United States
Environmental Protection
Agency
Office of Water
(4203)
EPA833-F-99-015
April 1999
Fact Sheet 4.0
vvEPA
Storm Water Phase II
Proposed Rule
Fact Sheet Series
Overview
1.0-Storm Water Phase II
Proposed Rule Overview
Small MS4 Program
2.0 - Small MS4 Storm Water
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 Minimum Control
Measure
2.4 - Public Participation/
Involvement Minimum Control
Measure
2.5 - Illicit Discharge Detection and
Elimination Minimum Control
Measure
2.6 - Construction Site Runoff
Control Minimum Control Measure
2.7 - Post-Construction Runoff
Control Minimum Control Measure
2.8 - Pollution Prevention/Good
Housekeeping Minimum Control
Measure
2.9 - Permitting and Reporting:
The Process and Requirements
2.10 - Federal and State-Owned
MS4s: Program Implementation
Construction Program
3.0 - Construction Program
Overview
Industrial "No Exposure"
4.0 - Conditional No Exposure
Exemption for Industrial Activity
Storm Water Phase II
Proposed Rule
Conditional No Exposure
Exemption for Industrial Activity
This fact sheet is basedon the Storm Water Phase II Proposed Rule. Therefore, the information provided herein is subject to
change upon publication of the final Phase II rule in November 1999. A revised series of fact sheets will be provided at that
time. A comprehensive list of the current fact sheets is in the text box at left.
Why Is the Phase I No Exposure Exemption Addressed in the Phase II Proposed
Rule?
The 1990 storm water regulations for Phase I of the federal storm water 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 "storm water discharge
associated with industrial activity," and the subsequent requirement to obtain an NPDES permit,
provided their industrial materials or activities were not "exposed" to storm water. 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 storm water (as opposed to all other regulated industrial
activity not exposed) is not a "storm water 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.
This fact sheet describes the conditional no exposure exemption as presented in the Phase II Proposed
Rule. EPA relied heavily upon the conditional no exposure exemption concept and rule language
developed by the Urban Wet Weather Flows Federal Advisory Committee. The Committee included a
balanced mix of representatives from State and local government, industry, construction, and
environmental groups.
Who Would Be Eligible to Claim No Exposure?
As revised in the Phase II Proposed Rule, the conditional no exposure exemption applies to ALL
industrial categories listed in the 1990 storm water regulations, regardless of the type of industry,
except for construction activities disturbing more than 5 acres (category ten (x)) and those facilities
individually designated by the NPDES permitting authority.
What Would Be Required Under the No Exposure Provision?
The Phase II proposal 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
exemption. Under the original no exposure provision, a light industry owner/operator was expected to
make an independent determination of whether there was "exposure" of industrial materials and
activities to storm water and, if not, simply not submit a permit application. Under the proposed
conditional no exposure exemption, however, an owner/operator seeking an exemption, including
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Fact Sheet 4.0 - Conditional No Exposure Exemption for Industrial Activity
Page 2
existing light industry owners/operators (i.e., category (xi)
facilities) claiming no exposure, would need to:
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 Proposed Rule includes a draft three-
page Checklist for No Exposure Certification that
uses a series of yes/no questions to aid facility
owners/operators in determining whether they have a
condition of no exposure. The Checklist serves as the
necessary certification of no exposure if the owner/
operator is able to answer all the questions in the
negative.
A copy of the draft Checklist can be obtained from
the U.S. EPA Office of Wastewater Management
(OWM) web site, the Storm Water Phase II Proposed
Rule published in the Federal Register, or by
contacting OWM.
Q Submit a copy, upon request, of the Checklist 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 owner/
operator of the system, to (1) inspect the facility and (2)
make such inspection reports publicly available upon
request.
A regulated industrial owner/operator would need to either apply
for a permit or submit a no exposure certification in order to be in
compliance with the NPDES storm water regulations. It is
important to note that any permit held before submitting a
certification would become null and void.
Even when an industrial owner/operator certifies to no exposure,
the NPDES permitting authority would still retain the authority to
require the owner/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.
What Is The Proposed 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 storm water a simplified way of complying with
the storm water 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
proposed regulatory definition of "no exposure" follows.
As proposed, no exposure means all industrial
materials or activities are protected by a storm-
resistant shelter so that they are not exposed to rain,
snow, snowmelt, or runoff. Industrial materials or
activities include, but are not limited to, material
handling equipment or activities, industrial
machinery, raw materials, intermediate products,
byproducts, or waste products, however packaged.
The term "storm-resistant shelter," as used in the proposed no
exposure definition, would include completely roofed and walled
buildings or structures, as well as structures with only a top cover
but no side coverings, provided materials under the structure are
not otherwise subject to any run-on and subsequent runoff of
storm water. While the intent of the proposed no exposure
provision is to promote a condition of permanent no exposure, it
would allow certain machinery, such as trucks, to pass between
buildings and, during passage, be exposed to rain and snow.
Adequately maintained mobile equipment (e.g., trucks,
automobiles, trailers, or other such general purpose vehicles
found at the industrial site that are not industrial machinery or
material handling equipment and that are not leaking
contaminants or are not otherwise a source of industrial
pollutants) also could be exposed to precipitation or runoff. Such
activities alone would not prevent a facility from certifying no
exposure under the proposed provision. 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, would not be considered exposed.
In addition, EPA recognizes in the proposed rule that other
instances could occur in which permanent no exposure of
industrial activities or materials is not possible and, therefore,
under such conditions, materials and activities could be covered
with temporary covers (e.g., tarps) between periods of permanent
enclosure. The proposed rule does not specify every such
situation, but NPDES permitting authorities could address this
issue on a case-by-case basis.
For purposes of the proposed exemption, 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 storm
water contamination would be considered not exposed. Visible
deposits of residuals (e.g., paniculate matter) near roof or side
vents would be considered "exposed." Likewise, visible "track
out" (i.e., pollutants carried on the tires of vehicles) or windblown
raw materials would be considered "exposed." Leaking pipes
containing contaminants exposed to storm water would be
deemed "exposed," as would past sources of storm water
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Fact Sheet 4.0 - Conditional No Exposure Exemption for Industrial Activity
Page 3
contamination that remain onsite. General refuse and trash, not of
an industrial nature, would not be considered exposed industrial
materials; however, industrial refuse and trash that is left
uncovered would be deemed "exposed."
Would There Be Any Concerns Related to Water
Quality Standards?
Yes. The proposed rule specifies that actions taken to qualify
for no exposure must not interfere with the attainment or
maintenance of water quality standards, including designated
uses. Designated uses can include use as a drinking water supply
or for recreational purposes.
Many efforts to achieve no exposure would 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 owners/operators
may make major changes at a site to achieve no exposure. These
efforts could include constructing a new building or cover to
eliminate exposure or constructing structures to prevent run-on
and storm water contact with industrial materials and activities.
Major changes undertaken to achieve no exposure, however,
could 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 storm water 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 the last
question on the draft Checklist, which asks, "Have you paved or
roofed over a large, formerly exposed, pervious area in order to
qualify for no-exposure? Please indicate approximately how
much area was paved or roofed over from the choices below."
The single purpose of this question is to aid the NPDES
permitting authority in assessing the likelihood of such actions
interfering with water quality standards. Completing this question
would not influence the ability to qualify for the conditional no
exposure exemption and would be used for informational
purposes only.
What Would Happen if the Condition of No
Exposure Is Not Maintained?
Under the proposal, the no exposure exemption would be
conditional and not an outright exemption. Therefore, in
cases in which there is a change in circumstances that causes
exposure of industrial activities or materials to storm water, the
owner/operator would be required to comply immediately with all
the requirements of the NPDES Storm Water Program, including
applying for and obtaining a permit.
Failure to maintain the condition of no exposure or obtain
coverage under an NPDES permit would result in the
unauthorized discharge of pollutants to waters of the United
States, which could result in penalties under the CWA. Where a
facility operator determines that exposure would occur in the
future due to some anticipated change at the facility, the operator
would need to submit an application and acquire storm water
permit coverage prior to the exposed discharge to avoid such
penalties.
Having the proposed no exposure exemption be conditional and
requiring submission of a written certification is EPA's response
to the court's second basis for the remand, which criticized
allowing the facility owners/operators to determine for themselves
that there was no exposure and then simply not apply for a permit
without any further action. The draft Checklist provides a greater
assurance of actual no exposure as defined by EPA, while the
conditional nature of the exemption removes the chance of
potentially harmful discharges being legally unpermitted.
For Additional Information
Contacts
ISP U.S. EPA Office of Wastewater Management
• Phone : 202 260-5816
E-mail: SW2@epa.gov
Internet: www.epa.gov/owm/sw2.htm
^ Your NPDES Permitting Authority. (A list of names
and phone numbers for each U.S. EPA Region is
included in Fact Sheet 2.9. Additional contact names,
addresses, and numbers for each State can be
obtained from the U.S. EPA Office of Wastewater
Management)
Reference Documents
•SP Storm Water Phase II Proposed Rule Fact Sheet
Series.
• Contact the U.S. EPA Water Resource Center at
202 260-7786 or at waterpubs@epa.gov
• Internet: www.epa.gov/owm/sw2.htm
"^ Storm Water Phase II Proposed Rule, published on
Jan. 9, 1998 in the Federal Register (63 FR 1536).
Internet: www.epa.gov/owm/sw2.htm
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