f/EPA
United States
Environmental Protection
Agency
Office of Water EPA 833-F-00-015
(4203) January 2000 (revised December 2005)
Fact Sheet 4.0
Storm water Phase II
Final Rule
Stormwater Phase II
Final Rule
Fact Sheet Series
Overview
1.0 - Stormwater Phase II Final
Rule: An Overview
Small MS4 Program
2.0 - Small MS4 Stormwater
Program Overview
2.1 - Who's Covered? Designation
and Waivers of Regulated Small
MS4s
2.2 - Urbanized Areas: Definition
and Description
Minimum Control Measures
2.3 - Public Education and
Outreach
2.4-Public Participation/
Involvement
2.5 - Illicit Discharge Detection
and Elimination
2.6 - Construction Site Runoff
Control
2.7 - Post-Construction Runoff
Control
2.8 - Pollution Prevention/Good
Housekeeping
2.9 - Permitting and Reporting:
The Process and Requirements
2.10 - Federal and State-Operated
MS4s: Program Implementation
Construction Program
3.0 - Construction Program
Overview
3.1 - Construction Rainfall
Erosivity Waiver
Industrial "No Exposure"
4.0 - Conditional No Exposure
Exclusion for Industrial Activity
Conditional No Exposure
Exclusion for Industrial Activity
Why Is the Phase I No Exposure Exclusion Addressed in the Phase II Final
Rule?
The 1990 stormwater regulations for Phase I of the Federal stormwater program identify
eleven categories of industrial activities that must obtain a National Pollutant Discharge
Elimination System (NPDES ) permit. Operators of certain facilities within category eleven (xi),
commonly referred to as "light industry," were exempted from the definition of "stormwater
discharge associated with industrial activity," and the subsequent requirement to obtain
an NPDES permit, provided their industrial materials or activities were not "exposed" to
stormwater. This Phase I exemption from permitting was limited to those facilities identified in
category (xi), and did not require category (xi) facility operators to submit any information
supporting their no exposure claim.
In 1992, the Ninth Circuit court remanded to EPA for further rulemaking the no exposure
exemption for light industry after making a determination that the exemption was arbitrary
and capricious for two reasons. First, the court found that EPA had not established a record
to support its assumption that light industrial activity that is not exposed to stormwater (as
opposed to all other regulated industrial activity not exposed) is not a "stormwater discharge
associated with industrial activity." Second, the court concluded that the exemption
impermissibly relied on the unsubstantiated judgment of the light industrial facility operator to
determine the applicability of the exemption. These findings resulted in a revised conditional no
exposure exclusion, the changes to which are described in this fact sheet.
Who is Eligible to Claim No Exposure?
As revised in the Phase II Final Rule, the conditional no exposure exclusion applies to ALL
industrial categories listed in the 1990 stormwater regulations, except for construction
activities disturbing 5 or more acres (category (x)).
What Is The Regulatory Definition of "No Exposure"?
The intent of the no exposure provision is to provide facilities with industrial materials and
activities that are entirely sheltered from stormwater a simplified way of complying with the
stormwater permitting provisions of the Clean Water Act (CWA). This includes facilities that are
located within a larger office building, or facilities at which the only items permanently exposed
to precipitation are roofs, parking lots, vegetated areas, and other non-industrial areas
or activities. The Phase II regulatory definition of "no exposure" follows.
No exposure is defined as all industrial materials and activities are protected by a storm resistant
shelter to prevent exposure to rain, snow, snowmelt, and/or runoff. Industrial materials or activities
include, but are not limited to, material handling equipment or activities, industrial machinery, raw
materials, intermediate products, by-products, final products, or waste products.
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Fact Sheet 4.0 - Conditional No Exposure Exclusion for Industrial Activity
Page 2
A storm-resistant shelter is not required for the following
industrial materials and activities:
Q Drums, barrels, tanks, and similar containers that are
tightly sealed, provided those containers are not
deteriorated and do not leak. "Sealed" means banded
or otherwise secured and without operational taps or
valves;
Q Adequately maintained vehicles used in materials
handling; and
Q Final products, other than products that would be
mobilized in stormwater discharges (e.g., rock salt).
The term "storm-resistant shelter," as used in the no exposure
definition, includes completely roofed and walled buildings or
structures, as well as structures with only a top cover but no
side coverings, provided material under the structure is not
otherwise subject to any run-on and subsequent runoff of
stormwater. While the intent of the no exposure provision is
to promote a condition of permanent no exposure, EPA
understands certain vehicles could become temporarily
exposed to rain and snow while passing between buildings.
Adequately maintained mobile equipment (e.g., trucks,
automobiles, forklifts, trailers, or other such general purpose
vehicles found at the industrial site that are not industrial
machinery, and that are not leaking contaminants or are not
otherwise a source of industrial pollutants) can be exposed to
precipitation or runoff. Such activities alone would not
prevent a facility from certifying to no exposure. Similarly,
trucks or other vehicles awaiting maintenance at vehicle
maintenance facilities that are not leaking contaminants or are
not otherwise a source of industrial pollutants, are not
considered "exposed."
In addition, EPA recognizes that there are circumstances
where permanent no exposure of industrial activities or
materials is not possible and, therefore, under such conditions,
materials and activities can be sheltered with temporary
covers (e.g., tarps) between periods of permanent enclosure.
The no exposure provision does not specify every such
situation, but NPDES permitting authorities can address this
issue on a case-by-case basis.
The Phase II Final Rule also addresses paniculate matter
emissions from roof stacks/vents that are regulated by, and in
compliance with, other environmental protection programs
(i.e., air quality control programs) and that do not cause
stormwater contamination are considered not exposed.
Paniculate matter or visible deposits of residuals from roof
stacks and/or vents not otherwise regulated (i.e., under an air
quality control program) and evident in stormwater outflow
are considered exposed. Likewise, visible "track out" (i.e.,
pollutants carried on the tires of vehicles) or windblown raw
materials is considered exposed. Leaking pipes containing
contaminants exposed to stormwater are deemed exposed,
as are past sources of stormwater contamination that remain
onsite. General refuse and trash, not of an industrial nature, is
not considered exposed as long as the container is completely
covered and nothing can drain out holes in the bottom, or is
lost in loading onto a garbage truck. Industrial refuse and
trash that is left uncovered, however, is considered exposed.
What is Required Under the No Exposure
Provision?
The Phase II Final Rule represents a significant expansion
in the scope of the original no exposure provision in terms
of eligibility (as noted above) and responsibilities for facilities
claiming the exclusion. Under the original no exposure
provision, a light industry operator was expected to make an
independent determination of whether there was "exposure"
of industrial materials and activities to stormwater and, if not,
simply not submit a permit application. An operator seeking
to qualify for the revised conditional no exposure exclusion,
including light industry operators (i.e., category (xi)
facilities), must:
Q Submit written certification that the facility meets the
definition of "no exposure" to the NPDES permitting
authority once every 5 years.
• The Phase II Final Rule includes a four-page
No Exposure Certification form that uses a series
of yes/no questions to aid facility operators in
determining whether they have a condition of
no exposure. It also serves as the necessary
certification of no exposure provided the operator
is able to answer all the questions in the negative.
EPA's Certification is for use only by operators of
industrial activity located in areas where EPA is the
NPDES permitting authority.
• A copy of the Certification can be obtained from the
EPA stormwater Web site
(http://www.epa.gov/npdes/stormwater). the
Stormwater Phase II Final Rule published in the
Federal Register (Appendix 4), or by contacting the
appropriate NPDES permitting authority.
Q Submit a copy, upon request, of the Certification to the
municipality in which the facility is located.
Q Allow the NPDES permitting authority or, if
discharging into a municipal separate storm sewer
system, the operator of the system, to: (1) inspect the
facility; and (2) make such inspection reports publicly
available upon request.
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Fact Sheet 4.0 - Conditional No Exposure Exclusion for Industrial Activity
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Regulated industrial operators need to either apply for a
permit or submit a no exposure certification form to be in
compliance with the NPDES stormwater regulations. Any
permit held becomes null and void once a certification form is
submitted.
Even when an industrial operator certifies to no exposure,
the NPDES permitting authority still retains the authority to
require the operator to apply for an individual or general
permit if the NPDES permitting authority has determined that
the discharge is contributing to the violation of, or interfering
with the attainment or maintenance of, water quality
standards, including designated uses.
Are There Any Concerns Related to Water
Quality Standards?
Yes. An operator certifying that its facility qualifies for the
conditional no exposure exclusion may, nonetheless, be
required by the NPDES permitting authority to obtain permit
authorization. Such a requirement would follow
the permitting authority's determination that the discharge
causes, has a reasonable potential to cause, or contributes to
a violation of an applicable water quality standard, including
designated uses. Designated uses can include use as a drinking
water supply or for recreational purposes.
Many efforts to achieve no exposure can employ simple
good housekeeping and contaminant cleanup activities such as
moving materials and activities indoors into existing buildings
or structures. In limited cases, however, industrial operators
may make major changes at a site to achieve no exposure.
These efforts may include constructing a new building or
cover to eliminate exposure or constructing structures to
prevent run-on and stormwater contact with industrial
materials and activities. Major changes undertaken to achieve
no exposure, however, can increase the impervious area of the
site, such as when a building with a smooth roof is placed in a
formerly vegetated area. Increased impervious area can lead
to an increase in the volume and velocity of stormwater
runoff, which, in turn, can result in a higher concentration of
pollutants in the discharge, since fewer pollutants are
naturally filtered out.
The concern of increased impervious area is addressed in one
of the questions on the Certification form, which asks, "Have
you paved or roofed over a formerly exposed, pervious area in
order to qualify for the no exposure exclusion? If yes, please
indicate approximately how much area was paved or roofed
over." This question has no affect on an operator's eligibility
for the exclusion. It is intended only to aid the NPDES
permitting authority in assessing the likelihood of such actions
interfering with water quality standards. Where this is a
concern, the facility operator and its NPDES permitting
authority should take appropriate actions to ensure that water
quality standards can be achieved.
What Happens if the Condition of No Exposure
Is Not Maintained?
Under the Phase II Final Rule, the no exposure exclusion is
conditional and not an outright exemption. Therefore, if
there is a change in circumstances that causes exposure of
industrial activities or materials to stormwater, the operator is
required to comply immediately with all the requirements of
the NPDES Stormwater Program, including applying for and
obtaining a permit.
Failure to maintain the condition of no exposure or obtain
coverage under an NPDES stormwater permit can lead to
the unauthorized discharge of pollutants to waters of the
United States, resulting in penalties under the CWA. Where a
facility operator determines that exposure is likely to occur in
the future due to some anticipated change at the facility, the
operator should submit an application and acquire stormwater
permit coverage prior to the exposed discharge to avoid such
penalties.
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Fact Sheet 4.0 - Conditional No Exposure Exclusion for Industrial Activity
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For Additional Information
Contacts
"^ U.S. EPA Office of Wastewater Management
http ://www. epa. gov/npdes/stormwater
Phone: 202-564-9545
t^ Your NPDES Permitting Authority. Most States and
Territories are authorized to administer the NPDES
Program, except the following, for which EPA is the
permitting authority:
Alaska
District of Columbia
Idaho
Massachusetts
New Hampshire
New Mexico
American Samoa
Guam
Johnston Atoll
Midway and Wake Islands
Northern Mariana Islands
Puerto Rico
Trust Territories
"^ A list of names and telephone numbers for each EPA
Region and State is located at http://www.epa.gov/
npdes/stormwater (click on "Contacts").
Reference Documents
"^ EPA's Stormwater Web Site
http ://www. epa. gov/npdes/stormwater
• Stormwater Phase II Final Rule Fact Sheet Series
• Stormwater Phase II Final Rule (64 FR 68722)
• National Menu of Best Management Practices for
Stormwater Phase II
• Measurable Goals Guidance for Phase II Small
MS4s
• Stormwater Case Studies
• And many others
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