Bridge Deck Runoff: Water Quality Analysis and BMP Effectiveness FINAL REPORT Prepared for the State of Alaska

Full text

Bridge Deck Runoff: Water Quality Analysis and
BMP Effectiveness
FINAL
REPOR
T
Prepar
e
d
for
Alaska University Transportation Center
Alaska
Depar
tmen
t
of Transportation and Public
F
acilities
Robert Perkins
Yildiz Dak Hazirbaba
University of
Alaska Fairbanks
The Alaska University Transportation Center
Institute of Northern Engineering
Fairbanks, AK 99775
Report # RR08.13
December
2010
1

Cover photo courtesy of R.A. Perkins
Acknowledgements
This work has been supported by the Alaska University Transportation Center under US
RITA Grant G00003238 and Alaska Department of Transportation and Public Facilities
grant, Project Number T2-08-11. Any opinions expressed in this material are those of the
authors and do not necessarily reflect the views of the funding agencies.
Recommended Citation:
Perkins, R.A., and Hazirbaba, Y.D. (2010). Bridget Deck Runoff: Water Quality and
BMP Effectiveness. University of Al;aska Fairbanks, Alaska University Transportation
Center. Report INE/autc10.04. Fairbanks, Alaska

TABLE OF CONTENTS
LIST OF ABBREVIATIONS AND ACRONYMS .......................................................... vi
EXECUTIVE SUMMARY ................................................................................................ 1
CHAPTER 1 ....................................................................................................................... 4
1.0 INTRODUCTION ........................................................................................................ 4
CHAPTER 2 ..................................................................................................................... 10
2.0 BASIC INFORMATION ............................................................................................ 10
2.1 Stormwater in General ................................................................................................ 10
2.2 Highway Runoff in General ........................................................................................ 11
Table 1 Highway runoff constituents and their primary sources ...................................... 12
Table 2 National recommended water quality criteria for priority toxic pollutants. ........ 14
CHAPTER 3 ..................................................................................................................... 15
3.0 BEST MANAGEMENT PRACTICES (BMPs) ......................................................... 15
3.1 National Menu of Stormwater Best Management Practices ....................................... 16
3.1.1........................................................................................................................... 16
3.1.2........................................................................................................................... 16
3.1.3........................................................................................................................... 16
3.1.4........................................................................................................................... 17
3.1.5........................................................................................................................... 17
3.1.6........................................................................................................................... 18
3.2 Highway Runoff BMPs............................................................................................... 18
3.2.1 Non-Structural BMPs....................................................................................... 18
3.2.1.1 Pollution Prevention.............................................................................. 18
3.2.1.2 Street sweeping ..................................................................................... 19
3.2.1.3 Litter Control ........................................................................................ 19
3.2.1.4 Catch basin cleaning ............................................................................. 19
3.2.1.5 Spill prevention and Clean-up .............................................................. 19
3.2.1.6 Salt storage and application .................................................................. 20
3.2.1.7 Deicing Controls ................................................................................... 20
3.2.2 Runoff Volume Minimization.......................................................................... 21
3.2.2.1 Using Compost as a Soil Amendment .................................................. 21

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3.2.3 Institutional BMPs ........................................................................................... 21
3.2.3.1 Pollutant Trading .................................................................................. 21
3.2.3.2 Mitigation Banking ............................................................................... 21
3.2.3 Structural BMPs ............................................................................................... 22
3.2.3.1 Bioretention........................................................................................... 22
3.2.3.2 Stormwater planter ................................................................................ 22
3.2.3.3 Ponds ..................................................................................................... 23
3.2.3.4 Constructed Wetland ............................................................................. 23
3.2.3.5 Stormwater Wetland ............................................................................. 23
3.2.3.6 Infiltration Practices .............................................................................. 23
Infiltration Basin ........................................................................................... 23
Infiltration Trench ......................................................................................... 24
Extended Detention Basin............................................................................. 24
Soakaway pit/ drywell................................................................................... 24
3.2.3.6 Filtration Practices ................................................................................ 24
Media Filter ................................................................................................... 24
Sand and organic filters ................................................................................ 25
Grassed swales .............................................................................................. 25
Grass drainage channel ................................................................................. 25
3.2.4 Supplemental Pre- and Post Treatment BMPs ................................................. 26
3.2.4.1 Drain Inserts .......................................................................................... 26
3.2.4.2 Catch basins insert ................................................................................ 26
3.2.4.3 Wet vault ............................................................................................... 26
3.2.4.3 Floatable skimmer ................................................................................. 26
3.2.4.4 Water quality inlets ............................................................................... 27
3.2.4.5 Vortex Separator ................................................................................... 27
3.2.4.6 Buffer boxes .......................................................................................... 27
CHAPTER 4 ..................................................................................................................... 28
4.0 BRIDGE DECK RUNOFF MANAGEMENT ........................................................... 28
4.1 Bridge Definition and Constraints .............................................................................. 28
4.2 Bridge Deck Runoff Applicable BMPs ...................................................................... 29
4.2.1 Nonstructural BMPs ......................................................................................... 30
4.2.1.1 Street Sweeping .................................................................................... 30
4.2.1.2 Catch Basin Cleaning ............................................................................ 31

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4.2.1.3 Scupper Cleaning .................................................................................. 32
4.2.1.4 Deck Drain Cleaning............................................................................. 32
4.2.1.5 Deicing Controls ................................................................................... 32
4.2.1.6 Traffic Management .............................................................................. 33
4.2.1.7 Maintenance Practices .......................................................................... 33
Bridge painting.............................................................................................. 33
Bridge cleaning ............................................................................................. 34
4.2.2 Structural BMPs ............................................................................................... 35
4.2.2.1 Structural Off-Bridge BMPs ................................................................. 35
Vegetated Buffer Strip .................................................................................. 36
Silt fence ....................................................................................................... 36
Rock or Compost Bags ................................................................................. 36
Riprap ............................................................................................................ 36
Temporary Sedimentation Basins ................................................................. 36
Filter Bag ...................................................................................................... 36
Floatation Silt Curtain ................................................................................... 37
Erosion control blanket ................................................................................. 37
Fiber Logs ..................................................................................................... 37
Mulch ............................................................................................................ 37
4.2.2.2 Structural On-Bridge BMPs .................................................................. 37
CHAPTER 5 ..................................................................................................................... 38
5.0 BMPs IN COLD CLIMATES .................................................................................... 38
Table 3 Challenges to the Design of Runoff Management Practices in Cold Climates ... 39
5.1 Practices in Cold Climate States ................................................................................. 40
5. 1.1 Maine DOT ..................................................................................................... 40
5.1.2 Minnesota DOT ............................................................................................... 41
5.1.3 Washington DOT ............................................................................................. 42
5.1.4 Wisconsin DOT ............................................................................................... 43
Figure 1 Pre-treatment chamber and cartridge filter bay .................................................. 44
5.2Practices in Other States ....................................................................................... 45
5.3 Practices in Some Other Countries ............................................................................. 45
CHAPTER 6 ..................................................................................................................... 47
6.0 ALASKA .................................................................................................................... 47
6.1 Climate ........................................................................................................................ 47

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Figure 2. Alaska Climate Zones........................................................................................ 47
6.1.1 Arctic Zone ...................................................................................................... 48
6.1.2 Continental Zone .............................................................................................. 48
6.1.3 Maritime Zone ................................................................................................. 48
6.1.4 Transitional Zone ............................................................................................. 49
6.1.5 Summary .......................................................................................................... 49
6.2 Current BMPs and Recommendations ........................................................................ 49
6.2.1 Deicing Practices ............................................................................................. 50
6.2.2 Snow Removal BMP........................................................................................ 50
6.2.3 Structural BMP for Alaska............................................................................... 51
Figure 3. Piping from a bridge deck drain. ...................................................................... 51
CHAPTER 7 ..................................................................................................................... 53
7.0 BRIDGE DECK RUNOFF PRIORITIZATION SCHEME ....................................... 53
7.1 Database ...................................................................................................................... 61
CHAPTER 8 ..................................................................................................................... 63
8.0 DECISION PROCESS ................................................................................................ 63
8.1 Is it in Urbanized Area (UA)? ..................................................................................... 63
8.2 Is it in Statewide Transportation Improvement Program (STIP)? .............................. 63
8.3 What is State ACWA Score? ...................................................................................... 64
8.4 Is the bridge is over the waters that feed Cook Inlet? ................................................. 64
8.5 What is Modified Prioritization Score (PS)? .............................................................. 64
8.6 Conclusion .................................................................................................................. 65
8.7 Bridge Selection Process Flowchart ........................................................................... 66
8.8 Checklist if BMP Indicated ..................................................................................... 67
CHAPTER 9 ..................................................................................................................... 68
9.0 FURTHER RECOMMENDATIONS ......................................................................... 68
9.1 Street sweeping ........................................................................................................... 68
Table 4 The Cost of Street Cleaning for Two Cities in Michigan .................................... 69
Table 5 Estimated Costs for Two Types of Street Sweepers ............................................ 69
9.2 Deicers ........................................................................................................................ 70
9.3 Close Follow-up on Bridge Retrofit/Replacement Projects ........................................ 71
REFERENCES ................................................................................................................. 72
APPENDIX 1 .................................................................................................................... 80
A1.0 OBSERVATIONS OF INTERIOR ALASKA BRIDGES ...................................... 80

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A1.1 Robertson River Bridge on the Alaska Highway ..................................................... 80
A1.2 Johnson River Bridge on the Alaska Highway ........................................................ 81
A1.3 The Gerstle River Bridge ......................................................................................... 83
A1.4 Salcha River Bridge on the Richardson Highway ................................................... 85
APPENDIX 2 .................................................................................................................... 87
A2.0 Anchorage Port Access Bridge, Bridge No. 455. .................................................... 87
A2.1 Section of 2008 Fracture Critical Inspection Report. .............................................. 87
APPENDIX 3 Annotated Bibliography ........................................................................... 96

vi
LIST OF ABBREVIATIONS AND ACRONYMS
AAC Alaska Administrative Code
ACWA Alaska Clean Water Actions
ADEC Alaska Department of Environmental Conservation
ADFG Alaska Department of Fish and Game
ADNR Alaska Department of Natural Resources
ADT Average Daily Traffic (Count)
ADOT Alaska Department of Transportation (& Public Facilities)
BMP Best Management Practice(s)
CMA Calcium magnesium acetate
CWA Clean Water Act
EPA U.S. Environmental Protection Agency
FHWA Federal Highway Administration
GPS Global Positioning System
HSD Hydrodynamic settling device
KA Potassium acetate
LRFD Load and Resistance Factor Design
MCTT Multi-chamber treatment train
MEP Maximum extent practical
MS4 Municipal separate storm sewer systems
NPDES National Pollutant Discharge Elimination System
ONRW Outstanding National Resource Waters
SAP/QAPP Sampling and Analysis Plan/Quality Assurance Plan
SFOBB San Francisco Oakland Bay Bridge
STIP Statewide Transportation Improvement Plan
SFD Stormwater filtration device
TMDL Total Maximum Daily Load
TSS Total Suspended Solids

1
EXECUTIVE SUMMARY
The Alaska Department of Transportation (ADOT) is responsible for more than 700
bridges – most span water bodies. Are these water bodies affected by stormwater runoff
from ADOT bridges? What are the regulatory and economic constraints on the ADOT
regarding this runoff? What actions, if any, should the ADOT take? The Alaska
University Transportation Center (AUTC) of the Institute of Northern Engineering (INE)
of the University of Alaska Fairbanks (UAF) performed a project, Bridge Deck Runoff:
Water Quality Analysis and BMP Effectiveness, to answer those questions.
Best Management Practices (BMP) are mandated or recommended for certain bridges.
Which BMP is best for each bridge is not defined in law, but requires selection by the
ADOT after consideration of the bridge characteristics, costs and benefits of candidate
BMPs, and practicalities of construction. In the body of this report are brief descriptions
of many types of stormwater BMPs, including general (not road-related) BMPs, and road
and highway related BMPs; there are many standard types. There are far fewer options
for bridges and fewer still that will work in Alaska’s cold climate. The options can also
be quite different for a bridge that is in service versus a bridge that will undergo major
repairs or new construction.
The project developed a database of all the state’s bridges and their parameters relevant
to stormwater runoff. From those parameters a numerical rating was developed for each
bridge. This rating, together with certain regulatory thresholds, is used to determine if
BMPs are required. Once the need for BMP at a particular bridge is established, the
ADOT should keep records of the BMP application. Unless the water body is impaired
by the bridge runoff – and this project did not find any bridges where that was the case –
there are a wide variety of BMPs that might be applied, ranging from low cost items such
as public education and review of de-icing practices, to more costly items such a street
sweeping or drainage modifications.
Are BMPs Required? Yes, if the bridge is:
 In an Urbanized Area. (66 bridges in Anchorage or Fairbanks, or perhaps Mat-Su)

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 In the STIP. (61 additional bridges are slated for construction in the next five
years)
 A state priority. (118 additional bridges were give a priority by ADF&G, ADEC,
or ADNR indicated such in the Alaska Clean Water Actions document)
 Over waters that feed Cook Inlet. (10 additional bridges in Beluga Whale habitat)
About 255 of the state’s 703 bridges should be considered for BMP based on those
definite criteria. For the other bridges, the priority score might indicate it should be
evaluated for BMP. In that case, however, the cut off score is not defined by regulation.
Using the median score, there would be an additional 10 bridges that should be
considered for BMP. For the remainder, the priority score might indicate a relative
ranking, but, absent bridge-specific issues, BMP is not required.
BMP types may be divided into non-structural and structural. Non-structural BMPs
include: public awareness, trash prevention, deicing changes, street sweeping, and snow
management. If the runoff flows to the bridge ends, or can be made to flow to the ends,
the structural BMP would refer to systems off the bridge, and these BMPs would be
similar to highway runoff control (for example, vegetation, swales, and rip-rap improve
the quality of the discharged water). Many of these strategies do not work in the winter,
of course, but with careful snow management, some can be useful. If a bridge does not
flow to the ends and cannot be practically altered to do so, some thought should be given
to on-bridge structural BMP, such as piping or treatment systems. Review of the typical
systems to handle bridge runoff and inquiries to all the northern tier US states, as well as
Canada and Norway did not identify any easy solutions that are likely to work well in
Alaska’s cold climate. Thus, non-structural BMPs would be indicated.
Street sweeping and de-icing changes are non-structural BMP that are worth considering.
With the EPA’s current emphasis on particulates, new high-efficiency street sweeping
machines have been developed. These may be economical BMP in urbanized areas.
“Smart technology” involving GPS and electronic sensing might make it feasible to use
special de-icers on bridges, or not use them at all, depending on the circumstances. But
reviewing de-icing practices with respect to bridges could be an economical BMP. If a
bridge or its associated approach roads are in the current STIP, they are noted in the

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database. Future STIPs will certainly include bridges and thus be candidates for BMP.
During the planning of these projects, the priority score can be used to rate the bridge
regarding its likely contribution to contamination. Thus the priority score can aide
decision-making regarding the likely benefits of any given BMP; that is, less expensive
BMPs would be indicated for lower priority scores.

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CHAPTER 1
1.0 INTRODUCTION
Contamination from the surfaces of roads and bridges may enter water bodies by runoff
from rain and snow melt. Generally this contamination is slight, unlikely to affect the
receiving waters, and not sufficient to warrant concern. Scientific studies in the Lower-
48 states have shown that, in some cases, the contamination can contributed to pollution
in the receiving waters (Oberts, 2003). Since it is the owner of state highways and
bridges, the ADOT must consider if contamination of water bodies from roads and
bridges is significant, and if it is, what should be done about it. This report considers
only bridges and the roadways closely associated with them.
ADOT’s responsibilities derive from two sources. The first source is the general
environmental stewardship obligation of all State of Alaska agencies. While this
obligation is not defined precisely, certainly not contributing significantly to pollution of
the state’s waters is included. The second source is the federal Clean Water Act (CWA)
of 1972 and parallel state laws. Here we focus on the CWA.
The CWA governs discharges to the nation’s navigable waters, which are very broadly
defined. Originally only “point sources” were regulated and these via the NPDES
(National Pollution Discharge Elimination System) permits. The CWA and its
regulations were later revised to cover “non-point sources,” such as stormwater runoff
from construction sites, and many other sources. In 1990, the EPA promulgated
regulations regarding stormwater from urban areas that entered the water bodies through
storm sewers. Since stormwater that entered via sanitary sewers was already regulated,
the new regulations were specified as “Municipal Separate Storm Sewer Systems”
(MS4). The rules came in two phases. Phase I in 1990 covered storm sewer systems in
municipalities of over 100,000 populations. Since these and the ADOT issues that derive
from that designation are clear, we will not need to spend any time here with Phase I,
which in Alaska is only Anchorage.

5
Phase II, extended the rule to “small” MS4s. This is a good place to define MS4. This
from the EPA:
The term MS4 does not solely refer to municipally-owned storm sewer
systems, but rather is a term of art with a much broader application that
can include, in addition to local jurisdictions, state departments of
transportation, universities, local sewer districts, hospitals, military
bases, and prisons. An MS4 also is not always just a system of
underground pipes – it can include roads with drainage systems, gutters,
and ditches. (EPA, 2008c)
Since that definition is very broad, the EPA further specifies the subset of those that is
regulated as “regulated MS4s.” And which are they? There are two tests to see if an
MS4 is regulated. First, is it in an Urbanized Area (UA)? This is defined per the US
census, which is published every 10 years. The definition used by the Census Bureau is
complex and involves both total population within a municipal boundary and overall
population density. However the EPA has the census bureau data on a website, so the
UA locations in Alaska are easy to find (EPA, 2007). There are only two – Anchorage
and Fairbanks. In addition, the next census may declare the Mat-Su Borough also is a
UA.
The second method a small MS4 may be regulated is if it is “designated by the NPDES
permitting authority.” That raised two questions, “Who is the NPDES permitting
authority in Alaska,” and “why are certain MS4s designated?” “Who” is clear. It was the
federal EPA, through their Region X office in Seattle. However Alaska recently received
authority both from the EPA and the Alaska Legislature, to assume the program in
Alaska. Thus, since late October 2009, primacy for the NPDES program rests with the
state and is administered by ADEC.
Why certain MS4s would be designed by either the EPA or the ADEC is set out in the
regulations and interpretations:

6
EPA recommended that the NPDES permitting authority use a balanced
consideration of the following designation criteria on a watershed or other local
basis:
 Discharge to sensitive waters;
 High population density;
 High growth or growth potential;
 Contiguity to a UA;
 Significant contributor of pollutants to waters of the United States; and
 Ineffective protection of water quality concerns by other programs (EPA,
2005b).
As of October 2009, the EPA has not designated any regulated small MS4 in Alaska.
Presumably the ADEC will work to the same list. So what if a bridge or roadway is
designated a “regulated MS4?” Then
Operators of regulated small MS4s are required to design their programs to:
 Reduce the discharge of pollutants to the “maximum extent practicable”
(MEP);
 Protect water quality; and
 Satisfy the appropriate water quality requirements of the Clean Water Act.
Implementation of the MEP standard will typically require the
development and implementation of BMP (EPA 2005a).
The most likely triggers for regulated status would a discharge to water that is deemed
“sensitive” or a discharge that is deemed “significant contributor of pollutants.”
Although that designation would take a public notification and hearing process, ADOT
needs to consider if such designation is likely in the future. Since almost all Alaskan
rivers have the status “drinking water quality” in the state’s CWA [AS 46.03.050 18] and
its water quality regulations [18 AAC 70], some analysis is needed, if there is measurable
discharge. The basic policy is that of “anti-degradation” of high quality waters. If a
discharge is found to degrade those waters, for non-point sources, the discharging party
would need to treat the discharges using “all cost-effective and reasonable best
management practices.” [18 AAC 70.015.a.2.E.ii] These treatments must be approved

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by the ADEC as part of a “permitting, certification or approval” process [18 AAC
70.015.b]. This opens a second route of scrutiny, namely through a consistency
evaluation of a project, for example a bridge approval by the Corps of Engineers, the
ADEC could ask for something in their consistency review, as could the public.
Since 18 AAC 70 refers to the water body, it seems unlikely that bridge discharges to the
water would cause it to exceed the standards set out in 18 AAC 70 and The Alaska Water
Quality Criteria Manual for Toxic and Other Deleterious Organic and Inorganic
Substances. The concept of “degradation” is more qualitative, but presumably it would
need to measurable and somehow significant. The ADOT should examine if conditions
of the roadway with respect to the water body should invoke concern. That is, is the
nature of the bridge and the likely relation to the water body plausibly cause
“degradation” of the water body? Later in this report, we have developed a numerical
scoring system, based on road location, traffic (ADT) and other parameters, to rank
bridges according to their likelihood of transferring contamination to the water.
Thus, ADOT must implement BMP in the Anchorage and Fairbanks UA, and should
prepare to implement in Mat Su. In addition, some judgment should be applied regarding
if a water body is likely to be designated by ADEC in the future. This is more difficult to
determine directly, but inquiry at ADEC and EPA should indicate if complaints have
been received that might generate some concern.
Integrated Water Quality Monitoring and Assessment Report
A further guide to sensitivity is the Integrated Water Quality Monitoring and Assessment
Report (ADEC 2008)
Under the federal Clean Water Act each state must develop a program to monitor
and report to the EPA on the quality of its waters. This report would characterize
the quality of all water bodies in the state and comment on those that do not meet
the water quality standards. But Alaska is not Arizona: Alaska is rich in water

8
quantity, water quality, and aquatic resources, with almost half of the total surface
waters of the United States located within the state. Because of Alaska‘s size,
sparse population, and its remote character, the vast majority of Alaska‘s water
resources are in pristine condition. More than 99.9% of Alaska‘s waters are
considered unimpaired. With more than 3 million lakes, 714,004 miles of streams
and rivers, 36,000 miles of coastline, and approximately 176,863,000 acres of
freshwater and tidal wetlands, less than 0.1% of Alaska‘s vast water resources
have been identified as impaired. Historically, Alaska‘s water quality assessments
focused on areas with known or suspected water quality impairments.
Thus some method must be used to focus attention on the water bodies that are of
interest. The EPA has done that using a categorization scheme that relies on professional
judgment. Part of that judgment process called for the state’s three agencies that are most
concerned with water: the Department of Natural Resources (ADNR), ADEC, and
ADFG, to rate each water body. These ratings then combined into Alaska Clean Water
Actions (ACWA) Priority Ranks. A high ranking by the three indicates that the water
body may be “sensitive”.
If the bridge is directly regulated BMP must be implemented. If it otherwise might be
termed sensitive based on ACWA or our scoring system, BMP should be considered.
Actions taken must be cost effective. Higher cost BMP would be warranted if the
likelihood of contamination is high, while lower cost might be sufficient is the likelihood
is low. And whatever BMP is recommended must be safe and efficient in Alaska’s
climate.
Thus, this report has three main sections.
 Chapter 2-6 overview BMPs – what is available and what might work in Alaska,
 Chapter 7 is a ranking of bridges in Alaska, that notes if they are regulated
directly, if because of ADEC, EPA, or other issues are likely to be regulated in the
future, and finally a general scoring matrix that indicates if the roadway warrants
concern.

9
 Chapters 8 and 9 have recommendations, for the process to decide if a bridge
needs to be considered for BMP and some specific BMPs that warrant
consideration.
Two appendices have photos of Alaskan bridges and a third appendix has an annotated
bibliography of stormwater and bridge papers.


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CHAPTER 2
2.0 BASIC INFORMATION
This Chapter presents basic information regarding to runoff in general. The topics
discussed are what storm water is, what the constituents and sources of highway runoff
are, and how this information is related.
2.1 Stormwater in General
Urban development alters the hydrology (rate and volume) of watersheds and streams by
disrupting the natural water cycle (Georgia Stormwater Manual, 2001). As development
increases, new roads, shopping centers, driveways and rooftops generate more
impervious surfaces, and eventually more storm water runoff.
By the passage of the federal Clean Water Act (CWA) in the 1970s, it was no longer
acceptable to pollute US water resources, even for governments. At first, when
implementing the provisions of the CWA, the focus was on those discharges coming
from the end of a municipal or industrial wastewater pipe. The Federal Water Pollution
Control Act of 1972 required a permit for all point source discharges into navigable water
bodies. In 1977 the Clean Water Act extended the scope of pollution control to “non-
point sources,” such as stormwater. Stormwater is an all-inclusive term that refers to any
of the water running off of the land’s surface after a rainfall or snowmelt event
(Minnesota Stormwater manual, 2005).
Stormwater runoff occurs when precipitation from rain or snowmelt flows over the
ground. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater
runoff from naturally soaking into the ground (EPA, 2008a).
Stormwater from rain events and snowmelt must be removed from the deck of highway
bridges quickly in order to protect traffic. When the bridge crosses a water body some
consideration is needed regarding the effect of this runoff on water quality.

11
2.2 Highway Runoff in General
The National Cooperative Highway Research Program (NCHRP) produced a report,
NCHRP 474, which states that because the characteristics of bridge deck runoff have not
been broadly documented, the characteristics of highway runoff may be directly
comparable with bridge deck runoff (NCHRP 2002). For this reason, to understand the
nature of bridge deck runoff, it is helpful to take a look at the constituents and sources of
highway runoffs, and its effects on the receiving water bodies.
As described in FHWA’s (Federal Highway Administration) Effects of Highway Runoff
on Receiving Waters–Volume IV Procedural Guidelines for Environmental Assessments
(Dupuis and Kobringer, 1985), several parameters affect the magnitude of pollution in
highway runoff. Parameters are grouped into the following general categories:
• Traffic characteristics—speed, volume, vehicular mix (cars/trucks), congestion factors,
and state regulations controlling exhaust emissions;
• Highway design—pavement material, percentage impervious area, and drainage design;
• Maintenance activities—road cleaning, roadside mowing, herbicide spraying, road
sanding/salting, and road repair;
• Accidental spills—sand, gravel, oils, and chemicals.
Highway runoff contains metals, such as lead, copper, and zinc; particulates, clay and
silt; polycyclic and other hydrocarbons of anthropogenic origin; nutrients, and salts and
road deicing chemicals. FHWA describes typical highway runoff constituents and
sources in Table 1.
Metals have acute and chronic toxicity to aquatic life, and particulates are the carriers of
other pollutants and sedimentation effects on aquatic habitat, nutrients can contribute to
eutrophication and salts have aquatic life toxicity effect and affects drinking water supply
taste.

12
Table 1 Highway runoff constituents and their primary sources (Dupuis
and Kobringer, 1985)
Constituent Primary Source
Particulates Pavement wear, vehicles, atmosphere, maintenance
Nitrogen, phosphorus Atmosphere, roadside fertilizer application
Lead Leaded gasoline (automobile exhaust), tire wear (lead
oxide filler material), lubricating oil and grease, bearing
Zinc Tire wear (filler material), motor oil (stabilizing
additive), grease, galvanizing.
Iron Automobile body rust, steel highway structures (guard
rails, etc.), moving engine parts
Copper
Metal plating, bearing and bushing wear, moving engine
parts, brake lining wear, fungicides and insecticides
applied by maintenance operations
Cadmium Tire wear (filler material), insecticide application
Chromium Metal plating, moving engine parts, brake lining wear
Nickel Diesel fuel and gasoline (exhaust), lubricating oil, metal
plating, bushing wear, brake lining wear, asphalt paving
Manganese Moving engine parts
Bromide Exhaust
Cyanide
Anti-cake compound (ferric ferrocyanide, Prussian blue
or sodium ferrocyanide, yellow prussiate of soda) used
to keep deicing salt granular

13
Constituent Primary Source
Sodium, calcium Deicing salts, grease
Chloride Deicing salts
Sulfate Roadway beds, fuel, deicing salts
Petroleum Spills, leaks or blow-by of motor lubricants, antifreeze
and hydraulic fluids, asphalt surface leachate
PCBs, pesticides Spraying of highway rights-of-way, background
atmospheric deposition, PCB catalyst in synthetic tires
Rubber Tire wear
Pathogenic bacteria
(indicators)
Soil, litter, bird droppings, trucks hauling livestock and
stockyard waste
On the follow page, in Table 2, the U.S. EPA recommendations are provided for some of
the pollutants listed in Table 1. These criteria are created with an intention to protect the
vast majority of the aquatic life in the United States

14
Table 2 National recommended water quality criteria for priority toxic
pollutants. Criteria Maximum Concentration (CMC) and Criterion Continuous
Concentration (CCC) (EPA, 1998)
Freshwater Saltwater
Priority
Pollutant
CMC
(g/L)
CCC
(g/L)
CMC
(g/L)
CCC
(g/L)
Cadmium 2.0 .25 40 8.8
Chromium III 570 74 - -
Chromium IV 16 11 1100 50
Copper 13 9.0 4.8 3.1
Lead 65 2.5 210 8.1
Nickel 470 52 74 8.2
Zinc 120 120 90 81
The CMC protects against short-term (acute) effects (i.e., lethality), whereas the CCC
protects against long-term exposure (chronic) effects such as significant reductions in
growth or reproduction (NCHRP, 2002).
These U.S. EPA criteria are for guidance, and each state may have different criteria for its
water quality standards. Because Alaska has diverse and rich water sources and aquatic
life, it may be possible and advisable to adopt water quality criteria on a site specific
basis for some values. Prior to implementing any best management practice (BMP) to
manage bride deck runoff, the practitioner should review the state water quality standards
directly applicable to the specific receiving water for the bridge(s) in question.
In the following Chapter, BMPs to prevent or reduce the movement of polluted runoff
from the land to surface or ground water is defined.


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CHAPTER 3
3.0 BEST MANAGEMENT PRACTICES (BMPs)
Here we review general BMPs for land and roadways as an introduction to the analysis of
bridge deck BMPs.
Best Management Practices are defined as a practice or combination of practices
determined to be an effective, practical, structural or nonstructural means of preventing or
reducing the movement of sediment, nutrients, pesticides and other non-point pollutant
sources from the land to surface or ground water (Hawaii BMPs, 2010).
The adoption and use of BMPs provide the mechanism to maintain the integrity of
streams and water bodies. A comprehensive understanding of BMPs available is
important in selecting site specific BMPs to achieve this goal. There may be more than
one correct BMP for reducing or controlling potential nonpoint source pollution for each
situation encountered at various sites. It is vital to decide on BMPs that are effective,
practical and economical.
Although our project focus is on the runoff from bridges, we will start with basic EPA
guidance about stormwater in general. In this Chapter, we will give the definitions of
most commonly used BMP in managing storm water runoff from highways. We consider
that in terms of BMPs, knowledge of all common practices in use in mitigating the runoff
should be available to bridge engineers so that they can judge their applicability to bridge
deck runoff. We present analyses more specific to bridges and bridges in cold climates in
the next Chapter.
In some cases, the Environmental Protection Agency (EPA) requires the use of BMPs to
reduce nonpoint source pollution. The EPA created a National Menu of Stormwater Best
Management Practices in October in 2000, and updates it on a regular basis. (EPA,
2008b) This Chapter covers EPA’s National Menu of Stormwater Best Management
Practices very briefly for all uses.

16
3.1 National Menu of Stormwater Best Management Practices
According to National menu, BMPs used for stormwater management in general
classified into six categories. These categories are public education, public involvement,
illicit discharge and elimination, construction, post-construction, and pollution
prevention/good housekeeping. Below, we paraphrase EPA’s National Menu of Storm
water Best Management Practices, which may especially be useful for bridge runoff
applications (EPA National Menu of BMPs, 2009).
3.1.1. Public Education –BMPs to inform individuals and households about ways to
reduce stormwater pollution. Developing a municipal outreach strategy, promoting the
stormwater message through classroom education, educational displays, pamphlets,
booklets, bill inserts, and promotional giveaways and providing education for
homeowners on pest control, pet waste management, trash and debris management, and
residential car washing and for businesses on pollution prevention practices are just few
of the BMPs suggested by EPA.
3.1.2. Public Involvement - BMPs to involve the public in the development,
implementation, and review of a stormwater management program. EPA put forward
some tools for public involvement to help spread the message on preventing stormwater
pollution, to take on group activities that highlight storm drain pollution, and to
contribute to volunteer community actions to restore and protect local water resources.
Examples are Adopt-A-Stream Programs, Reforestation Program, Storm Drain Marking,
Stream Cleanup and Monitoring, and Wetland plantings.
3.1.3. Illicit Discharge Detection & Elimination- BMPs for identifying and eliminating
illicit discharges and spills to storm drain systems. Because illicit discharges often
include pathogens, nutrients, surfactants, and various toxic pollutants, and unlike
wastewater, stormwater flows to waterways without any additional treatment, EPA
emphasizes on developing BMPs that focus on detection and elimination of these illicit
discharges. Examples mentioned are developing a storm sewer system map, an ordinance

17
prohibiting illicit discharges, a plan to detect and address these illicit discharges, and an
education program on the hazards associated with illicit discharges.
3.1.4. Construction – BMPs for construction site operators to address stormwater runoff
from active construction sites. During construction BMPs listed are: contractor training,
land grading, preserving natural vegetation, erosion control, chemical stabilization,
compost blankets, dust control, geotextile, mulching, riprap, seeding, soil retention, soil
roughening, temporary slope drains, temporary stream crossings, wind fences, and sand
fences, runoff control, check dams, grass-lined channels, permanent slope diversions,
temporary diversion dikes, sediment control, compost filter berm, compost filter socks,
brush barriers, fiber rolls, filter berms, sediment basins and rock dams, sediment filters
and sediment chambers, sediment traps, silt fences, vegetated buffers, good housekeeping
such as concrete washout, general construction site management, and having a spill
prevention and control plan. Some of the BMPs listed above will be explained if they are
applicable to highway runoffs. Otherwise, detailed information about each practice can
be found on the EPA website.
3.1.5. Post-construction - BMPs to address stormwater runoff after construction
activities have been completed. The best way to mitigate stormwater impacts from new
developments is to use practices to treat, store, and infiltrate runoff onsite before it can
affect water bodies downstream. EPA recommends that practices to reduce flows and
improve water quality can be achieved by BMP inspection and maintenance, ordinances
for post-construction runoff, post-construction plan review, zoning. Also, for site plans,
alternative turnarounds, conservation easements, development districts, eliminating
curbs and gutters, green parking, green roofs, infrastructure planning, Low Impact
Development (LID) and other green design strategies, narrower residential streets, open
space design, protection of natural features, riparian/forested buffers are suggested
BMPs. In addition, infiltration BMPs such as grassed swales, infiltration trenches,
permeable interlocking concrete pavement , pervious concrete pavement, porous asphalt
pavement and filtration BMPs such as rain gardens, catch basin inserts, sand and organic
filters, vegetated filter strips are advised. Retention/detention dry detention ponds, in-line
storage, on-lot treatment, stormwater wetland, and wet ponds.

18
3.1.6. Pollution Prevention/Good Housekeeping - BMPs for municipalities to address
stormwater runoff from their own facilities and activities These pollution prevention
BMPs includes winter road maintenance, minor road repairs and other infrastructure
work, automobile fleet maintenance, landscaping and park maintenance, building
maintenance, road salt application and storage. Also, pollutant removal BMPs such as
parking lot and street sweeping and storm drain system cleaning are categorized as good
housekeeping ones.
3.2 Highway Runoff BMPs
A list of BMPs can be generated out of EPA’s National Menu of BMPs for highway
runoff treatments. In general, there are four types of BMPs that need to be considered to
achieve water quality goals. These are nonstructural, institutional and structural BMPs
and storm water pre- and post treatment practices.
Further definitions regarding to each type is given below.
3.2.1 Non-Structural BMPs
Non-structural BMP is the first step of BMP application. They aim to prevent pollution
and minimize the increase in storm water. Non-structural BMPs can be achieved through
such things as education, management and development practices and can be categorized
as pollution prevention, runoff volume minimization, and sediment and erosion control
practices based on their function. Pollution prevention practices have their focus on water
quality while runoff volume minimization practices have focus on water quantity. There
are no physical structures associated with these types of BMPs. They often offer cost-
efficient and alternative approaches to reducing pollutant loads. We will discuss
sediment and erosion control practices in Chapter 4 as part of bridge BMPs.
3.2.1.1 Pollution Prevention
Stormwater management begins with simple methods that minimize the amount of runoff
that occurs from a site and methods that prevent pollution from accumulating on the land
surface and becoming available for wash-off (Minnesota Stormwater Manual, 2005).
Street sweeping, litter control, catch basin cleaning, chemical management, spill

19
prevention and clean-up, deicing and sediment control are a part of pollution preventive
solutions to highway runoffs. Brief descriptions to each BMP are provided below.
3.2.1.2 Street sweeping
Significant amount of pollutants such as sediment, trash, debris, trace metals, and road
salt accumulate on streets, roads, highways. They can be swept, and prevented from
contributing to stormwater runoff to surface waters. Street sweeping also helps dust
control and decreases the accumulation of pollutants in catch basins, which will be
discussed later.
3.2.1.3 Litter Control
The removal of litter from streets and other surfaces before runoff moves these materials
to surface waters is a very effective solution in terms of preventing the litter from
becoming pollution.
3.2.1.4 Catch basin cleaning
A catch basin, which is also known as a storm drain inlet or curb inlet, is an opening to
the storm drain system that typically includes a grate or curb inlet at street level where
storm water enters the catch basin and a sump captures sediment, debris and associated
pollutants. Catch basins are able to prevent trash and other floatable materials from
entering the drainage system by capturing such debris by way of a hooded outlet. The
outlet pipes for catch basins on combined sewers (sanitary waste and storm water in a
single pipe) are also outfitted with a flapper (trap) device to prevent the backflow of any
unpleasant odors from pipes. Catch basins act as pretreatment for other treatment
practices by allowing larger sediments to settle in the basin sump areas (Boston
Maintenance Project, 2009).
3.2.1.5 Spill prevention and Clean-up
To prevent discharge of contaminants and hazardous compounds into the storm water
system, spills should be promptly cleaned up. Spills and leaks are one of the largest
contributors of stormwater pollutants (California BMP Handbook, 2003). Many spills
can be cleaned simply by using absorbent material, which can then be scooped up and
disposed of properly. Cleanup material could be stored at ADOT maintenance facilities.

20
An effective plan should be created for ADOT to coordinate with agencies responsible
for spill prevention and response procedures.
3.2.1.6 Salt storage and application
The application and storage of deicing materials, most commonly salts such as sodium
chloride, can lead to water quality problems for surrounding areas (Koppelman, 1984,
EPA, 2009). Proper storage and application for equipment and materials is important.
Even though road salt is the least expensive material for the deicing, alternative road
deicing products such as calcium chloride, magnesium chloride, potassium chloride, urea,
calcium magnesium acetate are considered to have less adverse effects than road salt.
Salt management and chemical spill control can be local programs. Deicing with salt and
chemicals is usually a direct ADOT responsibility, while spill cleanup of oil and chemical
spills is usually the financial responsibility of the party that spilled, and the clean-up is
supervised, usually, by the state environmental agencies. In Alaska, this is usually
ADEC.
3.2.1.7 Deicing Controls
Deicers can represent a significant threat to water resources. Rock salt is the most widely
used deicer. Rock salt has sodium chloride which may impact roadside vegetation. It
often contains ferrous cyanide as an anticaking agent (Caraco, 1997). Other less toxic,
but higher cost, salts such as calcium magnesium acetate (CMA) and potassium acetate
(KA) can be used. These can melt snow at much lower temperatures, and have less
environmental impact (Caraco, 1997).
Other materials can also be applied along with salt, or alone with an abrasive such as
sand. Sand is typically applied with salt, and provides tractions at very low temperatures
where deicers may be less effective. One disadvantage of abrasives is that they tend to
increase both solids and phosphorus loading of runoff (SWRC 2003).

21
3.2.2 Runoff Volume Minimization
As development increases, new roads, driveways, shopping centers, and other
constructions creates impervious surfaces that prevent stormwater soaking into the
ground. Thus, more water runs off. Runoff minimization BMPs aim to increase pervious
area so that more water infiltrates and less runoff occur. Examples are permeable
pavement or “grass-crete” parking area with rock filled trench drains, adjacent vegetated
slopes and vegetated filter areas.
3.2.2.1 Using Compost as a Soil Amendment
Compost is the product resulting from the controlled biological decomposition of organic
materials that has been sanitized through the generation of heat and stabilized to the point
that it is beneficial to plant growth (Minnesota Stormwater Manual, 2005). Compost can
be used as a soil amendment. To increase infiltration, reduce runoff, improve soil
porosity, increase soil moisture holding capacity (reduce water demand of lawns and
landscaping), reduce erosion, absorb certain pollutants (increase cation exchange
capacity), and reduce fertilizer needs.
3.2.3 Institutional BMPs
Pollutant Trading and Mitigation Banking are two institutional BMPs that might be of
interest in complex projects that will emit a known amount of contaminants to a stressed
water body, or take sensitive wetlands.
3.2.3.1 Pollutant Trading
Pollutant trading is a business-like way of helping to solve water quality problems by
focusing on cost effective, local solutions to problems caused by pollutant discharges to
surface waters. The appeal of trading emerges when pollutant sources face substantially
different pollutant reduction costs. A party facing relatively high pollutant reduction costs
compensates another party to achieve an equivalent, though less costly, pollutant
reduction (Idaho Pollutant Trading Guidance, 2003).
3.2.3.2 Mitigation Banking
Mitigation banking entails the restoration, creation or enhancement of wetlands or
streams and placing the credits generated from the restoration, creation, or enhancement

22
into a bank for future mitigation needs. Mitigation banking is one approach to offsetting
impacts under the Section 404 of the Clean Water Act (CWA) permitting process that the
Districts for the United States Army Corps of Engineers (USACE) oversee. Banks allow
users to cost effectively fulfill mitigation needs without developing mitigation plans for
each project separately. The USACE has an inter-agency review team (IRT) that reviews
instrument applications and mitigation site designs and provides input on the value of the
proposed mitigation bank. It can take several months to several years to get a mitigation
bank approved, depending on the type, size, and complexity of the bank (SESWA, 2010).
3.2.3 Structural BMPs
Structural BMPs can be thought of as engineering solutions to stormwater management.
Structural BMPs are used to treat stormwater at the point of generation, the point of
discharge, or at any point along the stormwater "treatment train."
3.2.3.1 Bioretention
It is a soil and plant based filtration device that removes pollutants through a variety of
physical, biological, and chemical treatment processes. Grass buffer strips, organic or
mulch layers, sand beds, ponding areas, planting soil, and plants are used for this BMP.
The stormwater runoff velocity is reduced by passing over or through buffer strip and
subsequently distributed evenly along a ponding area. Exfiltration of the stored water in
the bioretention area planting soil into the underlying soils occurs over a period of days
(BMP Database, 2008). Stormwater planters are an example of such a system.
3.2.3.2 Stormwater planter
A stormwater planter is a small, contained vegetated area that collects and treats
stormwater using bioretention. Bioretention systems collect and filter stormwater through
layers of mulch, soil and plant root systems, where pollutants such as bacteria, nitrogen,
phosphorus, heavy metals, oil and grease are retained, degraded and absorbed.
Stormwater planters typically contain native, hydrophilic flowers, grasses, shrubs and
trees (CRWA, 2008).

23
3.2.3.3 Ponds
Stormwater ponds, retention ponds, and wet extended detention ponds are called wet
ponds. These constructed basins have a permanent pool of water throughout the year or
only throughout the wet season. They have a greater depth compared to constructed
wetlands. They work by treating incoming stormwater runoff by settling and biological
uptake. The primary removal mechanism is settling as stormwater runoff resides in this
pool, but pollutant uptake, particularly of nutrients, also occurs to some degree through
biological activity in the pond (BMP Database, 2008). Wet ponds are the most
commonly used BMP for stormwater runoff treatment. Extended detention wet pond is
the most widely used modification, where storage is provided above the permanent pool
in order to detain stormwater runoff and promote settling.
3.2.3.4 Constructed Wetland
These constructed basins have a permanent pool of water throughout the year. They are
similar to wet ponds, but they are in shallower and having greater vegetation coverage.
3.2.3.5 Stormwater Wetland
It is a manufactured wetland. Gravel substrate and subsurface flow of the stormwater
through the root systems force the vegetation to remove nutrients and dissolved pollutants
from the stormwater.
3.2.3.6 Infiltration Practices
Infiltration practices, such as infiltration trenches, remove suspended solids, particulate
pollutants, coliform bacteria, organics, and some soluble forms of metals and nutrients
from stormwater runoff. These practices have high pollutant removal efficiency and can
also help recharge groundwater, thus helping to maintain low flows in stream systems.
Infiltration Basin
An infiltration basin is a shallow impoundment that is designed to infiltrate stormwater.
Infiltration basins use the natural filtering ability of the soil to remove pollutants in
stormwater runoff. Infiltration facilities store runoff until it gradually exfiltrates through
the soil and eventually into the water table.

24
Infiltration basins can be challenging to apply on many sites, however, because of the
requirement for permeability. In addition, some studies have shown relatively high failure
rates compared with other management practices (California, BMP Handbook, 2003).
Infiltration Trench
An infiltration trench is a long, narrow, excavated trench backfilled with a stone
aggregate, and lined with a filter fabric. Runoff is stored in the void space between the
stones and infiltrates through the bottom and into the soil matrix. Infiltration trenches
perform well for removal of fine sediment and associated pollutants. Pretreatment using
buffer strips, swales, or detention basins is important for limiting amounts of coarse
sediment entering the trench, which can clog and render the trench ineffective. The
infiltration trench treats the design volume of runoff either underground or at grade.
Pollutants are filtered out of the runoff as it infiltrates the surrounding soils. Infiltration
trenches also provide groundwater recharge and preserve base flow in nearby streams
(Alameda Stormwater Technical Guide, 2003).
Extended Detention Basin
Dry ponds, extended detention basins, detention ponds, extended detention ponds are the
names used for this type of BMP.
These basins don’t have permanent pools. Their outlets have been designed to detain the
storm water runoff for some minimum time such as 48 hours to allow particles and
associated pollutants to settle (BMP Database, 2008).
Soakaway pit/ drywell
Drywells are usually designed to a frequent (first flush) design storm and therefore lose
their ability to treat runoff when their design capacity is reached (Dupage County
Manual, 2008).
3.2.3.6 Filtration Practices
Media filter, sand and organic filters, grassed swales, and grass drainage channel are
filtration practices discussed below.
Media Filter
Stormwater media filters are usually two chambered including a pretreatment settling
basin and a filter bed filled with sand or other absorptive filtering media. As stormwater

25
flows into the first chamber, large particles settle out, and then finer particles and other
pollutants are removed as stormwater flows through the filtering media in the second
chamber. There are a number of design variations including the Austin sand filter,
Delaware sand filter, and multi chambered treatment train (MCTT) (BMP Database,
2008).
Sand and organic filters
Sand filters are usually designed as two-chambered stormwater practices; the first is a
settling chamber, and the second is a filter bed filled with sand or another filtering media.
As stormwater flows into the first chamber, large particles settle out, and then finer
particles and other pollutants are removed as stormwater flows through the filtering
medium. There are several modifications of the basic sand filter design, including the
surface sand filter, underground sand filter, perimeter sand filter, organic media filter, and
MCTT. All of these filtering practices operate on the same basic principle. Modifications
to the traditional surface sand filter were made primarily to fit sand filters into more
challenging design sites (e.g., underground and perimeter filters) or to improve pollutant
removal (e.g., organic media filter) (EPA, 2006).
Grassed swales
Vegetated swales are open, shallow channels with vegetation covering the side slopes
and bottom that collect and slowly convey runoff flow to downstream discharge points.
They are designed to treat runoff through filtering by the vegetation in the channel,
filtering through a subsoil matrix, and/or infiltration into the underlying soils. Swales can
be natural or manmade. They trap particulate pollutants (suspended solids and trace
metals), promote infiltration, and reduce the flow velocity of stormwater runoff.
Vegetated swales can serve as part of a stormwater drainage system and can replace
curbs, gutters and storm sewer systems.
Grass drainage channel
This BMP provides a channel with a vegetative lining for conveyance of runoff. Drainage
ditches, roadside ditches, outlets for diversions, channels at property boundaries are
typical uses.

26
3.2.4 Supplemental Pre- and Post Treatment BMPs
These BMPs are used as a supplement to the primary treatment device. There are cases,
these devices are used as the only BMP on the runoff site.
3.2.4.1 Drain Inserts
Drain inserts are manufactured filters or fabric placed in a drop inlet to remove sediment
and debris. There are a multitude of inserts of various shapes and configurations,
typically falling into one of three different groups: socks, boxes, and trays. The sock
consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a
frame or the grate of the inlet holds the sock. Socks are meant for vertical (drop) inlets.
Boxes are constructed of plastic or wire mesh.
3.2.4.2 Catch basins insert
A catch basin insert is any device that can be inserted into an existing catch basin to
provide some level of runoff contaminant removal. The most frequent application for
catch basin inserts is for reduction of sediment, oil, and grease in stormwater runoff. The
most serious potential drawback to the use of some catch basin inserts is their tendency to
become clogged with sediment. Most devices depend on some type of bed-filtration for
treatment, and sediment quickly clogs the filter, rendering the unit ineffective. The
variable nature of stormwater runoff quantity and quality makes it difficult to determine
just how well the inserts work (South Carolina, Urban BMPs, 2008).
3.2.4.3 Wet vault
A wet vault is a vault with a permanent water pool, generally 3 to 5 feet deep. The vault
may also have a constricted outlet that causes a temporary rise of the water level (i.e.,
extended detention) during each storm. This live volume generally drains within 12 to 48
hours after the end of each storm.
3.2.4.3 Floatable skimmer
Floatable skimmers are devices used to retain floating debris and oil in detention areas.
The floating debris and oil eventually sink to the bottom of the detention area and
becomes part of the sediment or is removed from the surface through regular
maintenance. The effect of floatable skimmers on water quality will depend upon the

27
amount and type of floating material transported by runoff. Typically, a well designed
floatable skimmer can trap virtually all floating debris that reaches it. In an area with
large amounts of floating leaves, trash or oil, this can provide significant water quality
benefits (Weber County, Utah, BMP, 2010).
3.2.4.4 Water quality inlets
These devices are appropriate for capturing hydrocarbon spills, but provide very marginal
sediment removal and are not very effective for treatment of stormwater runoff. Water
quality inlets (WQIs) typically capture only the first portion of runoff for treatment and
are generally used for pretreatment before discharging to other best management
practices (BMPs). Some WQIs also contain screens to help retain larger or floating
debris, and many of the newer designs also include a coalescing unit that helps promote
oil/water separation.
3.2.4.5 Vortex Separator
Vortex separators: (alternatively, swirl concentrators) are gravity separators, and in
principle are essentially wet vaults. The difference from wet vaults, however, is that the
vortex separator is round, rather than rectangular, and the water moves in a centrifugal
fashion before exiting. By having the water move in a circular fashion, rather than a
straight line as is the case with a standard wet vault, it is possible to obtain significant
removal of suspended sediments and attached pollutants with less space. Vortex
separators were originally developed for combined sewer overflows (CSOs), where it is
used primarily to remove coarse inorganic solids.
3.2.4.6 Buffer boxes
These devices are used in situations where traditional best management practices (BMP)
like sedimentation basins cannot be installed. Buffer boxes are simple and cost-effective,
reducing the amount of sediment passing through storm drains by 26 to 34 percent for
fine sediment and 86 to 96 percent for coarse sediment(EPA, 2006).

28
CHAPTER 4
4.0 BRIDGE DECK RUNOFF MANAGEMENT
This Chapter covers bridge definition, bridge design and retrofit constraints to mitigate
the runoff, and current bridge deck runoff design practices.
4.1 Bridge Definition and Constraints
According to National Bridge Inspection Standards, a bridge is a structure, including
supports, erected over a depression or an obstruction, such as water, highway, or railway,
and having a track or passageway for carrying traffic or other moving loads, and having
an opening measured along the center of the roadway of more than 20 feet between under
copings of abutments or spring lines of arches, or extreme ends of openings for multiple
boxes; it may also include multiple pipes where the clear distance between openings is
less than half of the smaller contiguous opening.
Even though there has been much research done about best management practices to
manage highway runoff, there has been very little published about bridges. NCHRP
developed a report, which makes an assessment of the impact of bridge deck runoff
contaminants in receiving waters. This report, NCHRP 474, was found to be the most
specific and useful source about BMPs specific to bridge deck runoffs during our
research.
Of course, not every highway runoff BMP can be applied to manage bridge deck runoff
because of the bridge design and retrofit constraints at the receiving water crossing.
These constraints defined by NCHRP Report 474 as follows:
 There is no flexibility regarding the size of the foot print. There is no lateral right-
of-way on which to build mitigation measures. Mitigation measures can be
located on the bridge only at substantial cost, or storm water must be gravity-
drained back to land.
 The topography slope at some bridge locations preclude design or retrofit for
gravity drainage back to land.

29
 The additional load of storm water piping must be considered for retrofit and in
new bridge design.
 The length and slope of some bridges preclude gravity drainage to land. For
floating bridges, storm water cannot be routed to land without pumping
assistance.
 Maintenance may be difficult, and additional safety measures may need to be
considered for bridges that are retrofitted with storm water control measures.
NCHRP reported current runoff design practices for bridge deck runoff crossing waters
as follows;
 Discharging runoff through multiple open scuppers directly into the receiving
water
 Discharging runoff through piping down from the bridge deck directly into the
receiving water without treatment.
 Conveying the storm water runoff over the surface of the bridge to one or both
ends for BMP treatment or discharge.
 Conveying the storm water runoff via piping or open troughs over to one or both
ends of the bridge for BMP treatment or discharge.
 Detaining and treating the storm water under the bridge deck.
4.2 Bridge Deck Runoff Applicable BMPs
In NCHRP 474, Volume 2, there is a nonstructural and structural BMP evaluation
method presented for bridges. This simple evaluation process to select the BMP starts
with defining the need (e.g., heavy metals concentration reduction, discharge elimination)
and the constraints as the first steps. Next step is to decide on the purpose of the selection
(e.g., pollutant reduction, flow reduction).
It is mentioned in the handbook that nonstructural BMPs that are potentially applicable to
bridges include:
– Street sweeping,
– Inlet box/catch basin maintenance,

30
– Maintenance management,
– Deicing controls, and
– Traffic management (e.g., high occupancy vehicle lanes, and mass transit).
To be cost effective, it is suggested that to achieve the required benefits, first consider the
mentioned nonstructural BMPs for bridges and, if not, evaluate for institutional BMPs
(i.e., pollutant trading and mitigation banking). As a next step, structural BMPs should be
evaluated if both nonstructural and institutional BMPs cannot provide enough of the
desired water quality benefit/protection.
A critical component of the BMP analysis includes engineering evaluations related to the
type of drainage and storm water conveyance needed, and the effects these systems could
have on the structural design of the bridge. In selecting an appropriate BMP, required
pollutant removal benefits, site constraints, maintenance constraints, and potential
environmental or aesthetic enhancements need to be considered (NCHRP 2002, v2).
The next section gives more detailed information regarding to BMPs applicable to
bridges. They can be categorized into two sections as nonstructural, structural.
4.2.1 Nonstructural BMPs
Nonstructural mitigation methods are cost-effective and sometimes more efficient
pollutant removers. These methods can be used as source control and management
methods. Street sweeping, catch basin and scupper cleaning, deck drain cleaning, deicing
controls, traffic management, and management of maintenance activities are different
types of BMPs that can be implemented without any structural burden on the bridge. In
this category, temporary erosion and sediment control practices also included to give
ideas to practitioners to how to find temporary solutions to bridge slope runoff erosion.
See below for more on slope erosion.
4.2.1.1 Street Sweeping
Research conducted in the past few years has demonstrated that street sweeping can
effectively reduce pollutant loads from roadways because of improvements in equipment
and in sweeping methods. Besides improved mechanical sweepers, the introduction of

31
vacuum-assisted and regenerative air sweepers (which blow air onto the pavement and
immediately vacuum it back to entrain and filter out accumulated solids) has greatly
increased effectiveness, particularly with fine particles. In terms of improved sweeping
methods, tandem sweeping, which is mechanical sweeping followed immediately by a
vacuum-assisted machine have shown remarkable increases in percent pollutant
reductions (Sutherland and Jelen, 1997). In recent studies, a new type of street-sweeping
machine called the Enviro Whirl (which combines a broom with a powerful vacuum in
one unit) was found to be most effective, reducing total suspended solid (TSS) loading up
to 90 percent for residential streets and up to 80 percent for major arterials. The actual
percent reduction also depended on the number of cleanings per year, with the maximum
reduction reported for weekly cleanings. Results for biweekly cleanings are about 70
percent for both residential and major arterials.
Good planning in street sweeping is critical for obtaining high removal rates.
For example, spring snowmelt is widely recognized as being critical because of the most
polluted first flush snow melt. For Alaska, in the continental region, first flush snow melt
occurs in the mid-spring and it is important not to miss this highly polluted runoff
because of street sweeping schedule (if there is one). Thus, the sweeping schedule should
not be a cast iron plan; it should be flexible enough to respond to sudden needs.
Where structural BMP implementation is not an option because of BMP load design
constraints, street sweeping appears as a very good option as it is in the case of San
Francisco-Oakland Bay Bridge (SFOBB). In terms of cost and pollutant removal
efficiency with the bridge design considerations, high-efficiency, vacuum-type street
sweeping emerged as the most effective BMP for SFOBB (NCHRP, 2002).
4.2.1.2 Catch Basin Cleaning
Storm drain catch basins should be cleaned and maintained in order to prevent debris,
chemical, trash, sediment, and other pollutants from entering waterways.
There are several design options. One design option consists of a series of trays, with the
top tray serving as an initial sediment trap; the underlying trays filter out pollutants.

32
Another design option uses filter fabric to remove pollutants from runoff (Southeast
Michigan Council of Governments, SEMCOG, 2009).
The frequency and consistency of the cleaning increases the efficiency of the catch basin.
Also, it is important to remove the sediment accumulated during the winter months
before it is washed off by spring rains.
4.2.1.3 Scupper Cleaning
Scuppers need cleaning for traffic safety. Scuppers can be flushed with water under
pressure after the accumulated runoff material in them has been properly removed. U.S.
EPA recommends restricting use of scupper drains on bridges less than 400 feet in length
and on bridges crossing very sensitive ecosystems. Also, it suggests that on bridges with
scupper drains; provide equivalent urban runoff treatment in terms of pollutant load
reduction elsewhere on the project to compensate for the loading discharged off the
bridge. Bridge scuppers should be used only when necessary to maintain the spread of the
gutter flow onto the traveled way (Bridge Development, University of Maryland, 2007).
4.2.1.4 Deck Drain Cleaning
Bridge drainage covers the collection and removal of waters from a bridge deck. To
accomplish this function, drains are placed adjacent to curbs for collection of water which
is then either dumped directly into water or is conveyed to a suitable disposal point
(CALTRANS, 2009). Deck drains can be cleaned by getting flushed with water under
pressure after the removal of the accumulated runoff material.
4.2.1.5 Deicing Controls
Winter deicing activities add substantially to the pollutant loading from bridge decks.
Some alternative practices that can reduce the loading include using alternative deicing
compounds (e.g., calcium chloride or calcium magnesium acetate), designating “low salt”
areas on bridges over sensitive receiving waters, and reducing deicing applications
through operator education, training, and equipment calibration. In addition, using deicers
such as glycol, urea or Calcium Magnesium Acetate (CMA) reduces the corrosion of
metal bridge supports that can occur when salt is used. Use of clean sand, calcium

33
magnesium acetate (CMA) and potassium acetate (KA) are high cost salt alternatives. In
addition, using deicers such as glycol, urea or Calcium Magnesium Acetate (CMA)
reduces the corrosion of metal bridge supports that can occur when salt is used.
Smart deicing practices, which use GPS to distribute the amount of chemical according to
needs, can be adapted to control deicing affect on the runoff.
4.2.1.6 Traffic Management
In urbanized areas, the stormwater runoff from bridge decks is regulated because the
highly contaminated urbanized runoff may pollute the receiving waters. On the other
hand, even though they are not regulated under law because of low incidence of such
runoffs, preventive tactics should be considered to protect critical waters in rural areas for
the possible spills from trucks and hazardous material haulers, especially bridges over
critical waters. These spills obviously have the same or worse potential effect to
adversely influence the aquatic life in the receiving waters. As urban traffic, traffic
routing of these risky vehicles away from critical bridges is one tactic to follow for the
protection of these waters. Another way is to limit the number of trucks on these bridges
so that the incidence of accidents will decrease.
4.2.1.7 Maintenance Practices
Necessary maintenance activities such as bridge painting, substructure repair, drainage
structure repair, and pavement repair or repaving on bridges can have an adverse affect
on water quality in the receiving waters beneath the bridges
Bridge painting is probably the most common bridge maintenance practice and the one
with potentially the greatest adverse effects on the receiving water (NCHRP, 2002).
Blasting abrasives and paint chips from painting activities may fall into the receiving
waters below the bridge. Surveys have indicated that up to 80 percent of the bridges
repainted each year were previously painted with lead paint. These surveys have also
indicated that substantial amounts of used abrasives can be lost to the environment if
appropriate containment practices are not used (Young et al., 1996). Paint overspray and

34
solvents also may be toxic to aquatic life if they reach the receiving water (Kramme,
1985).
To avoid blasting abrasives and paint chips falling into the receiving water, it is important
to capture scraps, waste and paint from sanding or painting projects. Using suspended
tarps or nets below the bridge to catch falling debris may become necessary to protect the
receiving waters. Booms and vacuums to capture pollutants generated during bridge
maintenance will also help reduce the impacts. It is also important to transport and store
paint and materials in containers with secure lids, and also not to transfer, store or load
paint on a bridge.
Fully enclosed containment structures are capable of recovering 85 to 90 percent of
abrasive, paint particles, and dust for simple spans; however, this type of containment is
not feasible for high trusses or other complex structures (Appleman, 1992).
Worker training is also helpful in reducing the impacts of bridge painting on the receiving
waters. These practices would include not allowing paint to enter surface waters,
hanging drip tarps to catch drippings and dropped brushes, mixing paint or other
substances away from the water, having a plan for accidental spills, and using appropriate
cleaning procedures (Young et al., 1996). The use of airless sprayers and the elimination
of the use of solvents would greatly reduce the toxicity-related concerns associated with
chemicals entering the receiving water directly (Kramme, 1985).
The costs of implementing these measures to reduce the effects of bridge painting on
receiving water quality have been estimated at an additional 10 to 20 percent for
containment techniques and an additional 10 to 15 percent for waste disposal (Young et
al., 1996).
Bridge cleaning -Metal bridge cleaning is a significant water quality issue in some states,
particularly in Washington, Tennessee, and Oregon (Dupuis et al., 1999). According to
the study survey, the cleaning process produces a water solution, which generally needs

35
to be tested and/or treated before being either discharged to the receiving water or
otherwise controlled and managed off-site (NCHRP, 2002).
Recovery of wastes, containment of wastes, and training of maintenance workers to
increase their awareness of potential impacts on receiving waters are techniques that can
be used to decrease the impacts of bridge maintenance activities on receiving waters.
Containment of blasting abrasives and paint chips can be accomplished using shrouding,
total structural enclosures, and negative pressure containment systems.
By using a vacuum bag attachment at the point of surface application, placing barges
below the bridges, using containment booms in the receiving water, and funneling the
debris in the enclosed container to a disposal truck or storage compartment are ways to
capture the blasted materials and other residue before they run into the receiving water
below the bridges.
4.2.2 Structural BMPs
We divided bridge deck runoff structural BMPs off-bridge and on-bridge practices based
on the location of the treatments.
4.2.2.1 Structural Off-Bridge BMPs
Structural off-bridge BMPs are temporary construction erosion and sediment control
practices that prevents or reduce the movement of sediment from a site during
construction through the implementation of man-made structures, land management
techniques, or natural processes (Minnesota Stormwater Manual, 2005). Stormwater
runoff from construction is highly regulated in Alaska. However, the reason these
practices included here is to present solutions to erosion on bridge end slopes, which
impacts the quality of receiving water under the bridge. Sediment and erosion control
practices suggested here may be applicable to bridge end slope erosion and also, may
help in sediment control. Definition of each BMP is directly quoted from Minnesota
Storm Water Manual, 2005.

36
Vegetated Buffer Strip are also known as grassed buffer strips, vegetated filter strips,
filter strips, and grassed filters. These are vegetated surfaces that are designed to treat
sheet flow from adjacent surfaces.
Filter strips function by slowing runoff velocities and allowing sediment and other
pollutants to settle and by providing some infiltration into underlying soils.
Filter strips were originally used as an agricultural treatment practice and have more
recently evolved into an urban practice. With proper design and maintenance, filter strips
can provide relatively high pollutant removal. In addition, the public views them as
landscaped amenities and not as storm water infrastructure. Consequently, there is little
resistance to their use.
Silt fences filter sediment from runoff by allowing water to pass through a geotextile
fabric or by creating a pool to allow sediment to drop out of the water column. Fences
constructed of wood or steel supports and either natural (e.g. burlap) or synthetic fabric
stretched across an area of non–concentrated flow during site development trap and
retain on–site sediment due to rainfall runoff. Silt fences are installed to protect BMPs
and downstream receiving waters.
Rock or Compost Bags are filled bags that are used to filter water, control ditch grade, or
to provide inlet protection.
Riprap is appropriately sized rocks that reduce the energy of fast moving flows. Riprap is
used along channels and at outfalls.
Temporary Sedimentation Basins are depressions that capture runoff to slow the flow of
water and allow sediment to settle out.
Filter Bags are mesh bags that capture sediment but allow water to pass through. Filter
bags are installed in storm drain inlets.

37
Floatation Silt Curtain is a fabric fence installed in water bodies to contain sediment near
the banks of the work area. They must be used in conjunction with other sediment control
techniques.
Erosion control blanket is a mat made of netting layered with straw, wood, coconut or
man-made fibers that prevents erosion by sheltering the soil from rainfall and runoff
while holding moisture for establishing plants. Blankets are installed in channels or on
slopes where mulch would not be adequate.
Fiber Logs include straw, wood, or coconut fiber logs, compost logs, and rock logs that
slow water and filter sediment. Fiber logs are used for inlet protection, ditch checks, and
as perimeter control where silt fence is infeasible.
Mulch is wood fibers, compost, wood chips, straw, or hay that is applied as a cover to
disturbed soil. Mulch reduces erosion by absorbing energy from rainfall and runoff and
provides protection and moisture for the establishment of vegetation, when properly disc
anchored or spread.
4.2.2.2 Structural On-Bridge BMPs
Because of the bridge design and retrofit constraints explained in this Chapter, there are
not many options in terms of structural BMPs. Simple drainage back to land is sometimes
practical for relatively short bridges. The bridge deck is sloped so that the water runs to
either end by gravity. From the ends, the water is treated by some method, for example, a
grassy area or pond, prior to discharge to the receiving water.
Enclosed piping or open-trough drainage back to land is another practice in use, and
suggested for longer bridges. The NCHRP 474 report mentions a case study that uses a
series of collection trays or pans along the bridge deck that were periodically vacuum-
cleaned. Also, oil water separators are given as an alternative approach that can be used
in drainage treatment systems below the bridge. In the next Chapter, we discuss the
applicability of some of these to cold regions.

38
CHAPTER 5
5.0 BMPs IN COLD CLIMATES
Snowmelt runoff and rain-on-snow events present some of the highest pollutant loading
and most difficult management challenges in the course of a year in regions with cold
climate (Oberts, 2003). Most BMPs to control stormwater runoff treatment are based on
warm climates subject to summertime thunderstorms and other rainfall events.
Our literature review found that even though there have been a number of research
projects to assess the impacts of highway storm water runoff on receiving water in cold
climates, there is none specific to bridge deck runoffs.
However, cold climates can present additional challenges to the selection, design, and
maintenance of stormwater treatment BMPs due to cold temperatures, deep frost lines,
short growing seasons, and significant snowfall (SMRC, 2003). Identifying solutions for
bridges or cold climates are certainly challenging areas. Combining the two would make
it an extremely challenging task. Here is a summary not specific to bridges.

39
Table 3 Challenges to the Design of Runoff Management Practices in
Cold Climates (Caraco and Claytor, 1997)
Climatic Condition
BMP Design Challenge
Cold Temperatures

Pipe freezing
 Permanent pool ice Covered
 Reduced biological activity
 Reduced oxygen levels during ice cover
 Reduced settling velocities
Deep Frost Line

Frost heaving
 Reduced soil infiltration
 Pipe freezing
Short Growing
Season

Short time period to establish vegetation
 Different plant species appropriate
to cold climates than moderate climates
Significant Snowfall

High runoff volumes during
snowmelt and rainon- snow
 High pollutant loads during spring melt
 Other impacts of road salt/deicers
 Snow management may affect BMP
storage
Finding the best management practices that are suitable for cold climates and applicable
to bridges is the aim of the research.

40
5.1 Practices in Cold Climate States
The research involves a literature search to see what other states are doing, especially
northern tier states, and cold countries, such as Canada and Norway and what BMPs
exist. For this research, several DOTs contacted and questioned about their practices for
bridges. Below is a summary of our finding regarding to their practices.
5. 1.1 Maine DOT
According to personal communication with Maine DOT, their Bureau of Environment is
tasked with coordinating their efforts with the New Hampshire DOT. NH's recently
enacted Alteration of Terrain (AoT) rules will nearly eliminate the use of scuppers to
allow runoff to drop unimpeded to the river, below the bridge. Alteration of Terrain
protects surface water quality by controlling soil erosion and managing, treating, and
recharging stormwater runoff from development activities and an alteration of terrain
permit is required whenever a project proposes to disturb more than 100,000 square feet
of terrain (New Hampshire, 2008). Though, the scuppers would still be allowed to be
used for large tidal river crossings, where there is a lot of mixing and a large flow.
New Hampshire the Department of Environmental Services (DES) has released a new
NH Stormwater Manual. The Manual gives guidance towards how to apply the new rules,
but so far the Bridge Design staff has not had to wrestle with them. The Maine DOT has
been able to treat bridge runoff by letting it flow to the end of the bridge where it is
picked up in catch basins. Once it is off the bridge, Highway Design is responsible for
how to treat it, again, according to the new rules. The new rules seem to be requiring
larger areas for treatment. Regarding bridge runoff, the DOT does have an upcoming
project where they will need to use scuppers that are connected via a piping network to
get the runoff to the treatment facilities designed by Highway Design. Though, the
contacted DOT engineer thinks that this application will be a headache for their
Maintenance forces.

41
5.1.2 Minnesota DOT
There have been several BMP studies in Minnesota but none that were specifically
oriented towards bridge decks. Guidance in the LRFD (Load and Resistance Factor
Design) Bridge Design Manual is general and recommends bridge designer coordinate
with Hydraulics Unit on a case by case basis for water quality treatment options.
In general, according to LRFD bridge design manual, drainage must avoid entering state
waters; bridges less than 500 feet over state waters must be designed to shed water
longitudinally without deck drains, and longer required closed systems.
For most bridges, the water is conveyed to the ends of the bridge. For those few bridges
where that are not possible, they use a drainage system. This could be scuppers, a closed
drainage system or an open drainage system. The decision and design are done on a case
by case basis.
A trapezoidal trough system is considered as an innovative solution to clogging when
collecting stormwater from bridge decks used by MnDOT in a few cases. They do not
have specific information on the installations though the engineers from MnDOT
mentioned that it still has the same clogging problems. As for the most part, they design
bridges not to need deck drainage systems by conveying water to the end of the bridge
decks. So their approach is not to use them unless no other choice is left. When needed,
systems are selected and designed on a case by case basis
Minnesota DOT has a stormwater manual, which includes an Issue Paper on Cold
Climates does not differentiate between highway and bridge deck runoff.
Cost/benefit isn't the major factor in selecting BMP's at MnDOT. Meeting permit
requirements is the most important factor, but ROW and limited maintenance budget also
influence BMP selection.

42
In the storm water manual, there is a Chapter on cold climate impact on runoff
management. It provides guidance on cold climate BMP design adaptations, developing
snow management plans, implementing a management sequence, providing effective
pollutant removal and runoff control in winter.
In Minnesota, the use of liquid MgCl2 spray on bridge decks has proven to be an
effective way to avoid repeated NaCl application at high doses (Minnesota Stormwater
Manual, 2005).
5.1.3 Washington DOT
WSDOT developed a stormwater manual to comply with Washington state law and also
NPDES municipal stormwater permit regulations. WSDOT's Highway Runoff Manual,
provides the designers with the guidelines and design criteria for selecting BMP for
runoff treatment and flow control. In the manual, there is a Chapter that contains the
BMP selection process and the actual design criteria for BMPs. The manual also briefly
discusses special design considerations for stormwater management on bridges.
According to the information provided by the WSDOT engineer, high efficiency street
sweeping is emerging as an option and some are advocating further exploration. Also,
they mentioned that they are finding mixed/contradictory views regarding the
performance effectiveness of such a strategy in the existing literature. In 2005, a runoff
categorization study for several of the floating bridges was done.
There's also a WSDOT research effort in the early planning stages to conduct some
research and development exploring the use of innovative (i.e., non-traditional)
stromwater treatment BMPs for over-water fixed structures (i.e., bridges, ferry terminals,
etc.). This research started in October 2008, and completed Phase 1 - the literature
survey, WSDOT contacts, and a theoretical description of a new treatment system that
could be placed on pier cap structures underneath bridges to be used in combination with
high-efficiency street sweeping. In Phase 2, they plan on writing Sample Analysis Plans/
Quality Assurance Project Plans (SAPs/QAPPs) in anticipation of receiving federal

43
funding to construct and test a media/trickle filter in combination with high-efficiency
street sweeping.
5.1.4 Wisconsin DOT
In Wisconsin, the vast majority of existing small bridges have open-rail drainage
(NCHRP 2002). WisDOT currently does not have standards or design guidelines that
address bridge deck runoff. Rather, they address the issue on a case-by-case basis,
typically based upon the receiving water quality and/or DNR (Department of Natural
Resources) or local government concerns. The treatment approach they usually use is to
route the runoff from the bridge deck to the embankments, and then to filter the water as
much as possible through a grass swale or other vegetative filter system. Another option
available to use is generic hydrodynamic settling devices (otherwise known as
catchbasins) at the end of the bridge deck. They typically prefer not to use proprietary
filter systems because of the maintenance requirements.
They plan to begin working on our stormwater quality design guidelines in the WisDOT
Facilities Development Manual (FDM) soon, and bridge deck runoff will be one of the
issues they plan to address in it.
WisDOT also funded a study that analyzed two different treatment devices that treated
runoff from a freeway.
As a part of study, the treatment efficiency of two proprietary stormwater treatment
devices was tested at a freeway site in an ultra-urban part of Milwaukee. One treatment
device is categorized as a hydrodynamic settling device (HSD) that removes pollutants by
sedimentation and flotation. The other treatment device is categorized as a stormwater
filtration device (SFD) that removes pollutants by filtration and sedimentation. Filtration
is considered the primary method of treatment with sedimentation of larger particles in
the pre-treatment chamber and cartridge filter bay. See Figure 1.

44
Figure 1. Pre-treatment chamber and cartridge filter bay
Storm water runoff from the parking lot was piped into the StormFilter (red arrows) and
siphoned into a series of filter cartridges designed to remove sediment, metals, organic
compounds, phosphorous and oil (WisDOT, March 2009 Brief).
The Storm Filter reduced the load of total suspended solids by 50 percent, suspended
sediment by 89 percent, total phosphorous by 38 percent, dissolved copper by 16 percent,
total copper by 66 percent, dissolved zinc by 20 percent, total zinc by 68 percent and
chemical oxygen demand by 14 percent (WisDOT, March 2009).
Reducing stormwater contaminants with high-efficiency street sweeper has been
proposed as a best management practice because of its potential cost savings over more
expensive alternatives. In 2002, WisDOT had tried an old model (mechanical) street
sweeper, but were unable to determine the benefits of sweeping due to a variety of quality
control issues and mechanical failures. In result, the data did not sufficiently support the
expected benefits. WisDOT initiated Phase II sweeping study using a high-efficiency
vacuum assisted sweeper (the Whirlwind MV). Advances in sweeper technology allow
the Whirlwind MV to pick up greater volumes of dirt at increased speeds (WisDOT, June

45
2009). The project concludes that although an exact efficiency percentage for the amount
of dirt picked up has not been determined yet, the vacuum-assisted high efficiency street
sweepers are definitely an improvement over older models and only these newer models
appeared capable of picking up a significant percentage of finer particles.
5.2 Practices in Other States
It is typical for storm water to be conveyed over the surface to the end of the bridge deck,
if the bridge is short enough, and routed to a drain inlet that leads to a discharge via
grassy ditch or some sort of BMP, such as a pond. States that explicitly noted that they
follow this policy were Florida, Minnesota, Oregon, Washington, Massachusetts,
Delaware, Nevada, Maine, New Jersey, Utah, New Mexico, and Idaho. Other states
potentially follow this policy but did not explicitly mention it. Regardless, state DOTs
have identified this practice as effective and economical (NCHRP 2002).
5.3 Practices in Some Other Countries
Canada and Norway were contacted to find out about the practices that have been used to
mitigating the runoff from bridges.
Jiri Marsalek (personal communication, December 31, 2009) at Environment Canada’s
National Water Research Institute responded to our query and regretfully mentioned that
they haven’t been doing much with bridge deck runoff; generally, some splash pads are
installed underneath and those should distribute falling water over a larger area.
Also, based on our interview with Dr. Richard Frontier from Lavar University, bridge
deck runoff is not considered as an environmental issue in Northern Quebec. Dr. Frontier,
firstly mentioned that they don’t have many bridges in Northern Quebec to be concerned
about the runoff issues that can cause any environmental problems in the water bodies
that they crosses over. Second point, he made that North Quebec is formed from little
villages so it doesn’t have an urbanized crowded bridges. However, he also emphasized

46
that they don’t use any deicing on the bridges. Likely vehicles such as ATVs, snow
machines or cars just go slower when it comes to bridges. The water bodies pass under
the bridges has species such as Smallmouth Bass, Lake Trout, Landlocked Salmon,
Walleye, Rainbow Trout/Steelhead, Brown Trout, Northern Pike, Yellow Perch, Rainbow
Smelt and Catfish.
Because ADT is low and also, chemicals are not used on the bridges, for now, engineers
feels worry free about the likelihood of bridge deck runoffs polluting the water bodies
passes under.
We also contacted Bert Van Duin (personal communication, December 10, 2009) from
City of Calgary, Canada. In Canada, they try to solve the issue at the design stage with a
slight incline so that it drains to either side of the stream (in case of bridge crossings of
streams). In addition, runoffs from the ramps are intercepted by high capacity
interceptors /catch basins before the runoff could ever make it onto the bridge deck in the
first place. Also, depending on the availability of space runoff might then be routed
through some devices such as an oil/grit separator or in some cases a bioretention area.
Dr. Sveinn Thorolfsson from Norwegian Technical University also contacted and he
shared his studies with us. Nothing new came up, but he is working on the same topic.


47
CHAPTER 6
6.0 ALASKA
In this Chapter, Alaska’s climate and current BMPs for bridges are discussed in detail.
Also, some recommendations are presented.
6.1 Climate
Managing runoff for the safety of traffic, rain and snow melt must be conducted off the
driving surface and is important for the success of that BMP used for that bridge. Thus, it
is crucial to know how much and what kind of bridge deck runoff would occur and when
it would occur. Because the runoff from snowmelt may require different approach in
treatment than the runoff from rain, first, we analyzed the climate zones which each
bridge is located so that we would know that approximately when, how much, and what
kind of runoff each bridge has.
There are four general climate zones in Alaska, based on annual and monthly averages of
temperature and precipitation. These are 1) an arctic zone, 2) a continental zone, 3) a
maritime zone and 4) a transitional zone. Below are the definitions of each zone.
Figure 2. Alaska Climate Zones (from http://esp.cr.usgs.gov/research/alaska/figures/tafig2.gif

48
6.1.1 Arctic Zone
The arctic zone is characterized as a treeless plain located generally north of the Arctic
Circle and north of the Brooks Range, including the cities of Barrow and Prudhoe Bay.
There are two main seasons, winter and summer. The summer is very short with a
transitional period in May and September. The average temperature in the winter is
around -11.2°F (-24°C) and in the summer around 50°F (10°C). Winds blow almost
continuously, with an average wind speed of 30 miles per hour (48.3 km/h). There is little
precipitation; less than 10 inches (254 millimeters) per year, most of which is usually
snow. In addition, there is a permanent layer of frozen earth or “permafrost”, which in the
summer thaws just enough to make bogs, swamps and lakes the primary topography.
Permafrost is not defined by soil moisture content, overlying snow cover, or location; it is
defined solely by soil temperature. (This and the following zone descriptions are taken
from McVehill-Monett, 2006)
6.1.2 Continental Zone
The continental zone is best described as a zone with temperatures in the summer that
average around 60°F (15°C) in the warmest month and mean lows in the winter near
-10°F (-23.3°C), with an extreme of -45°F (-42.7°C) to -55°F (-48.3°C). Annual
precipitation is generally about 20 inches with the majority falling within the summer
months. In general, this zone is located south of the Brooks Range and inland. The sun
does not set for more than a month in the summer. Surface winds are lighter than those in
the Arctic. Overall there are only two seasons in this region as well: summer and winter.
6.1.3 Maritime Zone
Temperatures in the maritime zone usually reach 50°F to 55 °F (10°C to 12°C) for mean
maximums during summer and drop to around 23°F (-5°C) for mean lows during winter.
As a result of this temperate climate, seasonal change is not as obvious as in the other
zones. Because of the moderating effects of the ocean, very infrequently do temperatures
reach extreme highs of 70°F (21°C) and extreme lows of -22°F (-30°C). Winds are

49
typically between 13.8 mph (22.2 km/h) and 20.7 mph (33.3 km/h). Precipitation is much
greater than that of the interior or the arctic, with an average of about 40 inches per year.
6.1.4 Transitional Zone
The transitional zone includes as far west as Bristol Bay, the region around the Cook
Inlet, the Chugach Mountains and as far east as the southern Copper River basin. The
transitional zone follows approximately 1492 miles (2400 km) of the Alaskan Coast.
Unlike the other regions, this zone is difficult to define due to the large variation in
topography.
6.1.5 Summary
In this section of the Chapter, we looked into Alaska’s four types of climate zones.
According to our research and analysis of each type, we believe that it may be wise to
handle runoff from rain differently than the runoff from snowmelt. Knowing the region
where each bridge is located may help bridge engineers to understand the type of runoff
created from that bridge decks. For example, in arctic zone, because there is little
precipitation; less than 10 inches per year, most of which is usually snow, runoff from
bridges in this region may not be as critical as the ones from the bridges in continental
and maritime regions. In continental zone, annual precipitation is generally about 20
inches. In this region, it is important to consider first flush of snowmelt in the spring
time. Good planning in street sweeping may solve the problem by capturing the spring
melt on time before highly first flush goes into the receiving waters. In maritime zone,
precipitation is much greater than that of the interior or the arctic, with an average of
about 40 inches per year. Any kind of BMP may be justifiable because of the high
amount of runoff from the bridge decks.
6.2 Current BMPs and Recommendations
Alaska has divided into three ADOT regions. These are Central, Northern and Southeast
regions. To find out about current best management practices used for bridge deck
runoffs, bridge and maintenance engineers were contacted. Communications were made

50
via email with Southeast, and Central regions. Because of the proximity of its location,
Northern region ADOT engineers were interviewed in-person about the subject.
6.2.1 Deicing Practices
To find out about current deicing practices in Alaska, bridge maintenance engineers were
contacted in each region of Alaska.
In Central Region, they use sand mixed with salt (less than 5%) on all roads and bridges
with one exception. The Knik River bridge has an installed spray system that uses
potassium acetate. (Mike Zidek, January 23, 2010. Personal Communication. ADOT).
According to our interview with the Northern Region, Maintenance Engineer, no deicing
chemicals are used in Northern Region. Snow is scraped and pushed off the bridge decks
or hauled to the snow dumps whenever it is necessary. There is no certain schedule for
the cleaning. (Jays Bottoms, January 5 2010. Personal Communication. ADOT,
Fairbanks, AK).
In the Southeast Region, the ADOT has some roads that are “chemical routes” on which
deicing is applied. The typical treatment is spray brine. They are currently considering
adding a corrosion inhibitor to the brine.
6.2.2 Snow Removal BMP
In general, Alaskan bridges are plowed to remove snow. The plows push the snow to one
end and beyond. The plowing operation may leave snow in regions of the bridge where
there is curbing and the plow is limited by the guardrail. Once the snow is off the bridge,
the relation is no different than plowing of the highway itself, except that there may be
more at the ends of the bridge than other locations of the highway. A BMP is to take the
snow from the end of the bridge to a snow storage facility, where it falls under the same
regulations as any snow removed from roads.

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6.2.3 Structural BMP for Alaska
In longer bridges, where it is not practical to run the water to the ends of the bridge, deck
drains are commonly used. The deck drain typically has a short pipe under the bridge
deck that leads the water away from structural elements.
Figure 3. Piping from a bridge deck drain.
These deck drains require maintenance, since if they become plugged with soil, organic
material, or trash, the water load to the deck can be increased and become a safety hazard
to the public during a heavy rain.
If the deck drains lead to an impaired water body, and a determination in made that the
runoff should not enter the water body, a solution often applied in warm climates is to
connect the drains with a piping system and lead the water to some treatment or holding
system off the bridge. Even in warm climates retrofitting bridges in this manner has
difficulties.
 The pipes need to be self cleaning. This requires a slope of ½ to 1%. The
required drop may not be available.
 If the pipe becomes clogged, it is a difficult project to clean the pipe.
 Catch basins or other devices may be added to the system, but the space may not
be available under an existing bridge.

52
 Other solutions, such as open troughs may work, if the space is available.
 Lift stations or such may be required.
 The dead load on the bridge is increased.
However in cold climates, a much more difficult situation arises. The piping is under the
bridge deck in the shade, while the bridge deck is in the sunlight. Thus water can flow
into the colder pipe, where it can freeze. In addition if the pipe is clogged at one end and
frozen at the other, water can freeze and burst the pipe. If there are lift stations or other
appurtenances, these can freeze as well. Appendix 2 has an inspection report of a bridge
in Anchorage that has had freezing and leaking problems with a deck drain piping
system.
A logical solution to this would be to heat trace the pipes and appurtenances. The ADOT
has ample experience dealing with culverts that are filled with ice and various heat
tracing schemes. Electric tracing did not work. The current method in the interior is to
have smaller thaw pipes in the top of the culvert, which are capped each fall. Then in the
spring, during breakup, maintenance crews attach steam to the thaw pipes and thaw a
channel through the culvert. This requires timing to be sure the water is flowing to
enlarge the hole, but before there is enough water from the upstream side to overflow the
road. If the thaw pipes were broken, it is still possible to steam the entire culvert,
although the related work is much greater. Relating the labor intensive effort for culvert
thawing to work on a bridge, this would require special device to thaw from the top side
of the bridge. To thaw from underneath would require special safety precautions and
might not be practical.
In some Alaskan bridge locations, power is not available. Our research has probed other
states and none seemed to have solutions to this freezing and maintenance issues.

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CHAPTER 7
7.0 BRIDGE DECK RUNOFF PRIORITIZATION SCHEME
Here, we developed a prioritization scheme that will help identify which bridges should
be considered for BMP. The scheme is applied to our bridges in Alaska on an Excel
worksheet that accompanies this report. The scheme starts with similar scheme used in
Washington, and then adds factors from the ACWA, STIP and several other Alaskan
environmental parameters. The prioritization scheme can be used to indicate bridges
where the impacts of bridge deck runoff on the receiving water should be considered. For
example, when considering the benefits of constructing a new BMP or modifications to
existing BMPs, the weight can be given to the bridges with highest prioritization score.
To calculate prioritization scores (P-score) for more than 700 ADOT owned bridges in
Alaska, first, we gathered the data for all the bridges in the state, and created a database
with more than 30 parameters for reference and calculated P-score by using about 20 of
them.
We started with a storm water outfall prioritization system Washington DOT (WSDOT)
developed, which compares the impacts of one outfall with another and makes an
assessment of their overall impacts to determine cases in which retrofitting is warranted
(WSDOT, 1996). We present that first, then, added special information from Alaska.
Below is the prioritization equation developed by WSDOT. Following the equation are
summaries of each element of the equation.
P-Score = (A + B) + (C1 * D) + C2 + [(E1 + E2 + E3 + E4) * E5] + E6 + F.
Where:
A = Type and size of receiving water body.
B = Beneficial uses of receiving water body.

54
C = Pollutant loading.
D = Percentage contribution of highway runoff to watershed.
E = Cost/pollution benefit.
F = Values trade-off.
Next, we customized the prioritization score based on Alaska needs, and called it
Modified P- score.
Modified P score formulation is as follows;
M P-score= P score+ P+S+T+V+W+X
Where:
P= ADFG score
S= Maximum state priority score give by ACWA
T= Traffic type
V= Salty water
W= Silty water
X= Dimension of the bridge.
To emphasize the importance of fish bearing streams, we factored DF&G score twice in
calculating the Modified P, once as ADFG score and once as part of the maximum
ACWA priority score.
In the following section, the scoring used for the database input method is presented. It
also includes the summaries and provides an inclusive listing of the point values for each
element in the prioritization equation. It is indexed by column names from the database:

55
 A-column characterizes the type and size of receiving water body. Parameters
used as follows.
Column A- Type of Receiving Water Body
Groundwater 10
Small stream 8
Small lake 6
Sensitive wetland 6
Large stream 5
Large lake 3
River 2
Wetlands 2
Tidelands 2
 B- Column presents a score for beneficial uses of receiving water body.
Column B- Designated Uses of Receiving Water Body Value (B)
Drinking water standards violated (SV) 20
Drinking water prevention 18
Public health SV 16
Public health prevention 14
Fisheries SV 12
Fisheries prevention 10
Aesthetics 4
Flood protection 4
Column C- gives a score for pollutant loading, which is a measure of the potential
amount of contaminants from ADOT right of way that mix with runoff and could impact
surface water bodies. The loading scored based on the average daily traffic (ADT) which
represents the amount of traffic that travels on all lanes on a designated portion of
roadway in both directions during a 24-hour period. This information was collected from

56
Juneau AKDOT’s recent bridge database. The ADT is given in the Column “ADT” and
the score if given in Column C, per these values:
Column C- Pollutant Loading Value (C1)
Very high (30000+ ADT) 4
High (30000-15000 ADT) 3
Medium (15000-5000 ADT) 2
Low (5000-0 ADT) 1
 Column D - Percentage contribution of highway runoff to watershed.
Element D. Percentage Contribution of Highway Runoff to Watershed Value (D)
Less than 5% 5
2 to 5% 4
1 to 2% 3
0.5 to 1% 2
Less than 0.5% 1
 Column E1 through E6 focuses on the cost-benefit analysis of any application that
can be done on the bridge. Column E1 shows right of way and scores 4 for all
bridges because only ADOT owned bridges are considered for this study.
Column E1- Right-of-Way Cost Points
DOT-owned land 4
Rural (low cost) 3
Suburban/transitional 2
Urban (high cost) 1
Prohibitive 0

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Column E2 presents BMP capital cost for each bridge. Because no data available
regarding to this, this column scored as 3 for all bridges.
Column E2 Best Management Practice (BMP) Capital Cost Points
No cost 5
Low 4
Medium 3
High 2
Very high 1
 Column E3 is about the conveyance structure of the bridges. Because there is no
available data available for Alaska bridges, and needs to have a field check for
each bridge, impermeable (pipe or asphalt) conveyance structure were assumed
for each bridge.
Column E3 Conveyance Structure Points
Impermeable (pipe/asphalt) 4
Soil 3
Vegetation 1
Column E4 shows receiving water body characteristics. Each bridges was categorized
with the water body underneath according to Alaska’s Final 2008 Integrated Water
Quality Monitoring and Assessment Report (Alaska Integrated Water Report, 2008). This
report divides water bodies in Alaska into five categories. Below are the definitions of
each category taken from that report.
Category 1: Waterbodies are placed in this category if there are data to support a
determination that the water quality standards and all of the uses are attained.
Category 2: Waterbodies are placed in this category if some of the water quality
standards for the designated uses are attained.
Category 3: Waterbodies are placed in Category 3 if data or information are insufficient
to determine that the water quality standards for any of the designated uses are attained.
Category 4: Category 4 waters have been determined to be impaired but do not need a
TMDL.

58
Category 5: Waterbodies are placed in Category 5 if the water quality standard(s) are not
attained, i.e., the waterbody is impaired for one or more designated uses by a pollutant(s)
and requires a TMDL or waterbody recovery plan to attain Alaska‘s water quality
standards (18 AAC 70). There are 25 waterbodies identified for placement in Category 5
and Section 303(d) listed as impaired.
Column E4 Water Quality of Receiving Water Body Points
303(d) listed- Category 5 5
305(b) listed- Category 4 5
Sensitive groundwater 5
Class B or equivalent low classification- Category 3 4
Class A or equivalent mid-level classification- Category 2 3
Class AA, marine, or equivalent high classification- Category 1 2
 E5-column was scored as 1 because in Alaska, all waters are classified as drinking
water in order to protect the habitat.
Column E5 Water Quality Multiplier Points
Discharge to marine, large lake, low classification wetland 0.5
Discharge to all other surface waters, Class I or II wetland, or sensitive groundwater system 1
E6-column shows information on construction projected for the next three years (2010-
2013), was collected from ADOT website under STIP. This is based on the assumption
that is less expensive to construct a retrofit BMP while construction is underway.
Column E6 Future Construction Plans Points
Outfall [Bridge] is within the boundaries of a planned construction project 3
No projects planned in the area, the BMP would be a stand-alone project 1
Prioritization Score Column: This column shows the score found by using the
parameters- A, B, C, D, E1, E2, E3, E4, E5. This method is explained in detail in the
previous section.

59
 P- Element is the score given by DF&G to prioritize some waters over others to
protect critical fish bearing resources.
Element P DF&G Priority Score
High 5
Medium 3
Low 1
 S-Element shows the waters identified by the ACWA as high priority. Waters are
nominated and scored by DF&G, DEC, and DNR state agencies, and factored into
the calculation by their highest score from one of these agencies.
Element S State Priority Score
High 5
Medium 3
Low 1
 T-Element- In this element, heavy truck traffic identified for each bridge by using
traffic nature of each highway. If the bridge is exposed to heavy truck traffic,
heavy truck column marked as 1/0, yes or no.

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Element T Traffic Type
Heavy truck traffic 1
No heavy trucks 0
 V-Element-To be aware of the biological environment under the bridge in
general, a column described the water underneath the bridge as salty or fresh. It is
scored as -1, if it is salty water and scored as 1, if it is fresh water.
Element V Salty Waters
Fresh 1
Salty -1
 W-Element identifies silty water goes under the bridge. We gathered the data
from Juneau Department of Transportation. The column name is Silty, and
depending on the siltyness of the water goes under the bridge, that column marked
as silty /not silty, -1/1.
Element W Silty Waters
Silty water -1
Not silty water 1
 In Element X, the bridges were grouped into three sections depending on their
length. If the bridge is longer than 400 ft, it is considered Long and scored as 5. If
the length is between 200 and 400ft, its score is 3, and if it is less than 200 ft, it is
a short bridge, and scored as 1.
Element X Dimension of the Bridge
Long ( Longer than 400 ft) 5
Medium (200 to 400 ft) 3
Short ( Less than 200 ft) 1
After all the factors for each bridge/BMP retrofit are assimilated, the modified score can
be calculated. The highest scores should be given first priority for retrofitting. In the next
section, each entry in the database explained columnwise.

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7.1 Database
The database is contained in the Excel spreadsheets accompanying this report. The
worksheet with the priority scores is found on tab P Scores. Other worksheets have the
raw data and text explanations. Each column labeled as described below.
A. Bridge number
B. Bridge name
C. Average daily traffic (ADT)
D. Type and size of receiving water body
E. Beneficial uses of receiving water body
F. Pollutant loading
G. Percentage contribution of highway runoff to watershed
H. Right-of-way Cost points
I. BMP capital cost points
J. Conveyance structure points
K. Water quality of receiving water body points
L. Water quality multiplier points
M. Future construction plans points
N. Values trade-off
O. Prioritization score
P. ADFG score ( these next four items are explained below)
Q. ADEC score
R. ADNR score
S. Maximum score of ADFG, ADEC, and ADNR on the AWCA.
T. Traffic Type: In this column, heavy truck traffic identified for each bridge by
using traffic nature of each highway. If the bridge is exposed to heavy truck
traffic, heavy truck column marked as Y/N, yes or no.
U. Urbanized areas: By using EPA’s urbanized area maps for Alaska, each bridge in
these areas were identified

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V. Salty Waters: To be aware of the biological environment under the bridge in
general, a column described the water underneath the bridge as salty or fresh. It is
Y-yes, if it is a salty water, and it is N-no, if it is a fresh water.
W. Silty Waters: Another column spared for identifying silty water goes under the
bridge. We gathered the data from Juneau Department of Transportation. The
column name is Silty, and depending on the siltyness of the water goes under the
bridge, that column marked as Y/N.
X. Dimension: In this column, the bridges were grouped into three sections
depending on their length. If the bridge is longer than 400 ft, it is considered Long
and marked as L. If the length is between 200 and 400ft, it is Medium (M), and if
it is less than 200 ft, it is a short bridge, and shown as S.
Y. Urban fringe
Z. Modified score
AA. Climate: We overlaid climate zone map of Alaska on Alaska bridge map
provided by Juneau Department of Transportation by using Google Earth so that
we identified the bridge numbers in each zone, and marked them in our database.
If the bridge is in Arctic zone, in climate column, we marked as A- arctic zone. If
it is in Maritime zone, it is marked as M, if it is in continental zone, it is C, and if
in Transitional zone, and it is marked as T.
AB. Bridge length
AG. Facility carried the bridge
AH. Location of the bridge
AJ. Region of the bridge
AK. Main material of the bridge
The Highway Database and the Prioritization Scores are in the attached Excel File,
Bridge Deck Runoff June 2010. On the several worksheets are a list of all the states’
bridges, sorted by Modified P-score, a list of current STIP projects that involved bridges,
a text explanation of the columns in the file, and the full prioritization scores.

63
CHAPTER 8
8.0 DECISION PROCESS
A BMP selection process is developed to help bridge engineers prioritize bridges in terms
of the need for BMPs. Following check steps may help engineers to make a decision in
whether a BMP should be considered for a bridge or not. Of course some bridges have
“special issues.” For example, the Million Dollar Bridge and the Susitna River bridges
are on the National Register of Historic Places (NRHP). Such special issues, however,
should be well-known to ADOT engineers working on projects related to those bridges.
8.1 Is it in Urbanized Area (UA)?
According to EPA, an urbanized area defined as a land area comprising one or more
places – central place(s) – and the adjacent densely settled surrounding area- urban
fringe- that together have a residential population of at least 50,000 and overall
population density of at least 1000 people per square mile. EPA has developed a set of
digitized maps for each urbanized area as defined by 2000 U.S. Census. All waters are
regulated in UA according to new CWA regulations.
For our project, it means that if a bridge is located in UA of Alaska, BMP must be
considered for that bridge deck runoff to protect the water quality of receiving waters.
In the database, all bridges in UAs of Alaska are marked as Y, yes, and need to be
considered for some kind of BMP.
If it is not in UA, then is it in STIP?
8.2 Is it in Statewide Transportation Improvement Program (STIP)?
It is less expensive to construct a retrofit BMP while other construction is underway so if
the bridge is in STIP, then BMP options should be considered to handle deck runoff prior
to the completion of the project. (The STIP can be found on the ADOT’s website at
http://www.dot.state.ak.us/stwdplng/cip_stip/index.shtml .)

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8.3 What is State ACWA Score?
Under ACWA, ADNR, ADFG and ADEC have developed a water body nomination and
ranking process. ADNR hydrologists provide factor-ratings for water quantity, whereas
biologists in ADFG provide aquatic habitat factor ratings, and ADEC provides water quality
ratings. Each water body is assigned a high, medium, or lower priority. This provides a
general notion of how “sensitive” a water body is.
In the ranking process, the agencies use criteria that prioritize assessment, and corrective
action needs for polluted waters and waters at risk of pollution, waters with habitat
degradation, or water quantity problems. These criteria include the statutory criteria as
well as severity of pollution and uses to be made of the waters, per the Clean Water Act §
303(d) (1)(A).
Most waters that are listed as impaired under Categories 5 and 4 of State of Alaska Water
body category are ranked as high priority in ACWA. ACWA does not drive the listing
decision though. The Integrated Report plays a role in the ACWA prioritization process.
8.4 Is the bridge is over the waters that feed Cook Inlet?
The National Marine Fisheries Service proposes to designate a critical habitat under the
Endangered Species Act for the Cook Inlet Beluga whale. This would result in all
discharges to upper Cook Inlet coming under scrutiny.
8.5 What is Modified Prioritization Score (PS)?
Refer to Chapter 7 for modified P-score calculation. If a bridge in this analysis gets a
very high score, BMP should be considered. If it is low, there may not be any need for a
BMP. Most of the bridges that have high modified P scores will require BMP
consideration based on one of the four proceeding criteria, but a few may not. Here the
ADOT will need to set the threshold based on the score. Aside from the threshold, the
modified priority score serves as an index of importance of BMP for that bridge and
allows relative rankings between bridges.

65
8.6 Conclusion
In summary, the steps for determining if BMP must be considered will consist of serious
of threshold questions, as indicated in the flowchart, is the bridge is in UA, in STIP, or
does it cross over high priority waters listed by ACWA or waters that enter the Beluga
whale habitat? If so, BMP should be considered.
Additionally, a high prioritization score may still indicate that the bridge is a candidate
for a BMP. However, implementing the BMP decision should be finalized following
cost- effectiveness analysis. High prioritization score may justify a higher BMP for a
bridge.
In the following page, the BMP selection process is flowcharted.

66
8.7 Bridge Selection Process Flowchart
Alaska
Bridges
Cook
Inlet?
Is it in
STIP?
ACWA
Is it in
UA?
Higher
Prioritization
Score
Consider BMP
Consider BMP
Consider BMP
Consider BMP
Consider BMP
YES
YES
YES
YE
S
YE
S
NO
NO BMP REQUIRED

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8.8ChecklistifBMPIndicated
If a BMP is indicated at the end of the bridge BMP selection process, a check list for
BMP type is presented as follows.
I. Flow into the river via drains or sides
a. Can it be changed to flow to ends?
i. Unlikely – major engineering/construction project
ii. Perhaps if very short?
b. Can it be fitted with pipes to ends or treatment?
i. Unlikely –major project
ii. Little evidence of success in cold regions
iii. But give it some thought.
c. BMP, non-structural
i. Public awareness
ii. Trash prevention
iii. Deicing changes
iv. Street sweeping
v. Snow management
vi. Melting
II. Flow to ends
a. Non-structural BMP, same as I above
b. Structural BMP
i. Vegetation
ii. Swales
iii. Treatment
iv. Other.

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CHAPTER 9
9.0 FURTHER RECOMMENDATIONS
In this Chapter, we want to review two options that represent new technology coupled
with some tested ideas that might be useful BMP. Street sweeping and deicing practices
BMPs are not new, but should be reviewed if a BMP is needed. The sweeping and
deicing are BMP that can be used if BMP are required without structural alternations to
existing bridges- but they are not needed in all cases. Because small particulates are an
item of concern of the EPA, new and more efficient street sweepers are being developed.
9.1 Street sweeping
Street sweeping is emerging as a high priority option when the constraints of bridge deck
runoff design and/ or retrofit and challenges of cold climate conditions are considered.
Street sweeping on a regular basis minimizes pollutant export to receiving waters. With
the recent advancements in the street sweeper technology, even fine grained sediment
particles that carry a substantial portion of the storm water pollutant load can be picked
up.
The Massachusetts Department of Environmental Protection (DEP) reports that a better-
planned schedule of street sweeping could increase the pollutant reduction substantially
(1997). The Massachusetts DEP also reports that infrequent sweepings (less than 20
times per year) with conventional mechanical sweepers result in average TSS removal
efficiencies no greater than 20 percent (NCHRP 2002).
In colder climates, street sweeping is used during the spring snowmelt to reduce pollutant
loads from road salt and to reduce sand export to receiving waters. Seventy percent of
cold climate storm water experts recommend street sweeping during the spring snowmelt
as a pollution prevention measure (Caraco and Claytor, 1997). This method is applicable
to bridge deck runoff.

69
Cost data for two cities in Michigan provides some guidance on the overall cost of a
street cleaning program. Table 4 contains a review of the labor, equipment, and material
costs for street cleaning for the year 1995. The average cost for street cleaning was $68
per curb mile and approximately 11 curb miles per day were swept (SWRC, 2003).
Table 4 The Cost of Street Cleaning for Two Cities in Michigan
City Labor Equipment Material and Services Total
Livonia $23,840 $85,630 $5,210 $114,680
Plymouth Township $18,050 $14,550 $280 $32,880
Table 5 gives another example of sweeper cost data for two types of sweepers:
mechanical and vacuum-assisted. In this table, it is shown that while the purchase price of
vacuum-assisted sweepers is significantly higher, the operation and maintenance costs are
lower (SWRC, 2003).
Table 5 Estimated Costs for Two Types of Street Sweepers
Sweeper Type Life
(Years)
Purchase Price
($)
O&M Cost ($/curb
mile) Sources
Mechanical 5 75,000 30 Finley, 1996
SWRPC, 1991
Vacuum-
assisted 8 150,000 15
Finley, 1996
Satterfield,
1991
According to Clayton study done in 1999, the optimum sweeping frequency appears to
be once every week or two. More frequent sweeping operations yielded only a small
increment in additional removal.

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Effectiveness-New studies show that conventional mechanical broom and vacuum-
assisted wet sweepers reduce nonpoint pollution by 5 to 30%; and nutrient content by 0 to
15%, but that newer dry vacuum sweepers can reduce nonpoint pollution by 35 to 80%;
and nutrients by 15 to 40% for those areas that can be swept (Runoff Report, 1998).
9.2 Deicers
Use of clean sand, calcium magnesium acetate (CMA) and potassium acetate (KA) are
high cost salt alternatives to rock salt.
There is no perfect solution to deice roads at a reasonable price with no impacts to the
environment. However, some strategies can be applied to reduce the impact. In addition
to reducing the number of lane miles salted or sanded, the amount of sand applied can be
reduced by changing traditional road salting techniques, often requiring a purchase of
equipment by a community. A simple modification is to use spreaders which are
calibrated and adjusted with road speed, to reduce wasted salt application (SWRC, 2003).
Using a “clean” sand source, free of fine materials, can help reduce both the TSS and the
phosphorus loads associated with road sanding. Phosphorus control is critical in many
northern and mountainous regions, which are home to a majority of the natural lakes in
the lower- 48 United States (SWRC 2003).
It may become cost efficient to use these special deicers only on bridges. It may be
possible with GPS controlled equipment to have a dual system that uses the expensive
treatment only on the sensitive bridges.

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9.3 Close Follow-up on Bridge Retrofit/Replacement Projects
A cost effective approach to BMP requires some analysis of the benefit of the BMP, such
as regulatory approvals or improvement of the environment, to the cost of the BMP. If
the cost of the BMP is small, ADOT might want to install it even though they are not
under pressure to do so. If the cost is large, careful analysis of the situation is warranted
to find the BMP with the lowest cost that will satisfy the requirements. Thus, for new
bridge construction (which is often a replacement for an exisiting bridge) or major
renovations to existing bridges, and an analysis of which BMP might be installed should
be done, since these might be very small costs in the overall project.
In Alaska, statewide, more than 60 projects are bridge related projects mentioned in STIP
database. These are either new bridge construction, rehabilitation and/or bridge
replacement projects. In this Chapter, because it is less expensive to construct a new or
retrofit BMP while other construction is underway, these projects are briefly discussed to
draw attention so that bridge engineers may consider finding ways to integrate BMP
projects with the current ongoing projects already underway.
Bridge projects may be divided into three types. These are bridge rehabilitation projects,
new bridge construction, retrofit, and bridge replacements projects.
It is important to reduce costs by identifying opportunities to combine stormwater BMP
projects with construction projects such as bridge retrofits or replacement projects.
Retrofitting bridges with structural storm water BMPs is technically difficult and can be
very costly (NCHRP, 2002). Retrofitting can include the construction of new structural
BMPs or modifications to existing BMPs. Therefore, it is important to be knowledgeable
about the current and future construction plans. During our search of such plans in
Statewide Transportation Improvement Plan (STIP) database, bridge retrofit, replacement
and new construction projects are classified based on their regions. More detailed
information about each project can be found in the STIP database.

72
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f
ADEC (2003). Alaska Water Quality Criteria Manual for Toxic and Other
Deleterious Organic and Inorganic Substances, Alaska Department of
Environmental Conservation, May 15, 2003.
http://www.epa.gov/waterscience/standards/wqslibrary/ak/ak_10_toxics_manual.
pdf
ADEC (2008). Alaska’s Final 2008 Integrated Water Monitoring and Quality
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Anchorage, AK.
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Bottoms, Jays, (2010) January 2010. Personal Communication. Alaska Department of
Transportation (DOT), Fairbanks, AK.

73
California Stormwater Quality Association (2003). Spill Prevention, Control and
Clean-up SC-11. (2003). Retrieved January 2010 from
www.cabmphandbooks.com/Documents/Industrial/SC-11.pdf
California Stormwater Quality Association (2003). Infiltration Basin, California
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http://www.cabmphandbooks.com/Documents/Development/TC-11.pdf
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memo-to-designer/page/Section%2018/18-1.pdf
Caraco D. and R. Claytor (1997). Storm Water BMP Design Supplement for Cold
Climates. Center for Watershed Protection. Ellicott City, MD.
http://www.cwp.org/cold-climates.htm
Dupage County (2008). Dupage County Water Quality Best Management Practices
Technical Guidance, Illinois. (2008). Retrieved November 2009 from
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Dupuis, Thomas V. (2002). Assessing the Impacts of Bridge Deck Runoff
Contaminants in Receiving Waters, Volume 1: Final Report. Washington
D.C.Transportation Research Board, 2002
Dupuis, Thomas V. Assessing the Impacts of Bridge Deck Runoff Contaminants in
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Dupuis, T. V., and Kobringer, N. P., (1985) “Effects of Highway Runoff on
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(4203) EPA 833-F-00-002 January 2000 (revised December 2005) Fact Sheet
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EPA (2006). Sand and Organic Filter. Retrieved January 2010 from
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&Rbutton=detail&bmp=73&minmeasure=5
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http://www.pca.state.mn.us/water/stormwater/steeringcommittee/sc-manual.html
National Cooperative Highway Research Program, 2002. Assessing the Impacts of
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78
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Publication No.FHWA-PD-96-032 (June 1996).

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APPENDIX 1
A1.0 OBSERVATIONS OF INTERIOR ALASKA BRIDGES
In this Chapter, Dr. Perkins made observations in April 2010 from Robertson River
Bridge, The Gerstel Bridge, Salcha River Bridge are examples for this study.
A1.1 Robertson River Bridge on the Alaska Highway
Deck drains not clogged, 1 foot curb.
Drains over land were straight pipes.
This bridge is an over-truss. Note brown
stain under each drain.

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Deck drains over river had a bend and
discharged below the lowest truss
members.
A1.2 Johnson River Bridge on the Alaska Highway
Johnson River had “New Jersey Barrier-
type” sides instead of curbs and each
barrier had a 1 inch gap before the next
barrier and a scupper towards the center.
One of the scuppers is shown.
The outside of the scupper was flush to the
concrete and drained without a pipe. There
was a horizontal member below the
scupper. These had holes to avoid standing
water.

82
Note that the drainages through the
expansion joints of the barrier (actually, the
concrete barriers are separate pieces) hits
over a support.

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A1.3 The Gerstle River Bridge
The bridge is a series of through trusses.
It has deck drains that flow into a short
down pipe.
Blow the pipes are some stains
However more prominent are gravel spots
where, apparently, the snowplowing
operation pushed some snow with gravel
over the one foot high curb.

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Note that this gravel may not have had salt
or deicing in it, rather at this time of year,
April, the black gravel melts the ice. This
picture shows both the gravel in the lower
left and a spot that may have come from
the down pipe in the center. Both appear
black or dark because of the small gravel
chips that are used for traction sand. The
chips are typically less than a quarter inch
in longest dimension, but considerably
larger than “sand.”
The upstream side of the bridge piers has a
steel nose on it to break ice. There is little
room to put any structure here that would
be safe from ice. The downstream side has
more room.

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A1.4 Salcha River Bridge on the Richardson Highway
The Salcha River Bridge on the Richardson Highway is a steel beam bridge with a
concrete deck. The deck drains are in a depression in the concrete.
In the photos, the depression is outlined by
the gravel.
Note that there is a small “gravel fillet”
between the roadway and the curb. But
this is not prominent. Also, there is deck
drainage through the expansion joints.
These deck drains flow through square
pipes that run at about 45 degrees out and
are sufficient to move the water past the
lower flange of the beam. Note the old pipe
in the photo is not associated with the
stormwater system.
This photo shows the concrete seat of the
main beams and the expansion joint drains
between the concrete and the ends of the
beams. Note there is a steep gravel slope
from the bottom of the concrete to the
water.

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On all four bridges, I did not see any obviously clogged drains. This has been an unusual
year with not much snow. I examined several locations with the drainage over land and
did not note any issues – obvious deposits. The only evidence of the runoff is the
staining from the gravel chips on the ice – which is highly visible, but unlikely to be of
any environmental pollution significance.

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APPENDIX 2
A2.0 Anchorage Port Access Bridge, Bridge No. 455.
Attached is a file
A2.1 Section of 2008 Fracture Critical Inspection Report.
This section of the 2008 report has information on the piping and drainage problems,
including broken pipes and water damage, associated with this bridge which features a so

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Photograph No. 49 – Looking at the south exterior face of the cap for pier 2A between
Girders 4 and 4. Note: the drain pipe is cracked with signs of leakage present.
Photograph No. 50 – Looking at the west column for pier 2A. Note: a tree is growing
adjacent to the concrete pedestal at the west column.

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Pier 3A
Pier 3A consists of a welded box cap, 29.02 feet in length with two integral steel columns.
The top of the cap is a maximum of 43 feet above the ground. The cap was accessed by
using a self propelled lift. Girders 1 through 5 frame into the cap at varying degree of skew
between 26 and 27°. Girder 4 does not extend past the north face of the cap. Four access
hatches exist in the cap and one access hatch exists in each column. The following
deficiencies were observed:
• The drain pipe has a loose gasket in the north web near Girder 5.
• The east column has 2-inches of moist debris on the bottom of the inside of
the column (see Photograph No. 51).
• There is evidence of the drain pipe leaking in the east column at the location
where it enters the cap. This may be leaking onto the bottom surface of the
column which would cause the debris to stay moist.
• The slope is encroaching on the south face of both the east and west concrete
pedestals (see Photograph No. 52).
Photograph No. 51 – Looking down at the interior bottom surface of the east column for
pier 3A. Note: 2-inches of moist debris exists on the bottom surface.

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Photograph No. 53 – Looking east inside the cap of pier 4C, in the north cell between
Girders 3 and 4. Note: a slight misalignment exists between the bottom flange stiffener
plates in north cell at the splice.
Photograph No. 54 – Looking at the drain pipe between Girders 1 and 2 on the north web in

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pier 4C. Note: the drain pipe is leaking at the entrance through causing blistering paint
Photograph No. 55 – Looking at the bottom surface of the interior of the west column of
pier 4C. Note: standing water and moist debris; the lower flush pipe broken.

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Photograph No. 56 – Looking up through the interior of the west column of pier 4C. Note:
surface corrosion on the stiffening rings due to dysfunctional drainage system.

93
Photograph No. 57 –
Looking north at the east
column of pier 5. Note:
water drains from the inside
of the column onto the
concrete pedestal.
Pier 6
Pier 6 consists of a welded
box cap, 64.00 feet in length
with two integral steel
columns. The top of the cap
is a maximum of 57 feet
above the ground. The cap
was accessed by using a self
propelled lift. Girders 1
through 9 frame into the cap
with no skew. Four access
hatches exist in the cap and
one access hatch exists in
each column. The following deficiencies were observed:
• Signs of previous standing water exist on the cap bottom flange and webs. The
previous water line is approximately 3” high. Dry debris exists on the inside of the
east cell of the pier cap (see Photograph No. 58).
• Condensation exists on surfaces of the east column due to clogged drain pipe at the
bottom leaving moisture in the column. Surface corrosion is forming on top of the
bottom flange of pier cap due to condensation. Lower drain pipe is clogged and there
is debris on the bottom surface.

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Photograph No. 62 – Looking at the interior of the north cell at the east end of the cap of
pier 9. Note: signs of previous standing water on the bottom flange, webs, and stiffeners.
Photograph No. 63 – Looking at the lower drain pipe in the east column of pier 9. Note: the
drain pipe is clogged and standing water and wet debris exist on the bottom surface of the
east column.

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Photograph No. 86 – Looking south at the concrete collar of
the column of pier 18WS. Note: a 1 square foot by 1-inch deep
spall exists in the concrete collar under the drain.
Pier 19WS
Pier 19WS consists of a welded box cap, 28.53 feet in length with a single integral steel
columns. The top of the cap is a maximum of 25 feet above the ground. The cap was
accessed by using a self propelled lift. Girders 1 through 4 frame into the cap at varying
degree of skew between 18 and 20°. Three access hatches exist in the cap and one access
hatch exists in the column. The following deficiencies were observed:
• 1/2-inch deep ponding water exists between Girders 1 and 2 in the north cell. This is
causing peeling paint and surface corrosion on interior face of the cap bottom flange
and the bottom 3 inches of the longitudinal stiffeners and cap webs between Girders 1
and 2. Wet debris exists on cap bottom flange between Girders 1 and 2. Surface
corrosion exists on the interior of the cap bottom flange splice plate between Girders
1 and 2 (see Photograph No. 87).
One missing bolt exists in the cap top flange splice plate between Girders 1 and 2 in the south
cell (see Photograph No. 88).

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APPENDIX 3 Annotated Bibliography
The following are publications that we reviewed and have written a short abstract and
notes about their relevancy to bridge deck runoff.

97
Allan, Craig J.; Evett, Jack B.; Saunders, William L.; Wu, Jy S. “Characterization
and Pollutant Loading Estimation for Highway Runoff.” Journal of Environmental
Engineering, Vol. 124, No. 7, July 1998.
Abstract:
Three highway segments typical of urban, semi-urban, and rural settings in the Piedmont
region of North Carolina were monitored to characterize the respective runoff
constituent’s concentrations and pollutant discharge or export loadings. Runoff from the
impervious bridge deck (Site I) carried total suspended solids (TSSs) concentrations and
loadings that are relatively higher than typical urban highways, whereas nitrogen and
phosphorus loadings are similar to agricultural runoff. Site II included a pervious
roadside shoulder with traffic volume equal to that of Site I. Site III was a non-urban
highway having lower traffic counts and imperviousness due to the presence of a
roadside median. The existing roadside shoulder and median appeared to attain at least
10-20% hydrologic attenuation of peak runoff discharges, more than 60% reduction of
event mean concentration of TSSs, and attenuation of the first-flush concentrations for
most pollutant constituents. Bulk precipitation data collected at the bridge deck site
indicated that 20% of TSS loadings, 70-90% of nitrogen loadings, and 10-50% of other
constituent exports from the roadway corridors might have originated from atmospheric
deposition during dry and wet weather conditions. The long-term highway pollutant
loadings have been derived to provide a basis for comparing highway runoff with other
categories of non point sources (NPSs).
Notes:
According to this report, the TSS and loadings from the bridge deck site were larger than
those that would typically be expected from highway runoff. The report indicates that the
road shoulder and median present at the other sites were most likely responsible for the
reduced TSS and loadings found (591).

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Avelleneda, Pedro; Ballestero, Thomas P.; Briggs, Joshua; Houle, James. J; Roseen,
Robert M.; Wildey, Robert. An Examination of Cold Climate Performance
of Low Impact Development Stormwater BMPs in A Northern Climate.
Durham, NH: University of New Hampshire, 2006
Abstract:
Between 2004 and 2006 a range of six Low Impact Development (LID) designs were
tested and monitored over 11 storm events for cold climate performance including filter
media frost penetration and resulting hydrographs, seasonal variations on contaminant
removal efficiency, and attenuation of chloride pulses associated with melt events. LID
systems evaluated include 2 types of bioretention systems, a surface sand filter, a gravel
wetland, a tree filter, and porous asphalt. The LID performance data will be contrasted
with conventional structural BMPs (swales, retention ponds), and some select
manufactured stormwater systems. Winter monitoring includes both rainfall runoff data
and diurnal melt events. Contaminant event mean concentration (EMC), and performance
efficiency were evaluated for storms with varying rainfall runoff characteristics. Runoff
constituent analyses included total suspended solids (TSS), diesel range organics (DRO),
nitrate (NO3), and zinc (Zn). Several water quality parameters (temperature, dissolved
oxygen, pH, conductivity) were monitored as real-time data. Performance evaluations
indicate that LID designs have a high level of functionality during winter months and that
frozen filter media appears not be a concern. Trends in chloride attenuation are complex.
Notes:
This article provides information related to LID BMPs in northern climates. The LID’s
tested were: 2 bioretention systems, a surface sand filter, a gravel wetland, a tree filter,
and a porous asphalt (2). According to the results, the LIDs continue to operate efficiently
during the winter months, although chloride contamination becomes a significant issue
(11). The climate of the study area is defined as coastal, cool temperate forest. The annual
precipitation is approximately 48”, and the average low temperature in January is -9C
(4). While this does not compare to the majority of Alaska’s climate, it may be
appropriate for the southeast and southcentral coastal regions.

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Barnes, David; Carlson, Robert F.; Gould, Stephanie. “Stormwater Management
Model Development for Fairbanks Alaska,” 11th International Conference on
Cold Regions Engineering, Anchorage, Alaska. Reston, VA: American Society of
Civil Engineers, 2002
Abstract:
This joint government-university stormwater management development project will
eventually aid in compliance with Phase II National Pollution Discharge Elimination
System (NPDES) requirements. The project is enabling the inventory and initial
modeling and investigation of management techniques for the stormwater drainage
system of the interior Alaskan city of Fairbanks.
The City of Fairbanks is the lead agency and end user of this project and is primarily
coordinating, mapping, and inventorying their stormwater system. The Civil and
Environmental Engineering Department at the University of Alaska, Fairbanks (UAF) is
using the information gathered by the City to model the system. The hydraulic model
created will be a comprehensive tool required for understanding the system and is a
necessary foundation for continued development of a stormwater management program.
Data is also being collected for eventual support of a water quality component to the
model. Ancillary to this data collection, jet truck cleaning, the primary means of system
maintenance is being investigates for its potential as a water quality management
technique.
Notes:
This article outlines the initial efforts of the City of Fairbanks in gaining compliance with
Phase II NPDES regulations. This article may be used to develop an understanding of the
stormwater management plan currently used by the City of Fairbanks and the Fairbanks
North Star Borough, although it should be supplemented with more recent information.
Barret, Michael E.; Jackson, Andrew; Kramer, Tim; Malina, Joseph F. Jr.
Characterization of Stormwater Runoff from a Bridge Deck and Approach

100
Highway and Effects on Receiving Water Quality. Austin, TX: Center for
Transportation Research at The University of Texas at Austin, 2006
Abstract:
Nonpoint source pollution represents one of the largest environmental problems currently
facing water quality professionals. A fraction of this pollution is conveyed to receiving
waters by stormwater drainage from highways. Some highway runoff is treated by
structural or non-structural systems (best management practices/[BMPs]) or is diverted to
municipal treatment systems depending on locale. However, much highway runoff and
almost all bridge deck runoff enter receiving streams without treatment. Highway runoff
may contain suspended solids, metals, oil and grease, fecal coliform, and oxygen
demanding organics. Highway runoff characteristics have been reported in some detail
over the years; however, limited data on the characteristics of runoff from bridge decks
are available. The objectives of this study are:
• Characterization of bridge deck and approach highway stormwater runoff in three
different geographical areas of Texas,
• A statistical comparison of the water quality characteristics of stormwater runoff from
the bridge surface and the approach highway at each site, and
• An assessment of the impacts of the runoff on the quality of the receiving water at each
site.
Notes:
This report contains an excellent summary of previous research conducted on sources of
highway contaminants, factors affecting highway runoff, existing studies on bridge runoff
characterization, and effects of highway runoff on receiving waters and biota. The results
of the research conducted indicates that no adverse impacts occurred during testing due to
the bridge deck runoff at all three sites (31). The report concludes:

101
“Highway runoff data could be used as a conservative proxy for bridge
deck runoff for the constituents monitored in this study, if site-specific
bridge deck runoff data were unavailable (31).”
Bhattarai, Rishi Raj; Esalmi, Mehran; Griffin, D.M. Jr.; Shretha, Sashi.
Determination and Treatment of Substances in Runoff in a Controlled Highway
System (Cross Lake). Baton Rouge, LA: Louisiana Transportation Research
Center, 2003
Abstract:
Because bridges usually span bodies of water, quantifying and controlling non-point
pollutant flux from them will take on added significance as federal regulations begin to
address non-point contamination of the environment. The objectives of this study were to
examine the quality and quantity of the non-point contamination coming from the Cross
Lake Bridge and to examine the effectiveness of a detention pond (holding pond) in
removing contaminants from the runoff. These objectives were accomplished by
installing sampler/flow meters at the basin inlet and outlet to quantify the volume of
runoff and mass of conventional contaminants (COD, TSS, nutrients, hydrocarbons)
entering and leaving the basin. The runoff flow rate into and out of the basin was logged
at periodic intervals and discrete samples were collected across flow hydrographs
entering and leaving the basin. Using this data, the basin efficiency in removing
pollutants from runoff could be estimated. Study results show that runoff from the bridge
contains pollutant concentrations similar to those found in domestic wastewater.
However, the Cross Lake holding pond removed 100 percent of total petroleum
hydrocarbons, 82 percent of oil and grease, and 85 percent of the total suspended solids
entering the pond. Removal percentages for other contaminants were smaller and
exhibited greater variation. Analysis of pond sediments and the overlying water column
showed that the majority of the metals in the runoff were concentrated in (sorbed onto)
the sediments. Partitioning coefficients on the order of several thousand were measured.
Holding ponds are relatively simple, low-maintenance systems that could be employed as
a best management practice (BMP) at a number of DOTD facilities and be a major factor

102
in reducing non-point contamination at existing DOTD facilities such as district offices
and maintenance yards. Holding ponds appear to be a simple and relatively inexpensive
way of complying with upcoming federal and state mandates regarding export of non-
point contamination from DOTD facilities; however, such facilities must be cleaned on a
regular basis to remain functional.
Notes:
The results of this study show that detention ponds are a very efficient and cost effective
method for removing petroleum hydrocarbons, oil and grease, and total suspended solids.
It was found that most of the metals in the runoff were located within the sediments that
were removed by the detention pond (59).
Bingham, Ralph L.; El-Agroudy, Amr A.; Neal, Harry V. Characterization of the
Potential Impact of Stormwater Runoff from Highways on the Neighboring
Water Bodies Case Study: Tamiami Trail Project. Orlando, FL: PBS&J,
2002
Abstract:
Florida's rapid growth and urbanization generated vast amounts of land clearing resulting
in the creation of impervious surfaces which increased flooding and water quality
degradation. Stormwater runoff contributed sediment, nutrients and heavy metals to these
waters. Earlier research attributes 80 to 95% of heavy metal (mainly lead, zinc, and
copper) contributions to our waters to be from highways and parking lots. In recent years,
pollutant concentrations in stormwater runoff from highways have been significantly
reduced due to the stricter environmental regulations implemented to protect the natural
habitat and to enhance environmental conditions in rural/urban areas. This paper presents
a predictive model of heavy metal concentrations in stormwater runoff from highways
based on the most recent available data in Florida. The model was then used to evaluate
contaminant concentrations from the runoff of the Tamiami Trail / US 41 as a case study.
Predicted results of pollutant concentrations from the Tamiami Trail are compared to a)
existing trace metal levels in-situ and; b) Class III Fresh Water Criteria to evaluate the

103
need of a water treatment facility for the project area. The results of the investigation
suggest that pollutant levels in stormwater runoff from the Tamiami Trail will have little
effect on the quality of the water and the surrounding aquatic habitat in the Tamiami
Canal.
Notes:
Based on the model developed it was predicted that the runoff from the highway project
would have little effect on the quality of the receiving waters and the surrounding aquatic
habitat as far ahead as 2020 (234). Based on this prediction the authors recommend that
no current action should be taken to treat the stormwater. According to the authors, “It
would not appear prudent to provide stormwater treatment for existing conditions which
do not violate standards or future conditions which predictably meet standards, at the
expense of measurable, physical impacts to wildlife and wetlands supported and
protected by National Park covenants (234).”
Brownlee, B; Lawal, S.; Larkin G.A.; Mayer, T.; Marsalek, J. “Heavy Metals and
PAHs in Stormwater Runoff from the Skyway Bridge, Burlington, Ontario.,” Water
Quality Research Journal, Vol. 23, Issue No. 4, Burlington, Ontario: National
Water Resource Institute, Environment Canada, 1997
Abstract:
Samples of stormwater runoff from the Skyway Bridge in Burlington, Ontario, were
analyzed for five heavy metals (Zn, Pb, Ni, Cu, and Cd) and 14 polycyclic aromatic
hydrocarbons (PAHs) in dissolved and particulate-bound phases. Among the metals
studied, the highest mean event-mean concentrations in whole-water samples were found
for Zn, Cu, and Pb (0.337, 0.136, 0.072 mg*L-1). These data compared well with those in
the literature. Pb concentrations had to be compared to the most recent data reflecting the
use of unleaded gasoline. Zn, Ni, and Cu in the dissolved phase accounted for 35 to 45%
of concentrations in whole-water samples. Mean PAH event-mean concentrations in
whole-water samples ranged from 0.015 to 0.5 g*L-1 for individual compounds.

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Dissolved phase PAHs represents less than 11% of whole-water concentrations. Mean
concentrations of ZN, Cu and Pb (997,314, 402 g*L-1) in runoff sediment were rather
high and indicated that this sediment was “grossly polluted” according to the (Ontario)
Ministry of Environment and Energy guide lines for sediment quality. Metal
concentrations in the <45m size fraction were greater than in whole-sediment samples,
but with respect to metal loads, this enrichment was insignificant since this fraction
represented less than 1% of the total mass of solids. The runoff chemistry indicates that
uncontrolled discharges of highway (bridge) runoff could significantly impact receiving
water quality and may require remediation by appropriate stormwater best management
practices.
Caraco, Deb; Claytor, Richard. Storm Water BMP Design Supplement for Cold
Climates. Elliot City, MD: Center for Watershed Protection, 1997
Introduction:
Designing stormwater best management practices (BMPs) that are effective at removing
pollutants, acceptable to the public and affordable is not easy in any climate. Cold
climates present additional challenges that make some traditional BMP designs less
effective or unusable. Based on information gathered in a nationwide survey of cold
climate BMP experts, stormwater challenges are evaluated and recommendations are
made for BMP use in cold regions (9).
Some of the challenges of cold climates, such as freezing temperatures and high runoff
during snowmelt events, influence the effectiveness of traditional stormwater designs.
This document describes modifications to traditional stormwater designs to make them
more effective in these environments.
Notes:
This report is an excellent reference for issues related to stormwater BMPs in cold
regions. The report also provides some basic suggestions to solve to these problems, as

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well as several management methods for sand and deicer use to reduce their presence in
stormwater runoff (8-1).
Christopher, James E.; Harper, Harvey H.; Wanielista, Martin P.; Yousef, Yousef
A. “Management of Drainage Systems from Highway Bridges for Pollution
Control,” Transportation Research Record 896, 1983
Abstract:
Pollutants associated with runoff water from highway bridges were characterized and
quantified. These pollutants are directly discharged through scupper drains to adjacent
water bodies and floodplains or detained in ponds before being released to lakes and
streams. Selected heavy metals, such as lead, zinc, copper, chromium, iron, nickel, and
cadmium, were of particular concern because of their potential enrichment in biota.
Results show significant differences in heavy metal concentrations between water
samples from bridge runoff and adjacent streams. Heavy metals tend to concentrate in
bottom sediments, floodplains, and adjacent soils. For example, bottom sediment samples
from Lake Ivanhoe, north of Orlando, Florida, collected beneath bridges with scupper
drains showed significantly higher concentrations of heavy metals than did samples
collected beneath bridges without scupper drains. In addition, concentrations of heavy
metals in the sediments of detention ponds receiving bridge drainage were higher than
concentrations in sediments from adjacent lakes. It appears that management and careful
design consideration of highway bridge drainage systems could result in significant
reduction of the amount of pollutants released to adjacent water bodies.
Notes:
This is another classic study cited by most authors. The study was completed in 1983.
The research focuses mainly on the concentration of heavy metals, and found that most
heavy metals were found in the bottom sediments (54). The report provides an interesting
example of how construction fill requirements led to the creation of three detention ponds
under the Maitland Boulevard Overpass (52). This indicates that simple coordination
between the design and construction agencies can lead to bridge deck runoff solutions.

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Davis, Allen P.; Flint, Kelly R. “Pollutant Mass Flushing Characterization of
Highway Stormwater Runoff from an Ultra-Urban Area,” Journal of
Environmental Engineering, Vol. 133, No. 6, June 1, 2007.
Abstract:
Water quality of highway stormwater runoff from an ultra-urban area was characterized
by determining the event mean concentration (EMC) for several pollutants and by
evaluating pollutant flushing. Thirty-two storm events were monitored between June
2002 and October 2003. Mean EMCs in mg/L were 0.035, 0.11, 0.22, 1.18, 420, 3.4,
0.14, 1.0, and 0.56 for Cd, Cu, Pb, Zn, total suspended solids (TSS), total Kjeldahl
nitrogen (TKN), NO2–N, NO3–N, and TP. First flush as defined by flushing of 50% of
the total pollutant mass load in the first 25% of the event runoff volume occurred in 33%
of the storm events for NO2
−, 27% for TP, 22% for NO3
− and TKN, 21% for Cu, 17% for
TSS, 14% for Zn, and 13% for Pb. Median values for the mass flushed in the first 25% of
runoff volume were greater than the mass flushed in any 25% portion beyond the first for
all pollutants. The mass in later 25% volume portions were greater than in the first 25%
volume in at least 17% of the events for all pollutants, indicating that a significant
amount of the pollutant load can be contained in later portions of the runoff volume.
Nonetheless, management of the first 1.3 mm (1/2 in.) of runoff was able to capture 81–
86% of the total pollutant mass.
Dupuis, Thomas V. Assessing the Impacts of Bridge Deck Runoff Contaminants in
Receiving Waters, Volume 1: Final Report. Washington D.C.: Transportation
Research Board, 2002
Notes:
This is the first volume of results from a study complete by NCHRP to address the
impacts of bridge deck runoff contaminants. The results of the literature review, survey
of highway agencies, and the results of two thorough biological studies are presented (1).
The literature review section provides listings of pertinent research and the state the
research was conducted in, a summary of previous FHWA studies, and previous NCHRP

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studies. The findings of the literature review are also summarized by topic (source and
type of pollutants, pollution accumulation in sediments, biological impacts, etc.). The
summary at the end of this section identifies key gaps in published literature, including:
availability of literature and ease of use by bridge designers, the lack of studies directly
related to bridge deck runoff impacts, and little if any studies focused on the impact from
bridge maintenance and spills (46).
The survey of state and provincial highway agencies revealed that bridge deck runoff is
“becoming more prominent and difficult to address in many states” (46). Few northern
region states indicated that structural mitigation systems were being used or developed
(23-25). Washington appears to be taking the most progressive stance on bridge deck
runoff mitigation. States that are addressing bridge deck runoff are most often doing so
because pressure from state or federal environmental agencies (26). The survey also
indicated that regulatory decisions were based on a general feeling that bridge deck
runoff must be harmful rather than a site specific investigation (26).
Dupuis, Thomas V. Assessing the Impacts of Bridge Deck Runoff Contaminants in
Receiving Waters, Volume 2: Practitioner’s Handbook. Washington D.C.:
Transportation Research Board, 2002
Notes:
This is the second volume produced by the NCHRP’s research on bridge deck runoff.
This volume is intended to serve as a guide for professionals to help develop a strategy
for identifying problem bridges, design experiments to analyze the quality of the runoff,
and to implement proper mitigation efforts. Each chapter helps the user identify and
address site specific problems. Tables are used to guide the workflow Also, nineteen
different methods for analyzing bridge deck runoff are provided. This volume should
serve as the starting point to develop a strategy specific to Alaska’s bridges.
Grapentine, Lee; Marsalek, Jiri; Rochfort, Quintin. Assessing Urban Stormwater
Toxicity: Methodology Evolution from Point Observations to Longitudinal

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Profiling. Burlington, Ontario: Water Science and Technology Branch,
Environment Canada, 2008
Abstract:
The quality of aquatic habitat in a stormwater management facility located in Toronto,
Ontario, was assessed by examining ecotoxicological responses of benthic invertebrates
exposed to sediment and water from this system. Besides residential stormwater, the
facility receives highway runoff contaminated with trace metals, polycyclic aromatic
hydrocarbons (PAHs), and road salt. The combined flow passes through two extended
detention ponds (in series) and a vegetated outlet channel. Toxicity of surficial sediment
collected from 14 longitudinally arrayed locations was assessed based on 10 acute and
chronic endpoints from laboratory tests with four benthic organisms. Greatest overall
toxicity was observed in sediment from sites in the upstream pond, where mortality to
amphipods and mayflies reached up to 100%. Downstream pond sediment was less toxic
on average than the upstream pond sediment, but not the outlet channel sediment where
untreated stormwater discharges provided additional sources of contamination.
Macroinvertebrate communities in sediment cores were depauperate and dominated by
oligochaetes and chironomids, with minimum densities and diversity at the deeper central
pond sites. While sediment toxicity was associated with high concentrations of trace
metals and high molecular weight PAHs, benthic community impoverishment appeared
related to high water column salinity.
Guo, James C. Y. “Sand Recovery for Highway Drainage Designs,” Journal of
Irrigation and Drainage Engineering, Vol 125, No. 6, November/December, 1999.
Abstract:
Roadway sanding is a common practice in cold regions because sand increases the
roadway friction when mixing with snow. However, after snow melt, sand imposes
potential hazards to traffic. Recovery of sand from highways has become an increasing
concern not only for the reason of traffic safety, but also for being nonpoint pollution
sources to nearby wetlands and streams. In this study, a snow storage element is

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introduced to the renascence project of a mountainous highway that is running through an
environmentally sensitive forest area in Colorado. Recovery of winter sanding material
from the highway is design to be a joint effort of surface runoff and sweeping machines.
As a tradeoff exists between sand recovery and the size of a snow storage area, this study
also presents a maximization methodology by which the size of the snow storage area can
be determined by the diminishing return of sand recovery.
Irwin, G.A.; McKenzie Donald J. Water-Quality Assessment of Stormwater Runoff
from a Heavily Used Urban Highway Bridge in Miami, Florida. Tallahassee, FL:
U.S. Geological Survey, 1983
Abstract:
Runoff from a 1.43-acre bridge section of Interstate 95 in Miami, Florida, was monitored
during five storms to estimate loads of selected water-quality parameters washed from
this heavily traveled roadway. The monitoring was conducted periodically from
November 1979 to May 1981 in cooperation with Florida Department of Transportation
for the specific purpose of quantifying the concentrations and loads of selected water-
quality parameters in urban-roadway runoff which may have an adverse impact on State
surface waters.
Automated instrumentation was used during each of the five storms to collect periodic
samples of bridge runoff and to measure continuously the storm discharge from the
bridge surface and the local rainfall. For most target parameters, 6 to 11 samples were
collected for analysis during each event. Results of these analyses generally indicated that
the parameter concentrations in the stormwater runoff and the parameter load magnitudes
were quite variable among the five storms, although both were similar to the levels
reported for numerous other roadway sites. Storm intensity influenced the rate of loading,
but parameter concentration was the dominant variable controlling the overall magnitude
of loading.

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Although only a limited number of runoff events were sampled, the data were used to
estimate the following average, discharge-weighted parameter loads per storm per acre of
bridge surface: 28 pounds (total solids), 7.1 pounds (suspended solids), 12.8 pounds (total
volatile solids) 4.6 pounds (suspended volatile solids), 4.7 (total organic carbon), 11
pounds (chemical oxygen demand), 0.27 pounds (total nitrogen), 0.06 pounds (total lead),
and 0.03 pounds (total zinc). Results of a very limited sampling of loading and 10 percent
of the suspended solids loading originated from material that was transported directly to
the bridge surface by precipitation. Further, a cursory assessment suggested that the total
number of antecedent dry days and traffic volume were not conspicuously related to
either runoff concentrations or loads.
Notes:
This is one of several studies completed during the 1970’s and 1980’s, when storm water
was first becoming a concern. It is cited by nearly every work reviewed for this literature
review. The major findings of the report are given in the last paragraph of the abstract. It
has been noted that this study does not represent a good cross section of the majority of
the United States due to Florida’s unique setting and the age of the study (Barrett 11).
Minnesota Stormwater Management Design Manual
Authors: Emmons & Olivier Resources, Center for Watershed Protection, 2006.
Abstract:
The Center worked with Minnesota-based Emmons & Olivier Resources, a large
committee of state regulators, and other stakeholders to craft the Minnesota Stormwater
Manual, the most comprehensive one in the Upper Midwest to date. This manual
provides an updated discussion of cold climate issues as they influence design of
stormwater practices, like the challenge of high snowfall, springtime snowmelt, and
Minnesota’s thousands of sensitive lakes, trout streams, and wetlands that merit special
protection. The related issue papers, also from this site, introduced new stormwater
concepts to the state, such as unified sizing criteria, special receiving water performance
standards, and stormwater credits.

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Notes:
This manual has been used as a reference for our report, and it is great study about
snowmelt hydrology, stormwater practices in cold regions.
Nwaneshiudu, Oke. Assessing Effects of Highway Bridge Deck Runoff on Nearby
Receiving Waters in Coastal Margins Using Remote Monitoring Techniques.
Texas A&M University, 2004
Abstract:
Most of the pollution found in highway runoff is both directly and indirectly contributed
by vehicles such as cars and trucks. The constituents that contribute the majority of the
pollution, such as metals, chemical oxygen demand, oil and grease, are generally
deposited on the highways. These can become very harmful and detrimental to human
health when they come in contact with our water system. The connecting tie between
these harmful highway-made pollution and our water system, which includes our ground
waters and surface waters, is rainfall. The main objective of this runoff study was to
characterize and assess the quantity and quality of the storm water runoff of a bridge deck
that discharged into a receiving water body. The bridge deck and the creek were located
in the coastal margin region in the southeast area of Texas on the border of Harris and
Galveston counties. Flow-activated water samplers and flow-measuring devices were
installed to quantitatively determine the rate of flow of the bridge deck and determine
different pollutant loading by sampling the receiving water body (Clear Creek). The
collected samples were analyzed for total suspended solids, toxic metals, and other
relevant constituents of concerns. The results illustrated that the runoff from the bridge
deck exhibited low total suspended solids concentrations (which were highest in the
creek). However, other metal constituents like the zinc and cooper concentration were
high and above standards. The phosphate concentrations in the creek were the highest and
exceeded EPA standards. Several nitrate concentrations were also noticeably above EPA
standards.

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Notes:
The findings of this report indicate that the bridge deck runoff contained low TSS and
VSS concentrations, but some of the metal concentrations (especially zinc) exceeded
EPA standards. The study creek phosphate levels exceeded the EPA standards while the
bridge deck runoff concentration of phosphates was low (52).
Oberts, G. 2003. “Cold climate BMPs: Solving the management puzzle.” Water Sci.
Technol., 48_9_, 21–32.
Abstract:
Snowmelt runoff and rain-on-snow events present some of the highest pollutant loading
and most difficult management challenges in the course of a year in regions with cold
climate. Frozen conduits, thick ice layers, low biological activity, altered chemistry, and
saturated or frozen ground conditions all work against effective treatment of melt runoff.
Understanding the source, evolution and transition that occurs within a melt event and
defining the management objectives for specific receiving waters will help focus the
search for effective management techniques. Solving the management puzzle means
putting together a strategy for both soluble and solids-associated water pollutants.
Notes:
This report is an excellent reference for issues related to stormwater BMPs in cold
regions. The report also provides some basic understanding of snowmelt hydrology.
Oberts, G. 2003. Keynote Address:“Stormwater Management in Cold Climates-
Planning, Design and Implementation”, Portalnd, Maine, November3-5, 2003.
Abstract:
Tremendous strides have been made since the first international conference in Narvik,
Norway in 1990 dedicated completely to the understanding and management of snowmelt
in urban areas, to Maine in 2003. But with every discovery comes the need to know
more. The advent of sophisticated computers and software that can predict the sun’s

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effect on a snowpack, the chemical data to finally know what that snowpack will yield to
a receiving water, and the behavior of that water as a slug of heavily polluted meltwater
enters are all recent advances in the science. But knowing these things merely whets the
appetite to delve further. Drawing from participation in the series of conferences and
workshops beginning with Narvik, and from experience in the field, observations will be
made on what we have learned and how it applies to everyday practical application in
cold climate regions. Accompanying this will be the identification of the many
information needs that still exist for both theoretical and practical aspects, including:
accurate modeling of the spatial mechanics of melt generation within an urban area and
the runoff it generates; better definition of the nature, partitioning and fate of pollutants
as they move from snowpack into and through receiving waters (recipients); improved
chemical handling and the impact of chemicals on surface and ground water; the
effectiveness of MTPs (meltwater treatment practices) and how they differ from STPs
(stormwater treatment practices); the potential impact of climate change; and technical
transfer of information to a limited world audience. The very positive result of
identifying these needs is that today someone is working on every one of these elements
and new collaborative efforts are under way among those interested in cold climate
hydrology and water quality. We have moved past the problem recognition stage and are
on the verge of truly understanding how meltwater generation and runoff can be
anticipated and managed. This keynote address will set the stage for the conference,
which focuses on lessons learned and practical applications for the future.
Thorolfsson, Sveinn T. “Specific Problems in Urban Drainage in Cold Climate.”
Urban Drainage Modeling; Proceedings of the specialty symposium held in
conjunction with the World Water and Environmental Resources Congress, May,
2001.
This paper presents the specific problems in urban drainage in cold climate. The climate
affects the urban drainage by changing the urban hydrological cycle and it becomes more
complex in cold weather than in warm-weather. In cold climate the low temperatures and
the snowfall causes several problems to the urban drainage systems. The urban runoff is

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affected by: 1) frozen ground surfaces, 2) frost penetration into the ground, 3) snow on
ground, 4) rain-on-snow, 5) snowdrift, 6) natural and man-made snow redistribution and
7) snow removal. Additional problems are caused by frost penetration, frost heaving,
freezing in pipes, ice on ground surfaces, clogging of gutters and inlets, icing in manholes
and in storm sewers, ice in open watercourses, such as urban creeks and rivers, ponds and
lakes, etc.
There are also changes in the transport of urban runoff and stormwater pollutants, the
operation of runoff control facilities and sewage treatment plants. Snow may be stored on
the catchment and produce runoff during warmer weather. Frozen ground thaws slowly
and high runoff rates may occur when rain falls on frozen ground. In maritime cold
climate subsequent melting and freezing periods often give significant runoff periods.
Other problems are due to flooding, combined sewer overflows (CSO) and overloading
of wastewater treatment plants. Pollutants may be accumulated in the snow in streets.
When the last 10-20% most polluted part of the accumulated snowmelts and enters the
sewer system, a shock load of pollutants may occur. The sewer system is filled up from
previous inflow and a part of the concentrated pollutants may be discharge in overflows
to local recipients. The wastewater conveyed to the treatment plants is discharged in
overflows to local recipients. The wastewater conveyed to the treatment plants is cold, 2-
5C, due to high inflow/infiltration in rain-on-snow and melting periods. Problems to the
urban surface runoff are caused by the snow redistribution on sidewalks etc or temporary
surface water storage because of clogged inlets.
In cold climate areas the planning and designing procedures for urban drainage often do
not consider the presence of the snow and even not the operation and maintenance
procedures and guidelines. A great need for further research and development in urban
drainage is therefore needed, followed up by a relevant training and education, including
preparation of appropriate educational materials. Such work is going on at the
Department of Hydraulics and Environmental Engineering, NTNU.
Notes:

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This article provides some basic examples of problems related to urban drainage in cold
regions (freezing of pipes, frost heave, peak flow rates due to snow melt, etc.), but does
not contain much information directly related to non-point discharge elimination.
Wilson, Dean. Highway 520 Bridge Storm Water Runoff Study. Seattle, WA: King
County Water and Land Resources Division, 2005
Introduction:
The Highway 520 Bridge Storm Water Runoff Study is a data collection effort that is part
of the Sammamish-Washington Analysis and Modeling Program (SWAMP). SWAMP is
a water quality and quantity monitoring modeling project that was initiated in 2000 to
support a variety of potential water resource decisions for the majority of the Greater
Lake Washington watershed. The continued expansion of urban and suburban
development and associated hydrological changes affecting flow and degrading riparian
habitat arguably make this watershed on the most highly altered on the West Coast
(Kerwin, 2001). SWAMP provides a comprehensive evaluation of current and future
water quality conditions in the study area.
Watershed modeling is an integral part of the SWAMP program. During development of
the SWAMP work plan it was determined that water quality loadings from a limited
access highway were needed for watershed model calibration in the Lake Washington
watershed. Consequently, the primary purpose of this project is to assess the quality and
quantity of storm water runoff from the 520 Bridge and to estimate contaminant loadings
to Lake Washington.
The 520 Bridge was chosen for several reasons, including:
 Contaminant loadings from the bridge to the lake have not been directly measured.
 Contaminant sources to the road surface are assumed to be limited almost exclusively
to those associated with vehicle traffic; few other potential contaminant sources are
likely present on the bridge deck to confound results.

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 Results will also be used to better understand the contaminant characteristics of
bridge runoff to Lake Washington.
 Results will be used to calibrate/validate watershed models developed in the Lake
Washington watershed (1).
Notes:
The author indicates that the observed zinc concentrations were higher than previously
reported concentrations for other limited access highways. This anomaly was investigated
with additional testing of the 520 Floating Bridge and two other floating bridges. It was
determined that the elevated zinc levels were caused by the failure of the inner coating on
the bridge downspouts, which caused leaching of zinc into the runoff (20). Also, it is
mentioned that bird droppings likely elevated concentrations of ammonia and fecal
coliform (21).