklifts, industrial vehicles, etc.
  • Completely covered/plugged dumpsters.
  • Materials stored outside that do not contaminate stormwater, such as exposed pallets that are pollutant free, finished products that cannot be mobilized in storm events and are intended to be used outdoors, and used tires with no contamination.
  • Office buildings and parking lots where there are no industrial materials being stored or industrial activities being conducted.
  • Direct discharges of materials to a sanitary or combined sanitary sewer with prior approval from the receiving treatment facility.

Common Sources of Exposure and Solutions for Obtaining No Exposure

Proper Storage of Industrial Materials

If industrial materials are not stored properly, stormwater runoff picks up pollutants and discharges them into waterbodies or indirectly via storm sewer systems. One of the most common problems at facilities is not meeting the definition of a storm-resistant shelter. Storm-resistant shelters include completely roofed and walled buildings or structures, as well as structures with a top cover but no side coverings, provided the material under the structure is not otherwise subject to runon or runoff of stormwater. Storm-resistant shelters should prevent exposure or the potential for exposure of industrial activities and significant materials.

Runoff from areas where industrial activities occur can contain toxic pollutants (e.g., metals and organic chemicals) and other pollutants, such as trash, debris, oil and grease, when facility practices allow exposure of industrial materials to stormwater.

Windblown raw materials can cause a potential condition of exposure or disbursement of hazardous materials, wastes or pollutants. Even materials sheltered from precipitation can still be deemed exposed if they can be mobilized by wind.

Examples of materials that can be mobilized by the wind:

  • A pile of sawdust that is protected by a roof but not four walls.
  • Dust or particulate-generating processes include industrial activities with stack emissions or process dusts that settle on surfaces.

Dumpsters and Other Containers

  • Containers deteriorating to the point that they add pollutants to stormwater or containers without proper cover do not qualify for No Exposure Certification. The cover material (whether a lid or some other type of cover) must be durable and anchored in a way to keep water from entering the container). If the material fails and water enters the container, the facility no longer qualifies for the No Exposure Certification.  
  • Large roll-off type bins used outside for collecting scrap and other waste materials commonly are without covers or lids. To qualify for certification, these bins must have a cover or lid and be leak proof.
  • Open or unplugged dumpsters, commonly found at facilities, could cause a condition of stormwater exposure. If the material used for a cover fails and water enters the dumpster, the facility no longer qualifies for the NEC.

Solutions for Problems Regarding Dumpsters and Containers

  • Ensure the container is in good condition. The cover material should be durable and sturdy and not break down in sunlight. Inspect the container often to ensure the material does not allow stormwater to enter the container.
  • Maintain dumpsters by keeping lids closed and plugging all drain holes.
  • Replace dumpster when seams crack or holes develop.
  • Shelter or enclose stored containers and drums according to regulations. Remember, even closed containers can leak.
  • Provide appropriate shelter during loading and unloading activities.
  • Provide appropriate shelter for unused industrial equipment.

Proper Transfer of Liquids

Transfer of liquids can involve fueling vehicles or equipment, mixing wastes, loading and unloading products, etc. Material spills or losses in areas without secondary containment or not within storm-resistant shelters can cause discharge of pollutants during a storm.

  • Spills and leaks during fuel, liquid and material delivery.
  • Spills caused by “topping off” fuel tanks.
  • Precipitation falling on the material delivery area or stormwater running onto that area.
  • Hosing or washing down material delivery area.
  • Leaking storage tanks.
  • Exposure or leaks during loading and unloading of waste transporting activities.

Solutions for Problems Associated with the Transfer of Liquids

  • Loading and unloading operations must be conducted within a storm-resistant shelter.
  • Cover loading and unloading areas and perform these activities on an impervious pad to enable easy collection of spilled materials. Provide overhangs or door skirts to enclose trailer ends at truck loading docks. An example of adequate covering from a loading dock would be the roof of the facility covers the loading area and the loading area is raised over two feet off the ground preventing stormwater run-on.
  • Materials must be adequately covered (such as by a tarp or in an enclosed trailer) during transport.
  • Loading and unloading materials will not occur during a precipitation event or provide protection for loading docks.

Other Potential Exposure Considerations

There are other areas commonly found around an industrial facility which may present a potential exposure concern. These areas, though commonly exposed to precipitation, can be operated and managed in a way that would help to maintain the conditions of no exposure.

Trash Compactors

Trash compactors are industrial equipment and if located outside exposure may occur from hydraulic leaks, contents falling out of seams in equipment, or during loading or unloading. Larger printing facilities may have compactors, as well many other facilities. Make sure to inspect and maintain the compactor on a regular basis.

Bag Houses (or other particulate matter collection devices)

Facilities operating under an air permit may have particulate matter or visible deposits of residuals on the ground that come from roof vents or bag houses. Bag house filters are considered industrial equipment and may be found at cabinet shops, woodworking facilities or other industries with dust collection equipment. Sawdust (or other dust) conveyance systems that might feed into a semi-trailer may develop leaks or spill sawdust from trucks during the filling or removal operations. Preventative maintenance is a must in making sure these materials do not escape conveyance systems.

Nitrogen Gas Storage and Generation Equipment
Some facilities have the large white steel storage tanks that may have compressors or valves needing lubrication, etc. The tanks may be leased from vendors with unknown exposure risks. There also might be oxygen generation equipment in this same category. Keep these tanks and equipment in good condition to prevent leaks and spills.

Aboveground Storage Tanks and Secondary Containment

  • Facilities that are required to obtain a stormwater permit with SIC codes 40, 41, 42 (except 4221-25), 43, 44, 45 and 5171 involved with vehicle maintenance, equipment cleaning and airport deicing that use aboveground storage tanks are eligible for No Exposure Certification if the following apply: They must be physically separated from and not associated with vehicle maintenance operations.
  • There must be no piping, pumps or other equipment leaking contaminants that could contact stormwater.
  • It is recommended that aboveground storage tanks be surrounded by some type of physical containment (e.g., an impervious dike, berm or concrete retaining structure) to prevent runoff in the event of a structural failure or leaking transfer valve. Note: any resulting unpermitted discharge would violate the Clean Water Act.
  • Use of engineered double wall storage tanks would meet the no exposure requirements for aboveground storage tanks.

Adequately engineered secondary containment which prevents failure, leakage or overflow such that there would be no discharge can qualify for No Exposure Certification. Note: there must be proper disposal of any water or liquids collected from the containment (i.e., discharged in compliance with another NPDES permit, treated or trucked offsite). Aboveground storage tanks that are not in direct support of facility operations as identified above, but rather used for fueling vehicles, such as automobiles and forklifts, would be considered routine vehicle maintenance and therefore not eligible for the No Exposure Certification.

Provisions of 40 CFR 122.26(b)(14)(viii) apply to only those portions of the facility that are directly involved in vehicles maintenance, equipment cleaning, and airport deicing. Retail fueling or fueling activities conducted at but not associated with the operation of transportation facilities with Standard Industrial Classification Codes (SIC) 40, 41, 42 (except 4221-25), 43, 44, 45, and 5171, would not be considered vehicle maintenance and therefore eligible for NEC.  For example, the transfer of petroleum product to a distribution (tanker) truck from an aboveground storage tank at a facility with a SIC of 5171 (bulk petroleum storage) is not considered “fueling,” and would not require a stormwater permit. However, fueling for the tanker truck itself at the 5171 facility is considered to be part of routine vehicle maintenance and therefore would not meet the definition of no exposure.

The retail fueling of vehicles at such sites does not constitute “vehicle maintenance” and therefore would not require a stormwater permit. Only those portions of the SIC Code 5171 facility where vehicle maintenance operations and equipment cleaning take place are required to be covered under a stormwater permit.

Additional Resources

If you still are not certain about your eligibility for exclusion after evaluating your facility using this guidance please contact the appropriate department office for additional assistance.

Central Office
Water Protection Program -Operating Permits Section
P.O. Box 176
Jefferson City, MO  65102-0176
800-361-4827 or 573-522-4502
General Permits      
MOG – 05, 87
MOR – 240 (new)
All permitting actions located in Camden, Cole, Maries, Miller, Moniteau, Morgan, Osage, Phelps, Pulaski and Pettis counties.

Regional Offices
General Permits
MOG – 13, 14, 251, 35, 49, 50, 64, 67, 69, 75, 76, 84, 92, 94, 97, 251, 641, 698, 821, 822
MOR – 13, 22A, 22B, 22C, 23A, 23D, 23E, 60A, 80C, 80F, 80H, 203, 240 (renewal)

Nothing in this document may be used to implement any enforcement action or levy any penalty unless promulgated by rule under chapter 536 or authorized by statute.

For more information