1 / 35

A Tool for Determining the Effectiveness and Whole Life Costs of BMPs

A Tool for Determining the Effectiveness and Whole Life Costs of BMPs. Presentation to: 2008 Colorado Association of Stormwater and Floodplain Managers (CASFM) Conference. Presented By: Chris Olson, E.I.T. Larry A. Roesner, P.E., PhD Colorado State University Ben Urbonas, P.E., D.WRE

Faraday
Télécharger la présentation

A Tool for Determining the Effectiveness and Whole Life Costs of BMPs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Tool for Determining the Effectiveness and Whole Life Costs of BMPs Presentation to: 2008 Colorado Association of Stormwater and Floodplain Managers (CASFM) Conference Presented By: Chris Olson, E.I.T. Larry A. Roesner, P.E., PhD Colorado State University Ben Urbonas, P.E., D.WRE Urban Watersheds Research Institute

  2. Presentation Outline • Challenges and Needs • Project Objectives • The Tool – How it Works • Applications • Acknowledgements • Questions

  3. Challenges and Needs Challenge: Municipalities and other stormwater management agencies will continue to face regulatory and budget constraints. BMP planning must consider: • Pollutant Load Reduction • Runoff Reduction (total volume and peak flow) • Long-term Costs Need: Effective means for planning stormwater management strategies. “Which BMPs will allow the agency to meet regulations while minimizing cost?”

  4. Challenges and Needs Challenge: How do we predict BMP effectiveness for planning purposes? • Existing models typically use “percent removal” values for pollutant load reduction which can be misleading • Runoff volume reduction (from infiltration, ET, etc.) is typically estimated based on complex, fundamental governing equations Need: Develop a simple method to predict BMP effectiveness using empirical information.

  5. Challenges and Needs Challenge: Typically, “least-cost” BMPs are selected based on initial/capital costs only. Long-term maintenance and rehabilitation costs are not considered. Need: Develop/improve maintenance and rehabilitation costs estimates so as to make economic decisions based on whole life costs.

  6. Challenges and Needs Challenge: Existing stormwater models are complex, user-intensive, and typically not well understood by decision-makers. Need: A model that is easy to use, with results that are comprehendible by decision-makers, and that is appropriate for planning-level purposes.

  7. Project Objectives • Research/develop/improve initial, maintenance and rehabilitation costs for various BMPs • Develop an algorithm to predict pollutant loading and runoff volume reduction to receiving waters using various BMPs (i.e. BMP effectiveness) • Incorporate these into an Excel-based model (tool), appropriate for planning purposes, that can be used and understood by engineers, planners, developers, etc.

  8. The Tool – How it Works • Excel-based • Similar to other UDFCD spreadsheet tools • Primary processes are programmed in VBA 8

  9. The Tool – How it Works • Information contained on multiple, color-coded tabs • Table of contents describes each tab 9

  10. The Tool – How it Works (Inputs) 10

  11. The Tool – How it Works (Outputs) Pollutant load reduction to receiving waters Annual runoff volume reduction Net present value of whole life cycle costs 11

  12. The Tool – How it Works(Report) 12

  13. The Tool – How it Works(Report) 13

  14. The Tool – How it Works(BMP Effectiveness) Watershed Data Rainfall Data Legend User-Defined Data Default/User-Editable Values Calculated Values Annual Runoff Volume 85% Treated by BMP (annually) BMP 15% Bypasses BMP (annually) BMP Discharge Volume BMP Volume Loss/Attrition Runoff EMCs Effluent EMCs Annual Pollutant Mass Entering Waterbody 14

  15. The Tool – How it Works (BMP Effectiveness) Annual Runoff Volume = Annual Precipitation * Contributing Area * Runoff Coefficient Runoff Coefficients computed using UDFCD equations based on soil type and imperviousness BMP Volume Loss/Attrition = Annual Runoff Volume * 85% * %Volume Reduction % Volume Reduction values are based on empirical data collected and analyzed by UDFCD BMP Discharge Volume = Annual Runoff Volume * 85% * (1-%Volume Reduction) Annual Pollutant Mass Entering Waterbody = Annual Runoff Volume * 15% * Runoff Event Mean Concentration + BMP Discharge Volume * Effluent Event Mean Concentration • Runoff Event Mean Concentrations from UDFCD empirical data • Effluent Event Mean Concentrations from International BMP Database 15

  16. The Tool – How it Works (Whole Life Costs) Watershed Data Rainfall Data BMP Selection BMP Size & Quantity Cost Information Capital Costs Rehabilitation Costs Maintenance Costs Administrative Costs ENR CCI Inflation Rate Rate of Return Legend User-Defined Data Default/User-Editable Values Calculated Values Whole Life Cycle Costs (Net Present Value) 16

  17. The Tool – How it Works (Whole Life Costs) BMP Size(volume–based) = WQCV * Contributing Area * Additional Storage Factor • Water Quality Capture Volume is computed using UDFCD methods • Additional storage factor is defined in UDFCD Storm Drainage Criteria Manual BMP Size(Flow–based) = Runoff Coefficient * Rainfall Intensity * Contributing Area • Modified methods for determining rainfall intensity and time of concentration are provided in UDFCD Storm Drainage Criteria Manual BMP Number = (Contributing Area * Effective Imperviousness) / BMP Density • Effective Imperviousness accounts for source controls that minimize DCIA • BMP Density is defined in units of impervious acres 17

  18. The Tool – How it Works (Whole Life Costs) Capital Costs = (1 + CEA) * (C + XUα) + (LC * BMPsize * LCFCTR) CEA = factor accounting for contingencies/engineering/administration (%) C = base cost ($) X = unit cost ($ per unit) U = units α = economy of scale factor LC = land cost ($ per acre) LCFCTR = factor relating BMP size to the area of land consumed by BMP Example 18

  19. The Tool – How it Works (Whole Life Costs) Maintenance Costs (annual) = Freq * [Eff * Pers *(Rate + Rate * OH) + Eff * Equip + OC] * (BMPsize * UFCTR) UFCTR = factor relating BMP size to units of maintenance Freq = frequency of maintenance per year Eff = maintenance efficiency (units per hour) Pers = number of personnel Rate = hourly labor rate ($) OH = overhead factor (%) Equip = hourly equipment costs ($) OC = other unit costs ($ per unit) Example: Sediment Removal from Hydrodynamic Separator 19

  20. The Tool – How it Works (Whole Life Costs) Rehabilitation Costs = RehabFactor * Capital Costs • RehabFactor = percentage of capital costs • Capital Costs = original capital costs of unit • Rehabilitation costs are applied at intervals defined by the user (i.e. every 25 years) Administrative Costs = AdminFactor * Maintenance Costs AdminFactor = percentage of maintenance costs Maintenance Costs = annual maintenance costs 20

  21. The Tool – How it Works(Whole Life Costs) Total Annual Costs n = year of analysis CapCosts = sum of all capital costs RehabCosts = sum of all rehabilitation costs MaintCosts = sum of all maintenance costs AdminCosts = sum of all administrative costs IR = inflation rate (%) Net Present Value Costs n = year of analysis TC = total annual costs for year “n” ROR = rate of return (%) 21

  22. Questions? 22

  23. Application/Demonstration ** The tool is still being refined and tested, therefore the results of these demonstrations should not be taken as definitive at this time** Large-Scale (640 acre), Planning-Level Application Objectives • Evaluate costs and effectiveness of implementing extended detention basins vs. hydrodynamic separators • Evaluate extended detention basins over different scales of implementation 23

  24. Application/Demonstration Watershed 24

  25. Application/Demonstration BMP Scenario 1 – Extended Detention Basins • One basin treating each subarea 25

  26. Application/Demonstration BMP Scenario 2 – Hydrodynamic Separators • Each treating 5 impervious acres 26

  27. Application/Demonstration BMP Scenario 3 – Extended Detention Basins • Treating entire watershed with one “regional” basin 27

  28. Application/Demonstration (Results) * Preliminary results only 28

  29. Application/Demonstration * Preliminary results only Results 29

  30. Application/Demonstration User may edit cost variables in blue cells Cost curve is automatically generated How to edit cost information (Capital Costs) 30

  31. Application/Demonstration User may edit cost variables in blue cells How to edit cost information (Maintenance costs 1 of 2) 31

  32. Application/Demonstration User must enter an equation to relate BMP size to maintenance units Annual costs are updated How to edit cost information (Maintenance costs 2 of 2) 32

  33. Acknowledgments Funding provided by: • Urban Drainage and Flood Control District • Urban Watersheds Research Institute • City of Aurora • City of Denver • City of Lakewood • Arapahoe County • City of Pueblo • Colorado Stormwater Council

  34. Acknowledgments Model review and testing provided by: • Ben Urbonas – UDFCD/UWRI Information provided by: • Tom Williams and staff (Town of Parker) • John Burke and staff (City of Westminster) • David Van Dellen and staff (Town of Castle Rock) • Terry Baus, Lupe Martinez and staff (City of Denver) • Joe Chaplin and staff (City of Loveland) • Alan Searcy and staff (City of Lakewood) • Jim McCarthy and staff (City of Arvada) • Bruce Rabe and staff (Denver RTD)

  35. Questions?

More Related