EVALUATION OF VOLUME IN TWO BIOSWALE Judy Horwatich US Geological Survey
COOPERATORS Wisconsin Department of Transportation Wisconsin Department of Natural Resources
Support Changes to State Technical Standard Bioretention 1004 Measure Flow and Concentration from Highway VV, WI Measure Flow and Concentration from Bioswale Treating Highway VV Calibrate and Validate Biofilter Routine in WinSLAMMs (Source Loading and Management Model for Windows) STUDY DESIGN
TODAY S PRESENTATION Changes in Bioretention Technical Standard 1004 Sites Description Measured Data WinSLAMM Modeling
CHANGES IN BIORETENTION1004 Engineered Soil Mix Composition 50% Sand/ 50% Compost 85-75% Sand/ 15-25% Compost Engineered Soil Thickness 3 feet 2 feet
BIOSWALE DESIGN Linear Bioretention Follow Bioretention Design Located Along Roadways Runoff Enters Through Several Curb Cuts Filter Pollutants Through Engineered Soil Infiltrate to Native Soil and/or Storm Sewer
Study Site Two Engineered Mixes: 1. State Standard -75% Sand 25% Compost 2. Growth Layer -18 of Sand Top 6 Compost
MONITORING Inlet Flows Two Curb Cuts Monitored at Each Site Extrapolate to Entire Watershed Outlet Flows Drain Tile at Each Site
HIGHWAY SITE DESCRIPTION Newly Constructed 4-Lane Highway 2-Lane Divided Highway into East & West Bound Lanes 2 Inner Lanes Slope Towards Median Curb-Cuts Drain Highway Runoff into Median (~ 70-ft)
SURFACE AREAS Sites Number of Curb Cuts Highway Surface Area (ft^2) Bioswale Surface Area (ft^2) East 10 9,540 2,225 West 6 5,920 1,225
MEASURED HIGHWAY VOLUMES FROM TWO CURB CUTS Medians Identical Means within 5 percent
MEASURED OUTLET VOLUME 250 Mean Outliers(1) Outliers(2) Minimum/Maximum 200 150 Percent Volume Reduction: East 97 West 92 100 50 0 EAST WEST
CALIBRATE AND VALIDATE BIOFILTER ROUTINE IN WinSLAMM Simulate Highway Runoff Simulate Bioretention Transfer Project Results to WisDOT Future Projects
WinSLAMM PARAMETER FILE Rainfall Winter Load Pollutants Runoff Wisconsin Files Based on Measured Data Calibrated for Flow and Concentration Validated for Numerous Sites Solids Conc. Street Washoff Particle Size
Source Areas WinSLAMM INTERFACE Characterize Stormwater By Source Areas and Landuses Landuse Source Area and Regional Management Practices Management Practices Watershed Schematic
Percent Runoff 1.00 WinSLAMM SMALL STORM HYDROLOGY 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 Connected flat roofs Connected Pitched Roofs Directly connected impervious areas Directly connected unpaved areas Pervious areas - Sandy soils Pervious areas - Silty soils Pervious areas - Clayey soils Smooth textured streets Intermediate textured streets Rough textured streets High Traffic Urban Paved Areas High Traffic Urban Pervious Areas Near Shore, Woods Near Shore, Lawn Runoff Coefficient (Rv) Curves for at Least 14 Source Area Conducts a Continuous Water Mass Balance for Every Event 0.00 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 Rainfall depth
ASSESS BIOSWALE IN WinSLAMM Model Steps 1. Create Rainfall File Using Measured Values 2. Assess Runoff Inlet Event Volumes Measured vs Modeled 3. Assess Biofilter Event Volumes Measured vs Modeled
EVALUATION OF WinSLAMM Create Rainfall File Using Measured Values
RESIDUAL, CUBIC FEET (MEAUSRED-MODELED) RESIDUAL, CUBIC FEET (MEAUSRED-MODELED) MODELED VOLUME (CUBIC FEET) MODELED VOLUME (CUBIC FEET) INLET VOLUME COMPARISON MEASURED VS. MODELED USING DEFAULT HIGH-TRAFFIC URBAN Rv West Site Volume Comparison for 6-Inlets (HTU Rv) East Site Volume Comparison for 10-Inlets (HTU Rv) 1000 1000 100 10 10 100 1000 MEASURED VOLUME (CUBIC FEET) 500 West Site Inlet Residuals 100 10 10 100 1000 MEASURED VOLUME (CUBIC FEET) 500 East Site Inlet Residuals For Both Sites WinSLAMM is Over- Estimating Event Volumes ~50 percent 250 250 0 0-250 -250-500 -500-750 -750-1000 0 0.5 1 1.5 2 2.5 3 3.5 4-1000 0 1 2 3 4 RAINFALL (INCHES) RAINFALL (INCHES)
RUNOFF COEFFICIENT, Rv Split Dataset West Site Calibration East Site Validation 1 0.9 DEVELOP A NEW RUNOFF COEFFICIENT (Rv) Meaused Meaused West West Measured Measured East East Sheetflow Rv Current Current HTU RV HTU in WinSLAMM RV WinSLAMM Calibration Determine New Rv using Rainfall Extend Rv to Larger Events not Measured 0.8 0.7 0.6 y = 0.0455ln(x) + 0.6179 0.5 0.4 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 RAINFALL, IN INCHES
RESIDUAL, CUBIC FEET (MEAUSRED-MODELED) RESIDUAL, CUBIC FEET (MEAUSRED-MODELED) MODELED VOLUME (CUBIC FEET) MODELED VOLUME (CUBIC FEET) INLET VOLUME COMPARISON OF MEASURED TO MODELED HWY-VV Rv West Site Volume Comparison for 6-Inlets (Waukesha Rv) East Site Volume Comparison for 10-Inlets (Waukesha Rv) 1000.0 1000.0 Percent Error 100.0 100.0 West 1 East 7 10.0 10 100 1000 MEASURED VOLUME (CUBIC FEET) 10.0 10 100 1000 MEASURED VOLUME (CUBIC FEET) West Site Inlet Residuals Using Waukesha Rv East Site Inlet Residuals Using Waukesha Rv 500 500 250 250 0 0-250 -250-500 0 1 2 3 4-500 0 0.5 1 1.5 2 2.5 3 3.5 4 RAINFALL (INCHES) RAINFALL (INCHES)
Area Inf Rate BIOSWALE Modeling Biofilters Overflow Thickness Drain Tile
MODELED (CUBIC FEET) MEASURED-MODELED (CUBIC FEET) Modeled MEASURED-MODLED (CUBIC FEET) OUTLET VOLUME COMPARISON OF MEASURED TO MODELED West Modeled Outlet (Inf 0.5) West Modeled Outlet (Inf 0.5) West Measured Modeled 500 400 300 200 Percent Reduction 92 91 300 200 100 100 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0-100 Number of Event With Volume 12 18 0-200 0 100 200 300 400 500 Measured -300 RAINFALL (INCHES) East Modeled Outlet (Inf 0.5) East Modeled Outlet (Inf 0.5) West Measured Modeled 800 700 600 500 400 300 200 100 800 600 400 200 0 0.0-200 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0-400 Percent Reduction Number of Event With Volume 97 95 15 11 0 0 100 200 300 400 500 600 700 800 MEASURED (CUBIC FEET) -600-800 RAINFALL (INCHES)
VOLUME COMPARISON MEASURED VS MODELED West Measured (cf) Modeled (cf) Percent Difference Infiltration Rate (in/hr) Inlet 16,300 16,200 1 - Outlet 1,240 1,700 37 0.5 Outlet 1,240 1,300 5 0.6 East Measured (cf) Modeled (cf) Percent Difference Infiltration Rate (in/hr) Inlet 28,300 26,200 7 - Outlet 950 2,500 158 0.5 Outlet 950 1,770 86 0.6
CONCLUSION Bioswales Very Effective Along Highways WinSLAMM Modeled Results Match Measure Data WisDOT Achieving Reduction Goals