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Transferability of Post-Construction Stormwater Quality BMP Effectiveness Studies
NCHRP 25-25(92)
Project Objectives
Identify and review transportation-related BMP performance monitoring studies and existing BMP assessment protocols
Evaluate conditions and factors influencing the transferability of BMP performance monitoring results
Investigate the feasibility of establishing a central repository (BMP Database) for DOT post-construction stormwater
Transferability of Post-Construction Stormwater Quality BMP Effectiveness Studies (NCHRP25-25, Task 92) Report Organization
1. Introduction and Background
2. Survey of State Practices and Literature/Data Review
3. Effect of Geographic and Other Variables on BMP Performance
4. BMP Effectiveness Standardization Considerations
5. Resources Needed to Develop a BMP Database Portal for State DOTs
6. Summary and Conclusions
Survey of State Practices and Literature/Data Review
Existing BMP Acceptance/Assessment Protocols
Technology Assessment Protocol―Ecology (TAPE) Washington Department of Ecology (Active; adopted by many)
Technology Acceptance and Reciprocity Partnership (TARP) Protocol for Stormwater BMP Demonstrations Endorsed by California, Massachusetts, Maryland, New Jersey,
Pennsylvania, and Virginia (Partnership dissolved, but protocols still used in many states)
Environmental Technology Verification (ETV) Program EPA Office of Research and Development (Inactive)
Stormwater Testing and Evaluation for Products and Practices (STEPP) Water Environment Federation (WEF) and American Public Works
Association (APWA) (In development)
TAPE Summary
Minimum Hydrologic Performance: Capture 91% of long-term runoff Five Treatment Categories
Pretreatment : TSS removal 50% or achieve ≤50 mg/L Basic: TSS removal 80% TSS or achieve ≤20 mg/L Enhanced: DCu removal 30% or achieve ≤5 µg/L and
DZn removal 60% or achieve ≤20 µg/L Phosphorus: TP removal 50% or achieve ≤0.1 mg/L Oil: no visible sheen, TPH max ≤10 mg/L, daily average ≤10 mg/L
Three Designated Use Designations General Use Level Designation (GULD) Conditional Use Level Designation (CULD) Pilot Use Level Designation (PULD)
Note: Capture = Amount of runoff managed for volume and/or water quality
TARP Summary
General Acceptance Criteria A minimum of 15 storm events per monitoring location
At least 50% of the annual average rainfall sampled for a minimum of 15 inches of precipitation.
Average particle size: mean < 100 microns; approximate TSS distribution: 55% sand, 40% silt, and 5% clay
TSS influent concentration: 100 – 300 mg/L
Flows with a range up to 125% of design capacity
Scour tests
Participating states have additional requirements
ETV Summary
A public-private partnership between EPA and nonprofit testing and evaluation organizations, verified the performance of innovative technologies
No longer funded Latest protocol (Draft 4.1) was developed in 2002 Program stopped taking applications in 2013 Operations concluded in early 2014
STEPP Summary
On Feb 6, 2014, WEF's Stormwater Testing and Evaluation for Products and Practices (STEPP) Task Force released a white paper identifying the need and challenges of developing a national program
Alternative program structures Testing and Evaluation Certification Regional Standards Non-Programmatic Verifications Market-Based Verifications
Alternative funding mechanisms Public-private partnership Fee-for-service Grants Subscriber/membership
DOT BMP Certification and Evaluation Practices
Caltrans: Uses Stormwater Advisory Teams (SWATs) to evaluate new technologies submitted; Treatment BMP Technology Report, updated annually, lists BMP approved or considered for pilot study.
MassHighway: Acceptable protocols include those from the Massachusetts Strategic Envirotechnology Partnership (STEP), TARP, and ETV. Stormwater Policy Handbook updated with approved BMPs.
New Jersey: Certification requires verification of pollutant removal rates by N.J. Corporation for Advanced Technology (NJCAT), another TARP state, or third party testing organization. Acceptable BMPs are listed in the NJDEP Stormwater Best Management Practices Manual.
DOT BMP Certification and Evaluation Practices (cont.)
Oregon DOT: Proprietary BMP must have TAPE certification. BMPs not listed as “preferred” in the Hydraulics Manual must be approved by Hydraulic Engineering staff.
Virginia DOT: Evaluation based on TARP protocols and Virginia-specific requirements. Virginia’s Department of Conservation and Recreation (DCR) Stormwater Management Handbook lists approved BMPs.
Washington DOT: Requires TAPE certification. Acceptable BMPs listed on the Highway Runoff Manual.
Existing National Scale Stormwater Databases and BMP Study Clearinghouses
International Stormwater BMP Database (BMPDB) – relational BMP design and performance database that is actively populated, analyzed, and maintained
National Stormwater Quality Database (NSQD) – land use based water quality data set that include highway runoff data
FHWA/USGS National Highway Runoff Database (HRDB) - relational database focused on highway runoff; used as a preprocessor for the Stochastic Empirical Loading and Dilution Model (SELDM)
EPA’s Green Infrastructure Webpage – not a database, but provides links to databases and BMP performance summary reports and tools
Center for Watershed Protection (CWP) National Pollutant Removal Performance Database – focuses on percent removal with limited BMP design information; database not available online; findings are primarily disseminated through interpretive reports prepared by CWP
Other Links to BMP Studies and Research
Washington State DOT: http://www.wsdot.wa.gov/Environment/WaterQuality/Research/
Caltrans Monitoring & Research and Applied Studies: http://www.dot.ca.gov/hq/env/stormwater/special/newsetup/#monitoring
Washington Stormwater Center : http://www.wastormwatercenter.org/
VA Stormwater BMP Clearinghouse: http://vwrrc.vt.edu/swc/index.html
Villanova Urban Stormwater Partnership (VUSP): http://www1.villanova.edu/villanova/engineering/research/centers/vcase/vusp1.html
North Carolina State University: http://www.bae.ncsu.edu/stormwater/pubs.htm
University of Maryland/ Mid-Atlantic Water Program: http://archive.chesapeakebay.net/pubs/bmp/BMP_ASSESSMENT_FINAL_REPORT.pdf http://www.ence.umd.edu/~apdavis/LID-Publications.htm
University of Minnesota: http://stormwater.safl.umn.edu/
University of New Hampshire (UNH) Stormwater Center: http://www.unh.edu/unhsc/
Delaware DOT: https://www.deldot.gov/stormwater/publications.shtml
National LID Clearinghouse: http://www.lid-stormwater.net/clearinghouse/
Green Highways Program: http://www.lowimpactdevelopment.org/green_highways.htm
USGS Transportation-Related Research: http://water.usgs.gov/osw/TRB/index.html
University of Central Florida Stormwater Management Academy: http://www.stormwater.ucf.edu/
Literature Review
Research Category Number of Studies Reviewed
Capture Efficiency 5
Climatic and Meteorological Factors 9
Design Variables and Unit Treatment Processes 8
Hydro-modification Performance 3
Long-Term Pollutant Retention 1
Maintenance 9
Runoff Quality Characterization 27
Treatment Trains 1
Volume Reduction Performance 9
Water Quality Performance 44
TOTAL 116
Literature Review (cont.)
BMP Type Available Studies from Literature Search
Bioretention 9
Constructed & Pocket Wetlands 5
Dry Detention Basins 12
Infiltration Trenches/Basins 7
Manufactured Device 17
Permeable Pavement 7
Wet Retention Ponds 10
Sand/Media Filter 14
Vegetated Swales & Filter Strips 19
Wetland Basin/Channel 2
Geographic Distribution of BMP Performance Studies Identified in Literature
EPA Rainfall Zone Number Studies Found
Zone 1 - Great Lakes 12
Zone 2 - Northeast 8
Zone 6 - Southwest 7
Zone 3 - Southeast 6
Zone 7 - Northwest 5
Zone 5 - Texas 3
Zone 9 - Rocky Mountain 2Source: NPDES Phase I regulations, 40 CFR Part 122, Appendix E (USEPA 1990)
Overview of Studies and Data in the BMPDB
Total number of studies 434Total number of transportation-related studies 126Total number of states represented 23
Total number of states represented in transportation-related studies 10
Highest number of studies for any one state 78 (FL)
Highest number of transportation-related studies for any one state 66 (CA)
Total number of states with no studies 27Total number of BMP types in all studies 12
Number of Transportation-Related Studies in BMPDB
StateTOTAL
BMP Type CA DE FL MD MN NC TX VA WA WI
Bioretention 1 1 2
Dry Detention Basins 5 1 2 4 12
Filter Strips 34 3 2 1 40
Manufactured Device 9 7 1 3 1 21
Permeable Pavement 1 1
Retention Ponds 1 2 3
Sand/Media Filter 11 1 2 1 15
Vegetated Swales 6 6 2 10 24
Wetland Basin 5 5
Wetland Channel 1 2 3
Total 66 9 9 1 1 8 6 24 1 1 126
Effect of Geographic and Other Variables on BMP
Effectiveness
Overview of Factors Affecting BMP Performance
BMP performance is influenced primarily by influent characteristics and BMP unit operations and processes (UOPs)
Both of these factors are affected by geographic variables such as climate, soils, topography, and on-site and surrounding land uses
Primary UOPs provided by stormwater BMPs include
Hydrological/Hydraulic: flow attenuation/storage and surface runoff volume reduction (infiltration)
Physical Treatment: filtration and settling/sedimentation
Chemical Treatment: sorption and coagulation/flocculation
Biological: microbially-mediated transformation and plant uptake
Climate and Hydrology Effects
Differing rainfall intensity-duration-frequency can affect pollutant mobilization and hydraulic loading rates
Differences in evapotranspiration, soil moisture, temperature and other related factors that affect types and success of vegetation in stormwater systems
Temperature can affect viscosity of water which can affect infiltration rates and particle settling
Seasonality can affect the growing season, nutrient cycling in vegetative communities, seasonal groundwater levels, and decay/decomposition
Presence or absence of snow and frozen surfaces due to changes in temperature and differences in snow melt characteristics due to variations in sunshine, precipitation, temperature, and wind.
Distribution of Average Annual Precipitation (1981-2010)
Source: PRISM, Oregon State University, 2013
Distribution of Normal Mean Annual Temperature (1981-2010)
Source: PRISM, Oregon State University, 2013
Median Highway Runoff Concentrations by EPA Rain Zone
Median Highway Runoff Event Mean Concentration by EPA Rainfall
Zones
Constituent 1 2 3 4 5 6 7 8 9
TSS (mg/L) 134.1 38.9 30.7 83.9 81.1 51.3
TKN (mg/L) 2.02 1.81 1.58 1.75 1.03
NOx (mg/L) 0.83 1.43 0.90 0.62 0.26
TP (mg/L) 0.12 0.42 0.09 0.19 0.23 0.12
DP (mg/L) 0.05 0.10 0.04 0.13 0.08
TCu (µg/L) 46.1 18.7 15.9 6.00 28.7 11.0
TPb (µg/L) 12.2 72.3 3.24 58.9 15.5 4.74
TZn (µg/L) 193 108 85 58.8 154 70.1
COD (mg/L) 90.2 133 39.3 109 57.3 179 66.3 101 294
FC (MPN/100 mL) 2095 1883 2287
Data Source: National Stormwater Quality Database (NSQD) and Highway Runoff Database (HRDB) - Post 1983 data only
TSS Concentrations by Rain Zone
NOx Concentrations by Rain Zone
Total Phosphorus Concentrations by Rain Zone
Total Copper Concentrations by Rain Zone
Soils and Topography Effects
Soils vary in their degree of compaction, hydraulic conductivity, pH, erodability, particle density/size distribution, cohesion, pollutant sorption characteristics, and ability to retain water
All of these factors can affect stormwater runoff composition and UOPs within BMPs
Soils that are more easily erodible by wind can be blown onto impervious surfaces resulting in increased TSS levels and associated pollutants in runoff
Steeper slopes increase the velocity of runoff and the mobilization of pollutants
Traffic Volumes and Adjacent Land Uses Effects
Traffic volumes and adjacent land use activities can directly influence the quantity and quality of stormwater runoff influent to a BMP
Concentration of TSS, TKN, NOx, TP, TCu, TPb, and TZn tend to increase as the average annual daily traffic (AADT) increases, but TSS and TP correlations to AADT are weak
High traffic volume areas are typically in highly urbanized areas, so it is difficult to determine whether pollutant concentrations are due to traffic or adjacent land uses or both
Pollutants without a significant source from vehicular or road construction materials are likely more affected by adjacent land uses
Median Runoff Concentrations by AADT
ConstituentMedians (90%Confidence Intervals) by AADT Category
0 - 30K 30 - 90K 90K +TSS
(mg/L)44.0
(36.3 - 52.0)63.5
(53.9 - 67.0)100
(91.4 - 107.0)
TKN(mg/L)
1.03(0.85 - 1.18)
1.66(1.50 - 1.75)
2.15(1.96 - 2.39)
NOx(mg/L)
0.24(0.20 - 0.29)
0.66(0.60 - 0.71)
1.10(0.85 - 1.18)
TP(mg/L)
0.12(0.10 - 0.13)
0.18(0.15 - 0.19)
0.24(0.22 - 0.26)
TCu(µg/L)
9.81(8.20 - 11.00)
21.2(17.03 - 22.00)
48.5(43.00 - 52.00)
TPb(µg/L)
4.85(3.51 - 5.56)
9.13(7.33 - 10.88)
30.5(25.95 - 34.50)
TZn(µg/L)
55.0(48.48 - 62.50)
113(100.00 - 125.00)
217(200.0 - 235.90)
COD(mg/L)
49.3(43.0 - 54.0)
108(84.5 - 118.5)
95.8(86.0 - 107.3)
FC(MPN/100mL)
5,418(300 - 13,000)
No Data 1,735
(1,200 - 2,300)
Data Source: National Stormwater Quality Database (NSQD) and Highway Runoff Database (HRDB) - Post 1983 data only
TSS vs. AADT
NOx vs. AADT
Total Copper vs. AADT
Comparison of Highway Runoff Quality to Other Land Uses
Constituent
Median EMCs by AADT Category
Median EMCs by Land Use
0 - 30K 90K + Commercial Industrial ResidentialOpen Space
TSS (mg/L) 44.0 100.0 60.0 78.0 61.0 63.0
TKN (mg/L) 1.03 2.15 1.34 1.20 1.29 0.76
NOx (mg/L) 0.24 1.10 0.54 0.65 0.65 0.47
TP (mg/L) 0.12 0.24 0.21 0.22 0.27 0.19
TCu (µg/L) 9.81 48.55 15.00 18.00 12.00 9.50
TPb (µg/L) 4.85 30.48 12.24 16.09 8.67 10.00
TZn (µg/L) 54.98 217.41 120.00 154.00 74.00 70.00
COD (mg/L) 49.3 95.8 62.4 54.0 50.0 29.2
FC (MPN/100mL) 5,418 1,735 3,300 2,100 7,000 4,100
Data Source: National Stormwater Quality Database (NSQD) and Highway Runoff Database (HRDB) - Post 1983 data only
Effluent vs. Influent Concentrations
Effluent concentrations of most BMPs and pollutants are statistically correlated with influent concentrations, but many of the correlations are weak due to high variability in stormwater data sets
Effluent more correlated to influent concentrations for dissolved constituents than particulate-bound constituents
BMPs that include large wet pools or filtration media tend to be less sensitive to influent quality than those that do not
Detention basins show a relatively strong influent/effluent correlation for most pollutants (rho>0.5), while bioretention cells typically show weak influent/effluent correlation for most pollutants (rho≤0.5)
TSS Influent/Effluent Regression Curves
Regression equations developed for NCHRP Report 792 (Taylor et al., 2014) from data from the BMPDB
NOx Influent/Effluent Regression Curves
Regression equations developed for NCHRP Report 792 (Taylor et al., 2014) from data from the BMPDB
Total Phosphorus Influent/Effluent
Regression Curves
Regression equations developed for NCHRP Report 792 (Taylor et al., 2014) from data from the BMPDB
Total Zinc Influent/Effluent
Regression Curves
Regression equations developed for NCHRP Report 792 (Taylor et al., 2014) from data from the BMPDB
BMP Study Transferability Considerations
Environmental conditions, site characteristics, and BMP design features should be evaluated.
Relative importance of each of these can vary significantly depending on the pollutant, BMP type, and potential data application.
Climate may be the most important considerations due to the potential affect it can have on both influent quality and BMP treatment processes.
Land use and AADT should also be considered, but only for those BMPs and pollutants which are strongly tied to land use and where effluent concentrations are correlated with influent concentrations.
Soils should be assessed, particularly if evaluating volume loss or potential sources of nutrients, but other characteristics may be more important with regard to study transferability
BMP Effectiveness Standardization Considerations
Recommended Standardized BMP Study Reporting Protocols
International Stormwater BMP Database (BMPDB) is recommended as the DOT BMP study database due to its comprehensive design and long-term successful operation and maintenance:
Peer reviewed BMP monitoring and reporting protocols
Already contains xxx DOT BMP studies
Public access to the underlying data as well as interpretive reports
Managed by Water Environment Research Foundation with major support from FHWA
BMPDB reporting protocols and tools can be easily adapted/adopted to meet DOT needs:
Additional metadata
Transportation web-site portal
DOT specific interpretive reports
Recommended Standardized BMP Study Reporting Protocols
Every BMP study should report, at a minimum: Test site (location, climate, BMP type, etc.) Watershed (drainage area, land use characteristics, number of
lanes, AADT, etc) BMP design and maintenance (features, dimensions, activities, etc.) Monitoring program (study design, monitoring locations, equipment,
QA/QC, etc) Monitoring data (precipitation, flow, influent, and effluent by discrete
storm event) Construction, maintenance, and monitoring costs are also
recommended
Current General Structure of the BMPDB
Roadway-Specific Additional Metadata Recommendations
Roadway type Average ROW width Description of adjacent land use
and whether there is commingled flow
Road shoulder condition Monitored traffic lanes Lane widths Curb presence and type Vegetation clear zone maintained
adjacent to pavement Road cross-section type
Drainage system type Highway mile post Roadway maintenance
practices/frequencies Surface pavement type Date of last resurfacing and
surfacing material and sealants used
Deicing events/dates Use of studded tires
Scope of Work and Resources Needed to Develop BMP
Database Portal, Add Data Elements, and Prepare
Interpretive Reports for State DOTs
Potential Scope of Work
Phase 1 – Enhance Database and Develop DOT Portal
1.1 - Advisory Panel Meeting/Kickoff
1.2 - Communication and Training Promoting Use of the Database, Basic Website Updates, Administration and Coordination/Communication with Data Providers
1.3 - Update Web-based Retrieval and Analysis Tools
1.4 - Enhancements/Maintenance to Database Structure, Data Entry Spreadsheets, and User's Guide
Phase 2 – Expand Database and Prepare DOT-focused Reports
2.1 - New BMP Data Entry & Upload: includes new studies and may include expanded data sets/backfilling for existing studies
2.2 - Special Data Analysis Reports (Pollutant Categories or Advanced Analysis Reports; other Special Reports)
Estimated Budget and Schedule
Phase 1Task 1.1 $15,000Task 1.2 $15,000 to $20,000Task 1.3 $15,000 to $20,000Task 1.4 $5,000 to 10,000
Phase 1 Subtotal $50,000 to $65,000
Phase 1Task 2.1 $20,000 to $30,000Task 2.2 $25,000 to $35,000
Phase 2 Subtotal $45,000 to $65,000
Total Budget $95,000 to $130,000
1.1 Advisory Panel Meeting/Kickoff
1.2 Communication, Training, and Outreach
1.3 Update Web-based Retrieval and Analysis Tools
1.4 Enhancements to Database Structure
2.1 New BMP Data Entry and Upload
2.2 Special DOT Data Analysis Reports
Weeks from Notice to Proceed
Summary and Conclusions
Summary and Conclusions
BMP performance monitoring studies are concentrated in certain parts of the nation
Most states do not have established BMP monitoring and reporting protocols, but most states have a mechanism for accepting new treatment technologies
Climate and land use/AADT are the most important factors to consider with regard to BMP study data transferability
BMPDB is currently the most appropriate national-scale database that is actively maintained, populated and analyzed with public access to the underlying data as well as interpretive reports
BMPDB enhancements have been recommended to better support DOT objectives, including DOT specific metadata, a DOT “portal” to the BMPDB for customized data retrieval and analysis options
Questions?