Permeable Pavement Systems EGRA Stone ECO Stone CONSERVATION DESIGN FORUM
Permeable Pavement Presentation Outline Case Studies Benefits Hydrologic Design Engineering Design Construction Considerations CONSERVATION DESIGN FORUM
West Union Iowa s Green Street Pilot Project Green Pilot Streetscape Project A Sustainable Vision for West Union The City of West Union Main Street West Union Iowa Department of Economic Development CONSERVATION DESIGN FORUM
Charles City, Iowa CONSERVATION DESIGN FORUM
Oelwein, Iowa CONSERVATION DESIGN FORUM
CONSERVATION Portland, Oregon DESIGN FORUM
Stormwater Materials Street Permeable Paver: Eco-Optilock Sidewalk Permeable Paver: Eco-Prioria Bioretention Areas
Street Section CONSERVATION DESIGN FORUM
Summary of Results Pre-Project Post-Project % Reduction Threshold Event 0.05" 1" - 2-Year Event (2.91" rain) Runoff Volume (inches) 2.2 1.38 37% Peak Flow (cfs) 19.2 3.8 80% 10-Year Event (4.31" rain) Runoff Volume (inches) 3.49 2.53 28% Peak Flow (cfs) 29.8 5.8 81% 100-Year Event (6.36" rain) Runoff Volume (inches) 5.44 4.35 20% Peak Flow (cfs) 45.8 8.3 82% CONSERVATION DESIGN FORUM
Carol Stream Park District: LEED Silver Recreation Center
Site Plan
Site Objectives LEED Sustainable Sites Highest Environmental Performance Reduced Irrigation Increased Longevity Cost Effective
Construction
Charles City Permeable Streets CONSERVATION DESIGN FORUM
Charles City Permeable Streets CONSERVATION DESIGN FORUM
Jordan Cove Waterford, Connecticut CONSERVATION DESIGN FORUM
TABLE 2: PROTOTYPE MODEL RESULTS Rainfall* Existing Proposed % Reduction 6-Month Event Runoff volume (inches)* 1.91 0.28 0 100% Runoff Rate (cfs)** - 0.59 0 100% 1-Year Event Runoff volume (inches)* 2.36 0.45 0 100% Runoff Rate (cfs)** - 0.79 0 100% 2-Year Event Runoff volume (inches)* 2.98 0.75 0 100% Runoff Rate (cfs)** - 1.1 0 100% 10-Year Event Runoff volume (inches)* 4.38 1.59 0.59 63% Runoff Rate (cfs)** - 1.7 0.12 93% 100-Year Event Runoff volume (inches)* 7.07 3.6 2.46 32% Runoff Rate (cfs)** - 3.3 2.2 33% * Based on 24-hour rainfall ** Based on critical duration storm CONSERVATION DESIGN FORUM
Project Costs Remove & replace existing pavement & curbs 17 City Blocks 112,000 square feet Excavation Gravel Base Permeable Paving Water main & services Sanitary sewer services $3.7M construction cost $3.9M construction, engineering, fees CONSERVATION DESIGN FORUM
Permeable Pavement Design Benefits Hydrologic Design Engineering Design Construction Considerations CONSERVATION DESIGN FORUM
Types of Permeable Pavement Interlocking concrete pavers Pervious asphalt Pervious concrete Grid systems Gravel grass CONSERVATION DESIGN FORUM
Permeable Pavers CONSERVATION DESIGN FORUM
Pervious Concrete
Pervious Asphalt
Porous Pavement: Infiltration (Retention) and Detention Capacity Detention Volume Retention Volume
Permeable Pavement Benefits Space efficient detention and parking occupy same space Safety reduced surface icing (Lund Institute of Technology) Reduced frost heave (Lulea Univ of Technology) Can eliminate need for storm sewers & inlets Reduces surface runoff volumes and increases groundwater recharge Water quality benefits (See Tech Standard) Longevity (paver systems) Aesthetics (paver systems) CONSERVATION DESIGN FORUM
Water Quality Benefits Event runoff coefficient ~ 0.8 and annual C~0.5 for lined permeable pavement system (Nottingham Trent University) Reduced runoff temperature (subsurface) 5 to 7 o C (9 to 13 o F) relative to asphalt (University of Guelph) Microbial digestion of petroleum based hydrocarbons (Coventry University) > 95% removal of metals within gravel base (HydroCon GmbH, Hameln, Germany) CONSERVATION DESIGN FORUM
Site Analysis Soils Depth to groundwater at least three feet (varies by state) Avoid highly expansive clay soils Avoid contaminated soils unless lined California Bearing Ratio Soil permeability Location Avoid high sediment yielding areas Avoid locations of contaminated runoff or risk of spills Avoid significant run-on that could clog paving Provide proper setback or waterproofing for building foundations Provide proper setback from wells (varies by state) Traffic Loading Pavers most suitable for parking lots Limit paver use to streets with speeds < 30 mph May need to provide weight restrictions for porous asphalt or concrete CONSERVATION DESIGN FORUM
Hydrologic Design Surface drainage capacity Up to 100 in/hr for new permeable paver systems 10 in/hr minimum for WDNR Tech Standard Use 2-3 in/hr* for mature permeable paver installations Maximum subsurface drain time to prevent loss of subgrade strength based on CBR Provide perforated pipe drains if necessary to achieve drain time Locate drain at bottom of base for low permeability soils Locate drain above bottom to provide retention on moderate permeability soils CONSERVATION DESIGN FORUM
Hydrologic Design Hydraulic conductivity of base Darcy s law (Q=kia) #57 stone k~0.13 ft/s #2 stone k~22 ft/s (too high to use without restricted release) i = subgrade slope Restrict release to meet local standards Perforated pipe control (Mannings formula) Restrictor control (orifice equation) CONSERVATION DESIGN FORUM
Engineering Design Edge Restraint (permeable pavers) Necessary to maintain interlock between pavers Concrete curb or soldier course set in concrete Surface slope as low as 0.5% to 1% Open graded, crushed, clean stone for all courses Subgrade compaction minimum necessary Woven monofilament geotextile between subgrade and subbase Reduced blinding Lower elongation Select high permeability (permittivity > 1.2/s) CONSERVATION DESIGN FORUM
Concrete edge restraint Permeable paver Stone Chip Setting (C33, #8) Base (C33, #57) Subbase (#2 or #57) Uncompacted subgrade Woven Monofilament Fabric CONSERVATION DESIGN FORUM
Permeable paver Stone Chip Setting (C33, #8) Base (C33, #57) Subbase (#2 or #57) Uncompacted subgrade Woven Monofilament Fabric CONSERVATION DESIGN FORUM
Construction Considerations Soil erosion and sediment control is essential Consider constructing last or plan on replacing crevice fill material after site stabilization Protect subgrade from Construction Site traffic Protect subgrade from CS runoff Protect filter and storage layers from CS runoff Protect pavement surface from CS runoff CONSERVATION DESIGN FORUM
Questions? CONSERVATION DESIGN FORUM