LIUDD by Maria Ignatieva
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LIUDD by Maria Ignatieva
- 1. Low Impact Development Maria Ignatieva
- 2. West Coast of the USA • Oceanic climate • Quite high rainfall averages (920 mm) per year (Portland, Oregon)
- 3. Low Impact Development in Puget Sound Washington & Portland Oregon, USA
- 4. Paradigm Shift • View water as a resource instead of a nuisance to contend with during development – Replenish aquifers – Store & use rainwater – Remove some contaminants on site and deliver cleaner water downstream
- 5. Overview • Stormwater has harmed, and continues to harm, Puget Sound’s resources (for example, several species of Northwest salmon face the threat of extinction, numerous shellfish-growing beaches are too polluted to harvest) • Traditional land development and stormwater practices have not proven effective at preventing harm (pollution threatens the health of urban water and underwater sediments; runoff from stormwater contributes significantly to these problems) • Low impact development is a key piece in overall approach to managing stormwater
- 6. Effects of Stormwater on Water Quantity • Flooding and property damage. • Damage to stream channels during wet months • Lower stream flows during dry months, less groundwater recharge. Photo courtesy Hans Hunger, Pierce County Water Programs
- 7. Effects of Stormwater on Water Quality • Restrictions on shellfish harvest • Harm to fish and other aquatic life. • Polluted sediments Photo courtesy Taylor Shellfish Farms, Inc.
- 8. Many Puget Sound species are harmed by stormwater runoff Photo courtesy Al Latham, Jefferson Conservation District
- 9. Watershed Hydrology BEFORE Development evapotranspiration: 40-50% interflow: 20-30% surface runoff: <1%
- 10. Watershed Hydrology AFTER Development evapotranspiration: ~25% interflow: 0-30% surface runoff: ~30%
- 11. Traditional Approach to Land Development and Stormwater Management • Most trees and other vegetation are removed and native soils are compacted. • Management techniques are applied at the end of site design. • Relies on pipes, stormwater ponds and vaults. • Stormwater is managed far from source, after collection and conveyance.
- 12. Limitations of Traditional Approaches • Not all impacts can be mitigated. • Infrastructure is expensive. • Maintenance is expensive, often neglected. • Uses a lot of land, often not attractive. • Treats rainwater as a waste, not a resource.
- 13. Photo by Stuart Glasoe, Puget Sound Action Team
- 14. Low Impact Development • Uses suite of site design elements and practices. • Mimics site natural hydrology. • Protects and uses site’s natural features. • Uses many small-scale stormwater controls. • Manages stormwater close to the source. • Applies to urban, suburban & rural sites.
- 15. Key Elements of LID • Assess the site thoroughly. • Integrate stormwater management into site design from beginning. • Design site to cluster development and conserve vegetation, soils, and natural drainage features. • Reduce and disconnect impervious surfaces. • Use small-scale practices to disperse and infiltrate. • Maintain practices and educate landowners.
- 16. Benefits of LID • Can better protect water resources. • Can reduce infrastructure costs. • Creates more attractive, livable communities. • Can enhance property values. • Helps meet stormwater requirements.
- 17. Integrated Management Practices • Preserving-clustering- dispersing • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations High Point, Seattle
- 18. Integrated Management Practices • Preserving-clustering- dispersing • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy Seattle Public Utilities
- 19. Integrated Management Practices: Bioretention • Bioretention (rain gardens and swales): shallow, landscaped areas composed of soil and variety of plants rain gardens: stand alone feature-small depressions near homes and other buildings that collect runoff from a roof, driveway or yard and allow it to infiltrate into the ground. swales: part of a conveyance system High Point, Seattle: Swale Bioswales are shallow depressions created as opened storm water conveyance systems that are generally not as elaborately landscaped as bioretention systems and are primarly designed for transportation and infiltration of storm water
- 20. Rain Gardens: Portland, Oregon USA
- 21. • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy Seattle Public Utilities Integrated Management Practices
- 22. • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy 2020 Engineering Integrated Management Practices
- 23. Integrated Management Practices: Permeable pavement • Permeable pavement: allows water infiltrates and removes pollutants. Includes concrete, asphalt, pavers and grid system filled with grass or gravel. High Point, Seattle
- 24. • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy SvR Design Integrated Management Practices
- 25. Vegetated roof in Seattle
- 26. • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy Northwest Water Source Integrated Management Practices
- 27. • Bioretention • Amended soils • Permeable pavement • Vegetated roofs • Rainwater harvesting • Minimal excavation foundations Photo courtesy Tom Holz Integrated Management Practices
- 28. Applying LID Principles & Practices Graphic courtesy AHBL Civil and Structural Engineers
- 29. tree conservation • soil amendments narrower streets • open drainage • rain gardens on-site detention, storage and infiltration Photo courtesy LID Center Applying LID Principles & Practices
- 30. Example of using LID practice : High Point Public Housing Redevelopment in Seattle • 120 acre • Higher density • Mixed-used • Narrow street • Swales • Big retention pond • Pervious pavement High Point: Retention Pond
- 32. High Point, Seattle: Community Garden
- 33. Photo courtesy King County Rooftop rainwater collection, Seattle
- 34. Photo courtesy Bill Lewallen, Snohomish County Grass pave system, Everett
- 35. F New Seasons Market, Portland
- 37. F as art! New Seasons Market, Portland
- 38. LID examples • 2000-2003 the Seattle Street Edge Alternatives- SEA Streets project- Seattle Public Utilities Department • Prevented all dry season runoff and 90% of wet season runoff • Help protect nearby salmon streams by reducing stormwater volume by 99%
- 39. Welcome to the virtual tour of SEA Street, a Seattle Public Utilities Natural Drainage Systems (NDS) project located in northwest Seattle. This prototype project, the first NDS project in Seattle, shows a range of unique drainage and street design innovations. The tour begins at the intersection of 2nd Avenue NW and NW 117th Street, and moves north along 2nd Avenue NW to NW 120th Street. At each stop in the tour, labeled on the map of the project site below, you'll learn about the goals of this pioneering project: Drainage Water Quality Landscape Mobility Community Education Next Photo Courtesy Seattle Public Utilities
- 40. SEA Street Before…. Photo Courtesy Seattle Public Utilities
- 41. SEA Street After Photo Courtesy Seattle Public Utilities
- 43. SEA Street: 2007
- 44. Example of LID practice: rain garden in Portland, Oregon
- 45. Sustainable Construction Practices in USA Leadership in Energy and Environmental Design (LEED) • US Green Building Council rating system for designing, constructing, operating and certifying green buildings.
- 46. LEED Buildings Leadership in Energy and Environmental Design: • 11 buildings in Seattle: City Hall and Central Library
- 47. US Green Building: Chicago Center for Green Technology 1999 Chicago Department of Environment • Clean-up process of the site • Feature: Increasing Energy Efficiency: 1. Window, light fluorescent bulbs 2. Smart lights: maximum natural sunlight 3. Heating and Cooling Feature: Reducing vehicle emissions Feature: Electric outlets for cars Feature: Public transportation Feature: Bike parking Feature: Local materials
- 48. Chicago Center for Green Technology Outside: Rain Cisterns- use for watering plants
- 49. Chicago Center for Green Technology Outside: Solar Energy: Solar Panels
- 50. Low Impact Urban Design and Development in New Zealand
- 51. New Zealand Low Impact Urban Design and Development Programme LIUDD FRST subcontract: Landcare Research New Zealand Limited, a New Zealand Crown Research Institute 2003-2009
- 52. New Zealand Urbanization 87 % of New Zealand population live in an urban environment Biggest Cities: Auckland, Wellington, Christchurch The fastest growing urban areas by 2021: Auckland (population growth of 36%) and Selwyn District (south of Christchurch, 42%).
- 53. Urban ecology in New Zealand: Biodiversity of the urban environment • Major concern: loss of indigenous biodiversity • Problems with naturalized exotic species (plants, birds and animals) • New Zealand vascular flora: • 2500 indigenous (native) vascular species, • 2500 completely naturalized alien plants • Over 20,000 exotic vascular plant species • 10% of which have escaped into the wild • 13 more becoming naturalised every year • Native flora gets pushed back into inaccessible areas • Similar for wildlife
- 54. Urban biodiversity and design: New Zealand Low Impact Urban Design and Development (LIUDD) • Apply different sustainable devices (similar to the USA): swales, rain gardens, green roofs, impervious surfaces. Compact development principles. • The key goal is to protect and enhance native urban biodiversity • (LIUDD) associated with specifically employing native plants and attracting native species of wildlife
- 55. “Low Impact Urban Design and Development: Making it Mainstream” • Interdisciplinary approach: social researchers, environmental scientists, planners, engineers, landscape architects and ecologists
- 56. LIUDD • Planning & design for physical sustainability and biodiversity • Relevance (sense of place) and effectiveness will depend on visibility to the bulk of the population – in the urban environment
- 57. LUIDD: Stormwater best sustainable management practices at catchment scale • Follows the treatment train principle – slowing and lengthening the passage of water moving through the urban catchment from roof to sea or groundwater. • Main roads and secondary roads provide for biofiltration using vegetated swale systems. Swale design details from “Stormwater treatment devices from Low Impact Design” manual for Auckland Area • Permeable pavement (less paving areas, shared driveways) • Detention Pond • Rain gardens, rain cisterns, green roofs for an individual property (optional) • Permeable ecological surfaces (driveways) for individual properties (optional) • Ecological protection, restoration, design at local to landscape scale
- 58. LIUDD • Involve principles of landscape and urban ecology • Alternative, cost-effective design and development approaches that involve designing and working with nature - creating community environments that respect, conserve, and enhance by or with natural processes • Creating systems of ‘stepping stones’ and green corridor systems, that can lead native birds back into cities. • Reintroduction of native biodiversity in urban environment
- 59. LIUDD: Overall planning principles of subdivision • Spatial resource survey to identify significant values that must be protected • Respect existing topography, landforms and native vegetation as part of the legible landscape • Open green spaces (including native patches); emphasis on the organisation of common open spaces with native reserves and pedestrian linkages rather than cul de sacs. Concept plan for Regis Park Subdivision. DJ Scott, Auckland, New Zealand, 2003
- 60. 2005: Aidanfield (Christchurch) Analysis and developing scenario for LIUDD Design: Frazer Baggeley, 2005
- 61. Ecological Design in Lincoln Village Propose a System of Green Corridors for Lincoln Village and surrounding landscapes Possible connections between Lincoln Village and surrounding ecosystems such as Lincoln University, Landcare Research campus, Liffey River and even Port Hills. Design: James Rea, 2006
- 62. Clustaring Houses: saving energy and space for habitat • Localised high density; mixed-use subdivisions can allow larger areas of public open or green space • These creates more opportunities for core sanctuary habitat, rather than small fragmented or linear features with inadequate buffer zone Vegetated Swale J.Collett (2007). Proposal for Liffey Spring Subdivision
- 63. LUIDD principles • Provide for pedestrian/bike recreational loops (public walkways) and links from all subdivision roads. Narrow walkable street layout with more space for pedestrians and planting (swale planting, street trees, green space) Cross section of walkable narrow street for new Liffey Spring subdivision in Lincoln Village, New Zealand. Design: Simon Multrie, 2007
- 64. Narrow Roads and Streets Narrow Road. Lincoln, Christchurch. Photo: Robyn Simcock Narrow Road, Talbot Park subdivision, Auckland. Raingarden on right treating road runoff and forming a traffic-calming feature
- 65. LUIDD principles: Formation of storwater treatment trains • Series of elements or devices linked together from the top to bottom of the urban catchment (roof to gardens, swales and streets to ponds, groundwater and rivers to the ocean) that lengthen and slow the passage of water
- 66. Green Roofs A green roof is a roof partially or fully covered by plants.
- 67. Rain tanks for an individual property • These and rain barrels reduce runoff to waterways and provide water for irrigation without tapping into finite aquifers or potable supplies. • New plantings may need irrigation for the first few summers. Rainwater tanks and the retention of vegetation on upper catchment large lots are a mandatory requirement in various northern districts of NZ North Shore City. Photo: Penny Lysar
- 68. Permeable ecological surfaces (driveways) for individual properties • One of the most effective means of ameliorating rapid stormwater runoff is to minimise hard surfaces and to use permeable materials when needed for hard wearing or vehicle standing. Example of permeable paving with grass, Morning Star Apartments, Auckland, New Zealand.
- 69. Courtyard with four different permeable surfaces: wooden decking, gravel, permeable pebble pavers (around tree) and grass, at Waitakere Civic Centre, Auckland
- 70. LIUDD: Swales and filter strips Mown grass swale, (drainage gate at front pipes into inflitration bed)
- 71. LIUDD: Swales and filter strips • Unmown Carex cv and (Lower) - prostrate Coprosma bioretention/infiltration strips at Wharewaka Taupo (at least 1 m depth of non-consolidated material). Note stone detention dams used to reduce flow strength. Photo: Robyn Simcock
- 72. Swales Vegetated swale; Ryelands Subdivision, Lincoln, New Zealand
- 73. Swales Permanently wet swale with native Juncus species. Car park in Waitakere, Auckland, New Zealand. Design: Meghan Wraight.
- 74. Aidanfield (Christchurch): Swale Proposal Design: Frazer Baggeley, 2005
- 75. Detention Pond Vegetated swale and overflow detention pond, Aidanfield, Christchurch, Photo: Colin Meurk
- 76. Enhancing biodiversity in the home garden and public space • We have dealt with the hydrological and ecological service function of plants and suggested a number of indigenous species that can be used for these roles. • Under this heading we consider the specific intrinsic values of biodiversity, why we should promote it and how we can integrate it into the urban context. • In particular we focus here on the urban matrix of private gardens and public parks and other spaces.
- 77. Enhancing biodiversity in the home garden • Trees • Shrubs • Hedges • Rock gardens • Native lawns • Green walls • Herbaceous borders Green wall for private house at Liffey Spring Sbdivision, Lincoln. Design: Jason Collett, 2007
- 78. Green Wall at the Pacific Museum, Paris
- 79. Native lawn Gnaphalium audax in a Christchurch Lawn. Photo: Colin Meurk
- 80. Rock Gardens Rock Garden. The Bush City. Te Papa, Wellington
- 81. LUIDD in Urban Public Spaces: Parks. Street trees and avenues Native plants for traffic islands. Wellington
- 82. LUIDD principles in action: Waitangi Park, Wellington • LIUDD principles: stormwater treatment and using native plants as highly visible and key drivers of the overall design • Representation of rain gardens, wetlands, and coastal vegetation • Designer: M.Wreight
- 83. Ecological protection, restoration, design at local to landscape scale Revegetation of pasture blocks during rural residential subdivision at Owhanake, Waiheke Island. Photo: Marjorie van Roon
- 84. New Zealand LIUDD practical applications: the manual • How to Put Nature into Our Neighbourhood: Application of Low Impact Urban Design and Development (LIUDD) Principles, with a Biodiversity Focus, for New Zealand Developers and Homeowners
- 85. Demonstration Gardens in Christchurch Botanic Gardens “Design with Indigenous Plants” • Showcase ways to appropriately apply native species in particular settings • Gardens display at a realistic scale of private house situation • How principles of Low Impact Urban Design and Development can be implemented into an individual residential property to improve sustainability and biodiversity and reduce costs at both a site, and wider regional scale.
- 87. Demonstration Gardens in Christchurch Botanic Gardens “Design with Indigenous Plants”, May 2008
Hinweis der Redaktion
- Stormwater harms Puget Sound, degrading its water quality, contaminating or recontaminating urban bay sediments, and harming fish and other wildlife. Stormwater also threatens public and private property and drinking water supplies. Much of the harm is attributable to the way we develop land and manage stormwater. Traditional techniques that rely on extensive land clearing and use of pipes and ponds to collect and control stormwater, have not proven effective thus far at preventing harm. Low impact development (LID) is a more environmentally-friendly way to develop land and manage stormwater. LID is a key piece in our approach to manage stormwater.
- The Action Team was established in 1996 by the Legislature (Chapter 90.71 RCW) It is the successor to the Puget Sound Water Quality Authority, an independent state agency established in 1985. The chair and staff are part of the governor’s office The Action Team’s mission is to protect and restore the Sound and its diversity of life today and for future generations. The vision behind the founding legislation is to encourage agencies to work together to set goals and measurable outcomes, and carry out needed actions.
- There are 3 key components of the Action Team: The Action Team itself – directors of state agencies, local governments, tribal governments, and federal agencies. The Puget Sound Council – representatives from a broad array of interest groups, local governments, and legislators. Finally, Action Team staff – about 19 individuals.
- There are two main problems caused by stormwater runoff. First, studies show that after mature Pacific Northwest forest is converted to suburban development, surface runoff increases from about 1% to about 30% (LID Technical Guidance Manual for Puget Sound, 2005). This dramatic increase in surface runoff has led to flooding, property damage, and public safety concerns, and damage to stream channels needed by salmon and other wildlife. After development, much less water infiltrates, since rooftops, roads and other impervious surfaces prevent infiltration. This leads to lower in-stream flows during dryer months, and less water available to recharge aquifers and wetlands. This effects can have profound effects on the Sound’s fish and other wildlife.
- Second, contaminants in stormwater have polluted the Sound, leading to restrictions or closures of many productive commercial and recreational beaches. As of 2006, harvesting at several beaches was restricted largely due to stormwater runoff: Lynch Cove, North Bay, Henderson Inlet, and North Dyes Inlet. In addition to these areas, stormwater contributes to restrictions at many other beaches around the Sound.
- Stormwater harms fish, too. Recently, federal scientists from NOAA have drawn links between stormwater runoff and Coho dying before they can spawn in several Seattle creeks. The rate of “pre-spawn mortality” ranged as high as 80-90%. Stormwater contaminates, or re-contaminates, urban bay sediments. A multi-year clean-up of sediments in the Thea Foss waterway in Tacoma is now threatened by continuing stormwater runoff that contains pthalates (used in plastic products).
- This diagram, from the Low Impact Development Technical Guidance Manual for Puget Sound, shows how water moves over and through the land before development. Before development, the vast majority of water is either taken up by plants or evaporates back to the atmosphere (called evapo-transpiration) or infiltrates (either to become interflow in shallow layers or deeper infiltration. Surface runoff is only about 1 percent, and surface runoff moves to streams, wetlands and other waters very slowly, taking days, weeks or even months to slowly recharge streams, wetlands and aquifers.
- This diagram shows averages for suburban development. When forests are cleared, soils stripped away, and roads, rooftops, parking areas and other impervious surfaces are built, evapotranspiration and infiltration decrease and surface runoff increase dramatically. Note that surface runoff has increased from about 1% to about 30%. This is because so much rainfall is stored by trees, other vegetation and soils. These two graphics are representative of the Puget Sound lowlands. They were developed for the LID Technical Guidance Manual for Puget Sound by Curtis Hinman, WSU Extension Pierce County and AHBL of Tacoma. The numbers are approximate amounts, drawn from the collective research of Derek Booth, David Hartley, Rhett Jackson, Rich Horner, Chris May, and others.
- Traditional methods to develop land, which still dominate development projects today, result in extensive clearing of trees and other native vegetation and compaction of soils by heavy equipment. Stormwater controls are then added at the end of the site design process to manage stormwater to mitigate the effects of development. Stormwater is managed through a centralized collection and conveyance process, and management occurs far from where the stormwater originated. Stormwater systems are varied, but in most subdivisions use storm drains, conveyance pipes, and stormwater ponds.
- In the last 10-15 years, we’ve learned that once a development site’s native vegetation and soils are removed, it is extremely difficult (and costly) to mitigate all the impacts from stormwater runoff. Traditional approaches to stormwater management result in point source discharges from the site and the site’s natural hydrology (particularly the evapotranspiration and infiltration of rainfall) is significantly altered. And traditional BMPs often don’t clean stormwater sufficiently. All of these factors lead to previously discussed problems. Stormwater infrastructure is also costly to build, and costly and difficult to maintain. Often, stormwater facilities are not maintained properly. To manage greater amounts of stormwater, ponds recently are required to be much bigger. This results in often-valuable land being taken up by unattractive ponds surrounded by chain-link fences. Last, traditionally stormwater has been treated as a waste – something to get off of our properties as quickly as possible. This helps with flooding problems, but it doesn’t help protect the Sound.
- Example: Here’s a stormwater pond in south Puget Sound. Stormwater here has been imprisoned behind a chain link fence. The pond is not attractive and does nothing for neighborhood, or community esthetics.
- Low impact development, or LID, is a relatively new approach to land development and stormwater management. It’s used at the individual project scale. Equally important are broader watershed-wide or basin planning processes. It’s important to remember that LID is an overall approach that isn’t just a certain approach or two – it’s a suite of practices that, when combined, try to more closely approximate a site’s natural hydrology. LID planning protects and uses a site’s natural features: native vegetation, well-draining soils, topography, natural drainages, and so forth, Coupled with many small-scale, distributed stormwater controls, To manage stormwater as a resource close to where it started, on paved surfaces. The LID approach and individual practices can be applied on urban, suburban and rural sites.
- Here are the key elements of low impact development: First, assess the site’s topography, soils, natural drainage patterns, sensitive areas, and other key elements. Integrate stormwater management into site planning and design at the very beginning. This often involves a meeting with the developer, builder, and planning, public works and fire and safety staff. Design the site to cluster buildings and other development in a reduced development envelope. Protect sensitive areas and a large percentage of the site’s native vegetation and soils. Understand and work with the site’s natural drainage features. Reduce impervious surfaces by reducing the footprint of buildings, reducing road widths and lengths, and using pervious pavement, minimal excavation foundations, rooftop rainwater harvest, and vegetated roofs. Disconnect impervious surface that is created by using bioretention or pervious pavement. Use multiple, small-scale stormwater controls to manage stormwater close to the source. Maintain the practices and educate landowners.
- Although relatively new, LID has shown great promise for offering a better way to protect our water resources. For example, Seattle has been monitoring a project for several years (the SEA Street project) and has found that overall stormwater volume was reduced more than 97%. Several studies show that depending on the site, LID can actually be less expensive to use, especially with new requirements that ponds be much larger to try to provide adequate protection. (When determining the relative cost-effectiveness of LID, it’s very important to factor in the cost of alternative stormwater management and the full life cycle costs. For example, while vegetated roofs are more expensive to build, they’ve been shown to last twice as long, reduce stormwater volume by as much as 50%, reduce city temperatures, and provide recreational amenities to building tenants. Each of those benefits also has a value.) LID creates more attractive livable communities because they have more trees and other vegetation. Traffic studies show that narrower streets slow down traffic and are safer for kids and other pedestrians. LID can also enhance property values by making homes more attractive. The SEA Streets project in Northwest Seattle (117 th Street and 2 nd Avenue NW) is so popular that nearby residents and other visitors routinely walk or drive down it just to enjoy it’s beauty.
- Low impact development is just one new set of tools to help us protect resources, but it’s not the only one. LID should never be used instead of the thresholds, standards, and minimum requirements of our region’s stormwater manual, the Stormwater Management Manual for Western Washington, or a locally-developed manual that is technically equivalent. LID is just another way to meet the minimum standards of this manual. LID never replaces effective, local land use planning. This means that jurisdictions should first determine where in each watershed sensitive resources and lands should be preserved, and where future growth will be directed. Once this is determined, LID can be used in designated development areas. Steep shoreline bluffs may not be appropriate for increased infiltration of water (a geotechnical engineer should be consulted). However, certain LID approaches, such as maintaining native vegetation and soils and reducing impervious surfaces, can always be used. LID should be only part of a local, comprehensive stormwater program.
- The Puget Sound Action Team has many resources to help bring LID to communities. Action Team staff regularly provide presentations to local governments, community groups, tribal governments, and others. Periodically, the Action Team hosts or participates in education and training workshops. The Action Team web site has a wide variety of publications and links to information. The LID Technical Guidance Manual for Puget Sound, for technical audiences, is available for download or a copy may be requested from the Action Team. Every other year, the PIE (Public Involvement and Education) Fund provides funds on LID and other ways to help protect the Sound.
- One of the region’s most important LID tools is the 2005 LID Technical Guidance Manual for Puget Sound . The manual provides the region with a common understanding of the goals and principles of LID, detailed specifications on the practices, and research findings. The manual was authored by Curtis Hinman of WSU Extension Pierce County, with input from an advisory committee and numerous contributors. The Action Team edited, designed, printed, promoted and distributed the manual. Ecology provided funding for its development. The manual is guidance only and is not required. It represents our best current thinking on LID, and will need to be updated as we learn more. It complements Ecology’s Stormwater Management Manual for Western Washington by providing detailed information on the effects of development on water resources and detailed information on LID.
- LID uses numerous, small-scale practices throughout the site to manage stormwater. These are called “integrated management practices.” One of the most important practices is bioretention. This is a view of the SEA (Street Edge Alternatives) Street Project in Seattle (NW 117 th and 2 nd Avenue NW). This project uses open street conveyance (no curbs, gutters and storm drains) and long, linear bioretention swales to manage stormwater. UW researchers have monitored the site since 2000. This design has reduced overall stormwater volume by more than 97%. This project was a demonstration site, and Seattle was so impressed by its performance and cost-effectiveness that it’s now being replicated in numerous other Seattle neighborhoods. According to Seattle Public Utilities, this design is actually less expensive to build than a comparable street redesign with comparable treatment.
- Amending soils with compost is a great way to build healthier lawns and landscape areas. Soils amended with compost infiltrate stormwater better, reduce watering needs, reduce the need for fertilizers and pesticides, and provide a healthier medium for grass and garden plants. Here you see compost-amended soils in the form of “compost blankets.” The compost blankets are used for erosion control during construction and bioretention swales after construction.
- Permeable pavement acts just like regular pavement: You can walk on it, drive on it, and so on. But unlike regular pavement, permeable pavement allows rainwater to soak through, helping reduce surface runoff and replenishing aquifers. There are many different kinds of permeable pavements: Porous concrete (shown here, in Bellingham); porous asphalt, pavers, grass grid systems, and gravel grid systems. A six-year UW study of permeable pavement at a Kent parking lot showed that permeable pavement removes motor oil and dangerous metals: Motor oil was not detected in any samples that infiltrated through the permeable paving sections. (In the conventional asphalt parking spaces motor oil was found in 89% of the samples.) In the majority of samples from the permeable pavement, copper and zinc could not even be detected. (In the conventional asphalt researchers found toxic levels of those metals in 97% of samples.)
- Vegetated roofs hold and slowly release rainwater much better than a conventional roof does. Studies in Portland and Europe have shown that a vegetated roof (or green roof or eco-roof) can reduce stormwater runoff volume up to 50%. Vegetated roofs also last much longer than do conventional roofs (2-2.5x longer), they reduce inner city temperatures, and they provide recreational amenities for building tenants.
- Roofs generate a lot of stormwater runoff. Rainwater collected from a rooftop can be used to irrigate landscaping, flush building toilets, and, with a proper treatment system, serve as potable water. This is a house on San Juan Island that directs roof runoff to a large cistern hidden underneath the deck. Homeowners in the San Juans have used rainwater harvest systems for years to help meet domestic needs. The King Street Center in downtown Seattle has an extensive rooftop rainwater collection system. The system provides water for the building’s 105 toilets and landscaping. The system saves an estimated 1.4 million gallons per year, meeting over 60% of the building’s estimated annual water needs.
- Minimal excavation foundations reduce the excavation and land disturbance that normally occurs when a house or building goes in. Minimal excavation foundations use long pins driven into the earth to secure the foundation. This allows the natural, subsurface drainage patterns of a site to continue as they did prior to development. Tests in crawl spaces of houses with these systems shows normal humidity levels. This is a photo of a new medical complex being built in Olympia.
- As one example, the principles of LID, and many of the preceding LID techniques, were applied at a new subdivision in Pierce County. The project is challenging: The soils don’t infiltrate particularly well, there’s a nearby salmon-bearing stream, Hylebos Creek, and an uphill (conventional) subdivision was at one point pouring stormwater onto the project site. The site is about 9 acres, will have about 36 housing units on it, and most of the site’s vegetation was either protected or is being restored.
- LID really began on the East Coast, in Prince Georges County, Maryland. This is a subdivision that uses the overall LID approach, protects native vegetation, and uses the vegetation and bioretention to manage stormwater.
- Here’s a shot of the King Street Center, in downtown Seattl. Three cisterns hold a total of 16,000+ gallons.
- In Everett, Paine Field manages stormwater through the use of a grass pave system (shown here), a plastic grid system filled with soil and grass. This allowed the landowner to reduce the amount of conventional stormwater detention required.