INDUSTRIAL STORMWATER
FACT SHEET SERIES
Sector T: Treatment Works
U.S. EPA Office of Water
EPA-833-F-06-035
December 2006
What is the NPDES stormwater permitting program for industrial
activity?
Activities, such as material handling and storage, equipment maintenance and cleaning, industrial
processing or other operations that occur at industrial facilities are often exposed to stormwater. The
runoff from these areas may discharge pollutants directly into nearby waterbodies or indirectly via
storm sewer systems, thereby degrading water quality.
In 1990, the U.S. Environmental Protection Agency (EPA) developed permitting regulations under the
National Pollutant Discharge Elimination System (NPDES) to control stormwater discharges associated
with eleven categories of industrial activity. As a result, NPDES permitting authorities, which may be
either EPA or a state environmental agency, issue stormwater permits to control runoff from these
industrial facilities.
What types of industrial facilities are required to obtain permit
coverage?
This fact sheet specifically discusses stormwater discharges from treatment works including those
facilities:
4 Treating domestic sewage with a design flow of 1.0 M.G.D. or more,
4 Required to have an approved pretreatment program under 40 CFR Part 403
4 Having land dedicated to the disposal of sewage sludge within the confines of the facility
What does an industrial stormwater permit require?
Common requirements for coverage under an industrial stormwater permit include development of a
written stormwater pollution prevention plan (SWPPP), implementation of control measures, and sub-
mittal of a request for permit coverage, usually referred to as the Notice of Intent or NOI. The SWPPP
is a written assessment of potential sources of pollutants in stormwater runoff and control measures
that will be implemented at your facility to minimize the discharge of these pollutants in runoff from
the site. These control measures include site-specific best management practices (BMPs), maintenance
plans, inspections, employee training, and reporting. The procedures detailed in the SWPPP must be
implemented by the facility and updated as necessary, with a copy of the SWPPP kept on-site. The in-
dustrial stormwater permit also requires collection of visual, analytical, and/or compliance monitoring
data to determine the effectiveness of implemented BMPs. For more information on EPA's industrial
stormwater permit and links to State stormwater permits, go to www.epa.gov/npdes/stormwater
and click on "Industrial Activity."
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
What pollutants are associated with my facilities activities?
Pollutants conveyed in stormwater discharges from treatment works will vary. There are a number of
factors that influence to what extent industrial activities and significant materials can affect water
quality.
4 Geographic location
4 Topography
4 Hydrogeology
4 Extent of impervious surfaces (e.g.,, concrete or asphalt)
4 Type of ground cover (e.g., vegetation, crushed stone, or dirt)
4 Outdoor activities (e.g., material storage, loading/unloading, vehicle maintenance)
4 Size of the operation
4 Type, duration, and intensity of precipitation events
The activities, pollutant sources, and pollutants detailed in Table 1 are commonly found at treatment
works.
Table 1. Common Activities, Pollutants Sources, and Associated Pollutants at Treatment Works
Activity
Preparation of
chemical, biological
and physical treatment
processes
Soil amending and
grass fertilizing
Liquid storage in above
ground storage
Pest control
Sludge drying beds
Sludge storage piles
Sludge transfer
Septage transfer
Incineration
Equipment/vehicle
maintenance and
storage
Miscellaneous
Pollutant Source
Spills and leaks of process chemicals and
materials
Over fertilizing
External corrosion and structural failure
Installation problems
Spills and overfills due to operator error
Failure of piping systems (pipes, pumps,
flanges, couplings, hoses, and valves)
Leaks or spills during pumping of liquids from
barges, trucks, or rail cars to a storage facility
Large quantities of pesticide application,
pesticide storage
Sludge
Sludge
Sludge, vehicles, transfer equipment
Solid and liquid sanitary waste, vehicles
Ash impoundments/piles
Spills and leaks of lubricants and coolants
Grit and scum piles from clarifiers, screens,
exposed soil
Pollutant
Disinfectants, polymers and coagulants,
alum, ferric chloride, soda ash, lime, sodium
aluminate, sodium hypochlorite, caustic soda,
chlorine, sodium bisulfite.
Commercial brands of balance fertilizers
(6-6-6, 8-8-8 or 12-12-12), commercial sludge
based products, nitrogen, other nutrients,
phosphorous, ammonia. Aluminum sulfate,
iquid chlorine, liquid polymer, fuel, oil.
Aluminum sulfate, liquid chlorine, bisulfite,
liquid polymer, fuel, oil.
Diazanon, malathion, amdro, dimethylphthalate,
diethyl phthalate, dichlorvos, carbaryl, skeetal,
batex, liquid copper
Nitrate, IDS, TSS, ammonia, fecal pathogens.
Nitrate, IDS, TSS, ammonia, fecal pathogens.
Nitrate, IDS, TSS, oil, fuel, hydraulic fluids,
ammonia, fecal pathogens
Nitrate, IDS, TSS, oil, fuel, hydraulic fluids,
ammonia, fecal pathogens
Heavy metals, TDS, TSS
solvents, acids, oil, grease, arsenic, lead,
cadmium, chromium, chemical oxygen demand
(COD), and benzene
TSS, heavy metals, fecal coliform, nitrate
EPA-833-F-06-035
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
What BMPs can be used to minimize contact between stormwater
and potential pollutants at my facility?
A variety of BMP options may be applicable to eliminate or minimize the presence of pollutants in
stormwater discharges from treatment works. You will likely need to implement a combination or suite
of BMPs to address stormwater runoff at your facility. Your first consideration should be for pollution
prevention BMPs, which are designed to prevent or minimize pollutants from entering stormwater
runoff and/or reduce the volume of stormwater requiring management. Prevention BMPs can include
regular cleanup, collection and containment of debris in storage areas, and other housekeeping prac-
tices, spill control, and employee training. It may also be necessary to implement treatment BMPs,
which are engineered structures intended to treat stormwater runoff and/or mitigate the effects of in-
creased stormwater runoff peak rate, volume, and velocity. Treatment BMPs are generally more expen-
sive to install and maintain and include oil-water separators, wet ponds, and proprietary filter devices.
BMPs must be selected and implemented to address the following:
Good Housekeeping Practices
Good housekeeping is a practical, cost-effective way to maintain a clean and orderly facility to prevent
potential pollution sources from coming into contact with stormwater. It includes establishing proto-
cols to reduce the possibility of mishandling materials or equipment and training employees in good
housekeeping techniques. Common areas where good housekeeping practices should be followed in-
clude trash containers and adjacent areas, material storage areas, vehicle and equipment maintenance
areas, and loading docks. Good housekeeping practices must include a schedule for regular pickup and
disposal of garbage and waste materials and routine inspections of drums, tanks, and containers for
leaks and structural conditions. Practices also include containing and covering garbage, waste materi-
als, and debris. Involving employees in routine monitoring of housekeeping practices has proven to
be an effective means of ensuring the continued implementation of these measures.
Minimizing Exposure
Where feasible, minimizing exposure of potential pollutant sources to precipitation is an important
control option. Minimizing exposure prevents pollutants, including debris, from coming into contact
with precipitation and can reduce the need for BMPs to treat contaminated stormwater runoff. It can
also prevent debris from being picked up by stormwater and carried into drains and surface waters.
Examples of BMPs for exposure minimization include covering materials or activities with temporary
structures (e.g., tarps) when wet weather is expected or moving materials or activities to existing
or new permanent structures (e.g., buildings, silos, sheds). Even the simple practice of keeping a
dumpster lid closed can be a very effective pollution prevention measure.
Erosion and Sediment Control
BMPs must be selected and implemented to limit erosion on areas of your site that, due to
topography, activities, soils, cover, materials, or other factors are likely to experience erosion. Erosion
control BMPs such as seeding, mulching, and sodding prevent soil from becoming dislodged and
should be considered first. Sediment control BMPs such as silt fences, sediment ponds, and stabilized
entrances trap sediment after it has eroded. Sediment control BMPs should be used to back-up
erosion control BMPs.
Management of Runoff
Your SWPPP must contain a narrative evaluation of the appropriateness of stormwater management
practices that divert, infiltrate, reuse, or otherwise manage stormwater runoff so as to reduce the
discharge of pollutants. Appropriate measures are highly site-specific, but may include, among others,
vegetative swales, collection and reuse of stormwater, inlet controls, snow management, infiltration
devices, and wet retention measures.
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
A combination of preventive and treatment BMPs will yield the most effective stormwater
management for minimizing the offsite discharge of pollutants via stormwater runoff. Though not
specifically outlined in this fact sheet, BMPs must also address preventive maintenance records or
logbooks, regular facility inspections, spill prevention and response, and employee training.
All BMPs require regular maintenance to function as intended. Some management measures have
simple maintenance requirements, others are quite involved. You must regularly inspect all BMPs to
ensure they are operating properly, including during runoff events. As soon as a problem is found,
action to resolve it should be initiated immediately.
Implement BMPs, such as those listed below in Table 2 for the control of pollutants at treatment
works, to minimize and prevent the discharge of pollutants in stormwater. Identifying weaknesses
in current facility practices will aid the permittee in determining appropriate BMPs that will achieve
a reduction in pollutant loadings. BMPs listed in Table 2 are broadly applicable to treatment works;
however, this is not a complete list and you are recommended to consult with regulatory agencies
or a stormwater engineer/consultant to identify appropriate BMPs for your facility. Additionally,
treatment facilities should consider collecting all runoff and conveying it to the treatment works.
Table 2. BMPs for Potential Pollutant Sources at Treatment Works
Pollutant Source
BMPs
Preparation of chemical, biological
and physical treatment process
FJ Store process chemicals inside buildings.
FJ Use drip pans under drums and equipment where feasible. Inspect regularly the
storage yard for filled drip pans and other problems.
FJ Train employees on procedures for storing and inspecting chemicals.
Soil amending and grass fertilizing
FJ Use the appropriate amount of fertilizer.
FJ Train employees in timing and quantity to avoid overfertilization.
Liquid storage in above ground
storage containers
FJ Cover and/or enclose chemical storage areas (including temporary cover such as a
tarp that prevents contact with precipitation).
FJ Provide secondary containment around chemical storage areas.
FJ If containment structures have drains, ensure that the drains have valves, and
that valves are maintained in the closed position. Institute protocols for checking/
testing stormwater in containment areas prior to discharge.
Q Use double-walled tanks with overflow protection.
Q Locate storage areas away from high traffic areas and surface waters.
Q Inspect storage tanks and piping systems (pipes, pumps, flanges, couplings,
hoses, and valves) for failures or leaks and perform preventive maintenance.
Q Maintain an inventory of fluids to identify leakage.
Q Provide fluid level indicators.
Q Properly dispose of chemicals that are no longer in use.
Q Store and handle reactive, ignitable, or flammable liquids in compliance with
applicable local fire codes, local zoning codes, and the National Electric Code.
FJ Provide drip pads/pans where chemicals are transferred from one container to
another to allow for recycling of spills and leaks.
FJ Develop and implement spill plans or spill prevention, containment, and
countermeasure (SPCC) plans, if required for your facility.
Q Train employees on proper storage and transfer procedures.
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
Table 2. BMPs for Potential Pollutant Sources at Treatment Works (continued)
Pollutant Source
BMPs
Pest control
Pesticide Application
Q Apply pesticides only if needed.
Q Train employees in techniques to minimize pesticide application.
Sludge drying beds
FJ Ensure drying bed is draining properly (e.g., check for clogging).
Q Avoid overfilling drying bed.
Q Grade the land to divert flow around drying bed.
Q Berm, dike, or curb drying bed areas.
Q Cover drying beds.
Sludge storage piles
FJ Confine storage of sludge to a designated area outside drainage pathways and as
far from any receiving water body as possible.
Q Store sludge on an impervious surface (e.g., concrete pad).
Q Grade the land to divert flow around storage piles.
Q Berm, dike, or curb sludge storage piles.
Q Use control measures such as silt fence or waddles to control sediment from
leaving storage area.
Q Cover sludge storage piles.
Sludge transfer
Sludge drying beds
Q Conduct transfer operations over an impervious surface to enable easy collection
of spilled materials.
FJ Promptly remove any sludge spilled during transfer.
FJ Avoid transferring sludge during rain events.
FJ Grade the land to divert flow around transfer areas.
FJ Berm, curb, or dike transfer areas.
Mechanical Dewatering
Q Cover loading area and perform this activity on an impervious pad to enable easy
collection of spilled materials.
Q Avoid locating transfer operations near receiving water bodies.
Incineration-ash impoundments/
piles
Q Line ash impoundments with clay (or other type of impervious material).
Q Ensure ash impoundments will hold maximum volume of ash and a 10-year,
24-hour rain event.
FJ Curb, berm, or dike ash storage areas.
FJ Avoid locating ash storage areas near receiving waterbodies.
Equipment/vehicle maintenance
and storage
Good Housekeeping
Q Eliminate floor drains that are connected to the storm or sanitary sewer; if
necessary, install a sump that is pumped regularly. Collected wastes should be
properly treated or disposed of by a licensed waste hauler.
FJ Do all cleaning at a centralized station so the solvents stay in one area.
FJ If parts are dipped in liquid, remove them slowly to avoid spills.
FJ Use drip pans, drain boards, and drying racks to direct drips back into a fluid
holding tank for reuse.
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
Table 2. BMPs for Potential Pollutant Sources at Treatment Works (continued)
Pollutant Source
Equipment/vehicle maintenance
and storage (continued)
Miscellaneous
BMPs
Good Housekeeping (continued)
Q Drain all parts of fluids prior to disposal. Oil filters can be crushed and recycled.
FJ Promptly transfer used fluids to the proper container; do not leave full drip
pans or other open containers around the shop. Empty and clean drip pans and
containers.
FJ Clean up leaks, drips, and other spills without using large amounts of water. Use
absorbents for dry cleanup whenever possible.
FJ Prohibit the practice of hosing down an area where the practice would result in
the discharge of pollutants to a stormwater system.
Q Do not pour liquid waste into floor drains, sinks, outdoor storm drain inlets, or
other storm drains or sewer connections.
Q Maintain an organized inventory of materials.
FJ Eliminate or reduce the number and amount of hazardous materials and waste by
substituting nonhazardous or less hazardous materials.
FJ Label and track the recycling of waste material (e.g., used oil, spent solvents,
batteries).
Q Store batteries and other significant materials inside.
FJ Dispose of greasy rags, oil filters, air filters, batteries, spent coolant, and
degreasers in compliance with RCRA regulations.
Minimizing Exposure
Q Perform all cleaning operations indoors or under covering when possible.
Conduct the cleaning operations in an area with a concrete floor with no floor
drainage other than to sanitary sewers or treatment facilities.
Q If operations are uncovered, perform them on a concrete pad that is impervious
and contained.
Q Park vehicles and equipment indoors or under a roof whenever possible and
maintain control of oil leaks/spills.
FJ Check vehicles closely for leaks and use pans to collect fluid when leaks occur.
Management of Runoff
Q Use berms, curbs, or grassed swales other diversion measures to ensure that
stormwater runoff from other parts of the facility does not flow over the
maintenance area.
Q Collect the stormwater runoff from the cleaning area and provide treatment or
recycling.
Q Discharge vehicle wash or rinse water to the treatment works, a land application
site, or recycle on-site. DO NOT discharge washwater to a storm drain or to
surface water.
Inspections and Training
FJ Inspect the maintenance area regularly to ensure BMPs are implemented.
FJ Train employees in waste control and disposal procedures.
Q Dispose of grit/scum at a licensed landfill.
Q Dispose of screenings on a daily basis.
FJ Maximize vegetative cover to stabilize soil and reduce erosion.
Q Routing stormwater to the treatment works.
Q Cover compost piles.
FJ Cover exposed materials at septage or hauled waste receiving stations.
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INDUSTRIAL STORMWATER FACT SHEET SERIES
Sector T: Treatment Works
What if activities and materials at my facility are not exposed to
precipitation?
The industrial stormwater program requires permit coverage for a number of specified types of
industrial activities. However, when a facility is able to prevent the exposure of ALL relevant activities
and materials to precipitation, it may be eligible to claim no exposure and qualify for a waiver from
permit coverage.
If you are regulated under the industrial permitting program, you must either obtain permit coverage
or submit a no exposure certification form, if available. Check with your permitting authority for
additional information as not every permitting authority program provides no exposure exemptions.
Where do I get more information?
For additional information on the industrial stormwater program see
www.epa.gov/npdes/stormwater/msgp.
A list of names and telephone numbers for each EPA Region or state NPDES permitting authority can
be found at www.epa.gov/npdes/stormwatercontacts.
References
Information contained in this Fact Sheet was compiled from EPA's past and current Multi-Sector
General Permits and from the following sources:
4 Pierce County Washington Public Works and Utilities. "Stormwater Pollution Prevention Manual:
A Guide to Best Management Practices for Industries, Businesses, and Homeowners."
www.co.pierce.wa.us/pc/services/home/environ/water/wq/bmpmanaul.htm
4 U.S. Department of Defense, Department of the Navy. "Storm Water Best Management Practices
(BMP) Decision Support Tool - Stormwater Pollution Prevention Options by Category: Industrial
WWTP."
http://205.153.241.230/stormwaterbmp/cgi-bin/P2Cat.cfm?Cat=lndustrial%20WWTP
4 U.S. Department of Defense, Department of the Navy. "Storm Water Best Management Practices
(BMP) Decision Support Tool - Stormwater Pollution Prevention Options by Category: Sanitary
WWTP."
http://205.153.241.230/stormwaterbmp/cgi-bin/P2Cat.cfm?Cat=Sanitary%20WWTP
4 U.S. EPA. September 1992. Stormwater Management for Industrial Activities: Developing
Pollution Prevention Plans and Best Management Practices. EPA 832-R-92-006.
www.epa.gov/npdes/stormwater
4 U.S. EPA, Office of Science and Technology. 1999. Preliminary Data Summary of Urban
Stormwater Best Management Practices. EPA-821-R-99-012.
www.epa.gov/OST/stormwater/
4 U.S. EPA, Office of Wastewater Management. NPDES Stormwater Multi-Sector General Permit for
Industrial Activities (MSGP).
www. epa .go v/n pd es/sto rm wate r/msg p
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