EPA/600/R-20/214 | September 20201 www.epa.gov/research
SrEPA
United States
Environmental Protection
Agency
Current Best Practices in Maintaining
Hydraulic Control at Fueling Facilities
Office of Research and Development
Center for Environmental Solutions and Emergency Response
Land Remediation and Technology Division
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EPA/600/R-20/214
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Current Best Practices in Maintaining
Hydraulic Control at Fueling Facilities
By
Brian Dyson
Land Remediation and Technology Division
Center for Environmental Solutions and Emergency Response
Cincinnati, Ohio, 45268
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EPA/600/R-20/214
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Notice/Disclaimer
The U.S. Environmental Protection Agency, through its Office of Research and Development,
funded and conducted the research described herein. This report reviewed the current state of
approaches and methods for hydraulic control at fueling facilities and was done without the use
of secondary or existing data. It has been subjected to the Agency's peer and administrative
review and has been approved for publication as an EPA document. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
This is a contribution to the EPA ORD Sustainable and Healthy Communities Research Program.
The citation for this report is:
Dyson, B., 2020. Current Best Practices in Hydraulic Control of Stormwater at Fueling Facilities.
U.S. Environmental Protection Agency, Cincinnati, OH, EPA/600/R-20/214
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EPA/600/R-20/214
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Foreword
The U.S. Environmental Protection Agency (US EPA) is charged by Congress with protecting the
Nation's land, air, and water resources. Under a mandate of national environmental laws, the
Agency strives to formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and nurture life. To meet this
mandate, US EPA's research program is providing data and technical support for solving
environmental problems today and building a science knowledge base necessary to manage our
ecological resources wisely, understand how pollutants affect our health, and prevent or
reduce environmental risks in the future.
The Center for Environmental Solutions and Emergency Response (CESER) within the Office of
Research and Development (ORD) conducts applied, stakeholder-driven research and provides
responsive technical support to help solve the Nation's environmental challenges. The Center's
research focuses on innovative approaches to address environmental challenges associated
with the built environment. We develop technologies and decision-support tools to help
safeguard public water systems and groundwater, guide sustainable materials management,
remediate sites from traditional contamination sources and emerging environmental stressors,
and address potential threats from terrorism and natural disasters. CESER collaborates with
both public and private sector partners to foster technologies that improve the effectiveness
and reduce the cost of compliance, while anticipating emerging problems. We provide technical
support to EPA regions and programs, states, tribal nations, and federal partners, and serve as
the interagency liaison for EPA in homeland security research and technology. The Center is a
leader in providing scientific solutions to protect human health and the environment.
This report summarizes current best management practices for fueling facilities recommended
by a various academic, watershed protection, state, county, and municipal stormwater
management resources.
Gregory Sayles, Director
Center for Environmental Solutions and Emergency Response
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Abstract
Fueling facilities generate stormwater runoff from precipitation such as rainstorms and
snowfall. Runoff can transport solids, trace metals, hydrocarbons, road salts, trash and debris
that may impair receiving water bodies. Effective management of pollutant transport from
fueling facilities entails hydraulic management of stormwater generated at these sites and
source reduction of pollutants. Current Best Management Practices for hydraulic control and
treatment of runoff and planning and maintenance approaches for reducing pollution
generation at fueling facilities are presented.
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« II <11" . I11 " : In'- II in -
Appreciation is extended for the helpful comments and suggestions from reviewers Erin
Knighton and James Brauksieck, EPA/OLEM/OUST, Release Prevention Division, James
Brauksieck EPA/OLEM/OUST. and two external reviewers.
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Table of Contents
Notice/Disclaimer iii
Foreword iv
Abstract v
Acknowledgements vi
List of Figures viii
List of Tables ix
Acronyms and Abbreviations x
Executive Summary xi
1.0 Introduction 1
1.1 Quality Assurance and Quality Control 1
2.0 Hydraulic Control at Fueling Facilities 2
2.1 Fuel Transfer Activity at Fueling Facilities 2
2.2 Fueling Facility Best Management Practices 3
2.3 Structural Best Management Practices 6
2.3.1 Fueling Facility Design 6
2.3.2 Runoff Capture and Treatment Best Management Practices 10
2.3.3 Cold Weather Design Considerations 12
2.3.4 Infiltration Prohibition 13
2.4 Non-Structural Best Management Practices 13
2.4.1 Fuel Transfer Spillage and Fueling Area Maintenance 13
2.4.2 Storage Tank Maintenance 14
2.4.3 Site Management Planning 15
3.0 Flood Mitigation at Fueling Facilities 18
3.1 Extreme Event Tracking 19
References 21
Appendix A: BMP Guidance Fact Sheets 25
Appendix B: Structural Best Management Practices 45
Appendix C: Online Resources 66
Best Management Practices Databases 66
Stormwater Manuals and Resources 66
Natural Disaster Databases 66
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Figure 1. Schematic of fueling island typical of newer fueling facilities (SDCI, 2017), displaying
runoff routing and treatment (structural) and spill prevention (non-structural) best
management practices commonly required by most states/cities 2
Figure 2. Typical gas station design showing onsite pollution control measures and containment
pad flow treatment options. (City of Knoxville, 2018) 5
Figure 3. UST spill bucket. (PEI, 2017) 9
Figure 4. Automatic tank gauging system. (USEPA, 2016a) 9
Figure 5. Diagram of a Deep Sump Catch Basin. (CT DEP, 2004) 10
Figure 6. Diagram of a three-chambered oil/water separator. (CT DEP, 2004) 11
Figure 7. Perimeter sand filter. MA (DEP, 2008b) 11
Figure 8. Diagram of perimeter sand filter. (WV DEP, 2012) 12
Figure 9. Bioretention cell with underdrain. (WA DEC, 2019) 13
Figure 10. Fueling station spill kit next to fuel dispenser. (City of Honolulu, 2013) 14
Figure 11. Auto Service Station Facility Scenario, https://www.epa.gov/oil-spills-prevention-
and-preparedness-regulations/spill-prevention-control-and-countermeasure-19#covered
18
Figure 13. Location of fueling facilities with underground storage tanks. (USEPA, 2020b) 19
Figure 12. eNatech Database recording details on natural disaster caused technology accidents
searchable by event, hazard type, location and country of origin.
https://enatech.jrc.ec.europa.eu/ 20
VIII
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List of Tables
Table 1. Fueling Station Pollution Control Best Management Practices (MA DEP, 2008a; City of
Juneau, 2010; SDCI, 2017; WA DEC, 2019) 8
Table 2. Assessment Areas from the Hotspot Site Investigation (HSI) worksheet (Wright et al.,
2005) 16
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Acronyms and Abbreviations
AST
Above-Ground Storage Tank
BMP
Best Management Practice
BTEX
Benzene Tolulene Ethylbenzene Xylene
EPA
U.S. Environmental Protection Agency
GIS
Geographic Information System
HSI
Hotspot Site Investigation
Natech
Hazardous material releases from Nature caused technology failures
NOAA
National Oceanic and Atmospheric Administration
NPDES
National Pollution Discharge Elimination System
NWS
National Weather Service
OUST
Office of Underground Storage Tanks
SCP
Source Control Plan
SMP
Snowmelt Management Plan
SPCC
Spill Prevention Control and Countermeasures
USGS
United States Geological Survey
UST
Underground Storage Tank
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Executive Summary
EPA/600/R-20/214
September 2020
Fueling facilities generate stormwater runoff from precipitation such as rainstorms and
snowfall. Runoff can transport solids, trace metals, hydrocarbons, road salts, trash and debris
that may impair receiving water bodies. Effective management of pollutant transport from
fueling facilities entails hydraulic control of stormwater generated at these sites and source
reduction of pollutants.
Best Management Practices (BMP) for hydraulic control and pollution reduction include a mix
of infrastructure and treatment technologies (structural BMPs) and operational procedures and
policies (non-structural BMPs). Structural BMPs for fueling facilities include physical or
mechanical means to contain, route, and process runoff. These BMPs cover fueling island
design and construction, runoff capture and treatment structures, and underground storage
tank (UST) devices to minimize spills during fuel transfer. Necessary design modifications for
cold weather conditions, and BMP prohibitions for fueling facility hydraulic management are
discussed. Non-structural BMPs include procedures and policies for day-to-day operations and
longer-term planning. These practices pertain to fueling activity spill response, storage tank
maintenance, source control planning, snowmelt management, and approaches for above-
ground storage tanks (ASTs) which transfer, handle or store oil may be subject to the Spill
Prevention Control and Countermeasures (SPCC) rule.
Flooding at fueling facilities can lead to fuel storage and transfer infrastructure damage and
contribute to offsite hydrocarbon pollution. Resources are presented that can help assess the
risk of potential flooding and provide information to help better prepare for, mitigate, and
recover from flooding events.
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1 n
Where construction and urban development occur, the local hydrology can be altered, reducing the
ability of the natural landscape to absorb, infiltrate, and intercept rainfall. With increasing impervious
surfaces, rainfall becomes stormwater runoff, requiring infrastructure to hydraulically route the runoff
to sewer systems, if acceptable, with final discharge to downstream water bodies (Scheuler, 2000a).
Runoff from impervious surfaces can transport solids, trace metals, hydrocarbons, road salts, trash and
debris that can impair receiving water bodies (MDE, 2000). Effective management of pollutant
transport from fueling facilities entails hydraulic control of stormwater generated at these sites and
source reduction of pollutants. This report provides an overview of and best management practices
(BMPs) for hydraulic control and treatment to prevent offsite transport of pollutants, and information
and strategies for reducing hydrocarbon pollution generation at fueling facilities.
A related issue is the mitigation of the effects of flooding at fueling facilities, which can lead to fuel
storage and transfer infrastructure damage and contribute to offsite hydrocarbon pollution (USEPA,
2020a). Resources are presented that can help assess the extent of potential flooding and provide
information to help better prepare for, mitigate, and recover from flooding events.
I I I III , ¦ I'll Ik ¦' llif1 1 III 11 lliill II
This report does not contain environmental data or use existing data and therefore no discussion of
the quality of the data or limitations on the use of the data with respect to their original intended
application is included. Peer reviews were completed and discussed for all research described herein.
The conclusion of the QA and peer review process is that results presented in this report accurately
reflect the course of the research and are scientifically valid and defensible.
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2.0 Hydraulic Control at Fueling Facilities
Fueling facilities generate stormwater runoff from precipitation e.g. rainstorms and snowfall. The
objectives of hydraulic control of stormwater at fueling facilities are to separate and route 1)
stormwater from the containment pad (Fig. 1) for treatment and disposal in a sanitary sewer and 2)
route stormwater that does not reach the containment pad to stormwater sewers (NH DES, 2008;
Scheuler, 2000b, NH DES, 2019). Figure 1 provides examples of structural and non-structural best
management practices that may be found, especially in newer facilities. This flow separation and
routing helps reduce the risk of stormwater entering underground storage tanks and the transport of
spilled fuel off the containment pad and into stormwater sewers.
Oil/water
separator
Shutoff valve
To sanitary sewer -
or dead-end sump
Roof or canopy extending
past containment pad
r Catch basin
J
4-inch
sill/berm
Catch basin
Roof drains to
drainage system
Spill kit
Containment pad
(Portland Cement
concrete)
Figure 1. Schematic of fueling island typical for newer fueling facilities (SDCI, 2017), displaying runoff
routing and treatment (structural) and spill prevention (non-structural) best management practices
required by some states/cities.
2.1 Fuel Transfer Activity at Fueling Facilities
The U.S. Environmental Protection Agency (EPA) handbook Preventing Leaks and Spills at Service
Stations A Guide for Facilities (USEPA, 2003) describes general areas of focus for owners and operators
to improve housekeeping and best practices at service stations to prevent fuel delivery and dispensing
spillage and minimize cleanup costs. These areas broadly cover events/activities associated with the 1)
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transfer of fuel from tanker trucks to underground storage tanks (UST) and subsequently from UST to
vehicles. During these transfers, small amounts of fuel may be spilled. Hilpert et al, (2015) estimate 125
gallons of spilled gas at the dispenser island from a medium sized gas station annually. A fraction of
this spilled fuel can infiltrate cracks and crevices in the concrete pad that fuel dispensers are installed
on, contaminating soil and groundwater, and another fraction can be washed off the pad by
stormwater runoff. Hydrocarbons in the runoff can then adsorb to suspended solids (White, 1997)
entering and settling in surface waterbodies (Mora and Hilpert, 2017). To prevent this, all concrete
joints within the fuel island should be sealed to prevent migration of contaminants. The proper design
and installation of the slab and sub-grade will prevent settling and the resulting cracking. Finally,
fueling facilities that are required to develop SPCC plans, typically triggered by AST storage capacity,
are required to address spill prevention requirements for transfers from a tanker truck into the UST
system and from the UST dispenser into a vehicle. These requirements only apply at fueling facilities
that are subject to the SPCC requirements. For more information see section 4, SPCC Planning
Requirements for Fueling Facilities.
Stormwater quality studies indicate significant differences in hydrocarbon and associated pollutant
concentrations, between point source pollutant-generating sites (direct runoff from fueling facilities or
groundwater discharge from leaking USTs) and non-point sources such as roads and parking lots
(Borden et al., 2002; Gnecco et al., 2006). Termed "hotspots" (Schueler, 2000b), these point sources
are distinguished in the urban stormwater landscape for having greater loadings of hydrocarbons and
trace metals as compared to other areas. Hotspots are linked to locations where vehicles are fueled
and serviced like gas stations, bus depots, and vehicle repair shops.
' ' II iI'lliiiiit- II '.-illiii, rost Management hi tices
Because fueling facilities may have potentially higher levels of pollutants in runoff, a few BMPs are
often recommended e.g. (Vehicle Fueling Fact Sheet H-2, Appendix A). Best Management Practices are
a mix of engineered infrastructure and technologies (structural) and operational procedures and
policies (non-structural) for treating or minimizing pollution, which "may include a schedule of
activities, prohibition of practices, maintenance procedures, or other management practices. BMPs
may include, but are not limited to, treatment requirements, operating procedures, or practices to
control plant site runoff, spillage, leaks, sludge or waste disposal, or drainage from raw material
storage" (USEPA, 2010b; USEPA, 2011a).
Figures 1 and 2 show schematics of fueling islands typical of most fueling facilities (SDCI, 2017; City of
Knoxville, 2018), depicting runoff routing and treatment (structural) and spill prevention (non-
structural) BMPs recommended by states/cities. Many States, Counties, and localities often use the
terms commercial and/or hotspot in stormwater management guidance documents as means to
identify certain structural and non-structural BMPs appropriate for the conditions at sites like fueling
facilities (MDE, 2000; King County, 2016; SFWater, 2010).
The information in the following sections provide an overview of BMPs that may be appropriate for
hydraulic control and treatment of stormwater and spill prevention at fueling facilities. The cited
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resources (appendices and report references) may enable owners/operators of fueling facilities to
learn about relevant BMPs and requirements considered by state and local agencies..
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ACTIVITY: Vehicle and Equipment Fueling
AM - 15
-jf~Z
Install uphill curb or ditch
divert stormwater runoff
NOT TO SCALE
Trash
dumpster
%
See IC-10, Dumpsters, and also
AM-OS, Waste Management and
Recycling, for information
regarding trash dumpster3.
%
Speed bumps or swales .
(to contain stormwater)
Retail gasoline station
1
(with convenience store)
i
&
\
v— Covered refueling area —1
\ P,J
I Street |
Trench drains installed into pavement Street
Jypasses the
o/w separator
ft
Offsite storm drain J
Oil/water separator
Notes:
This typical layout (at the intersection of two streets) only shows a typical design layout for a retail
gas station and is meant to illustrate the following points:
• Need an oil/water separator (see ST-07, Oil/Water Separator)
• Segregate clean offsite water
• Control areas with potential leaks or spills (see AM-07, Spill Prevention and Control)
• Control areas which may be pressure washed or steam cleaned (see IC-08, Power or Pressure
Washing)
Retail gasoline stations must apply to the City of Knoxville for a Special Pollution Abatement Permit.
See Chapter 7 of the BMP Manual for more information.
Roof drains should also generally bypass the oil/water separator. This layout does not provide any
required detention for stormwater. Designed facilities must contain structural measures rather than
solelv relvine on Dersonnel to iinolement necessarv BMP orocedures.
Figure AM-15-1
Typical Layout - Retail Gasoline Stations
Knoxville BMP Manual
Activities &. Methods
AM I? 4
Mm 2003
Figure 2. Gas station design showing onsite pollution control measures and containment pad flow
treatment options, (City of Knoxville, 2018)
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' ¦ i 11 ii II r -' st Manageme i h r ii actices
Structural BMPs include physical or mechanical means to contain, route, and process stormwater.
BMP examples include capturing water (catch basin), conveying water (sloped concrete pads) and
separating pollutants (sand filters). These practices pertain to 1) site design, and 2) runoff capture and
treatment (WA DEC, 2019).
2 mil ¦ 1 ;#"/! 1 • gn
WA DEC, (2019) indicates that "new or substantial remodeling of fueling stations must be constructed
on an impervious concrete pad under a roof to keep out rainfall and stormwater run-on. A treatment
BMP must be used for contaminated stormwater and wastewaters in the fueling containment area
[pad]". Substantial remodeling is further defined as "replacing the canopy or relocating or adding one
or more fuel dispensers in a way that modifies the paving in the fueling area". Examples of state,
county, and local BMP guidance for fuel facilities (MA DEP, 2008c; City of Juneau, 2010; SDCI, 2017; WA
DEC, 2019) show a set of best practices (Table 1) commonly recommended for fueling area design,
water conveyance, treatment, and fuel transfer. Specific requirements may vary by location and
owners/operators should refer to the guidance applicable to their locality.
Fueling Island Design
Fueling island design guidelines (Table 1) describe containment pad runoff collection devices (dead end
sumps, catch basins), specifications for containment pad construction (slope, construction material),
and canopy (minimum size). Runoff guidance covers captured runoff conveyance to treatment BMPs
(oil/grit separators, sand filters) and/or final release to sanitary sewer systems. It also provides (Option
2) a means to separate clean runoff from containment pad runoff through a raised berm on the pad,
allowing for a smaller fraction of runoff needing BMP treatment (described in Fig. 2). Additionally,
New Hampshire (NH DES, 2019) requires positive limiting barriers (PLBs) comprised of grooves in the
concrete around the edge of the dispensing area designed to contain five gallons per dispenser. Some
have found limitations in the use of berms due to safety risks for pedestrians and for snow removal
operations. Lastly, grading of the tank pad to avoid sheet flow across the tank pad should be
considered when possible. Proper installation and grading of tank manholes and spill containment
buckets will prevent water intrusion into the tank system. UST fuel deliveries describes necessary site
conditions to minimize spills during fuel transfer.
Underground Storage Tank Release Prevention
The EPA requires release prevention for USTs including spill and overfill protection.
• Spill protection entails containment around the fill pipe (spill bucket) that catches small drips or
spills (Fig. 3) that occur when the delivery hose is disconnected from the fill pipe. Proper
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management of water in the spill bucket needs to be maintained to prevent water ingress in
the tank.
• Overfill protection devices either shut off product flow, restrict product flow or alert the
delivery operator (Fig. 4), with an alarm when the tank is close to being full.
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Table 1. Fueling Station Pollution Control Best Management Practices (MA DEP, 2008c; City of Juneau, 2010; SDCI, 2017; WA DEC, 2019)
Best Management Practice
Description
Fueling Island Design
Option 1
Design the fueling island to control spills (e.g., sump catch basins) and to treat collected
stormwater and/or wastewater to required levels.
Slope the concrete containment pad around the fueling island toward drains leading to a
sump catch basin.
Drains from containment pads must have a normally closed shutoff valve. The valve may
be opened to convey contaminated stormwater to oil removal treatment such as an API
or CPI oil/water separator, or equivalent treatment, and then to a basic treatment BMP.
Option 2
Alternatively, design the fueling island as a spill-containment pad with a sill or berm
raised to a minimum of four inches to prevent the runoff of spilled liquids and to prevent
run-on of stormwater from the surrounding area.
Options 1 and 2
The fueling pad must be paved with Portland cement concrete, or equivalent. Asphalt is
not considered an equivalent material.
Canopy Design
The roof or canopy should, at a minimum, cover the spill containment pad (within the
grade break or fuel dispensing area) and preferably extend several additional feet to
reduce the introduction of windblown rain. Convey all roof drains to storm drains outside
the fueling containment area.
Stormwater Conveyance/Disposal
Convey the stormwater collected on the fuel island containment pad to a sanitary sewer
system, if approved by the sanitary authority; or to an approved treatment system such
as an oil/grit separator, sand filter or equivalent. Alternatively, stormwater collected on
the fuel island containment pad may be collected and held for proper off-site disposal.
Underground Storage Tank Deliveries
Transfer the fuel from the delivery tank trucks to the fuel storage tank in impervious
contained areas and ensure that appropriate overflow protection is used. Alternatively,
cover nearby storm drains during the filling process and use drip pans under all hose
connections.
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FIGURE 7-1. Spll Bucket Spill buckets contain smaiV
spr/rs during the uncoupling of delivery hoses. Care In
installation and maintenance is necessary lo minimize
the infiltration of surface and subsurface water.
Figure 3. UST spill bucket. (PEI, 2017)
;C
/OvJr«Ms'
Alarm
Automatic
Tank Gauge
JL
T
f a— «
ODCDGDCD
ill
In-Tank
Inventory
Probe
Electronic
Housing
Product
1 Level Float
Water
Level
, Float
Figure 4. Automatic tank gauging system, (USEPA, 2016a)
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2.3.2 Runoff Capture and Treatment Best Management Practices
Sump Catch Basins
Sump catch basins (Fig. 5) (sometimes termed deep sump or oil arid grease catch basins), are installed
under the containment pad and capture trash, debris, and coarse sediment from stormwater runoff.
For fueling facilities, they can also serve as temporary containment for oil and grease and provide
pretreatment for other BMPs like oil/water separators. (MA DEP, 2008b).
tKUOA
(Um wction
itch baitn frtm* miuS gran
M7
t
HWffH-R
t
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// ^ JC
4 Mm I f-** t/A
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lk3— 1 A—,1 1
4 71 s rj V
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/
t
91
40 m»n-
!
jl' nlln. J x Hooded owtkc M»e
Im
I' 4
n
K« A
E9
Figure 5. Diagram of a Deep Sump Catch Basin. (CT DEP, 2004)
Oil/Water Separators
Oil/Water Separators (sometimes termed Oil/Grit Separators) are multi-chamber underground
structures designed to remove sediment and hydrocarbons from urban runoff. Oil/grit separators are
commonly used in areas with high potential for petroleum spills such as parking lots, fueling facilities,
roads, and loading areas (US DOT, 2020). They can be used separately, or as a follow-on treatment
after sumps and catch basins. Figure 6 shows a three-chamber separator. The first chamber is for
settling sediment and other trash/debris. The second chamber allows oils and grease to float to the
surface, with an inverted pipe drawing water from the bottom of the chamber to the third chamber for
discharge to sanitary sewers (US DOT, 2020), if approved by the sanitary sewer authority.
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Elbow irwt (12" Aimcttr) it
pemwtew «n«r turtkct eievico
extend 1' btfcyw tu^Ki <
Tjrp«cal nunhoi* lUtti wth iit^i
exh (huniiMf
\ 2' typol
1 typicat
Balfl* to (low teormwitc 4
t
rtrmirvtoi wiur
*kv»ooo
O\xft<
Tnuh rack ovtt every op«mng •' TypxiMy miuS * 4* domcccr ortŁc«
(tociwd b«4ow WJttf Uirfict- for every IS" of bai*r> width
(i t. lour onflcM iy » V towt)
Figure 6. Diagram of a three-chambered oil/water separator. (CT DEP, 2004)
Filtration Basins
Filtration basins can be used instead of oil/water separators for high load hydrocarbon hotspots (MA
DEP, 2008b; WV DEP, 2012). Also known as sand filters, these filters are typically installed as parallel
self-contained basins at the edge of parking lots and fueling facilities (Fig. 7).
Figure 7. Perimeter sand filter. MA (DEP, 2008b).
Perimeter sand filters have two parallel trenches connected by an overflow weir. The first trench (Fig.
8) pre-treats runoff by settling, the second trench contains the sand filter, and subsurface drainage
pipe to convey treated runoff to the sanitary sewer, if acceptable by the sanitary sewer authority.
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H'ArtKtrlC I IJTSHF- I =.Cw
CURB SHOPS
N ¦¦-II ..
PLAN
~ UTLET =IPE Zt>J.EC"10N SV5TEM
VIEW
Figure 8. Diagram of perimeter sand filter. (WV DEP, 2012).
Bioretention
Bioretention is also suggested as an alternate filtering method used in place of oil/water separators
(MA DEP, 2008b). Bioretention cells (Fig. 9) are shallow depressions constructed from sandy soil, mulch
and vegetation. The conveyed runoff percolates through the engineered soil bed and, in the case of
hotspots, is collected in an underdrain for release to a sanitary sewer system, if acceptable. Hotspot
bioretention filters must also use an impermeable liner (WV DEP, 2012, WA DEC, 2019).
2.3.3 Cold Weather Design Considerations
The filtration BMPs discussed (sand filters and bioretention) require design modification for better
function in cold weather and for snow and snowmelt management. Perimeter and other surface sand
filters can freeze reducing effectiveness in cold weather. Installing sand filters underground, below the
frost line makes these systems function more effectively (Caraco and Claytor 1997). Bioretention cells
can suffer from reduced filtration rates in colder weather. Cold weather modifications include using
salt tolerant herbaceous (non-woody) plants to manage increased chloride concentrations from road
salts, extending the filter bed and underdrain pipe below the frostline, and oversize the underdrain
pipe to prevent freezing over. Oversizing the bioretention area aids in using bioretention cells for snow
storage (Caraco and Claytor 1997; NH DES, 2008; WV DEP, 2012).
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Provide a 1" drop
from the edge of
pavement
BSM bottom width
varies, 1' minimum
Overflow structure
or flowpath
6" min. freeboard
Ponding depth
varies
Provide a 1" drop
from the edge of
sidewalk
Sidewalk
2" woodchip mulch
or aggregate
3" coarse compost
in ponding area
18" Bioretention Soil Mix
(BSM)
Mineral aggregate
Underdrain pipe
Low permeability liner
Width
varies
Edge of
pavement
or curb-cut
2" woodchip mulch
or aggregate
Figure 9. Bioretention cell with underdrain. (WA DEC, 2019)
2.3.4 Infiltration Prohibition
Because of the potential for groundwater contamination, BMPs for infiltration and pervious pavements
are prohibited by some States for use at hotspots (AK DEC, 2011; MDE, 2000; NH DES, 2008). Check
State and local guidance for site specific information. Appendix B contains examples of runoff
treatment BMPs recommended for fueling facilities.
2.4 Non-Structural Best Management Practices
Non-structural BMPs include procedures and policies for day-to-day operations and longer-term
planning. These practices pertain to 1) spill response and fueling area maintenance and 2) site
management planning.
2.4.1 Fuel Transfer Spillage and Fueling Area Maintenance
Examples of state, county, and local BMP guidance for fuel facilities (CSQTF, (1997); Scheuler et al.,
2005; City of Juneau, 2010; WA DEC, 2019; Alachahua County, 2020) show a set of best practices
commonly recommended. Specific requirements may vary by location and owners/operators should
refer to the guidance applicable to their locality. Additional examples of guidance from several state
and local sources on structural and non-structural BMPs can be found in Appendix A.
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Spill Response Plan
• Prepare an emergency spill response and cleanup plan.
• Ensure that employees are trained on the elements of the plan
• Have available trained personnel accessible at all times to promptly implement cleanup
• Information on what to do in response to a spill must be visible to all customers and employees
Spill Kit
• Have a spill kit onsite, fully stocked with contents suitable for the product spilled, accessible,
(Fig. 10)
• Keep suitable cleanup materials such as dry absorbent pad and granular materials, safety
glasses, nitrile gloves, and drain covers.
Fueling Area Maintenance
• Do Not use dispersants to clean up spills. Dispersants are not allowed to enter storm drains
• Clean fuel-dispensing area with dry clean-up methods
• Ensure any wash water is collected and disposed in the sanitary sewer system if allowed.
• Keep drained fuel filters and spent dry clean up materials in a suitable container or drum
Fuel Dispensing
• Post signs prohibiting "Topping Off" of vehicle tanks during filling, topping off may cause
spillage
• Ensure automatic shut-off on dispenser fuel nozzles are functioning properly
Figure 10. Fueling station spill kit next to fuel dispenser. (City of Honolulu, 2013)
2.4.2 Storage Tank Maintenance
Preventing water from entering into storage tanks is critical for protecting tank infrastructure and
preserving fuel quality. Water in tanks can lead to corrosion, resulting in leaks and product
degradation. Improperly sealed and maintained orifices e.g. loose fittings or plugs, can let accumulated
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water in from sumps and moisture through the air vents, or condensation from temperature changes.
(STI, 2006).
Tank Water Management Prevention Practices (CRC, 2016):
• Remove standing water, ice, and/or snow around tank fill covers
• Ensure all tank opening bungs and caps are tight, inspect and replace broken gaskets
• Keep fill and vapor recovery buckets clean. Pump out any water, clean out excess fuel and dirt
without depressing drain plungers to prevent contamination into the tank
• Avoid extended times with low tank volumes to prevent water condensation
• Inspect fill and vapor caps for damages and for missing gaskets, replacing as necessary
• Inspect product and spill containment buckets and proper disposal of water if found (do not
drain back into the tank)
• Audit the fuel delivery process and water content
• Use water-sensitive fuel filters and monitor for slowed-down fueling
• Employ a qualified professional to examine the inside of the tank, remove any water and
sludge, and clean the tank periodically
Manual tank gauging and/or automatic tank gauging can be used to detect water. Periodic product
sampling can also detect the presence of water. Samples should be collected from the from the low
end of the tank and from more than one location. Samples that are not clear may indicate water and
the presence of microbial activity, indicating conditions conducive to corrosion.
2.4.3 Site Management Planning
Source Control Planning
Some States recommended developing Source Control Plans (SCPs) for sites that are hotspots (AK DEC,
2011; NH DES, 2008). The plans help organize a range of housekeeping, prevention and disposal
activities at a fueling facility hotspot. As an example, the Center for Watershed Protection (Wright, et
al., 2005) and the West Virginia Department of Environmental Protection (WV DEP, 2012) developed
the Hotspot Site Investigation (HSI) worksheet and Stormwater Hotspot Checklist (Appendix A) that
provide methods to quantify hotspot activity impacts to sub-watersheds and help identify appropriate
source control and pollution abatement methods. The HSI worksheet enables fueling facility
owner/operators to assess six distinct pollution sources (Table 2) and formulate possible pollution
prevention/abatement methods to address these sources.
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Table 2. Assessment Areas from the Hotspot Site Investigation (HSI) worksheet (Wright et al., 2005)
HSI Pollution Source
Description
Vehicle Operations
Evaluates routine vehicle maintenance and storage
practices at the site, as well as vehicle fueling and washing
operations
Outdoor Materials
Examines the type and exposure of any outdoor materials
stored at the site
Waste Management
Assesses housekeeping practices for waste materials
generated at the site
Physical Plant
Assesses maintenance practices used for cleaning,
remodeling or repairing buildings, outdoor work areas and
parking lots
Turf/Landscaping Areas
Examines the practices used to maintain lawn or
landscaping areas, with special emphasis on fertilizer use
and non-target irrigation
Storm Water Infrastructure
Evaluates the condition of practices used to convey or
treat storm water, including the curb and gutter,
catch basins, and any storm water treatment practices
Additional components of a SCP include structural practices for flow control to minimize fuel spills
contacting cleaner stormwater, e.g. diverting runoff with extruded curbs uphill of the fueling area to
stormwater drains or as sheet flow over vegetated areas (swales) (Fig. 2), and designated locations for
snow storage (NH DES, 2008; NH DES, 2019).
Snowmelt Management Planning
In areas with snowfall sufficient to impact onsite flow regimes as snow melts, a Snowmelt
Management Plan (SMP) organizes the planning for clearing, storing, removing, and treating snowmelt
volume and pollution (AK DEC, 2011; MPCA, 2020). Site planning e.g. cleared snow storage locations
(NH DES, 2008) and their proximity to other snow management practices such as salting and sanding
roads my provide additional information regarding where snowmelt can be discharged (stormwater or
sanitary sewer), and the level of treatment required.
The Minnesota Pollution Control Authority (MPCA, 2020) provides guidelines for a snowmelt
management plan that could be implemented in conjunction with a SCP (NH DES, 2008) for fueling
facilities where snow and snowmelt could be a significant part of hydraulic management.
Recommended practices include snow removal and disposal, road salt and deicing chemical
application, and modifications for structural BMPs (discussed in Section 2.3.3).
Snow disposal guidelines at the state and local level (CT DEP, 2004; MA DEP, 2008b; City of Juneau,
2010) provide specifications for site selection generally recommending snow be deposited on upland
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EPA/600/R-20/214
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sites (with certain restrictions) on or near pervious land for infiltration as snowmelt. Recommended
areas include parking lots or public parks, not directly over storm drains to avoid clogging, and away
from environmentally sensitive areas such as wetlands, private and public drinking water sources.
Following snow melt, remaining debris (gravel, sand, trash, etc.), must be removed. An online
Geographic Information System (GIS) mapping tool helps find acceptable sites in Massachusetts.
SPCC Planning Requirements for Fueling Facilities
Fueling facilities with Aboveground Storage Tanks (ASTs) which transfer, handle or store oil may be
subject to the Spill Prevention Control and Countermeasures (SPCC) rule. More information regarding
SPCC requirements and applicability can be found on the Oil Spills Prevention and Preparedness
Regulations website (https://www.epa.gov/oil-spills-prevention-and-preparedness-regulations). The
SPCC Rule and Plan are part of Oil Pollution Prevention
regulation (40 CFR part 112). Fueling Facilities may
need to prepare a SPCC plan if that facility:
• Stores, transfers, uses or consumes oil or oil
products, such as diesel fuel, gasoline, lube oil,
hydraulic oil, adjuvant oil, crop oil, vegetable oil
or animal fat; and
• Stores more than 1,320 U.S. gallons of oil in total
of all aboveground containers (only count
containers with 55 gallons or greater storage
capacity) or more than 42,000 gallons of oil in
certain completely buried containers; and
• Could reasonably be expected to discharge oil to
navigable waters of the U.S. or adjoining shorelines, such as lakes, rivers and streams.
There are streamlined SPCC requirements for certain simpler facilities and more information can be
found at the "Is My Facility a "Qualified Facility" under the SPCC Rule? website. EPA has developed a
fact sheet to determine if this option is applicable. The EPA provides a useful sample plan guide for a
gas station that would need to complete a streamlined SPCC Plan. Figure 11 shows a diagram of this
example facility. This example station is using the streamlined Tier I option for a SPCC Plan due to
aboveground storage of fuel. The underground storage tanks, such as those listed in this diagram are
typically exempt from the SPCC rule as they are regulated by the UST Rule (CFR 280 or 281).
Regardless, this site would need to complete the spill prevention plan and in doing so the USTs would
be afforded the same protective measures and planning.
EPA's oil spill prevention program
includes the Spill Prevention, Control,
and Countermeasure (SPCC) and the
Facility Response Plan (FRP) rules. The
SPCC rule helps facilities prevent a
discharge of oil into navigable waters or
adjoining shorelines. The FRP rule
requires certain high risk SPCC facilities
to submit a response plan and prepare
to respond to a worst-case oil discharge
or threat of a discharge. For more
information see the EPA website for oil
spill Prevention and Preparedness.
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EPA/600/R-20/214
September 2020
Tier I Template SPCC Plan - Gas arvd Care Express Service Statiion
This faciity diagram is only for illustrating the example facility to help readers visualize the information in the scenario and the sample SPCC Ran. Inclusion
of a facifty diagram in the SPCC Plan is not a requirement for a Tier f Qualified Facility opting to complete the Tier I QuaJifed Facility SPCC Plan Template.
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EPA/600/R-20/214
September 2020
• United States Geological Survey (USGS) Flood Information
o provides information on hourly flood conditions.
• National Weather Service (NWS) Interactive Flood Information Map
o provides information on state-wide flooding
Hurricane-related flood events result in greater releases of petroleum as compared to other natural
hazards (Sengul et al, 2012), Several online sources are available to help assess the flood risk for a
facility in a coastal hazard-prone area. Examples of sites include:
• National Oceanic and Atmospheric Administration (NOAA) Coastal Flood Exposure Mapper
o Visualization tool for assessing coastal flooding hazards
o Creates user defined maps to communicate flood exposure and potential impacts
• National Oceanic and Atmospheric Administration (NOAA) Coastal Inundation Dashboard
o provides real-time and historic coastal flooding information
If a facility is assessed to be at risk of flooding, the EPA Underground Storage Tank Flood Guide (USEPA,
2020a) provide simple guidelines and useful information in the event of a threatened or actual flood. It
includes information about preparing a UST for a flood, important actions after the disaster strikes, and
information on financial assistance.
3.1 Extreme Event Tracking
There is an increasing awareness of pollution and risks to health, environment, and economy from
technological infrastructure failure caused by natural disasters such as floods. The occurrence and
severity of these Natech (hazardous material releases from nature caused technology failures) events
is an area of continuing study (Young et al., 2004; Necci et al., 2018). Trends of greater population
19
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EPA/600/R-20/214
September 2020
density and industrial development in disaster prone areas increase the likelihood of these release
events and severity of negative impacts (Young et al., 2004); prompting the development of resources
to track and provide information for more effective Natech risk management.
One example is the eNatech Database (eNatech, 2020), a product of the European Commission Joint
Research Center and catalogs specifics on Natech events (Fig. 12), hazardous releases, and locations. It
is searchable by date, location, country of origin, across 23 different types of causative natural hazards
covering five broad categories of geological, meteorological, hydrological, climatic, and fire. Similar
extreme event databases are listed in Appendix C.
Home | Login | Legal Notice | Privacy Statement | Contact Us | Search lEnglish (en) ~
JOINT RESEARCH CENTRE
eNatech - Natural hazard-triggered technological accidents database
European Commission > JRC > eNatech
Natechs
I
Hazards
Sites
eNatech Database
Technological accidents triggered by a natural hazard or disaster which
result in consequences involving hazardous substances (e.g. fire, explosion,
toxic release) are commonly referred to as Natech accidents. The aim of this
database is to systematically collect information on Natech accidents that
occured worldwide and allow the searching and analysis of Natech
accident reports for lessons-learning purposes.
Figure 13. eNatech Database recording details on natural disaster caused technology accidents
searchable by event, hazard type, location and country of origin. https://enatech.jYc.ec.europa.eu/
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References
Alachahua County, (2020). Pollution Prevention, Best Management Practices for Controlling Runoff
from Gas Stations. Alachahua County, FL.
https://www.alachuacountv.us/Depts/EPD/Documents/WaterResources/Gas%20Stations.pdf Accessed
3/20/2020.
AK DEC, (2011). Alaska Storm Water Guide. Alaska Department of Environmental Conservation.
Division of Water, https://dec.alaska.eov/water/wastewater/stormwater/euidance/ Accessed
4/2/2020.
Borden, R.C, Black, D.C., McBlief, K.V., (2002). MTBE and aromatic hydrocarbons in North Carolina
stormwater runoff, Environmental Pollution, 118:141-152.
Caraco, D., Claytor, R. (1997). Stormwater BMP Design Supplement for Cold Climates. Center for
Watershed Protection, Ellicott City, MD.
City of Honolulu, (2013). Storm Water Best Management Practices: Best Management Practices: Retail
Gas Stations. https://www.honolulu.gov/rep/site/dfmswq/librarv/Retail Gas Stations brochure 2013~05.pdf
Accessed 3/20/2020.
City of Juneau, (2010). City and Borough of Juneau Manual of Stormwater Best Management Practices.
City of Knoxville, (2018). Best Management Practices (BMP) Manual. City of Knoxville, Engineering
Department, Stormwater Engineering Division.
http://knoxvilletn.gov/government/citv departments offices/engineering/stormwater engineering division/b
mp manual Accessed 4/2/2020.
CASQA, (2003). Stormwater Best Management Practice Handbook, New Development and
Redevelopment. California Stormwater Quality Association.
CRC, (2016). Coordinating Research Council (CRC) Report 672. http://crcsite.wpeneine.com/wp~
content/uploads/2019/05/CRC~672.pdf Accessed 6/26/2020
CSQTF, (1997). Best Management Practice Guide Retail Gasoline Outlets, California Stormwater Quality
Task Force
https://www.waterboards.ca.gov/rwqcb4/water_issues/programs/stormwater/municipal/los_angeles
_ms4/tentative/121301_rgo%20swqtf%20bmps%20a nalysis.pdf
Cozzani, V., Campedel, M., Renni, E., Krausmann, E. (2010). Industrial accidents triggered by flood
events: Analysis of past accidents. J. Haz Materials, 175: 501-509
CT DEP, (2004). Connecticut Stormwater Quality Manual. Connecticut Department of Environmental
Protection.
King County, (2016). Stormwater Pollution Prevention Manual: Best Management Practices for
Commercial, Multi-Family and Residential Properties. King County, Department of Natural Resources
and Parks, Stormwater Services Section.
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eNatech (2019), eNatech - Natural hazard triggered technological accidents database. European
Commission Joint Research Center, https://enatech.jrc.ec.europa.eu/. Accessed 3/8/2020.
Gnecco, I., Beretta, C., Lanza, L.G., La Barbera, P., (2006). Quality of stormwater runoff from paved
surfaces of two production sites, WatSci Tech, 54:177-184.
Hilpert, M., Mora, B.A., Ni, J I, Rule, A.M., Nachman, K.E., (2015). Hydrocarbon release during fuel
storage and transfer at gas stations: environmental and health effects. Curr Envir Health Rpt, 2: 412-
422
MA DEP, (2008a). Massachusetts Stormwater Handbook Vol 2, Ch 1, Three Components of Stormwater
Management. Massachusetts Dept. of Environmental Protection.
https://www.mass.gOv/guides/massachusetts-stormwater-handbook-and-stormwater-standards#-stormwater"
handbook-volume-2-. Accessed 3/18/2020.
MA DEP, (2008b). Massachusetts Stormwater Handbook Vol 2, Ch 2, Structural BMP Specifications for
the Massachusetts Stormwater Handbook. Massachusetts Dept. of Environmental Protection.
https://www.mass.gov/guides/massachusetts-stormwater-handbook-and-stormwater-standards#-stormwater-
handbook-volume-2-. Accessed 3/18/2020.
MA DEP, (2008c). Massachusetts Stormwater Handbook Vol 2, Appendix: Operating & Source Control
BMPs. Massachusetts Dept. of Environmental Protection, https://www.mass.gov/guides/massachusetts-
stormwater-handbook-and-stormwater-standards#-stormwater-handbook-volume-2- Accessed 3/18/2020
Maryland Department of the Environment (MDE). 2000. Maryland Stormwater Design Manual:
Volumes 1 and 2. Maryland Department of the Environment, Baltimore, MD.
MPCA, (2020). Minnesota Stormwater Manual. Minnesota Pollution Control Agency.
https://stormwater.pca.state.mn.us/index.php?title=Main Page Accessed 4/2/2020
Mora, B.A, Hilpert, M. (2017). Differences in infiltration and evaporation of diesel and gasoline droplets
spilled onto concrete pavement, Sustainability, 9:1271, doi:10.3390/su9071271
Necci, A., Girgin, S., Krausmann, E., (2018). Understanding Natech Risk Due to Storms - Lessons learned
and recommendations, EUR 29507 EN, European Union, ISBN 978-92-79-98274-3, doi:10.2760/21366,
JRC114176.
NH DES, (2008). New Hampshire Stormwater Manual: Volume 2 Post-Construction Best Management
Practices Selection & Design. New Hampshire Department of Environmental Services.
NH DES, (2019). Preventing Groundwater Contamination at Gas Stations - What Municipalities and
Water Suppliers Can Do. New Hampshire Department of Environmental Services, Environmental Fact
Sheet WD-DWGB-22-20.
https://www.des.nh.gov/organization/commissioner/pip/factsheets/dwgb/documents/dwgb-22-
20.pdf
PEI, (2017). Recommended Practices for Installation of Underground Liquid Storage Systems.
Petroleum Equipment Institute, PEI/RP100-17
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Sengul, H., Santella, N., Steinberg, L.J. and Cruz, A.M. (2012). Analysis of hazardous material releases
due to natural hazards in the United States. Disasters, 36: 723-743. doi:10.1111/i.l467-
7717.2012.01272.x
Schueler, T. (2000a). Why Stormwater Matters: The Practice of Watershed Protection. Center for
Watershed Protection, Ellicott City, MD. Pages 365-370
Schueler, T. (2000b). Hydrocarbon Hotspots in the Urban Landscape: Can They Be Controlled?: The
Practice of Watershed Protection. Center for Watershed Protection, Ellicott City, MD. Pages 19-21
Schueler, T., Swann, C., Wright, T., Sprinkle, S. (2005). Manual 8: Pollution Source Control Practices.
Urban Subwatershed Restoration Manual Series. Center for Watershed Protection, Ellicott City, MD.
SDCI, (2017). City of Seattle Stormwater Manual. Volume 4: Source Control. Seattle Department of
Construction and Inspections. Seattle, WA.
SFWater, (2010). San Francisco Stormwater Design Guidelines. Appendix A: BMP Fact Sheets.
https://sfwater.org/index.aspx?page=446. Accessed 3/18/2020.
STI, (2006). Keeping Water Out of Your Storage System.
https://www.steeltank.eom/Portals/0/pubs/KeepingWaterOutofYourStorageSvstem updated%20 2 .pdf?utm
source=TANK+TALK+MAY+2014&utm campaign=Tank+Talk+MAY+2014&utm medium=email Accessed
6/26/2020
USDOT, (2020). Environmental Review Toolkit: Stormwater Best Management Practices in an Ultra-
Urban Setting: Selection and Monitoring. Federal Highway Administration.
https://www.environment.fhwa.dot.eov/Env topics/water/ultra urban binp rpt/uubmp3pl.aspx.
Accessed 3/18/2020.
USEPA (2003). Preventing Leaks and Spills at Service Stations A Guide for Facilities. Pacific
Southwest/Region 9. EPA 909-K-03-001
USEPA (2010b). NPDES Permit Writer's Manual. Office of Water Washington, DC. EPA-833-K-10-001
USEPA (2011a). National pollutant discharge elimination system (NPDES) definitions, 40 C.F.R.
§ 122.2 (2011a). Washington, DC
USEPA (2016a). Release Detection For Underground Storage Tanks And Piping: Straight Talk on Tanks.
EPA 510-K-16-003.
USEPA (2020a). Underground Storage Tank Flood Guide. Office of Underground Storage Tanks. EPA-
510-B-20-001. https://www.epa.gov/ust/underground-storage-tank-flood-guide Accessed 8/28/2020.
USEPA (2020b). Underground Storage Tanks Application. Office of Underground Storage Tanks.
WA DEC, (2019). Stormwater Management Manual for Western Washington, Washington Department
of Ecology, Publication Number 19-10-021
White, H. (1997). Factors influencing the behavior of hydrocarbons in stormwater runoff during
quiescent settling. Master's Thesis, Virginia Polytechnic Institute and State University, Falls Church, VA.
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WV DEP, (2012). West Virginia Stormwater Management and Design Guidance Manual. West Virginia
Dept. of Env. Protection.
Wright, T., Swann, C., Cappiella, K., Schueler,T. (2005). Manual 11: Unified Subwatershed and Site
Reconnaissance: A User's Manual. Urban Subwatershed Restoration Manual Series. Center for
Watershed Protection, Ellicott City, MD.
Young, S., BaMuz, L.S., & Malilay, J. (2004). Natural and technologic hazardous material releases during
and after natural disasters: a review. The Science of the total environment, 322: 3-20.
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Appendix A: BMP Guidance Fad Sheets
This appendix contains a collection of representative Best Management Practice Fact sheets.
The included Sheets are:
• H-2 Hotspot Source Area: Vehicles, Vehicle Fueling Schueler et al., (2005)
• Hotspot Site Investigation Worksheet Wright, et al., (2005)
• Stormwater Hotspot Checklist WV DEP, (2012)
• Best Management Practices for Controlling Runoff from Gas Stations Alachahua County, (2020)
• SD 30 Fueling areas CASQA, (2003)
• Bmp 10: Fueling at Dedicated Stations SDCI, (2017)
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H-2
Hotspot Source Area: Vehicles
E*WICr
VEHICLE FUELING
Table 1: Pollution Prevention Practices for Fueling Operation Areas
Description
Spills at vehicle fueling operations have the
potential to directly contribute oil, grease, and
gasoline to storm water, and can be a significant
source of lead, copper and zinc, and petroleum
hydrocarbons. Delivery of pollutants to the
storm drain can be sharply reduced by well-
designed fueling areas and improved operational
procedures. The risk of spills depends on
whether the fueling area is covered and has
secondary containment. The type, condition,
and exposure of the fueling surface can also be
important. Table 1 describes common pollution
prevention practices for fueling operations.
Application
These practices can be applied to any facility
that dispenses fuel. Examples include retail gas
stations, bus depots, mannas, and fleet
maintenance operations (Figure 1). In
addition, these practices also apply to temporary
above-ground fueling areas for construction and
earthmo\ ing equipment. Many fueling areas are
usually present in urban subwatersheds, and they
tend to be clustered along commercial and
highway corridors. These hotspots are often a
priority for subwatershed source control.
Figure 1: Covered Retail Gas Operation
Without Containment for Potential Spills
• Maintain an updated spill prevention and response plan on premises of all fueling facilities (see
Profile Sheet H-7)
• Cover fueling stations with a canopy or roof to prevent direct contact with rainfall
• Design fueling pads for large mobile equipment to prevent the run-on of storm water and collect
any runoff in a dead-end sump
• Retrofit underground storage tanks with spill containment and overfill prevention systems
• Keep suitable cleanup materials on the premises to promptly clean up spills
• Install slotted inlets along the perimeter of the "downhill" side of fueling stations to collect fluids and
connect the drain to a waste tank or storm water treatment practice. The collection system should
have a shutoff valve to contain a large fuel spill event
• Locate storm drain inlets away from the immediate vicinity of the fueling area
• Clean fuel-dispensing areas with dry cleanup methods. Never wash down areas before dry
cleanup has been done. Ensure that wash water is collected and disposed of in the sanitary
sewer system or approved storm water treatment practice
• Pave fueling stations with concrete rather than asphalt
• Protect above ground fuel tanks using a containment berm with an impervious floor of Portland
cement. The containment berm should have enough capacity to contain 110% of the total tank
volume
• Use fuel-dispensing nozzles with automatic shutoffs, if allowed
• Consider installing a perimeter sand filter to capture and treat any runoff produced by thestation
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Primary Training Targets
Training efforts should be targeted to owners,
operators, attendants, and petroleum
wholesalers.
Feasibility
Vehicle fueling pollution prevention practices
apply to all geographic and climatic regions. The
practices are relatively low-cost, except for
structural measures that are installed during new
construction or station remodeling.
Implementation Considerations
Fueling Area Covers - Fueling areas can be
covered by installing an overhanging roof or
canopy. Covers prevent exposure to rainfall and
are a desirable amenity for retail fueling station
customers. The area of the fueling cover should
exceed the area where fuel is dispensed. All
downspouts draining the cover or roof should be
routed to prevent discharge across the fueling
area. If large equipment makes it difficult to
install covers or roofs, fueling islands should be
designed to prevent storm water run-on through
grading, and any runoff from the fueling area
should be directed to a dead-end sump.
Surfaces - Fuel dispensing areas should be paved
with concrete; the use of asphalt should be
avoided, unless the surface is sealed with an
impervious sealant. Concrete pads used in fuel
dispensing areas should extend to the full length
that the hose and nozzle assembly can be pulled,
plus an additional foot.
Grading - Fuel dispensing areas should be
graded with a slope that prevents ponding and
separated from the rest of the site by berms,
dikes or other grade breaks that prevent run-on
of urban runoff. The recommended grade for
fuel dispensing areas is 2 - 4% (CSWQTF,
1997).
Cost - Costs to implement pollution prevention
practices at fueling stations will vary, with many
of the costs coming upfront during the design of
a new fueling facility. Once a facility has
implemented the recommended source control
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measures, ongoing maintenance costs /stormwater/la ms4 tentative/RGOPaperSupple
should be low. ment 12-01 .pd
Resources
Best Management Practice Guide -
Retail Gasoline Outlets. Prepared by
Retail Gasoline Outlet Work Group.
http ://www. swrcb. ca. gov/rwacb4/html/pro g
rams
/stormwater/la ms4 tentative/RG
O BMP Guide 03-97 .pdf
Stormwater Management Manual for
Western Washington: Volume IV —
Source Control BMPs.
http: //www.ecv. wa. gov/biblio/9914 .html
California Stormwater Quality
Association. 2003 California
Stormwater BMP Handbook: New
Development and Redevelopment.
http: //www .cabmphandbooks .com/
City of Los Angeles, CA Best
Management Practices for Gas Stations
http ://www. lacitv. or g/S AN/wpd/downloads
/PDF s/gasstation.pdf
City of Dana Point Stormwater Best
Management Practices (BMPs) For
Automotive Maintenance And Car Care
http://www.danapoint.org/water/WC-
AUTOMOTIVE.pdf
Alachua County, FL Best Management
Practices for Controlling Runofffrom Gas
Stations http: //environment. alachua-
countv.org/Natural Resources/Water Qua
litv/D ocuments/Gas%20Stations.pdf
California Stormwater Regional Control
Board Retail Gasoline Outlets: New
Development Design Standards For
Mitigation Of Storm Water Impacts
http ://www. swrcb. ca. gov/rwacb4/html/pro g
rams
/stormwater/la ms4 tentative/RGOpaper.
pdf
http ://www. swrcb. ca. gov/rwqcb4/html/pro g
rams
28
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EPA/600/R-20/214
September 2020
Canadian Petroleum Products Institute
Best Management Practices Stormwater
Runoff from Petroleum Facilities
http://www.cppi.ca/tech/BMPstormwater.p
df
City of Monterey (CA). Posters of Gas
Station BMPs.
http ://www .monterev. org/public works/storm
edu c.html
Pinole County, CA Typical
Stormwater Violations Observed in
Auto Facilities and Recommended
Best Management Practices (BMPs)
http://www.ci.pinole.ca.us/publicworks/dow
nloa ds/Auto Stormwater.pdf
29
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EPA/600/R-20/214
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Hotspot Site Investigation HSI
1 Watershed:
SUBWATERSHED:
T Unique Site IB:
jl> '•
Assessed By;
Camera ID:
Rci;
| Mat Giro;
Lat • '
" Long *
'
LMK#
Name and Address:
SIC code (if available):
KPDES Status: O Regulated
[J Unregulated [_j Unknown
Category; i_i Commercial O Industrial Miscellaneous
I~1 Institutional Q Municipal O Golf Coarse
[~l Transport-Related O Marina
~ Animal Facility
Basic Descriptiaa of Operation:
INDEX*
! B. Vehicle Operations LJ N/A t'Skip to part C>
Observed Pollution Source?
Bl. Types of vehicles.: [J Fleet vehicles |_J School buses Li Otter: _
B2. Approximate camber of vehicles.
13. Yehiile activities, 'circle as!ahatapphy Maintained Repaired Xecycled Fueled Wished Stored
B4. Are vehicles stored and or repaired outside"1 _j Y |_ N [_! Can't Tell
_Arejhe3ej;eliLcle3jackmg™QfljiveRiq5_methods?_ fl_Y I ! X i ;_Can't Teli
15. Is there evidence of spills leakage from vehicles? IL! Y |~1 N D Can't Tell
16. Are uncovered outdoor fueltas areas present? G Y [U N I I CgrJtTeH
B7. Are fueling areas directly connected to stcrtr. drams? [J Y 1_] N U Can't Tell
BS. Art vehicles "iVEsbed cutdrort? '1 Y [ ' X [""1 Can't Teli ~ ~
Does the area where vehicles are washed discbarge to the stjnn dram" [J Y _J X C
I C. Outdoor Materials L_j X/A tSkip tc part D>
CI. Are loading unloading operations present?1 LJ Y LI X [L Can't Tell
If ve-j. are they uncovered am'draining towards a storo dram islet? LJ Y UN LJ Can't Tell
C2. -Are materials stored outside? . J Y | ] X , JCan'cTell If yes. are they | ) Liquid 1, J Solid Description: _
Where are die;,' stored? LJ grass, dirt area U concrete asphalt LJ bermed area
o
o
o
o
o
Can't T*ll_
i Observed Pollution Source?
C3. Is the storage area directly or indirectly ccnnectedte storm dram [circle one)? C'l" LI N Q Can't Tell
CM. Is staining or discoloration around the area visible? LJ Y LI N IL Can't Tell
C5. Does cutdcor storage area lack a cover? LJ Y _] N J Can't Tell
C6. Are liquid materials stored without secondary contairunent? LI Y LI ^ _i Can't Tell
C7. Are storage containers misting labels ci hi poor condition (rusting"1 Y I N | 1 Can't Tell
! D. W aste Management LLX/A fSkip ta part E) j Ob
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EPA/600/R-20/214
September 2020
Hotspot Site investigation
HSI
E2, Parking Lot: Approximate age yri Condition' F~] Clean [j Staised d Dirty \ ' Breakne up
Surface mEterial [J Pa\*d Concrete [_ Cii'Vi _] Permeable _J Don't kamv
13. Do drnmpouts discharge to impervious surface11 Lj Y Qn Lj Dent know |_| JJeoe viable
Are downspouts directly connected to storm drams? Fl Y fl X fl Don't know
E4. Evidence of poor cleaning practices for coutractkn activities i items leading to stcna dram)? HI V CX O Can't Tell
F. Tukf/Lakdscaplnc Are.
'skip to part Ci
Fl. % of site with: Forest canopy _
% Turf sxass
Landscaping _
Bare Soil
o
o
o
Observed Pollution Source?
o
F2. Rue the turf management status: Q High ! J Medium (J Low
o
F3. Evidence of permanent irrigation or "non-target" irrigation ~ Y ON O Can't Tell
o
F4. Do landscaped areas drain to the
~ Y ON ~ Can't Tell
GI, Are storm water treatment practices present? O Y Q N O Unknown If yes, plena describe:
G2. Are private storm drains located at the facility? O Y [] N 0 Unknown
Is trash present in gutters leading to storm drams? If so, complete the index below.
Index Rathia ft* Accuaialation in Gutters
o
Clean
Fihhv I
Sediment
C -
~
~
n
4i»
~
".^1
Organic material
i„ -
~ 2 L 1 3
L 4 ~ 5
Litter
" :
O 2 U3
f 4 ~ 5
1 GS. Catch basin inspection - Record SSD Ur
lique Site ID here:
Condition: ~ Dntv lJ Clean
Not a hotspot (fewer than 5 circles aid no boxes checked) ~ Potential hotspot (5 to 10 circles but no boxes checked)
Q Confirmed hotspot i 10 to 15 circles and/or 1 bos checked) Q Severe hotspot (>15 eird.es audf'or 2 or more boxes checked)
Follow-np Action:
J. I 3,efer fbi immediate enforcement
1 1 Suggest fallow-up on-site inspection
~ Test fcr illicit discharge
H Include in future education effort
j_J Check to see if hotspot is an NPDES non-filer
H Ons ite non-res idenaal retrofit
~ Pervious ares restoration; complete PAA sheet and record
Unique Site ID here:
Q Schedule a review of storm water pollution, prevention plan
Notes;
A-6 Urban Suhwatershmi Restoratkm. Mania.!
31
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EPA/600/R-20/214
September 2020
Stormwater Hotspot Cover Sheet
Project Name:,
Applicant Name:,
Date:
Please indicate the appropriate hotspot operations for your project (check all that apply). If none apply check N/A,
Stormwater Hotspot Operations:
Vehicle Maintenance and Repair
Vehicle/Truck/Aircraft Fueling
Vehide/Truck/Machinery Washing
Vehicle/Fleet/Construction Equipment Storage Area
Petroleum Storage
Auto/Metal Scrap/Recyting
Solid Waste/Composting
Aircraft Maintenance
Grease Traps/Grease Storage
Loading and Unloading
Outdoor or Bulk Material Storage
Storage/Application of Fertilizers/Pesticides
Other:
N/A
Other Stormwater Permics/Plans Required For the Site:
__ Multi-Sector Genera) Permit. Permit P~
Other Industrial Stormwater Permit Permit #:
Storm Water Pollution FVevention Plan (SWPPP) Completed. Submit with site plan.
If "N/A" is checked, please include this sheet only with plan submittal.
If a multi-sector general permrt, other industrial stormwater permit, or SWPPP is not required for the site, please complete
and submit the attached Stormwater Hotspot Checklist with the site plan.
Stormwater Hotspot Checklist attached
S. Stormwater Hotspots
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EPA/600/R-20/214
September 2020
Stormwater Hotspot Checklist
Instructions; Complete the following site information;
Requirement
Description
Site
Description
List the type of facility and
facility address
Site
Operations
Describe the operations to
be conducted on-site.
Receiving
Waters
Name(s) of the receiving
waters). If drains to a mu-
nicipal storm sewer system,
include ultimate receiving
waters,
Site Materials
Significant materials to
be stored on site (specify
indoor or outdoor storage)
Stormwater
Management
Practices
List the stormwater man-
agement practices being
used to treat runoff from
the site. Where appropri-
ate, include description of
design modifications ap-
propriate for treatment of
hotspot runoff
Spill Prevention
and Response
Describe methods to
prevent spills along with
clean-up and notification
procedures.
Employee Edu-
cation Program
Description of employee
orientation and education
program.
West Virginia Stormwater Management & Design Guidance Manual
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EPA/600/R-20/214
September 2020
^Pollution Prevention
Best Management Practices for Controlling
Runoff from Gas Stations
Alachua County Water Quality Code
(Ordinance 02-27) prohibits non-
stormwater discharges into storm
water management systems.
The Storm Drain System was built to
collect and transport rain to prevent
flooding in urban areas. Anything that
flows or is discharged into the storm
drain system goes directly into local
creeks without any treatment.
The Sanitary Sewer System collects
and transports sanitary wastes from
interior building plumbing systems to
a wastewater treatment plant where
the wastewater is treated.
Best Management Practices (BMPs)
are methods and practices such as
good housekeeping, spill prevention,
or treatment measures to prevent or
minimize pollutant discharges.
Illegal Discharges or Illicit
Connections discharge non-storm
water to municipal storm drain
systems and contribute to water
pollution.
Urban Runoff is rain and any other
water that passes through and out of
developed areas into the storm drain
system and eventually to creeks and
other waters.
This Fact Sheet provides background
information and Best Management
Practices for gas station facilities.
Incidental spills from vehicular fueling,
when improperly managed, can result
in high loads of pollutants to our local
water bodies and may result in
violations of the Water Quality Code.
Storm water runoff from gas stations
can be a mixture of gasoline, diesel,
antifreeze and other automotive fluids
accumulated at the site. Following the
BMPs on the back of this sheet will
help you be in compliance with the
Water Quality Code and will make a
significant impact on improving water
quality in Alachua County.
Small spills from vehicle fueling can allow
pollutants to enter our creeks and lakes when
rainfall washes these materials into the storm
drain system.
34
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EPA/600/R-20/214
September 2020
Best Management Practices
Controlling possible contamination at its source is the best way to prevent
pollutants from ever reaching the storm water system. Here are some ways to
accomplish this:
• Maintain fuel dispensing areas using dry cleanup methods such as sweeping for
removal of litter and debris, or use of rags and absorbents for leaks and spills.
• Check dispenser hoses frequently, train employees on spill prevention, and
proper inspection of pumps.
• Provide spill kits.
• Provide an emergency shut-off button in plain view with bold red letters.
• Provide a roof over the area where refueling is done to prevent storm water
intrusion.
• Construct containment system to keep rainwater out of the fueling area. Small
speed bumps usually are enough.
• Do not allow patrons to change oil. antifreeze or conduct automotive repairs on
the property.
• Supervise refueling operations to make sure no spills occur, but if they do, that
fuel is drained from the sump and all absorbent materials are disposed of
properly.
Other Best Management Practices that can be implemented involve retro fitting of
storm drains with filtration devices, screens, or centrifuges to reduce pollutant
loadings before discharge.
Proper cleanup of incidental spills at gas
stations is essential to reducing the load of
pollutants that enters our creeks and lakes.
Many of these pollutants entering our water
bodies adsorb onto sediments degrading
benthic habitat as well as water quality in
aquatic ecosystems.
For more information contact:
Alachua County Environmental
Protection Department
201 SE 2"J Avenue, Suite 201
Gainesville, Florida 32601-6538
352/264-6800
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EPA/600/R-20/214
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Fueling Areas
SD-30
Design Objectives
Maximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
Protiibtt Dumping ol Improper
Materials
0 Contain Polulanls
0 Collect and Convey
Description
Fueling areas have the potential to contribute oil and grease, solvents, ear batten,' and, eoolant
and gasoline to the stormwater conveyance system. Spills at vehicle and equipment fueling
areas can bo a significant source of pollution because fuels contain toxic materials and heavy
metals that are nut easily removed by storimvater treatment devices.
Approach
Project plans must be developed for cleaning near fuel dispensers, emergency spill cleanup,
containment, and leak prevention.
Suitable Applications
Appropriate applications include commercial, industrial, and any other areas planned to haw
fuel dispensing equipment, including retail gasoline outlets, automotive repair shops, and major
non-retail dispensing areas.
Design Considerations
Design requirements for fueling areas are governed by Building
and Fire Codes and by current local agency ordinances and zoning
requirements. Design requirements described in this fact sheet
are meant to enhance and be consistent with these code and
ordinance requirements.
Designing New Installations
Covering
January 7003 California Stormwater BMP Handbook I of 3
New Development and Redevelopment
wwM.cabmptiandbooks.com
36
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EPA/600/R-20/214
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SD-30 Fueling Areas
fuelcl'-.iiHfiMiip m*.t* .-IhuiI.I provide an overhanging tool' structure or canopy, Theeowsr's
minimum dimension* must be equal to or greater than the mm within the grade tweak. The
cow* watt mm drain onto Ilie M dispensing area and the downspouts mast be routed to
prevent drainage across the fueling area, Ti»e fueling area should drain m the protect'a
treatment control BMPCs) prim to discharging to tint stormwater conveyance system. Note • II
fueling large equipment «r vehicles that would prohibit the use <#««« or tmi$, the feeSag
islatuishouy lK&signedtosoi?ici#Mty accommodate the krgerve!ii> i. .ml. in ,».«! ><>
prevent Mnakt nut-on and nmoft, Gimie to direct stormwater t® • dead-end swap,
Snrfimng
R*l dispensing areas should 1* paved with Portland cement eoncmt* {or wtpMm smooth
. • ».f *. .. 1 C|*l, ,, .4 * . . I , * t. .. I. » ... • ...... | I. , .1.1 S v *„.«« *.1 « *1 „t I f . . ..I. ..It J .... . i *
S*l! t» Ut ^ /. i CJI. lit 21 tOItCttH# MlOJitCI prt^tUOU^u I. il&pi lil II CO
pewlerl aspliAft paved areas surrounding the fueling area. This provision may I* made to sites
that haw pre-existing asphalt swltcet.
The concrete fuel dispensing area showli I |i», \t»>« (<• ( • >m «»;»i«i of 6.5 ft tmtm 11* ©outer of
each fuel dispenser, or the lengthat which the hum and noawJe assembly may lie operated pin* t
ft, whichever is less.
Dispensing areas should It aw an appropriate <«» j< »<}»hn,4, ai-j \ be v*p anted from
the mm *rf the site by a grade break that prevents roii-ot» ef urban runoff. (Slope is required to
be 2 to 4%»» some jurisdictiaas' storm water biw? ui.-nt m.l mmgatioa plans.)
Purling nmu should lie graded to drain toward adead-end sump. Runoff from
should l» tlirwfwl • way lw*»» fueling mm. Do not Immie atom «lmii»# »«t lit#
vicinity ®f III# fnaliag mm.
Kmtimmlmpmg KximUmg Immmltmtmmm
ViuSous »l®ii»»wiil*r iiM«in»||tiueiil and initig«ti«ti pkitm (SIJSMF, W'QMP»tie,}
definem !n««- ^ .miwunt*ofadditioaaiitttperviMiaarro,increaaes ingiwin
floor mm »ttd/or exterior con»tnKtit», anil Imiil 1»b (SDSMP), Ijbs Aagffles Comity
Department of Puttc Wurfcu, Muy 2002,
MotfcJ Shinclartl Krimii Storm Water Ban (SVSMf) far S111.1 IMego Con»»ly, Pott of
Sm» Diego, and OUaa in Sim Meg® C
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EPA/600/R-20/214
September 2020
Fueling Areas SD-30
Model Water Quality Management Han (WQM 1*1 for County of Orsaige, Orange County Flood
Control District, aiiti the Incorporated Cities of Orange County, Draft February 2003,
Ventura Countywidc Technical Gttititiic* Miami fer Stormwater Qiiitlity Control Measures,
July 200a,
tmm rcbmtittWKlboolu.com
% ef 1
38
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EPA/600/R-20/214
September 2020
Chapter 3 - Commercial and Industrial Activity
Volume 4 - Source Control Best Management Practices
3.2,2, BMP JO: Fueling at Dedicated Stations
This BMP applies to businesses and public agencies that operate a facility used exclusively
for the transfer of fuels from a stationary pumping station to vehicles or equipment. This
type of fueling station includes aboveground or underground fuel storage facilities, 'which
may be permanent or temporary. Fueling stations include facilities such as, but snot limited
to, commercial gasoline stations, 24-hour convenience stores, car washes, warehouses,
manufacturing establishments, maintenance yards, port facilities, marinas and boatyards,
construction sites, and private fleet fueling stations.
D - "! fl of P • " -i"
Typicaiy, stormwater contamination at fueling stations is caused by leaks or spills of fuels,
lubrication oils, radiator coolants, fuel additives, and vehicle washwater, These materials
contain organic compounds, oils and greases, and metals that can be harmful to humans and
aquatic life. These pollutants must not be discharged to the drainage system or directly into
receiving water,
A spill can be a one-time event, a continuous leak, or frequent small spills. All types must be
addressed.
Required BMP Elements
All BMPs related to fueling at dedicated stations must be consistent with the requirements of
the Seattle Fire Code (SMC, Chapter 22.600). The water quality requirements presented in
this manual are separate from, and in addition to, the requirements of the Seattle Fire Code.
These water quality requirements relate to fuel storage tanks, fuel dispensing equipment,
area lighting, spill control and secondary containment, signage, maintenance, and operations.
For current requirements, refer to the Seattle Fire Code.
New or substantially altered stations* require the following (refer to Figure 7}:
•Substantial alteration of fueling stations includes replacing the canopy or relocating,
replacing, or adding one or more fuel dispensers in such a way that the Portland cement
concrete (or equivalent) paving in the fueling area is modified. Addition of fuel tanks to a
site also triggers implementation of source control BMPs. For further guidance on determining
the actions considered substantial remodeling, contact the Department of Planning and
Development (DPP}.
* Construct fueling stations on an impervious concrete pad under a roof to keep out
rainfall and to prevent stormwater run-on. Pave the fueling island and containment
pad with Portland cement concrete or equivalent. Asphalt is not considered an
equivalent material.
• Use an oil control treatment BMP for contaminated stormwater and wastewater in the
fueling containment area with discharge to the sanitary sewer. Alternatively,
discharge to a dead-end sump.
Sto'mw«e> Knii! Directors' Rule 17-2017, DWW-200
AujjstlOl? B.W 10 3-11
39
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EPA/600/R-20/214
September 2020
Chapter 3 - Commercial and Industrial Activity
Best Management Practices
Volume 4 - Source Control
r Catch basin
Roof or canopy extending
past containment pad
-4-inch
sill/berm
Roof drains to
drainage system
Spill kit
Containment pad -
{Portland Cement
concrete)
Shut off valve
To sanitary sewer -
or dead-end sump
Figure 7. Fueling Island Schematic.
Design the fueling island (Figure 8) to minimize stormwater contamination, to control
spills, and to collect and direct contaminated stormwater and/or wastewater to a
pretreatment facility that will achieve the performance goal per 3,5.2.1. Oil Control
Treatment Volume 3 - Project Stormwater Control. The fueling island must be
designed in compliance with all applicable codes.
Drains from the fueling island must discharge to the sanitary sewer or to a dead-end
sump.
The fueling island spill containment pad must be designed with the following:
o A sill/berm (or equivalent control) raised to a minimum of 4 inches to contain
spilled liquids and to prevent the run-on of stormwater from the surrounding area.
Raised sills are not required at open-grate trenches that connect to an approved
drainage control system.
o A concrete containment pad sloped around the fueling island toward the fuel pad
drains. The slope of the drains must not be less than 1 percent.
Collect runoff from the fuel island containment pad and convey it to either (1) the
sanitary sewer—if approved by SPU and King County—using an approved oil/water
separator, or (2) hold for proper offsite disposal.
o For discharges to the sanitary sewer, a catch basin shall be installed upstream of
the oil/water separator.
o The dead-end sump must be easily inspected.
Directors' Rule 17-2017, DWW-200
Stormwater Manual
August 2017
40
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EPA/600/R-20/214
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Chapter 3 - Commercial and Industrial Activity
Volume 4 - Source Control Best Management Practices
d Collected runoff from the fuel island containment pad discharged to the sanitary
sewer must comply with Seattle Municipal Code SMC 21.16.300 - Prohibited
discharge of certain substances. Comply with pretreatment regulations prohibiting
discharges that could cause a fire or explosion (WAC, Section 173-216-060).
o The minimum spill retention volume of the oil/water separator or dead-end sump
shall be (1) 15 minutes for the flow rate of the dispensing mechanism with the
highest through-put rate, or (2) if the area is uncovered, the 15-minute peak flow
rate of the 6-month, 24-hour storm event over the surface of the containment pad -
whichever is greater. The volume of the spill containment sump should be a
minimum of 50 gallons with an adequate grit sedimentation volume.
o For further requirements and guidance related to the storage of fuel-contaminated
stormwater, refer to BMP 26 in Section 3.4.5.
• For discharges to the sanitary sewer, an automatic shutoff valve is required at the
discharge point of the oil water separator. The valve must be closed In the event of a.
spill. The spill control sump must be sized in compliance with the Seattle Fits Code
and the international Fire Code. For more information, contact the Seattle Fire
Department (206) 386-1400.
• Construct a roof or canopy over the fueling island to prevent precipitation from falling
directly onto the spill containment pad (Figure 8). The roof or canopy must;
c. At a minimum, cover the spill containment pad (within the grade break or fuel
dispensing area) and preferably extend several additional feet to reduce the
introduction of windblown rain.
o Roofs and canopies 10 feet or less in height must have a minimum overhang of
3 feet on each side. The overhang must be measured relative to the berm or other
hydraulic grade break.
o Roofs or canopies greater than 10 feet in height must have a minimum overhang of
5 feet on each side.
StmnivKer Manual Directors" Rute 17-2017, DWW-2X
AUJUK2017 BM? 10 3-13
41
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EPA/600/R-20/214
September 2020
Chapter 3 - Commercial and Industrial Activity
Best Management Practices Volume 4 - Source Control
Figure 8. Roof at Fueling Island to Prevent Stormwater Run-on.
Directors' Rule 17-2017, DWW-200 Stormwater Manual
3-14 BMP 10 August 2017
42
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EPA/600/R-20/214
September 2020
Chapter 3 - Commercial and Industrial Activity
Volume 4 - Source Control Best Management Practices
• Convey runoff collected in roof or canopy drains to a drainage system or receiving
water outside the fueling containment area. This vrill prevent the mixing of
uncontaminated runoff from the roof with contaminated runoff from the fueling
island.
• A roof or canopy may not be practical at fueling stations that regularly fuel vehicles
10 feet in height or more, particularly at industrial or transportation sites. Additional
BMPs or equivalent measures are required. At these types of fueling facilities, the
following BMPs apply, as well as all of the other required BMPs and fire prevention
requirements {Seattle Fire Code and Uniform Fire Code):
o The concrete fueling pad must be equipped with an emergency spill control device
that includes a shutoff valve for drainage from the fueling area.
o The shutoff valve must be closed in the event of a spill. An automatic shutoff valve
is preferred to minimize the time lapse between spill and containment.
Obtain all necessary permits for installing, altering, or repairing side sewers. Restrictions on
certain types of discharges may require pretreatment befote they enter the sanitary sewer.
The following BMPs or equivalent measures are required for all fueling stations:
• Implement all citywide BMPs (refer to Chapter 2).
• Train employees on the proper use of fuel dispensers.
• Do not use dispersants to dean up spills or sheens.
« Post signs related to the operation of fuel dispensers in accordance with the Seattle
Fire Code. For example, post "No Topping Off* signs near fuel dispensers flopping off
gasoline tanks results in spillage and vents gasoline fumes to the air),
• Ensure that the person conducting the fuel transfer is present at the fueling
dispenser/fueling pump during fuel transfer, particularly at unattended or self-service
stations. Post "Stay with Vehicle during Fueling" signage near fuel dispensers.
• Ensure that the automatic shutoff on the fuel nozzle is functioning property.
• Ensure that at least one designated trained person is available either on site or on call
at all times to promptly and properly implement spill prevention and cleanup. If the
fueling station is unattended, the spill plan most be visible to all customers using the
station, and the spill kit must also be accessible and fully stocked at all times.
• Keep suitable cleanup materials, such as dry adsorbent materials, on site to enable
employees to promptly dean up spills.
• Transfer the fuel from the delivery tank trucks to the fuel storage tank in impervious
contained areas and ensure that appropriate overflow protection is used.
Alternatively, cover nearby inlets/catch basins during the filling process and use drip
pans under all hose connections.
Sta.-mwa-er Manual Directors' Ruts 17-2017, DWW-200
Aujjk2017 B.W 1C 3-15
43
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EPA/600/R-20/214
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Chapter 3 - Commercial and Industrial Activity
Best Management Practices Volume 4 - Source Control
The following additional BMPs or equivalent measures are required for fueling over open
water, such as at marinas or boatyards:
• Have an employee supervise the fuel dock,
« Use automatic shut-off nozzles and promote the use of "whistles" and fuel/air
separators on air vents or tank stems of inboard fuel tanks to reduce the amount of
fuel spiled into receiving waters during fueling of boats.
• During fueling operations, visually monitor the liquid level indicator to prevent the
tank from being overfilled.
• The maximum amount of product received must not exceed 95 percent capacity of the
receiving tank.
• Spilled fuel and contaminated storrnwater must be conveyed either to the sanitary
sewer-if approved by SPU and/or King County-or to an oil removal treatment facility,
such as an American Petroleum Institute (API) oil/water separator, coalescing plate
oil/water separator, or equivalent treatment and then to a basic treatment facility
{refer to Volume 3 — Project Storrnwater Control).
Facilities and procedures for the loading or unloading of petroleum products must comply
with U.S. Coast Guard requirements. Refer to specifications in the Storrnwater Management
Manual for Western Washington (SWMMWW), Volume IV, Appendix IV-D (Ecology 2014).
• Provide information to all appropriate parties on collection and recycling programs for
oil, oil absorbing pads, and oil filters.
• Direct all appropriate parties to the proper disposal of all used hydrocarbon products
through the use of signs, mailings, and other means.
Directors* Rut* (7-2017, DWW-I00 StD.mv.it*- Manual
3-14 BMP 10 ijgs.lt 2317
44
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EPA/600/R-20/214
September 2020
I | ''M'"i II 1 -IIii. mi v! II ¦ ¦ i hi vh v,j<'in in II i .<;tices
This appendix lists examples of structural best management practices suitable for fueling facilities.
The included examples are:
• Oil/Grit Separator Units (USDOT, 2020)
• Select BMPS from the Connecticut Stormwater Quality Manual (CT DEP, 2004)
45
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EPA/600/R-20/214
September 2020
Fact Sheet - Oil/Grit Separator Units
The typical oil/grit separator (OGS) unit operates by settling sediment and particulate matter,
screening debris, and separating free surface oils from stormwater runoff. The unit typically
consists of three or four chambers. Figure 21 is a schematic of a typical water quality oil/grit
separator unit. In the case of a conventional OGS unit, the first chamber, termed the grit
chamber, is designed to settle sediment and large particulate matter; the access from the first
chamber to the second chamber is covered with a trash rack, which operates as a screen to
prevent debris from passing through to the second chamber. The second chamber, termed the oil
chamber, is designed to trap and separate free surface oils and grease from the stormwater
runoff. The third chamber houses the stormwater outlet pipe that discharges the overflow to the
storm drain system.
Figure 21. Schematic of an oil/grit separator (OGS)
(adapted from Schueler, 1987)
Side View
Stormdrain
Inlet
Permanent
Pool
113 M
of Storage Per
Contributing
Acre.
1.2 M Deep
Access
Manholes
Reinforced
Concrete
Construction
First Chamber
(Sediment
Trapping)
Second Chamber
(Oil Separation)
Third Chamber
Most OGS units are designed to be placed in highly impervious parking areas that drain about
0.4 ha (1 ac). Results from one OGS study conducted in the State of Maryland showed that the
treatment capacity of most conventional OGS units inventoried was less than 5.1 mm (0.2 in) of
runoff for the service area (Schueler and Shepp, 1993). Because of the limited retention capacity,
conventional OGSs are not capable of removing large quantities of stormwater constituents.
Instead, they are designed and implemented to control hydrocarbons, debris, large organic
matter, and coarse sediments that are commonly associated with heavily traveled parking areas.
Applicability
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The OGS unit is designed to trap and settle large sediments and particulate matter, debris, and
hydrocarbons from highly impervious areas such as parking lots, gas stations, loading docks, and
roadside rest areas. The OGS unit is constructed beneath the surface of the impervious area, and
as such does not require additional space. Because of this, it can be easily retrofitted into existing
impervious land use conditions, which makes it suitable for ultra-urban environments. Results
from an OGS study in the State of Maryland have shown that detention times for conventional
OGS units are generally less than 30 minutes during storm events (Schueler and Shepp, 1993).
Trapped sediments and particles tend to resuspend during subsequent storms and exit the
chambers. Because settling and trapping are temporary, actual pollutant removal occurs only
when the units are cleaned out. Therefore, these devices are best suited for an off-line
configuration where only a portion of the first flush is treated by the unit and clean out occurs
after every major storm event. A study produced by the Metropolitan Washington Council of
Governments showed that particulate matter within conventional OGS units remained the same
or decreased over a 20-month period (Shepp et al., 1992).
Effectiveness
Conventional OGS units have demonstrated poor pollutant removal capabilities. The primary
removal mechanism of the OGS is settling; with short detention times, and resuspension
occurring after every storm event, removal effectiveness is limited to what is physically cleaned
out after every storm. If the unit is not cleaned after each storm, resuspended trace metals,
nutrients, organic matter, and sediments will eventually pass through each chamber and into the
storm drain system.
A study performed on OGS units in the State of Maryland showed that negative sediment
deposition from storm to storm indicated that re-suspension and washout were a common
problem (Schueler and Shepp, 1993). The only constituent that was trapped with some efficiency
in the second chamber was total hydrocarbons. This was probably due to the inverted siphon,
which is designed to retain free surface oils and grease (Schueler et al., 1992; Schueler and
Shepp, 1993).
Siting and Design Considerations
The OGS unit is a structural BMP that is easily installed in areas of high imperviousness such as
parking lots, gas stations, commercial and industrial sites, and shopping centers, and even along
roadways. The OGS unit would be well suited for ultra-urban environments where available land
area is a major constraint. OGS units typically are sized for highly impervious drainage areas of
less than 0.4 ha (1 ac), though up to 0.61 ha (1.5 ac) is feasible. Locating the units off-line would
alleviate some of the problems associated with the retention and resuspension of pollutants.
The OGS units are designed using a three- or four-chamber configuration. Settling of larger
sediments, trash, and debris takes place in the first chamber. The primary function of the second
chamber is to separate oils and grease from the stormwater runoff; some absorption of oils and
grease to smaller sediments and settling will also occur in the first chamber. The third chamber
houses the overflow pipe. The OGS unit typically is sized based on the drainage area, which
often includes rooftops, and the percent imperviousness of the basin. One common practice is to
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size the unit based on a design storm to provide some amount of storage. In general, OGS units
are rectangular in shape, with the largest chamber being the initial settling chamber.
Approximate dimensions for an OGS unit located in a parking area that drains 0.4 ha (1 ac)
would be 1.82 m deep by 1.22 m wide by 4.23 long (6 ft deep by 4 ft wide by 14 ft long) (inside
dimensions). The length of the first chamber would be 1.82 m (6 ft) with 1.22 m (4 ft) for each of
the other two chambers.
Specific dimensions for each OGS design are dependent on site characteristics and local design
storm requirements. Improvement in OGS performance can be achieved by extending the interior
chamber walls to the top of the chamber, thereby eliminating recirculation and overflow from
one chamber to another. In addition, placing the OGS off-line from the main stormwater system
helps to reduce resuspension of oil and grit.
Additional design examples and information can be found in Controlling Urban Runoff: A
Practical Manual for Planning and Designing Urban BMPs (Schueler, 1987), and Northern
Virginia BMP Handbook: A Guide to Planning and Designing Best Management Practices in
Northern Virginia (NVPDC, 1992). Because studies have shown that water quality inlets are a
marginal method for removing particulate matter (Schueler and Shepp, 1993), other design
references (Claytor and Schueler, 1996) do not recommend them for sand filter pretreatment.
Maintenance Considerations
Very few structural or clogging problems have been reported during the first five years of OGS
operation (Schueler and Shepp, 1993). The OGS unit should be inspected after each major storm
event. Clean-out would require the removal of sediments, trash, and debris. In reality, OGSs are
rarely cleaned out after every storm because such intensive maintenance is beyond most budgets.
The removal of oily debris, sediments, and trash might require disposal as a hazardous waste.
However, some local landfills may accept the sediment and trash if it is properly dewatered.
Cost Considerations
OGS units can be either cast-in-place or precast. Precast concrete chambers are usually delivered
to the site partially assembled and tend to cost slightly less than the cast-in-place option. The cost
associated with a cast-in-place concrete OGS unit is a function of several parameters.
Excavation, gravel bedding, amount and size of rebar, amount of concrete and form work, and
grate and clean-out access holes all contribute to the total cost of the OGS unit. In 1992, OGS
units were reported to cost between $5,000 and $15,000 fully installed. On average, costs per
inlet ranged from $7,000 to $8,000 (Schueler et al., 1992).
References
Botts, J., L. Allard, and J. Wheeler. 1996. Structural Best Management Practices for Storm Water
Pollution Control at Industrial Facilities. Watershed '96, pp. 216-219.
48
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EPA/600/R-20/214
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Claytor, R.A., and T.R. Schueler. 1996. Design of Stormwater Filtering Systems. The Center for
Watershed Protection, Silver Spring, MD.
NVPDC. 1992. Northern Virginia BMP Handbook: A Guide to Planning and Designing Best
Management Practices in Northern Virginia. Prepared by Northern Virginia Planning District
Commission (NVPDC) and Engineers and Surveyors Institute.
Schueler, T.R. 1987. Controlling Urban Runoff: A Practical Manual for Planning and Designing
Urban BMPs. Metropolitan Washington Council of Governments, Washington, DC.
Schueler, T.R., P. A. Kumble, and M.A. Heraty. 1992. A Current Assessment of Urban Best
Management Practices - Techniques for Reducing Non-Point Source Pollution in the Coastal
Zone. Metropolitan Washington Council of Governments, Department of Environmental
Programs, Anacostia Restoration Team, Washington, DC.
Schueler, T.R., and D. Shepp. 1993. The Quality of Trapped Sediments and Pool Water Within
Oil-Grit Separators in Suburban Maryland. Chapter 6. Interim Report for the Maryland
Department of the Environment Hydrocarbon Study, 81-115.
Shepp, D., D. Cole, and F.J. Galli. 1992. A Field Survey of the Performance of Oil/Grit
Separators. Prepared for the Maryland Department of the Environment by the Metropolitan
Washington Council of Governments, Department of Environmental Programs, Washington, DC
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Treatment Practice Type
Primary Treatment Practice
Secondary Treatment Practice •
Deep Sump Catch Basins
Stormwater Management
Benefits
Pollutant Reduction
Sediment ¦
Phosphorus
Nitrogen
Metals
Pathogen*
Roatables
Oil and Grease
Dissolved Pollutants
Runoff Volume Reduction
Runoff Capture
Grourvdwater Recharge
Stream Channel Protection
Peak How Control
1
Key
¦
¦ Partial Benefit
n Low or Unknown
Benefit
Si«urve N««npe .storms
> Cannot effectttely remote soluble pollutants or fine fxtrtkles.
) May become mosquito breeding habitat betueen rainfall etents
(EPA. 2002).
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Suitable Applications
O For limited removal of trasb, debris, oil and
greasr, and sediment from stormicater runoff
from relatively small impervious areas (parking
his, gas stations, arid other commercial
det^elopmenl).
3 To providepretreatmerit for other storm water
treat met it practices.
O For retrofit of existing stormtmler drainage
Systems So provide Jloatahfes and limited sedi-
ment control. See Chapter Ten for examples
of catch basin storm water retrofits.
Design Considerations
Drainage Area: The contributing drainage urea to
any deep sump catch basin generally .should not
exceed 1 i acre of impervious cover.
Design; Catch basin performance is related to the
volume of the sump below the outlet A recom-
mended catch basin swing criterion relate* the catch
basin .sump depth to the diameter of the outlet pipe
(D), as follows.
0 7 he sump depth (distance from the bottom of the
outlet pipe to the bottom of the basin) should he
at feast 4D and increased if cleaning is infre-
quent or if the contributing drainage area has
high sediment toads
) 7 he diameter if the catch basin should ire at
least -t feet
> 't he bottom of the outlet pipe shauld !>e at
least 4 feet from the bottom of the catch hasiti
inlet grate.
(Lager et al., 1997). Where high sediment loads are
anticipated, the catch basin can be sized to accom-
modate the volume of sediment tliat enters the
system, with a factor of safety (Pitt et al., 2000).
for outlet pipes larger than 24 inches in diameter.
Catch basin hoods tliat reduce or eliminate siphoning
should be used Catch basins stomld he watertight to
maintain a permanent pool of water and provide
higher floatable capture efficiency. Catch basin
inserts, which are described elsewhere in this chapter,
can be used to filter runoff entering the catch basin,
although then effectiveness is unproven and they
require frequent sediment removal-
Maintenance: y pica I maintenance of catch basins
includes trash removal from the grate (and screen or
other debris-capturing device if one is used) and
removal of sediment using a vacuum truck. Studies
have shown that catch basins can capture sediments
up to approximately 50 percent erf' the sump volume.
Ahove this volume, catch basins reach steady state
due to re-suspension of sediment (Pitt, 1984).
Frequent cieanout maintains available sump volume
for treatment purposes.
Catch basins should be cleaned at least annually, after
the snow arid ice removal season is over and as soon
as possible lx*fore spring rainfall events. In general, a
catch basin should be cleaned if the depth of deposits
is greater than or equal to one-half the dejtfh from the
bottom of the basin to the invert of the lowest pipe in
the Ixisin (F.PA, 1999) If a catch basin significantly
exceeds this one-half depth standard during the
annual inspection, then it should be cleaned more
frequently.
In addition, areas with higher pollutant loadings or
discharging to sensitive water bodies should also be
cleaned more frequently (WEF and ASCE, More
Irequent cleaning of drainage systems may also be
needed in areas with relatively flat grades or low
flows since they may rarely achieve sufficiently high
flows for self-flushing (Fergusen et a I., 1997).
Plans for catch basins should identify detailed inspec-
tion and maintenance requirements, inspection and
maintenance schedules, and those parties responsible
lor maintenance.
Where feasible, deep sump catch basins should be
designed as off-line systems (i.e., collectors or pre-
ceded by a flow diversion structure) to minimize
re-suspension of sediment during large storms. The
basic design should also incorporate a hooded outlet
consisting of an inverted elbow pipe to prevent float-
able materials and trash from entering the storm
drainage system Hooded outlets may be impractical
Sediment Disposal: Polluted water or sediment
removed from catch basins should be properly
handled and disposed in accordance with local, state,
and federal regulations Before disposal, an appropri-
ate chemical analysis of the material should be
performed to determine proper methods for storage
and disposal (EPA, 1999)-
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Figure 11-S3-1 Typical Deep Sump Catch Basin
Catch bas»n frame and grate
Steps -
Riser section .
Base section -
Weepbole
• Hooded outlet p«pe
J
SfRircc Adapted fwm L'tlxin S(r»tmwater Management .md Technology- Upclulc and I nn, OiikIc, 19^7
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K
References
Ferguson, 1", Gignac. R., Stoffan, M., Ibrahim, A., and
J. Aldrich. 1997. Rouge fitter national Wet Weather
Demonstration Project; Cost Estimating Guidelines,
Best Management Practices and Engineered Confirms
Wayne County, Michigan.
lager. J . Smith. W. Finn. R . and E. Fuinemore, 1997
Urban Stormwater Management and Technology.
Ufxtate and User's Guide Prepared for U.S.
Environmental Protection Agency EPA-600/K-77-014
Pin, R. and P. BLssonnette. 1984. BelJei'ue U/fkitt
Runojf Program Summary Report. U.S. Knviron menial
Protection Agency. Water Planning Division
Washington, D.C..
Pitt, R.M., Nix. S., Durrans, .S R.. Burian, S., Voorhecs,
J., and J Martinson. 2000 Guidance Matuutl for
Integrated lVe/ Weather Flott (WWF) Collection and
Treatment Systems for Xetely Vrttanizeil Arena (Sew
WWF Systems) U.S. Environmental Protection
Agency. Office of Research and Development
Cincinnati, Ohio.
United States Environmental Protection Agency (EPA)
1999. Ptvhmtnary Data Summary of Urban Storm
Water Best Management Practices EPA 821-R99-OI2.
United Stales Environmental Protection. Agency (EPA)
2002. National Menu of Best Management Practices
for StormmUer Phase If UHL:
linn , wivw.cna.miv. nnilfs ni«'nin>nimnvnwnu him
Last Modified January 24, 2002.
Water Environment Federation (WEF) and American
Society of Civil Engineers
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Treatment Practice Type
Primary Treatment Practice
Secondary Treatment Practice •
Stormwater Management
Benefits
Pollutant Reduction
Sediment ¦
Phosphorus
Nitrogen
Metals
Pathogen*
Roatables
Oil and Grease
Dissolved Poflutants
Runoff Volume Reducoon
Runoff Capture
Groundwater Recharge
Stream Channel Protection
Peak How Control
Key
_
¦
¦ Partial Benefit
n Low or Unknown
Benefit
Suitable Applications
Pretreatment
Treatment Tw
Utra-Urban
Stofmwater Retrofits
Otfier
Oil/Particle Separators
.vniftr City of Komvilli- Jihii
Description
OU/paitklc separators, also called oiLgril separators, water quality inlds,
and oilwater separators, consist of out* or more chambers designed tci
remove trash and debris and to promote sedimentation of coarse materials
and separation of free oil (as opposed to emulsified or dissolved oil) from
sturmwater runoff Oil. panicle separators ait typically designed as oil--line
systems for pretrealment of runoff from small impervious areas, and there-
fore provide minimal attenuation of How Due to their limited storage
caput HV and volume, these systems have only limned watet quality treat-
ment capabilities While oil/paitkk' separators can effectively trap
floatable* and oil and grease, they are ineffective at removing nutrients and
metals and only capture coarse sediment
.Several conventional oil particle separator design variations exist, including
) Coriiwiiona!grtuHty separators (water t/uaiity inlets)
) CoaJesiltt# plate lull water) separators
Conventional gravity separators (also called A men tan Petroleum Institute
Of API separators) typically consist of three baffled chambers and rely «wi
gravity and the phy sical characteristics of ml and sediments to achieve pol-
lutant removal The first chamber is a sedimentation chamber where
floatable debits is trapped and gravity settling of sediments occurs The
second chamber is designed primarily for oil separatum, and lite third
chamber provides additional settling prior to discharging to the storm drain
system or downstream treatment practice Many design modifications exist
to enhance system performance including the addition of orifices, inverted
elbow pipo and diffusion structures Figures 1I-S4-1 and 11-S4-2 illus-
trate several examples of conventional gravity separator designs
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Conventional gravity separators used for sconnwater
treatment are .similar to wastewater oil/water .separa-
tors. hut have several important differences Figure
11-S4-3 shows a typical oil/water separator designed
to treat wastewater discharges from vehicle washing
and floor drains. As shown in the figure, wastewater
separators commonly employ a single chamber with
tee or elbow inlet and outlet pipes. The magnitude
anil duration t>f storm water Hows art* typtcally much
more variable than wastewater flows and, therefore,
the single-chamber design does not provide sufficient
protection against re-suspension of sediment dunng
runoff events. Single-chamber wastewater oil water
separators should not be used for stormwater
applications
The basic gravity separator design can \x- modified by
adding coalescing plates to increase the effectiveness
of oil/water separation and reduce the size ol tile
required unil. A series of coalescing plales, con-
structed of oil-attracting materials such as
polypropylene and typically spaced an inch apart,
attract small oil droplets which l*egin to concentrate
until they are targe enough to float to ihe water sur-
face and separate from the stormwater (EPA. 1999)
Figure 11-S4-4 shows a typical coalescing plate
separator design.
A number of recently developed proprietary separator
designs also exist. These are addressed in the
Hydrodynamk: Separators section of this chapter
Truck loading areas
Gas stations
~ Refueling areas
~ Automotive refiuii) facilities
~ Fleet maintenance yards
~ Commercial vehicle washing facilities
~ / ndlist rial facilities.
O To provide pretrecitment for other stormwater
treatment practices
> For retrofit of existing slarmttttier drainage
systems, particularly in highly developed
(ultra- urban) areas
Design Considerations
Drainage Area.: The contributing drainage area lo
conventional oil particle separators generally should
be limited to one acre or less of impervious cover.
Separators should only be used in an off-line config-
uration to treat the design water quality flow (peak
How associated with the design water quality vol-
ume) Upstream diversion structures can be used to
divert higher flows around the separator On-line
units receive higher flows that cause increased turbu-
lence and re-suspension of settled material
(EPA, 1999).
Reasons for Limited Use
> Limited pollutant removal Cannot effectively
remote soluMe pollutants or fine particles.
1 > Can become a source of pollutants due to
re-suspension of sediment unless maintained
frequently. Maintenance often neglected
("out of sight and out of mind"/
O Limited to relatively small contributing
drainage areas
Suitable Applications
> For limited removal of!rush, debris, oil and
grease, and sediment from stormwater runoff
from relatively small impervious areas with
high traffic vttlumes or btgh pot en tied for spills
such as;
~ Parking lots
J Streets
Sizing/Design: i'he combined vol tune of the perma-
nent pools in the chambers should lie i(K) cubic feel
per acre of contributing impervious area The pools
should be at least •=» feet deep, and the third chamber
should also Ijc used as a permanent pool.
A trash rack or screen should lxj used to cover the
discharge outlet and orifices Iteiween cltambers. An
inverted elbow pipe should be located between the
second and third chambers, and the bottom of the
elbow pipe should he at least 3 feet below the second
chamber permanent pool. Each chamber should be
equipped with manholes and access steps'ladders for
maintenance and cleaning Potential mosquito entry
points should lie sealed (adult female mosquitoes can
use openings as small as I L6 inch to access water for
egg laying).
Maintenance: Maintenance is critical for proper
operation of oil/purl icle separators. Separators thai
arc n+>: maintained can be significant sources of pol-
lution. Separators should be inspected at least
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Figure I I-S4-I Example of Conventional Gravity Separator Design
(Design Alternate I)
Elbow invert (12" diameter) at
permanent water surface elevation,
extended 3' below surface ¦
Typical manhole access with steps
at each chamber
Baffle to slow stormwater
Permanent water.
surface elevation \
Inlet
4' minimum
Trash rack over every opening
(located below water surface)
Outlet
' Typically install a 6" diameter orifice
for every 15" of basin width
(i.e., four orrfices for a 5' wide basin)
Simri t' i'.C.x i/ Kni>\ villi* i'.K.H
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Figure I I-S4-2 Example of Conventional Gravity Separator Design
(Design Alternate 2)
Ladder
20' max.
Inflow recommendec
Access cover (typ.) w/ ladder access
to vault If >1250 sf. provide 5' x 10'
removable panel over inlet/outlet pipe
Inlet pipe (8" min.)
Manhole
High flow bypass
Ventilation pipes
(12" min.) at comers
Outlet pipe (8" min.)
shut of valve w/
riser & valve box
Plan View
Varies (can be
constructed on
grade without
risers)
Removable tee
(recommended)
Sludge retaining baffle
Oil retaining baffle
U3-L/2
(appro*)
L=5W
Section View
gravity drain
Source: Wash injstiHv 2000.
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Figure 11-S4-3 Example of a Typical Wastewater Oil/Water Separator
Inlet '
Minhnlm
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Figure II-S4-4 Example of Coalescing Plate Separator Design
ladder
shut off valve w/
riser & valve box
oudet pipe (8* min.)
coalescing place pack
access cover
(over oudet)
Plan View
Ventilation pipes 12"
min. at corners
High flow bypass
access door allowing removal of
place pack or provide full length
removable covers across entire cell
submerged .nlec pipe
varies (can be constructed
on grade without risers)
L'3 min.
(L/2 recomm.)
mm
(L/4 recomm.)
Coalescing plate pack
Inlet weir-solids retaining
bafRe or window wall
(see text)
Section View
StiutCC Wa&IlkriKton, iiXX).
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monthly and typically need to t>e cleaned every one
to >ix month*. Typical maintenance includes removal
of accumulated oil and gieuse. floalables, and sedi-
ment using a vacuum truck or other ordinary catch
basin cleaning equipment
Huns for oil/particle separators should identify
detailed Inspection and maintenance requirements,
inspection and maintenance .schedules, and those par-
lies responsible for maintenance
Sediment Disposal: Polluted water or sediment
removed front separators should be properly handled
and disposed of in accordance with local, slate, and
federal regulations. Before disposal, appropriate
diemicai analysts of the material should he performed
to determine proper methods for storage and disposal
References
Connecticut Department of Environmental Protection
(DEC). 2001 General Permit for the Discharge of
Vehicle Maintenance Wastewater Issuance Date
January 23. 2001
City of Knoxville 2001 Knoxville UMP Manual City of
Knoxville Engineering Department Knoxville.
Tennessee
United States Environmental Protection Agency (EPA)
2002 National Menu of Best Management Practices for
Siormwater Phase U L'RL
hlip www.epa.gov,-npcK-s. menwrthmps. menu htm.
Last Modified Januaiy 24. 2002.
United Slates Environmental Protection Agency (EPA).
1W Storm Wbter Technology Pact Sheet Writer
Quality Inlets EPA 832-F-99-029 Office of Water
Washington, D.C.
Washington State Department of Ecology
(Washington) 2000 Siormwater Management Manual
lor Western Washington, Final Draft. Olympia,
Washington
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Treatment Practice Type
Primary Treatment Practice
Secondary Treatment Practice •
Hydrodynamic Separators
Stormwater Management
Benefits
Pollutant Reduction
¦
Phosphorus ¦
Nrtrogen ¦
Melals ¦
Pathogen
¦
Oil and Grease
Dissolved Pollutants
RunoffVolume Reduction
Runoff Capture
Graurvdwater Recharge
Stream Channel Protection
Peak How Control
Key
¦
¦ Partial Benefit
n Low or Unknown
Benefit
Suitable Applications
Pretreatment I
Treatment Train I
l*b»Urban I
Stormwater Retrofits I
Other' (Industrial applications) I
Source: Adapted tnmt City ui Kiwncviltc. Ml
Description
This group of stoiiiiwater treatment technologies includes a wide variety of
proprietary devices that luve been developed in recent years Tliese
dcvict's, also known as swirl WHKcntratrws. arc modifications of traditional
oil/particle separators that commonly rely on vortex-enhanced sedimenta-
Uun U ii pollutant removal They are designed lo remove coarse solids and
large oil droplets and consist prtmanly of cylindrical-shaped devices lhat arc
designed lo fil in or adjacent to existing stormwater drainage systems
(Washington. 2000). In these structures, storatwaier enters as tangential inlet
How into the cylindrical structure As the stormwater spirals through the
chamber, the swirling motion causes Ihc sediments lo settle by gravity,
removing them from ihe stonmvaier (EPA. 2tX)2> Some devices also have
compartments or chatnlieis to trap otl and oilier floatable-. Figure 11-S10
1 show s several examples of common hydrodvnamic separator designs (no
endorsement of any panicular product is intended)
Allliough swirl concentration ts the most common technology used in
hydmdvnamic separator*, others use circular screening systems or engi-
neered cylindrical sedimentation Circular screened systems use a
combination of screens, tallies, and mice and outlet .structures to remove
debris, large particle total suspended .solids, and huge oil dmplet.s.
stntcturrs using engineered cylindrical sedimentation use an arrangement
of internal haflles and an oil and sediment storage compartment Oil ier pn>-
pnetary technologies incorporate an internal high flow bypass w ith a bailie
system in a rectangular slmcture to .simulate plug flow operation. When
properly engineered and tested, these systems can also lie an improvement
over conventional Oil/panicle separators and offer removal efficiencies sim-
ilar to swirl clumber technologies. Sorhcnts can also l>c added to these
structures to increase removal efficiency i Washington. 20(M>>
Reasons for Limited Use
3 limited peer-reviewedperformance data Some independent studies
suggest only moderate pollutant remotaJ. (See Chapter Six for a
description of tJw rectmimended efaliuttion criteria and prittoctds
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for consideration of these technologies as primary
treatment practices).
> Cannot effectively remove soluble pollutants or
fine particles.
3 Can become a source of pollutants due to
re-suspension of sediment unless maintained
regularly. Maintenance often neglected / 'out
of sight and out of mind").
Suitable Applications
3 Wberu bigbei sedtment and pollutant removal
efficiencies are required ot era range of flow
conditions, as compared to comvntional oil/
particle or oil/grit separators
O For limited removal of trash, debris, oil and
grease, and sediment from stormuater runoff
from relatively small impervious areas ti ith
high traffic volumes or high jxAential far spills
such as.
~
Parking lots
~
Streets
J
Truck loading areas
J
Gas stations
~
Refueling areas
~
Automotive repair facilities
~
Fleet maintenance yards
~
Commercial vehicle washing faciluie
~
Industrial facHitws
3 To prot ide pretreatment for other storm water
treatment practices
O For retrofit
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Figure 11-SI 0-1 Examples of Common Hydrodynamic Separator Designs
Design Example I
Diversion weir
Inlet
Profile View
Design Example 3
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September 2020
References
Cily of Knoxvillu 2001. Knoxrifte BMP Mantled. City
of Knoxville Engineering Department, KnoxviJle,
Tennessee.
t inned Stales Environmental Proiection Agency (UFA )
2002 National Menu of Best Management Practices
for Stormwater Phase II. URL;
Imp fiv.1 |x n , ripil.";. ni.'i lTmi|Wm«iu litrn
Last Modified January 24, 2IW2.
Washington Slate Department of Ecology
(Washington). 2000. Sknmimter Management Manual
for Western Washington, I'inal Draft Olympla.
Washington.
2004 Connecticut Stormwntcr Quality Manual
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EPA/600/R-20/214
September 2020
Chapter 3 - Commercial and Industrial Activity
Volume 4 - Source Control Best Management Practices
d Collected runoff from the fuel island containment pad discharged to the sanitary
sewer must comply with Seattle Municipal Code SMC 21.16.300 - Prohibited
discharge of certain substances. Comply with pretreatment regulations prohibiting
discharges that could cause a fire or explosion (WAC, Section 173-216-060).
o The minimum spill retention volume of the oil/water separator or dead-end sump
shall be (1) 15 minutes for the flow rate of the dispensing mechanism with the
highest through-put rate, or (2) if the area is uncovered, the 15-minute peak flow
rate of the 6-month, 24-hour storm event over the surface of the containment pad -
whichever is greater. The volume of the spill containment sump should be a
minimum of 50 gallons with an adequate grit sedimentation volume.
o For further requirements and guidance related to the storage of fuel-contaminated
stormwater, refer to BMP 26 in Section 3.4.5.
• For discharges to the sanitary sewer, an automatic shutoff valve is required at the
discharge point of the oil water separator. The valve must be closed In the event of a.
spill. The spill control sump must be sized in compliance with the Seattle Fits Code
and the international Fire Code. For more information, contact the Seattle Fire
Department (206) 386-1400.
• Construct a roof or canopy over the fueling island to prevent precipitation from falling
directly onto the spill containment pad (Figure 8). The roof or canopy must;
c. At a minimum, cover the spill containment pad (within the grade break or fuel
dispensing area) and preferably extend several additional feet to reduce the
introduction of windblown rain.
o Roofs and canopies 10 feet or less in height must have a minimum overhang of
3 feet on each side. The overhang must be measured relative to the berm or other
hydraulic grade break.
o Roofs or canopies greater than 10 feet in height must have a minimum overhang of
5 feet on each side.
StmnivKer Manual Directors" Rute 17-2017, DWW-2X
AUJUK2017 BM? 10 3-13
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September 2020
Appendix C: Online Resources
This appendix provides weblinks related to hydraulic control at fueling facilities
Best Managen dices Databases
International Stormwater BMP Database
The Interstate Technology and Regulatory Council (ITRC) BMP Screening Tool
NPDES National Menu of Best Management Practices (BMPs) for Stormwater Documents
Stormwater Best Management Practices in an Ultra Urban Setting: Federal Highway
Administration
Stormwater M I m>' Imi
The Center for Watershed Protection: Online Watershed Library (OWL)
Wiki of State Stormwater Manuals (Courtesy of Minnesota Polluti trol Agency)
11 ii'i I Diisi ¦ >1""i I r tabases
Analysis, Research and Information on Accidents (ARIA)
eMARs: Major Accident Reporting System: European Commission. Joint Research Center
eNatech Database: European Commission, Joint Research Centre
Failure and Accidents Technical information System (FACTS)
National Response Center: U.S. Coast Guard
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v>EPA
United States
Environmental Protection
Agency
PRESORTED
STANDARD
POSTAGE & FEES
PAID EPA
PERMIT NO. G-35
Office of
Research and
Development
(8101R)
Washington, DC
20460
Offal Business
Penalty for Private Use$300
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