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?