1. Low Impact Development for Prince William Advanced Master Gardeners Frank Reilly

2. Why Me? Army Engineers Waterways Experiment Station Army Engineers Waterways Experiment Station 9 Years of Wetlands Workshops 9 Years of Wetlands Workshops www.WetlandsWorkGroup.org www.WetlandsWorkGroup.org www.WetlandsWorkGroup.org Green Highways Initiative Green Highways Initiative www.GreenHighways.org www.GreenHighways.org

3. Review Precipitation Precipitation Runoff Runoff Infiltration Infiltration Evaporation Evaporation

4. Natural Conditions

5. Developed Conditions

6. More impervious surface = more runoff

7. So What? Degraded habitat Degraded habitat bacteria, sediments, nutrients, and petroleum products bacteria, sediments, nutrients, and petroleum products Impaired watersheds Impaired watersheds Loss of habitat Loss of habitat Silting in wetlands Silting in wetlands Destruction of SAV Destruction of SAV Oyster reef Oyster reef Increased regulation Increased regulation TMDLs TMDLs Rain tax Rain tax

8. So what for me? Flooding Flooding stormwater Tax stormwater Tax stormwater maintenance stormwater maintenance

9. Q T Developed Condition, Conventional CN (Higher Peak, More Volume, and Earlier Peak Time) Existing Condition Hydrograph

12. How can we make residential developments function hydrologically like natural systems?

13. Challenges of traditional stormwater management include: Engineering, design and infrastructure can be more costly than mimicking natural systems Engineering, design and infrastructure can be more costly than mimicking natural systems Maintenance can be more expensive Maintenance can be more expensive Significant space required for detention ponds Significant space required for detention ponds Flow and volume of stormwater may not be adequately controlled, leading to: Flow and volume of stormwater may not be adequately controlled, leading to: Erosion Erosion Flooding Flooding Slope destabilization Slope destabilization

14. LID, as an alternative emphasizes: Using natural hydrologic functions as the design framework Using natural hydrologic functions as the design framework Relying on natural features and processes Relying on natural features and processes Integrating stormwater management early in site planning activities Integrating stormwater management early in site planning activities Applying simple, nonstructural and low cost methods Applying simple, nonstructural and low cost methods Distributing small-scale practices throughout the landscape Distributing small-scale practices throughout the landscape

15. Low Impact Development (LID) stormwater Management Ecosystem Based Functional Design “Uniformly Distributed Small-scale Controls” “Integration of Controls with Sites, Streets and Architecture ”

16. What is LID? A stormwater Management Strategy Concerned With: A stormwater Management Strategy Concerned With: Maintaining or Restoring the Natural Hydrologic Functions of a Site Maintaining or Restoring the Natural Hydrologic Functions of a Site Helps Meet Construction (New & Retrofit) stormwater Management Goals Helps Meet Construction (New & Retrofit) stormwater Management Goals Fulfilling Environmental Regulatory Requirements Fulfilling Environmental Regulatory Requirements Helps Reach NPDES Permit Limits & TMDL Goals Helps Reach NPDES Permit Limits & TMDL Goals Meeting Natural Resource Protection Objectives Meeting Natural Resource Protection Objectives Using Low Maintenance & Native Vegetation Using Low Maintenance & Native Vegetation Protection of Watersheds Protection of Watersheds LID Employs Natural & Built Features that: LID Employs Natural & Built Features that: Reduce Runoff Reduce Runoff Filter Out Pollutants Filter Out Pollutants Facilitate Water Infiltration Facilitate Water Infiltration Thanks, Larry Coffman

17. Where can LID apply? New development: residential & commercial New development: residential & commercial Zoning: applying impervious surface ceilings to sensitive watersheds or basins Zoning: applying impervious surface ceilings to sensitive watersheds or basins Land-use planning: selecting appropriate watersheds, soils and hydrology for new development; minimizing road and utility distances to serve new development Land-use planning: selecting appropriate watersheds, soils and hydrology for new development; minimizing road and utility distances to serve new development Watershed planning: integrating LID with other management practices Watershed planning: integrating LID with other management practices Renovation/retro-fit: building remodels, road repair/paving, updating stormwater systems Renovation/retro-fit: building remodels, road repair/paving, updating stormwater systems

18. LID Practices (No Limit!) Bioretention / Rain Gardens Bioretention / Rain Gardens Strategic Grading Strategic Grading Site Finger Printing Site Finger Printing Resource Conservation Resource Conservation Flatter Wider Swales Flatter Wider Swales Flatter Slopes Flatter Slopes Long Flow Paths Long Flow Paths Tree / Shrub Depression Tree / Shrub Depression Turf Depression Turf Depression Landscape Island Storage Landscape Island Storage Rooftop Detention /Retention Rooftop Detention /Retention Roof Leader (Gutter) Disconnection Roof Leader (Gutter) Disconnection Parking Lot / Street Storage Parking Lot / Street Storage Smaller Culverts, Pipes & Inlets Smaller Culverts, Pipes & Inlets Alternative Surfaces Alternative Surfaces Reduce Impervious Surface Reduce Impervious Surface Surface Roughness Technology Surface Roughness Technology Rain Barrels / Cisterns / Water Use Rain Barrels / Cisterns / Water Use Catch Basins / Seepage Pits Catch Basins / Seepage Pits Sidewalk Storage Sidewalk Storage Vegetative Swales, Buffers & Strips Vegetative Swales, Buffers & Strips Infiltration Swales & Trenches Infiltration Swales & Trenches Eliminate Curb and Gutter Eliminate Curb and Gutter Shoulder Vegetation Shoulder Vegetation Maximize Sheet flow Maximize Sheet flow Maintain Drainage Patterns Maintain Drainage Patterns Reforestation……………….. Reforestation……………….. Pollution Prevention………….. Pollution Prevention………….. “ “ Creative Techniques to Treat,Use, Store, Retain, Detain and Recharge”

19. LID PRACTICES Compact Design Compact Design Distributed Subsurface Storage Distributed Subsurface Storage Pervious Pavement Pervious Pavement Dispersion of Runoff Dispersion of Runoff Bioretention Cells/Rain Gardens Bioretention Cells/Rain Gardens Amended Soils Amended Soils Green Roofs Green Roofs Rooftop Rainwater Harvesting Rooftop Rainwater Harvesting

20. Compact Design Description: An approach to site design that clusters buildings and infrastructure in designated, compact areas of a development site. Benefits: Leaves larger percentage of development site in natural conditions (preserving native vegetation, topsoils and hydrology) Leaves larger percentage of development site in natural conditions (preserving native vegetation, topsoils and hydrology) Reduces the infrastructure needed to service the area (roads, utilities, stormwater) Reduces the infrastructure needed to service the area (roads, utilities, stormwater) Enables larger and more effective buffers between development and critical areas (streams, wetlands, steep slopes) Enables larger and more effective buffers between development and critical areas (streams, wetlands, steep slopes) Enhances property value and aesthetic by preserving open space and viewscapes Enhances property value and aesthetic by preserving open space and viewscapes

21. But you have to keep the “promise” Golf Courses sold Golf Courses sold Bash and Build Bash and Build

22. Compact Design is “retrofit-able”

23. Distributed Subsurface Storage Description: Underground stormwater storage in decentralized areas using rock matrix, cellular storage media and underdrains Benefits: Can be carried out under parking lots, sports fields etc. in a shallow depth, levering large areas of often unused space Can be carried out under parking lots, sports fields etc. in a shallow depth, levering large areas of often unused space Eliminates the need for surface ponds or large vaults. Eliminates the need for surface ponds or large vaults. Can be combined with filtration and ground water recharge Can be combined with filtration and ground water recharge

24. Distributed Subsurface Storage

25. Pervious Pavement Description: Special types of porous pavement that enable water to flow or pass through it, made from a variety of materials (cement, aggregate, fly ash, asphalt). Benefits: Many different options enable variety of applications and uses (grass blocks, pavers, porous asphalt). Many different options enable variety of applications and uses (grass blocks, pavers, porous asphalt). Enables water to infiltrate, recharging groundwater and reducing total volume of runoff from a site. Enables water to infiltrate, recharging groundwater and reducing total volume of runoff from a site. Provides filtration and can enable treatment of pollutants. Provides filtration and can enable treatment of pollutants.

26. Pervious Pavement Here is how well some of this works Here is how well some of this works this Here is how good some of this looks Here is how good some of this looks

27. Dispersion of Runoff Description: Stormwater is dispersed evenly and uniformly, across a wide area, using outlets designed to spread concentrated flow into sheet flow. Benefits: Helps restore natural sheet flows to existing drainage has been altered by development. Helps restore natural sheet flows to existing drainage has been altered by development. Reduces velocity of flows, preventing scouring and erosion. Reduces velocity of flows, preventing scouring and erosion. Disconnecting the flow from other drainpipes reduces overall quantity of water that must be treated. Disconnecting the flow from other drainpipes reduces overall quantity of water that must be treated.

28. Bioretention Cells/Rain Gardens Description: Shallow, landscaped areas that use porous soils and vegetation to store and treat runoff. Sometimes called rain gardens. Benefits: Can promote groundwater recharging through infiltration. Can promote groundwater recharging through infiltration. May enable greater evapotranspiration, reducing runoff from site. May enable greater evapotranspiration, reducing runoff from site. Helps maintain pre-development discharge rates and timing, more closely replicating natural watershed conditions. Helps maintain pre-development discharge rates and timing, more closely replicating natural watershed conditions. Filters and treats pollutants, such as heavy metals, petroleum products, nutrients and fertilizers. Filters and treats pollutants, such as heavy metals, petroleum products, nutrients and fertilizers.

30. Amended Soils Description: Soil amendments are needed when development removes top layers of soil and compacts subsurface layers, thereby reducing ability of soils to store and treat runoff. Benefits: Increases soil permeability, enabling greater storage capacity and infiltration, reducing overall runoff from development site. Increases soil permeability, enabling greater storage capacity and infiltration, reducing overall runoff from development site. Can effectively filter and treat. pollutants. Can effectively filter and treat. pollutants. Reduces the need for extensive use of irrigation and fertilizers. Reduces the need for extensive use of irrigation and fertilizers.

31. Green Roofs Description: Lightweight vegetated surface laid over an impervious roof area. Benefits: Improves a building’s energy performance (both heating and cooling) by adding a thermal layer. Improves a building’s energy performance (both heating and cooling) by adding a thermal layer. Provides significant stormwater storage and evapotranspiration – reducing need for other SW practices on site. Provides significant stormwater storage and evapotranspiration – reducing need for other SW practices on site. Improves air quality (filters large percentage of particulates in the air). Improves air quality (filters large percentage of particulates in the air). Provides wildlife habitat. Provides wildlife habitat. Increases lifespan of conventional roof (can double lifespan of roof). Increases lifespan of conventional roof (can double lifespan of roof).

32. Two Main types Intensive Intensive require deeper substrate layers (usually > 10 cm (4 in)) require deeper substrate layers (usually > 10 cm (4 in)) are generally limited to flat roofs are generally limited to flat roofs require ‘intense’ maintenance, and require ‘intense’ maintenance, and are often park-like areas accessible to the general public are often park-like areas accessible to the general public variety of plant species that may include trees and shrubs variety of plant species that may include trees and shrubs Extensive Extensive Can have shallower substrate layers (usually < 10 cm (4 in)) Can have shallower substrate layers (usually < 10 cm (4 in)) require minimal maintenance, and require minimal maintenance, and are generally not accessible to the public are generally not accessible to the public limited to herbs, grasses, mosses, and drought tolerant succulents such as Sedum limited to herbs, grasses, mosses, and drought tolerant succulents such as Sedum

33. Chicago City Hall after 18 months 33

34. Wetlands Mitigation? 34

35. Rooftop Rainwater Harvesting Description: Collection system designed to capture rainwater and store for dry-period irrigation or for graywater use within a building. Smaller systems referred to as “rain barrels”. Benefits: Use of graywater provides significant conservation water. Use of graywater provides significant conservation water. Use of stored water enables inexpensive irrigation during dry periods. Use of stored water enables inexpensive irrigation during dry periods. Reduce overall runoff from a development site. Reduce overall runoff from a development site.

36. There are many ways to go here

37. Disconnect Benefits: Retains water on site Retains water on site Available systems for almost any density Available systems for almost any density Can be retrofitted Can be retrofitted Can help attain stormwater goals at lower cost Can help attain stormwater goals at lower cost Definition: Interrupt the rapid flow of stormwater off site

38. Separation Plan in CSO 006 Area (Est. Cost = $3,900/private property) New Storm Sewer Connection New Storm Sewer in Street Roof Leader Disconnected and Rain Barrel (LID) Used* *No Extension on Private Property Required (May Result in 10-50% savings). Disconnects Combined Sewer Converted to Sanitary Sewer

39. Splash Blocks by Myersculpture Low Cost Alternatives

40. Moderate Cost Alternatives

41. Flow-through Planter

42. “High” Cost Alternatives Doing Nothing! Doing Nothing! Flood Damage Flood Damage County-wide re-plumbing to meet TMDLs County-wide re-plumbing to meet TMDLs

43. Comparison of Conventional and LID Site Conditions

44. Many LID tools are “retrofit-able”

45. Next Time What can Master Gardeners do? What can Master Gardeners do? Specific Ideas for our clients Specific Ideas for our clients Rain garden techniques Rain garden techniques Rain barrel techniques Rain barrel techniques Dis-connectivity techniques Dis-connectivity techniques