Assessment Of Permeable Pavement In High Volume Urban Flooding

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  • I would at least give a range for the unit pavers, otherwise, kinda useless to have them here.
  • Clarify last bullet: Reduction in porosity with age is a reality….
  • I assume here you will talk about what the underlying soil permeability is or is estimated to be.
  • Is the range really 0 to 100%? No runoff from a 10 year storm with .22 in/hr max infiltration? I suppose there must be no pre-existing storage in the reservoir layer when the storm hits. Should note that.
  • Interesting. You should note here when you discuss this what the 100 year rainfall depth is for the area.
  • Assessment Of Permeable Pavement In High Volume Urban Flooding

    1. 2. Today’s Discussion
    2. 3. General Characteristics of Permeable Pavement
    3. 4. General Characteristics of Permeable Pavement (Continued) <ul><li>Key Factors Impacting Capture Rate (ICPI Study, NC State) </li></ul><ul><ul><li>Proper Maintenance Increases Capture Rate 66% </li></ul></ul><ul><ul><li>Locating Pavement Away From Sources of Fines. Potential Impacts 99% </li></ul></ul><ul><ul><li>Reduction of Performance with Age is a Reality That Needs to Be Acknowledged </li></ul></ul>
    4. 5. General Characteristics of Permeable Pavement (Continued) <ul><li>All Share Concept of Stone Reservoir of Base Material (18” Typical) </li></ul><ul><ul><li>Varies as a Function of Soil Subgrade “R” Value and Traffic Loading </li></ul></ul><ul><ul><li>Void Ratios on the Order of 35% </li></ul></ul><ul><ul><li>Effective “C” Coefficients (SD County LID Handbook) </li></ul></ul><ul><ul><ul><li>Pervious Concrete and Permeable AC, “very low to nil” </li></ul></ul></ul><ul><ul><ul><li>Unit Pavers, 0.13-0.80 </li></ul></ul></ul>
    5. 6. Case Study Background <ul><li>0.15-acre Public Health Center Facility Parking Lot </li></ul><ul><li>Located within the City of San Diego </li></ul><ul><li>Prop 84 Grant funding (Chollas Creek Watershed) </li></ul><ul><li>Construction Completed in September 2010 </li></ul>
    6. 7. Case Study Background (Continued) <ul><li>Site selected and designed with water quality monitoring in mind (not specifically intended for flood control) </li></ul><ul><li>Monitoring Data Collected </li></ul><ul><ul><li>Precipitation from on-site and La Mesa rain gauges </li></ul></ul><ul><ul><li>Atmospheric pressure </li></ul></ul><ul><ul><li>Storage depth within pavement section </li></ul></ul><ul><ul><li>Visual Observation </li></ul></ul>
    7. 8. Case Study Background (Continued) <ul><li>Design Features </li></ul><ul><ul><li>Level subgrade (unlined) </li></ul></ul><ul><ul><li>6” Subsurface berms </li></ul></ul><ul><ul><li>Subdrain/outlet system </li></ul></ul><ul><ul><li>Perimeter protection </li></ul></ul><ul><ul><li>Soils Information, Ex Subgrade Compacted Fill (Clayey Sand, Clay Chunks, Silt, and Sand) </li></ul></ul>6” SUBGRADE PAVEMENT SURFACE 13” min.
    8. 9. Monitoring Data Winter 2010-2011 Dates: 12/19-12/23 Total Depth: 7.37 inches Peak Intensity: 1.4 in/hr Less than 2-year based on peak intensity Greater than 100-year, 24-hour based on total volume
    9. 10. Monitoring Data Winter 2010-2011 Dates: 3/20-3/22 Total Depth: 1.42 inches Peak Intensity: 1.0 in/hr Less than 2-year based on peak intensity Less than 2-year, 24-hour based on total volume
    10. 11. Assessment of Actual Performance During Winter 2010-2011 Traditional Pavement Permeable Pavers 12/19 3/20 31% 11% 3/20 Storm 2.5% 12/19 Storm 1% Traditional Pavement
    11. 12. Creation and Calibration of Performance Model Assumed average infiltration rate that produced equivalent water level/flow from weir: 0.22 in/hr
    12. 13. Creation and Calibration of Performance Model Assumed average infiltration rate that produced equivalent water level/flow from weir: 0.05 in/hr
    13. 14. Predictive Assessment of Performance During High Volume Conditions <ul><li>Summary of Predictive Scenarios Modeled, “As Built Design” </li></ul><ul><ul><li>“ Standard” 100-Year 6-Hour </li></ul></ul><ul><ul><ul><li>Antecedent Moisture Similar December 19 th </li></ul></ul></ul><ul><ul><ul><li>Antecedent Moisture Similar to March 20 th </li></ul></ul></ul><ul><ul><li>“ Standard” 10-Year 6-Hour </li></ul></ul><ul><ul><ul><li>Similar Moisture Variations as Above </li></ul></ul></ul><ul><ul><li>Aged/”Un-maintained” Pavement in a Variety of Storms, Moisture Conditions </li></ul></ul><ul><ul><li>All of the Above with “Traditional” Pavement </li></ul></ul><ul><ul><li>Varying Ratios of “Off Site” (Uncontrolled Flow) Contribution </li></ul></ul><ul><li>Optimized Storage/Alternative Design </li></ul>
    14. 15. Predictive Assessment of Performance During High Volume Conditions
    15. 16. Predictive Assessment of Performance During High Volume Conditions
    16. 17. Predictive Assessment of Performance During High Volume Conditions
    17. 18. Predictive Assessment of Performance During High Volume Conditions Ratio of Total Area to Porous Asphalt VOLUME PEAK FLOW Antecedent Moisture from 12/19 Storm with 10-Year Precipitation and Well-Maintained/ New Surface Combination with Off Site Flow (10-Year Event)
    18. 19. Conclusions <ul><li>Despite “Poor” Native Soil Conditions, Porous Asphalt Pilot Project Shown to Provide Substantial Peak and Volume Reduction Benefits During Winter 2010-2011 </li></ul><ul><li>Predicted Volume Reduction Benefits for 100-Year Event (34-55%). Extent Functions with Antecedent Moisture. </li></ul><ul><li>Predicted Peak (Potentially) and Volume Benefits up to 10-Year. Antecedent Moisture Influences Peaks Highly at this Statistical Range (Volumes to a Lesser Extent). Impact of Age/Maintenance for this Event and Lower Insignificant. </li></ul><ul><li>Peak Flood Protection Benefits Obtained During 10-Year Event Lost with Introduction of “Off Site” (Un-mitigated) Area Ratios as Small as 1.3:1. </li></ul>
    19. 20. Recommendations <ul><li>Optimize Available Storage! </li></ul><ul><ul><li>Alternative Design Scenario Modeled (“Full” Storage, 12”Berm) During 100 Year Storm, and Infiltration of 0.05 in/hr </li></ul></ul><ul><ul><ul><li>Peak Flows at 26% of Traditional Pavement (New System) </li></ul></ul></ul><ul><ul><ul><li>Volume at 22% of Traditional Pavement (New System) </li></ul></ul></ul><ul><ul><ul><li>Minor Performance Loss Anticipated with Age (Peak Flows at 31% of Traditional, Volume Reduction No Impact) </li></ul></ul></ul>
    20. 21. Recommendations (Continued) <ul><li>Consider Retrofit within Flood Prone Urban Areas </li></ul><ul><ul><li>Porous Asphalt Appears to Provide Benefit in Areas Already Controlled By Distressed (Under-designed) Regional Detention Facilities or Pipe Systems (Peak Flow and Volume Reduction) </li></ul></ul><ul><ul><li>Viable Option in “Land Challenged” Areas </li></ul></ul><ul><ul><li>Simpler/Cheaper Long Term Maintenance Compared to Basins and Pipe Systems </li></ul></ul><ul><ul><li>Flow Reduction Expected Even in Poorly Infiltrating Soil (i.e., 0.05 in/hr) </li></ul></ul><ul><ul><li>Work with Project Soils Engineer to Develop Berm/Cutoff Designs That Optimize Storage and Preserve Structural Integrity </li></ul></ul>
    21. 22. Resources <ul><li>SURFACE INFILTRATION RATES OF PERMEABLE PAVEMENTS Eban Bean, EI; Dr. Bill Hunt, PE; David Bidelspach, EI; Jonathan Smith, PE11Graduate Student, Assistant Professor & Extension Specialist, Extension Associate, and Extension Engineer Biological & Agricultural Engineering, North Carolina State University. Funding by the Interlocking Concrete Pavement Institute (ICPI) </li></ul><ul><li>Low Impact Development Handbook, Stormwater Management Strategies County of San Diego, July 2007 </li></ul>
    22. 23. Contact Information Richard Lucera, PE, CFM [email_address] Scott Cartwright, PE [email_address] 9755 Clairemont Mesa Blvd, Suite 100 San Diego, CA 92124 858.614.5000

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