RUNOFF TREATMENT BMP DESIGN FOR HIGHWAY RUNOFF
IN COLD CLIMATES
Michael E. Barber, Ph.D., P.E.
Associate Professor
Department of Civil & Environmental Engineering
Marc Beutel, Ph.D.
Assistant Professor
Department of Civil & Environmental Engineering
David Yonge, Ph.D.
Professor
Department of Civil & Environmental Engineering
Rollin H. Hotchkiss, Ph.D., P.E.
Associate Professor
Department of Civil & Environmental Engineering
Washington State University
Transportation Research Center
PO Box 642910, Pullman, WA 99164-2910
August 3, 2004
TABLE OF CONTENTS
page
Problem Statement ...........................................................................................................................1
Background ......................................................................................................................................1
Objectives ........................................................................................................................................3
Benefits ............................................................................................................................................3
Work Plan ........................................................................................................................................4
o Task 1 – Review existing literature and models for precipitation, cold climate, and
snowmelt/runoff processes...................................................................................................4
o Task 2 – Identify field site locations ....................................................................................4
o Task 3 – Purchase and install instrumentation.....................................................................4
o Task 4 – Modify rainfall simulator ......................................................................................4
o Task 5 - Sample runoff quality/quantity ..............................................................................4
o Task 6 - Analyze, modify, and calibrate runoff prediction model .......................................5
o Task 7 – Develop design criteria .........................................................................................5
o Task 8 – Conduct regional workshop ..................................................................................5
o Task 9 – Project Report and Publications ............................................................................5
Facilities Available ..........................................................................................................................5
Staffing Plan.....................................................................................................................................6
Level of Effort..................................................................................................................................7
Time Schedule .................................................................................................................................8
Budget Estimate ...............................................................................................................................9
References ......................................................................................................................................10
i
Runoff Treatment BMP Design for Highway Runoff in Cold Climates
PROBLEM STATEMENT
Existing and pending state and federal regulations require significant reductions in pollution
from stormwater runoff from all urban settings including drainage from highways and bridge
decks. In developing the draft Eastern Washington Stormwater manual (Ecology 2003), it
became clear that many Best Management Practices (BMPs) for controlling stormwater runoff
treatment and flow control were based on model predictions developed for warm-weather
climates subject to summertime thunderstorms and other rainfall events. In the Pacific
Northwest, this is generally not the case as most runoff is generated because of rain-on-snow
events or during fall months after a prolonged dry season. Furthermore, cold climates can also
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). Regions that have average daily maximum temperatures of 35 degrees or less
during January, and which have a growing season less than 120 days, are especially vulnerable to
the effects of cold weather. These cold weather conditions exist in many parts of eastern
Washington and the Cascades and are therefore important design concerns.
BACKGROUND
For runoff treatment BMPs, the goal is to treat the 6-month storm, which is approximately 90%
of the annual pollutant load (Shueler, 1992). This requires that sizing for rainfall and snowmelt
events be completed in the context of the precipitation for the entire year. Ecology is proposing a
long duration storm hyetograph to account for snowmelt conditions although insufficient data on
runoff modeling currently exists for justification of actual values. Design storms in the
Northwest are often associated with spring or fall precipitation that occurs prior to or after the
primary growing season. A technical memo by Righellis (2003) stated that literature was
essentially non-existent for arid region long and short duration storms except for the recent
development of the regional storms for Eastern Washington by MGS. Moreover, traditional
NRCS curve number approaches are not recommended for storm durations longer than 24 hours.
As such, DOT personnel, State regulatory officials, and consultants have questioned the validity
of treatment volumes based on existing design storms. A future effort of rainfall-runoff data
collection and modeling correlation should be undertaken to improve the best available science
beyond what exists today. The research being proposed in this study will address these specific
issues.
Four regional storms for Eastern Washington have been proposed by MGS Engineering
Consultants. Based on differences in storm characteristics and seasonal variations, the four
regions have been identified as: 1) East Slopes of Cascade Mountains, 2) Central Basin, 3)
Okanogan, Spokane and Palouse, and 4) Northeastern and Blue Mountains (MSG, 2003). The
short and long term storms from these areas will be used as the basis for runoff model
development.
1
In addition to improving the modeling runoff volumes, the treatment efficacy of BMPs relying
on biological activity, vegetation, or infiltration in arid, cold climates must also be established.
At the 2004 Water Environment Research Federation Research and Subscriber meeting, cold
weather impacts ranked in the top eight in the list of stormwater concerns above the impacts of
global climate change and pollution source control (Pitt and Urbonas, 2004). Similarly, Strecker
and Quigley (2003) concluded that there was a “real need to sponsor BMP performance studies
that include snowmelt runoff and treatment.” Because of the temporal nature of runoff in the
Pacific Northwest, design storms generally occur prior to the establishment of vegetation or after
the growing season under near-dormant conditions. For example, rain-on-snow events in January
through April produce a significant amount of runoff from melting snow along highway
shoulders. However, the biological activity of BMPs receiving the runoff during this period is
significant below summer expectations. Regional correction factors must be developed.
Similarly, the rate of infiltration in frozen soils is limited, especially when ice lenses form. The
question becomes, is the ground frozen when it becomes runoff? Insufficient data currently exists
to confirm the importance of this process. There are potentially two results of this reduced
infiltration. First, BMPs that rely on infiltration to function are ineffective when the soil is
frozen. Second, runoff rates from snowmelt are elevated because the ground underneath the
snow is frozen. Research into predicting the performance of infiltration rates is needed. For
BMPs such as bio-infiltration swales and biofiltration swales, vegetation is integral to their
proper function. When the growing season is short, establishing and maintaining this vegetation
becomes more difficult. Some plant species go dormant at the onset of colder temperatures,
reducing the pollutant removal efficiency in BMPs that rely on actively growing plant life while
others are dormant simply because of the lack of summer precipitation in the Pacific Northwest.
Regardless of the cause, information concerning design requirements for fall/early winter rainfall
events is needed. Consequently, research should be done on the performance of cold climate
impacts on sizing and design requirements.
Proposed Research Approach:
Modeling Design Storms for Runoff Calibration
Modeling and field calibration of the regional storms developed by MGS will be established for
Eastern Washington. Similar storms will be created for parts of northern Idaho and eastern
Oregon as data permits. Although several models will be examined during this process, emphasis
will be placed on modification of the NRCS model used in the Santa Barbara Urban Hydrograph
procedure due to its historic application in Eastern Washington. The traditional method for
infiltration in the NRCS runoff method is a non-time dependent initial abstraction term related to
the curve number. Applying this approach to a long duration storm event does not account for
the additional infiltration likely to occur and may therefore overestimate the amount of runoff
volume and the size of the necessary treatment BMP. Correlations between rainfall when snow is
reported on the ground will be established to better link runoff design events with seasonal
precipitation records. A mobile rainfall simulator developed by Yonge et al will be modified and
used to examine plot scale rain-on-snow events. This information will be scaled to drainage
basin by developing the relationship to data collected using Davis weather stations and flumes
2
installed in small watersheds in the region to collect site specific runoff data for rain-on-snow
events. Seasonal ranges, temperatures, and ground conditions, will be based on this information.
Runoff Treatment BMP Evaluations
The performance of existing filter strips and biofiltration swales vegetated with native bunch
grass and composted amended vegetated filter strips (CAVFS) BMPs will be examined in terms
of 1) how much stormwater runoff is prevented? 2) what is the hydraulic performance of the
BMP (how much runoff is treated?) and 3) what is the effluent concentration versus influent
concentration. Temperature and soil moisture probes will be installed at two depths at each
biofiltration swale and CAVFS study location. An assessment of vegetation condition will be
made using % vegetation moisture as the biomarker. Using the mobile rainfall simulator to
supply various quantities and patterns of rainfall, fall and winter runoff samples will be collected
from the BMPs. Mechanisms of removal (both short-term and long-term) will be identified and
the effects of temperature on performance will be established. Design criteria for typical BMPs
will be determined. Updates to the 1975 degree-day and growing season maps will be created so
that BMP performance can be linked to a traditional marker for potential users across the
northern states.
OBJECTIVES
The overall goal of this project would be to enable engineers to better predict runoff treatment
volumes and BMP performance in cold, semi-arid climates. This research will answer cold
weather design concerns for runoff treatment issues related to two distinct areas:
1. The modeling efforts associated with predicting runoff treatment flow rates and
volumes from short duration and long duration storms in Eastern Washington and
Northern Idaho; and
2. The performance efficiency of runoff treatment BMPs in cold, semi-arid climates.
BMP performance measures of filter strips, biofiltration swales, and compost amended vegetated
filter strips related to metals, nutrients, and deicers will be specifically addressed in the proposed
research. These BMPs were chosen as the most applicable after discussions with WSDOT
personnel.
BENEFITS
This research will enable improved design of stormwater runoff treatment facilities in cold
regions. By insuring that BMPs are properly designed, transportation personnel will be able to
better plan cost-effective controls for treating highway and bridge deck runoff. Regulators will
also be able to more quickly assess performance and so permitting should also be easier.
Furthermore, since many areas are now requiring implementation monitoring of stormwater
runoff treatment facilities, designing BMPs correctly will save costly retrofits.
3
WORK PLAN
The overall work plan will involve developing model correction procedures and BMP design
changes necessary to account for climatic conditions in semi-arid, cold climates. To accomplish
these objectives, the following tasks will be completed:
Task 1 – Review existing literature and models for precipitation, cold climate, and
snowmelt/runoff processes.
A complete review and evaluation of existing literature and models for precipitation, cold
climate, and snowmelt/runoff processes. This will be a comprehensive search of information
from countries around the world so see which models and processes may be applicable to the
Pacific Northwest. Especially important will be inclusion of internal or non-published work
currently going on at WSDOT (Haderlie, 2004).
Task 2 – Identify field site locations
Researchers will coordinate efforts with WSDOT personnel to find potential field site locations
for the four climatic regions in Eastern Washington. Field visits will then be made to potential
sites to evaluate the suitability. These sites will be in high traffic areas when possible.
Task 3 – Purchase and install instrumentation
Specifications for weather stations (precipitation, solar radiation, relative humidity, wind speed),
temperature probes, soil moisture equipment and flow measuring devices will be developed in
conjunction with the development of a sample analysis plan. The equipment will be purchased.
Upon arrival, the instruments will be calibrated as required to insure proper field measurement.
The instruments will then be installed at or near the field sites.
Task 4 – Modify rainfall simulator
The rainfall simulator developed by Yonge et al will be modified such that rainfall temperature
and droplet size can be varied. This will involve adapting some heating mechanism and nozzle
adjustments to the current apparatus.
Task 5 - Sample runoff quality/quantity information
The amount and timing of runoff volumes will be measured for both real and hypothesized
winter, spring and fall rainfall events at all four field locations. Where necessary, additional
snow may be placed on the BMP before simulated rainfall is applied. Changes in soil moisture
and temperature within the BMP will be monitored during the events. Water quality information
involving heavy metals, deicers, and nutrients (nitrogen and phosphorus) will be collected.
4
Task 6 - Analyze, modify, and calibrate runoff prediction model
The data collected in Task 5 will be analyzed to determine how the short and long term
precipitation events should be modeled. This will include examining models such as HEC-HMS,
HSPF, and SBUH with the existing short and long term storm events and varying calibration
coefficients to fit the measured runoff data. Defensible modifications to the equations used in
one or more of these models will be developed.
Task 7 – Develop design criteria
Based on the results determined in Task 6, researchers will develop recommendations for
changes in modeling procedures and BMP design. We will continue to work closely with
WSDOT personnel during this task to insure the practicality of the proposed solutions.
Task 8 – Conduct regional workshop
A regional workshop will be held in Moses Lake, Washington with the participants involved in
the development of the Eastern Washington Stormwater Manual invited to participate.
Additional representatives from Idaho and Oregon will also be invited. The workshop will be to
disseminate the information collected and receive feedback from a broad audience of potential
users.
Task 9 – Project Report and Publications
Draft and final project reports documenting the procedures and results of the study will be
completed. The information will be submitted to WSDOT and to the Washington Department of
Ecology for consideration in their stormwater manuals. Conference presentations and journal
papers will also be written to disseminate the major findings of this research project. It is
anticipated that two papers to the national TRB conference will be completed as well as
submissions to other appropriate conferences/journals.
FACILITIES AVAILABLE
Much of the research will be conducted at field sites from four regions in the inland Northwest.
An example of such a location is shown below. Researchers will work closely with personnel
from the Washington State Department of Transportation to identify the study sites.
The WSU Department of Civil and Environmental Engineering has over 17,000 square feet of
teaching and research laboratory space that is equipped with a wide range of state-of-the-art
analytical equipment for both air and water analysis. The water quality samples collected as part
of the BMP evaluation will be analyzed in these laboratories.
5
Figure 1. BMP site with compost for treating bridge/highway runoff (Peralta, 2004)
STAFFING PLAN
The principal investigator for this project is Michael Barber, Associate Professor of Civil and
Environmental Engineering and Director of the State of Washington Water Research Center at
Washington State University in Pullman, Washington. His research has included field
investigations and numerical modeling of nutrients and primary productivity in rivers and lakes,
evaluated the performance of stormwater facilities for pollution control, investigated improving
watershed management assessment strategies, pipeline rehabilitation, and modeling contaminant
transport. Dr. Barber has also been involved with a number of wetland and wet pond projects
including a project funded by the National Cooperative Highway Research Program to develop
design criteria for wet ponds. He is currently working on investigation BMPs for the effective
coexistence of salmonids and agriculture and TMDL issues.
There are three co-investigators for this project: Marc Beutel, David Yonge, and Rollin
Hotchkiss. Dr. Marc Beutel is an Assistant Professor of Civil and Environmental Engineering
specializing in the examination of pollutant impacts on receiving water bodies. Dr. Beutel has
particular expertise in the interactions between oxygen and contaminated sediments.
6
Dr. David Yonge is a Professor of Civil and Environmental Engineering and Director of the
Center for Multiphase Environmental Research. His research experience includes work in the
areas of: 1) physical and chemical wastewater treatment process: adsorption phenomena, metal
partitioning, precipitation, facilitated metal transport mechanisms, vapor extraction of
chlorinated solvents, 2) adsorption and desorption of hazardous organics and metals on soil and
activated carbon, 3) removal of metals from industrial waste streams and 4) the fate and transport
of highway runoff contaminants. Dr. Yonge has been involved in numerous studies involving
transportation issues surrounding environmental impacts for WSDOT and NCHRP.
Dr. Rollin Hotchkiss is an Associate Professor of Civil and Environmental Engineering with
background in sediment transport and open channel flow phenomenon.
One Ph.D. student will participate in all phases of this research project, and one M.S. student will
participate in most phases of the project. An undergraduate student will also assist in the project.
LEVEL OF EFFORT
The anticipated level of effort for each task described above is broken out by individual and
presented in the following table.
Level of Effort (hours per task)
Personnel
Barber
Beutel
Yonge
Hotchkiss
Ph.D. Student
M.S. Student
Undergraduate
Task Task Task Task Task Task Task Task Task
1
2
3
4
5
6
7
8
9
40
8
8
8
40
40
40
8
40
16
8
20
8
20
8
20
8
8
72
16
20
8
40
4
8
16
4
8
240
40
160
80
540
580
160
40
240
160
40
160
160
720
320
320
40
160
- 200
120
80
-
7
Total
232
100
172
40
2080
2080
400
TIME SCHEDULE
The anticipated time to complete this project is broken out by task and presented in the Figure below. The project assumes a start date of
October 1, 2004 and that graduate assistants are appointed beginning in January 2005. The time to completion is two-and-a-half years.
2005
TASKS
2006
2007
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
1
2
3
4
5
6
7
8
9
8
BUDGET ESTIMATE
As illustrated in the table shown below, the budget estimate for conducting this research totals
$200,000 over the life of the project.
Category
Personnel
Faculty
Graduate Students
Undergraduate Students
Benefits
Faculty
Graduate Students
Undergraduate Students
Goods and Services
Supplies
Temperature Loggers
Moisture Probes
Laboratory Analyses
Non-capital Equipment
Weather Stations
Flow Gages
Travel
Domestic travel to field sites
Indirect F&A
TOTALS
Year 1
Year 2
Year 3
8,181.
19,422.
2,000.
12,091.
31,840.
2,000.
12,125.
-
20,272.
63,387.
4,000.
2,780.
9,239.
30.
4,111.
17,088.
30.
7,947.
-
6,891.
34,274.
60.
2,842.
2,400.
1,000.
5,000.
2,000.
5,000.
500.
-
5,342.
2,400.
1,000.
10,000.
4,400.
4,000.
-
-
4,400.
4,000.
4,169.
15,076.
80,049.
4,169.
16,826.
95,157.
3,735.
24,307.
8,338.
35,637.
200,000.
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Total
REFERENCES
Ecology, 2003. Stormwater Management for Eastern Washington, Washington State Department of
Ecology, 03-10-038B, Olympia, WA.
Haderlie, G. 2004. Cold Climate Considerations for WSDOT. Internal memorandum developed at
WSDOT Headquarter Hydraulics Office, Olympia, WA.
MSG. 2003. Background Information on Design Storms, Appendix to Chapter 4 – Hydrologic
Analysis and Design, MSG Engineering Consultants.
Pitt, B. and B. Urbonas, 2004. Stormwater Session – WERF Subscriber and Research Council/STAC
Meeting, March 18-19, 2004, http://www.werf.org/pdf/stormwater.pdf
Righellis, A.O., 2003. Modeling Methodology for Custom Design Storms in Eastern Washington,
Technical Memorandum, Harper-Houf-Righellis, Inc.
SMRC, 2003. Stormwater Practices for Cold Climates, Stormwater Manager’s Resource Center,
http://www.stormwatercenter.net/Cold%20Climates/cold-climates.htm
Strecker, E. and M. Quigley, 2003. Assessment of Cold Weather Highway Runoff Water Quality
and BMP, Stormwater Management in Cold Climates, Portland, ME.
10