Guidance for No Exposure Certification for Exclusion from Stormwater Permit Requirements

Water Protection Program fact sheet
Division of Environmental Quality Director: Ed Galbraith

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 Resouces’ regional office if you need assistance with the form or wish to participate in a compliance assistance visit  to determine eligibility for exclusion. A map of regional offices with addresses and phone numbers is available online at


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.

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

Final products that are meant to be used outdoors (i.e., 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 (i.e., 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. A map of regional offices with addresses and phone numbers are available online at

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 Certificatation 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.

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

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 (i.e., metals and organic chemicals) and other pollutants such as trash, debris, and 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:

Dumpsters and Other Containers

Solutions for Problems Regarding Dumpsters and Containers

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.

Solutions for Problems Associated with the Transfer of Liquids

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

Adequately engineered secondary containment which prevents failure, leakage or overflow such that there would be no discharge can qualify forNo 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 eligble 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 matinenance, equipment cleaning, and airport deicing. Retail fueling or fueling activities conducted at but not associated with the operation of transporation 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 eliglibe 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

Guidance Manual for Conditional Exclusion from Stormwater Permitting Based on “No Exposure” of Industrial Activities to Stormwater--EPA 833-B-00-001

Stormwater Phase II Final Rule – Conditional No Exposure Exclusion for Industrial Activity--Revised 2005, EPA 833-F-00-015.

Missouri Department of Natural Resources Publication 223 – The Stormwater Issue July 2014

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)