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IDEAL
Stormwater BMP Modeling
Framework
May 8, 2007
Brian T. Bates, PE
Integrated
Design and
Evaluation
Assessment of
Loadings Model
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History/Background of IDEAL
Modeling Approach
State of the model
Demo
Discussion
Woolpert IDEAL Demonstration
An OCRM Dilemma
1999
2000
2001
2002
2003
 Compliance with Antidegradation &
TMDLs
 Needed an explicit BMP model
− Model Hydrology & Hydrualics and
pollutant yield from urban areas.
− Estimate BMP performance.
− Base predictions on accepted
predictive procedures.
Woolpert IDEAL Demonstration
2004
IDEAL Initiated
2001
2002
2003
2004
2005
 Woolpert hired by OCRM
 Scope of Model
 Literature review
 Watershed Framework
 Post Construction BMP Design Aid
Manual and IDEAL Spreadsheet
Woolpert IDEAL Demonstration
IDEAL Development
 Primary Researchers
Dr Bill Barfield – Oklahoma State University
Dr. John Hayes – Clemson University
Woolpert IDEAL Demonstration
IDEAL OCRM version
 BMP Trapping
Sedimentology and
soil isotherms
 Hydrology
Single storm and
Total annual runoff
 4 pollutants
 3 BMPs
 Pond routing
 Single watershed
 Post-construction
Woolpert IDEAL Demonstration
Watershed Modeling Framework
Pervious and
Unconnected
Impervious
Imp
BMP
Directly Connected
Impervious
Impervious
BMP
Pervious
Outflow From
Watershed
Woolpert IDEAL Demonstration
Dry/Wet
Detention
Basin
Rainfall Statistics
12 Storms
0.25’’ to
10.5’’
Precip
Amount
Prob P
Values for
Greenville,
SC
Dormant
Season
P=0.336
Growing
Season
P=0.664
AMC 1
AMC 2
AMC 3
P=0.797
P=0.104
P=0.100
Woolpert IDEAL Demonstration
AMC 1
AMC 2
AMC 3
P=0.543
P=0.231
P=0.226
Sediment Yield
 Pervious Areas - MUSLE
 Impervious Areas - EMC Approach
− EMC varies with type of impervious area
− Modeling dependability improves as local data is
collected
 Model Sediment Size Distribution
− Used to determine sediment trapping in Vegetated
Filter Strip and in ponds
− Nutrients and bacteria are sorbed on the exchange
phase of the clay particles, hence need to know
concentration of clay size particles
− Pervious areas based on CREAMS equations
− Impervious areas based on NURP data
Woolpert IDEAL Demonstration
Nutrient and Bacteria Loading
 Modeling Nutrients
− Yield based on event mean concentrations
(EMCs) for each chemical
− EMCs vary based on land use
 Modeling Indicator Bacteria
− Yield based on event mean concentrations
(EMCs) for bacteria
− EMCs highly variable
• National average ~ 15,000 number/100ml
• Depends a great deal on presence of pets,
wildlife, leaky sewers, etc
Woolpert IDEAL Demonstration
BMP Trapping
 Predicts trapping of sediments in ponds through overflow
rate calculations for 5 particle classes.
 Predicts nutrient trapping by settling of particulate matter
and sorbed portion on trapped active clay content of the
sediment by isotherms.
 Predicts bacteria trapping using isotherms and mortality
 VFS trapping uses the KY VFS model
Woolpert IDEAL Demonstration
IDEAL OCRM Model
Limitations
 Only for use on the SC coast
 Limited outlet configurations
 Numerous spreadsheet constraints
 Untested BMP algorithms
 No resuspension, denitrification, direct
loading on BMP, or bacteria growth.
Woolpert IDEAL Demonstration
Greenville County
2001
2002
2003
2004
2005
 Woolpert hired by County
 Isotherms and Rainfall Analysis
 Continue to use spreadsheet
Woolpert IDEAL Demonstration
Greenville County
2001
2002
2003
2004
2005
 Dry pond
verification study
Woolpert IDEAL Demonstration
Greenville County
2001
2002
2003
2004
 VB GUI developed
 Bioretention cell research begun
 Multiple watersheds
 Literature review
− Swales & Engr. Devices
Woolpert IDEAL Demonstration
2005
Greenville County
2001
2002
2003
2004
Sept
 EPA BMP Design Manual
EPA/600/R-04/121
Woolpert IDEAL Demonstration
2005
Greenville County
2002
2003
2004
2005
 Bioretention cell added and
revised
− Greenhouse study
− Greenville Co. study
Woolpert IDEAL Demonstration
2006
Greenville County
Woolpert IDEAL Demonstration
Greenville County
2002
2003
2004
2005
 Bioretention cell added and
revised
− Greenhouse study
− Greenville Co. study
 FC loading function
Woolpert IDEAL Demonstration
2006
Greenville County
Woolpert IDEAL Demonstration
Greenville County
2002
2003
2004
2005
2006
 Sand filter and bioswale added
 Conceptual algorithms developed for
engr. devices
 Conveyance routing algorithms
− Pipe, Channel, Simple translation
 Model presented to EPA Region 4
 VB GUI revised to current layout
− Distributed Jan 2007 to GC engineers
Woolpert IDEAL Demonstration
Greenville County
 Object oriented VB.net “Drag n Drop” version
Woolpert IDEAL Demonstration
Ongoing Improvements
 Technical Advisory Group
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Barfield and Hayes
Dr. John Sansalone –University of Florida
Dr. Bob Pitt –University of Alabama
Mike Borst – EPA-Office of Research & Development
Mark Schlautman – Clemson University
Khaled Gasem – Oklahoma State University
 Enhanced Bioswale research with EPA-ORD,
Edison, NJ
 User’s Manual
Woolpert IDEAL Demonstration
Summary of versions
OCRM
Spreadsheet
Pollutants
VB.Net
Sediments, Nutrients, Bacteria
Watersheds
1
200+
BMPs
Wet/Dry Ponds, VFS
Wet/Dry Ponds,
VFS, Bioretention
cells, Sand filter
Conveyances
None
Pipes, channels,
and translation only
Isotherms &
Rainfall
Analysis
SC Coast
Greenville Co.
Woolpert IDEAL Demonstration
IDEAL
DEMONSTRATION
Uses
 BMP design for small to large development projects
 TMDL compliance
 Antidegradation restrictions
 Watershed master planning
 LID design
Woolpert IDEAL Demonstration
Future Enhancements
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Expansion of Isotherms
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Bacteria growth function
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Rainfall statistics
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Engineered device algorithms development
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Bioswale algorithm revision
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Conveyance design functionality
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GIS/CAD interface
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Optimization
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Large scale watershed considerations
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Performance enhancement and user support
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Continue to use best science available
Woolpert IDEAL Demonstration
Questions?