Learning Objectives Make Your Vegetated Roof Work Harder as a Stormwater BMP Richard C. Hayden, RLA ASLA CLARB American Hydrotech, Inc. Brian Taylor, PE AMEC 1. Learn how vegetated roofs can be used as stormwater BMP 2. Learn how stormwater is stored and released in a vegetated roof assembly 3. Learn how vegetated roofs mimic natural hydrology 4. Learn how vegetated roof are different than other BMPs Components of a Vegetated Roof Assembly Green and Gray Infrastucture Slide 3 of 64 Water A constant supply The Green Lane Environment Canada 1
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Clean Water Act Originally enacted - 1948 Federal Water Pollution Control Act Revised in 1976 Became Clean Water Act Enforced by EPA Sets standards for pollution discharge Requires Permits through NPDES system National Pollutant Discharge Elimination System Implemented by Municipalities Obtains NPDES permits Clean Water Act Reduce the stormwater Quantity Increase the stormwater Quality Increase stormwater Delay into the receiving systems (sewers, sanitary systems, etc.) 5
EPA Research 2007 Release Evaluated 17 case studies Includes vegetated roofs as BMP technique EPA Research Penn State Researchers 2009 release Evaluated GR as a storm water management tool EPA Research Released 2009 Pre-development hydrology For Federal projects Includes vegetated roofs as BMP option Old Stormwater Methods Put stormwater in pipes To rivers and streams To ponds and reservoirs 24 6
Newer Stormwater Methods LID - Low Impact Development Carefully integrated development plan Multi-faceted approach Many BMP s to use Parking Traffic Stormwater Stormwater BMP Goals Reduce stormwater volume Increase stormwater quality Delay stormwater entry into receiving systems. 25 Stormwater Management Plan Required by EPA and Municipalities Developed by Civil Engineers and Landscape Architects Stormwater Submitted to Municipal Engineers Management Defines Volume to handle Plan Defines How to handle Store Detain (to delay) Retain (to hold onto) Where to handle (BMP s) Requires Stormwater Management Permit 26 Stormwater Management Plan BMP Elements Components of a Vegetated Roof Assembly Stormwater Management Plan Vegetated Roofs and other BMPs 27 Slide 28 of 64 7
Permeable Pavements Permeable Pavements Permeable Pavements Rain Gardens Infiltration Landscapes 8
Infiltration Streetscapes Vegetated Roofs Green Roofs Vegetated Roofs Vegetated Roofs 9
Vegetated Roofs How do vegetated roofs help? Vegetated Roofs Permeable Pavement Underground Storage Bio-swales Infiltration Feature 38 How do vegetated roofs help? Slow the rate of runoff Reduce volume of runoff Improve water quality Mimics natural hydrology How to measure performance? Understand the vegetated roof systems Extensive Intensive Image property of American Hydrotech, Inc 10
Typical components Plants Engineered media Filter fabric Drainage panel Insulation Root barrier Protection board Waterproofing membrane Roof deck Drainage, retention, aeration Provides ventilation, air exchange and moisture transfer Engineered Growing Media Components of a Vegetated Roof Assembly Engineered Growing Media Components of a Vegetated Roof Assembly Lightweight aggregate Growing media consists of three main components Proportions dictated by region, climate and intended plantings Provides a stable structure for the anchorage of the plants' root system Compost Mid-range to fine aggregates Plant roots Lightweight aggregate Smaller aggregates and sands Organic materials Water Air spaces Slide 43 of 64 Slide 44 of 64 11
Engineered Growing Media Tested to ASTM 2399 standards Hydraulic conductivity How fast does water flow fhrough the media Air Content Maximum water storage capacity Dry weight Maximum weight at water capacity Gradation testing Particle distribution 1/2 3/8 lightweight aggregate Coarse, medium and fine sands Silt and clay particles Components of a Vegetated Roof Assembly How to measure performance? Understand the green roof system Understand the components Remember: not all green roofs are created equal! Slide 45 of 64 Basic hydrology benefits Green Roof Hydrographs Flow Elapsed Time 12
Reduction in Stormwater Flow Benefits of Vegetated Roofs Delay in Stormwater Release Benefits of Vegetated Roofs Ballasted roof Project roof Vegetated Roof Flow reduction Increase in run-off delay Start of ballasted roof runoff Vegetated Roof Runoff Start Flow reduction Slide 49 of 64 Slide 50 of 64 Calculations based on: Overall Roof Area Vegetated Roof Area Vegetation Type Sedums, Lawn, Perennials Depth of media Type of media Drainage components Specific weather data Rainfall intensity and amount Storm events (2, 5, 10, 25, 50, 100-year events) Overall Roof Area Vegetated Roof Area Results Quantity of stormwater retained Inches, gallons and cubic feet Composite curve numbers To accommodate the combined vegetated and overall roof areas C-Factors Hydrographs and supporting data To be used in stormwater management plan Overall Roof Area Vegetated Roof Area 13
Who generates these results? Simple online calculators Very generic Not media specific Not project location specific Civil Engineers Using assumed media performance values Green Roof Manufacturers Using tested data for medias and Using tested data for assembly components Using specific local weather data Rainfall amounts and intensities Here s what you should expect: Quantitative results Based on test data and accepted modeling (e.g. TR-55) Total vegetated roof capacity Gallons / inches / cubic feet / acre-feet Curve numbers and C-factors For vegetated & non-vegetated areas of roof Storm event modeling 24-hour 2, 5, 10, 50 and 100 year events Vegetated roof performance data Stormwater Management Plan 54 Components of a Vegetated Roof Assembly Multi-tasking Benefits of Vegetated Roofs Membrane Protection Conventional Roof membrane Insulation Substrate (deck) PMR Protected membrane roof Ballast or green roof Insulation Roof membrane Substrate (deck) Slide 55 of 64 14
Reduce Heat Island Effect Benefits of Vegetated Roofs Add development green space Pre-development condition Post-development condition Slide 57 of 64 58 Little Village Library and Engine Company 109, Chicago, IL Create new amenity spaces Create new healing spaces Church Street Station, Chicago, IL Resurrection Hospital, Chicago, IL 15
Create unique designs Create unique spaces Lincoln Center, New York, NY ASLA National Headquarters, Washington, DC Create new food resources Create new food resources Whole Foods, Lynnfield, MA Scholar House, Louisville, KY 16
Does it all simultaneously! Captures and holds stormwater Saves money in other stormwater elements Create green space Create value to users Cleans air Cools surrounding areas Provides habitat for wildlife Provides food production opportunities Make your vegetated roof work in as many ways as possible! The American Society of Landscape Architects is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-aia members are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. Learning Objectives 1. Learn how vegetated roofs can be used as stormwater BMP 2. Learn how stormwater is stored and released in a vegetated roof assembly 3. Learn how vegetated roofs mimic natural hydrology 4. Learn how vegetated roof are different than other BMPs The American Society of Landscape Architects 17
Questions & Answers 18