Intro to Water Quality Modeling: Estimating Pollutant Load Reductions for Project Reporting

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Intro to Water Quality Modeling Estimating
Pollutant Load Reductions for Project Reporting
Scott DalyUtah Division of Water
Quality801.536.4333sdaly_at_utah.gov
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Objective

• UAFRRI Utah Animal Feedlot Runoff Risk Index
• Overview
• Data Inputs
• Load Reductions/Risk Assessment
• STEPL Spreadsheet Tool for Estimating Pollutant
  Loads
• Overview
• Data Inputs
• Model Setup
• Load Reduction
• Limitations
• Data Sources
• WQ Models and Project Planning

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Utah Animal Feedlot Runoff Risk Index (UAFRRI)

• MS Excel spreadsheet
• Inputs physical and management characteristics
• Output - Nutrient loading and load reduction
  estimates (N, P, and BOD5) Feedlot Risk
  Assessment

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(No Transcript)
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Spreadsheet Tool for Estimating Pollutant
Loads(STEPL)

• MS Excel spreadsheet
• Easy to use
• Inputs can be modified by user (optional)
• Calculates nutrient (N, P, and BOD5) and sediment
  loads by land use type
• Calculates expected load reductions
• Data driven and highly empirical

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STEPL Process
Load
Processes
User Input



Land Uses
Runoff
BMPs/LIDs
Nitrogen
Animals
Groundwater
Sheet/Rill Erosion
Phosphorus

• Precipitation
• Irrigation

Load Reduction
BOD
Soil and USLE Parameters
Gully/ Streambank Erosion
Sediment

• Septic Systems
• Direct Discharges

Pollutant Transport
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STEPL Web Site
Link to download
http//it.tetratech-ffx.com/steplweb/
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STEPL Main Program

• Run STEPL executable program (STEPL.exe)
• Start All Programs STEPL

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STEPL Spreadsheet
Composed of four worksheets
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Data Input
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BMPs
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Urban BMP Tool
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Gully/Streambank Loading
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Add New Data to BMP List

• In STEPL customized menu, click View/Edit BMP
  List
• BMP List worksheet is shown, add or delete BMPs

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Add New Data to BMP List
Update BMP button (BMPList worksheet)
New BMP added! (BMPs worksheet)
New BMP added!

• Click Update BMP Data button to update the BMP
  selections in the BMPs worksheet
• Click Save Updates to save changes to text
  files (comma delimited)
• Cor D\Stepl\Support\AllBMPstepl.csv
• C or D\Stepl\Support\AllBMP.csv

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STEPL BMP Calculator

• Calculates combined efficiency of a BMP train for
  a given land use.

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STEPL BMP Calculator
Filter strip
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STEPL BMP Calculator
4. Calculate combined efficiency
1. Add BMP box

• Describe schematically BMP configuration
• Number and linkages
• BMP type and efficiency
• Land use area
• Calculate combined
• efficiency
• Enter calculated efficiency
• in table 7 on the BMP tab

5. Delete Connection
2. Draw Connection
3. Move BMP box
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Other Ways to Use STEPL

• Model changes in land use and runoff before and
  after BMPs instead of modeling efficiencies
• Estimate BMP efficiencies
• BMP efficiency (Pre BMP load Post BMP load)
  / Pre BMP load
• Project planning
• Compare two projects to determine which has the
  most potential for load reduction
• Compare multiple BMPs within the same project
  area

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Model Limitations

• Driven by empirical relationships
• Emphasis for project-specific data
• Model calibration/validation
• Not easy to calibrate
• Designed to produce rough loading estimates,
  NOT precise loading

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Discussion
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Data Resources

• Table 1. Input watershed land use area (ac) and
  precipitation (in)
• 1. Precipitation (a). Local observation (b).
  http//www.wrcc.dri.edu/
• (c). http//www.wcc.nrcs.usda.gov/snow/
  (d). nws.noaa.gov
• Table 4. Modify the Universal Soil Loss Equation
  (USLE) parameters
• K Factor - http//websoilsurvey.nrcs.usda.gov/app
  /HomePage.htm
• LS Factor Field measurements for slope length
  (L) and slope (S), then consult the following
  tables. USDA Agricultural Handbook 703 Tables
  4-1 through 4-9.
• Cover Management Factor USLE Appendix A - Cover
  Managment Factor.doc and http//www.iwr.msu.edu/r
  usle/doc/cfactors.pdf
• Support Practice Factor http//www.omafra.gov.on
  .ca/english/engineer/facts/00-001.htm Table 5

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Data Resources

• Table 5. Select average soil hydrologic group
  (SHG)
• Soil Hydrologic Group Hydrologic Soil Group
• http//websoilsurvey.nrcs.usda.gov/app/HomePage.ht
  m
• Table 6. Reference runoff curve number (may be
  modified)
• 1. SCS Runoff Curve Number Computations.pdf,
  Appendix A Table 2-2