The City of Seattle was one of the early pioneers of utilizing green infrastructure as a stormwater best management practice with projects primarily concentrated on reducing stormwater flows in various creek basins. Over the last few years, the City has turned its attention to using green infrastructure for controlling Combined Sewer Overflows (CSOs) within the city. While there is currently no consent decree, the City has established a control target of one untreated overflow per outfall per year for CSO discharged based on a 5-year rolling average (Washington Administrative Code (WAC) 173-245). The highest priority for these efforts has been overflows within Lake Washington. Green infrastructure practices are estimated to contribute to this target by controlling 12% of the 16 million gallons needed to be addressed to achieve the City’s goal. The remaining portion will be controlled by conventional grey infrastructure strategies.

The Ballard Roadside Rain Gardens was the first green infrastructure project designed specifically for controlling CSOs. The $1.4 million pilot project was funded by an American Reinvestment and Recovery Act (ARRA) loan and involved installing a series of rain gardens in the right-of-way along eight blocks in the Ballard neighborhood. The rain gardens were installed in December of 2010 and with the expectation that they would reduce discharge volumes by 59,000 gallons or 1% of the the total within the specic NPDES basin. Unfortunately, many of these rain gardens did not perform as anticipated. As a result, over the last few months the project has received negative press and vocal neighborhood opposition over their performance.

The City conducted an extensive post-construction analysis, and determined  a third of the rain gardens were not draining and another third were underperforming. The main shortcoming identified was that the geotechnical analysis conducted prior to construction was not specific to each rain garden location and therefore could not account for subtle changes in their infiltration rates. As a result, the underperforming rain gardens did not have sufficient infiltration rates to drain within twenty-four hours and underdrains were not used.

After the post-construction evaluation and a comprehensive community outreach effort, the City took corrective action. The public’s main issues included the dangers of standing water (i.e. drowning, mosquito habitat, smell), steep side slopes of the rain gardens, and their overall aesthetics. The corrective action included removing several of the rain gardens, reducing the depths and steepness of side slopes of others, and adding underdrains where they were effective. These changes resulted in reducing the original estimated CSO volume control by 36%.

The City went further and identified recommendations to improve future implementation of green infrastructure projects. Some examples of their recommendations included the following:

Community Engagement

• Get out into the community early
• Introduce the problem you are trying to solve, before you present the solution
• Utilize several communication media to disseminate information and get feedback.

Planning

• Develop a Project Management Plan (PMP) that outlines roles and responsibilities, schedule, budget, and risks that is approved by management.

Geotechnical

• Integrate geotechnical engineers into all phases of the project and empower them to speak up.
• If the corrected (design) infiltration rate is between 0.25 and 0.5 inches per hour, build a redundant system into the design, such as an underdrain.

Design

• Provide the design for the flow control/bypass plan and erosion and sediment control plan. Do not leave it to the contractor.
• Review project design, how it functions, and the critical project components with Construction Management ahead of time.

Construction

• Balance funding sources with the ability to course correct during construction and the documentation requirements.
• Involve geotechnical engineers in construction to field verify that the excavated or exposed soil look as anticipated.
• Maintain an open dialogue between contractor, construction management, project manager, designer, and geotechincial engineer.

The City of Seattle should be commended for recognizing the shortcomings of the project and taking quick corrective action. The project serves as a reminder of how important the success of pilot projects are to the future of green infrastructure not only locally but also nationally. News travels fast and high profile failures can cast doubt on the effectiveness of these types of systems and fuel future opposition to projects. When approaching any green infrastructure project, the details and execution are crucial to a project’s success, but when the project is intended to set the standard and introduce the public to green infrastructure practices, it becomes even more critical.

-Brian Phelps

Sources:
Email interview with Shanti Colwell, Environmental Engineer with Seattle Public Utilities
Seattle Public Utilities Case Study
Ballard Roadside Raingardens, Phase I-Lessons Learned

The American Society of Landscape Architects recently released 479 Green Infrastructure Case Studies. The case studies provide an informative snapshot of the type of green infrastructures are being implemented across the country. We are excited the two projects we submitted (The Pinnacle at Symphony Place green roof and Deaderick Green Street) were included in the list. You can check out the entire list here.

-Brian Phelps

The post included some assertions that quantified the financial value of some of the soft benefits of green roofs. These included

“…average stormwater mitigation benefit is $4.26/sf” and  a view of a green roof improves property values of nearby buildings by 11%”

These figures are based on research by Smart Cities Research Services, Montreal.  “The Monetary Value of the Soft Benefits of Green Roofs” report prepared by Ray Tomalty, Ph.D. and Bartek Komorowski, MUP with the assistance of Dany Doiron, published last year. The report includes research on developing heuristic methods for quantifying seven soft benefits of green roofs: including: change in property values, marketing benefits, food production and food security, sound attenuation, stormwater retention, air quality, and green house gas (GHG) sequestration. The following is a summary of their findings:

I did not include the marketing figures in the table above, due the complexity of their findings.

Since there is little to no research specific to green roofs, the heuristic methods described in the report rely on other related research. Examples include:

• Tree planting along a street in front of a property increase the property’s value by up to 9% Source: Determinants of Neighborhood Transformations in Philadelphia-Identification and Analysis: The New Kensington Pilot Study (2004) prepared by The Wharton School at the University of Pennsylvania.
• Homes adjacent to public parks have about a 20% higher property value than similar homes distant from parks, Source: The Impact of Parks on Property Values: Empirical Evidence from the Past two Decades in the United States (2005) by J. Crompton.
• Average properties abutting typical community gardens increased in value by 7.4% within five years. Source : The Effects of Community Gardens on Neighboring Property Values (2008) by Voicu, I. & Been.

Supply and demand play a critical role in determining one values and this is not any different for green infrastructure. For urban areas that may incorporate little to no green infrastructure (i.e. parks, green roofs, street trees) and are predominantly unsightly parking lots and roofs, projects that include green roofs should be more valuable and those properties surrounding it should benefit in some way as well. The report provides a great starting point for financially quantifying the soft benefits of green roofs. Over time, data specific to green roofs will eventually become available and we will be able to more accurately quantify their specific benefits.

-Brian Phelps

One of the first bike share program in the US was started in Portland, OR in 1994. The program simply released bicycles into the city for unrestrictive use, but proved unsuccessful due to theft and vandalism. Other cities such as Madison, WI tried similar programs, but eventually modified to a more restrictive system requiring deposits for use of the bicycles. Washington DC instituted the first high-tech European style bike share program in the US in 2008, called SmartBike DC.
Montreal has the largest bike sharing program in North America, called Bixi. In 2009 the system had some 400 stations where bicycles can be rented with a credit card, there are over 5000 bicycles in the system. The system has had so much success that Washington DC/Arlington is also adopting the Bixi program, as well as Washington State University. This particular program offers varied pay scales from $5/day to $78/year. Pretty reasonable if you live or work in the city and have the need to use a bicycle. By the way, Menominee’s Yellow Bike program is completely free, you just need to show your drivers license and leave a phone number, the advantage of a small town.

There are many other bike share program in cities throughout the US, the Bike-sharing Blog has a lot of additional links and information if interested. Also, something to be aware of in the coming months,  Nashville has plans to start its own bike share program soon.

-Sara Putney

Yellow Bikes at Menominee Airport

Just to give you an idea the area is home to more than 250 species of crayfish (70% of all the species in the entire U.S.), more than 300 species of mussels (over 1/3 of these live in Tennessee), and more than half the freshwater fish species in the U.S. Because of this great diversity, Tennessee has more freshwater fish that are at-risk than any other state. These species are at-risk largely due to pressures from development practices, which allow sediments and pollutants to wash into our rivers and streams. This and other topics concerning protection of critical watersheds can be found in, Rivers of Life or States of the Union: Ranking America’s Biodiversity, just some of the publications found on the NatureServe’s website.

Graphic from 'Rivers of Life', published by NatureServe

As mentioned in an earlier post, the implementation of ‘green street’ practices on Deaderick Street in downtown Nashville will divert approximately 1.2 million gallons of stormwater a year from the Cumberland River. This is water that would have otherwise run unabated into the river carrying all of the pollutants and sediments from the street. Understanding the significance of the region’s biodiversity is a good reminder of what we are trying to protect when implementing green infrastructure planning and strategies –and why this is especially important here in the Southeast and Middle Tennessee.

-Sara Putney

Our office was invited to tour the Tennessee Concrete Association’s (TCA) new headquarters in Nashville. The focus of the tour was to learn more about their experience with pervious concrete. They had a few examples of pervious concrete pours on site, and I thought the one in the photograph above was particularly interesting. TCA is experimenting with mixes to increase the Solar Reflectance Index (SRI) value of pervious concrete. Mix A in the left side of the photograph is a pervious concrete mix that replaces 20% of the required cementitious content with fly ash. Mix B to the right has replaced 50% of the required cementitious content with slag. Both substitutes are by-products of industrial process. Fly ash is from the process of burning coal for energy and slag is from the production of both iron and steel.

As you can see there is a noticeable difference in the color between the two samples. The slag sample is much lighter in color. We were told it was difficult to determine the SRI of pervious concrete due to the voids. As a result, TCA could not definitively tell us the SRI value. They are interested in finding someone to perform more testing.

In regard to cost, TCA stated the slag is readily available in Tennessee but not all producers carry it. Fly Ash is the less expensive option compared with cement and slag, but slag is typically less expensive than cement (especially white cement)

It does appear the slag mix  provides a great option to improve solar reflectance. I hope more data will be available in the near future that supports this.

-Brian Phelps

]]> http://hpigreen.com/2010/02/10/pervious-concrete-and-solar-reflectance/feed/ 2 hpigreen porous concrete http://hpigreen.com/2010/01/22/finding-water-in-the-desert/ http://hpigreen.com/2010/01/22/finding-water-in-the-desert/#comments Fri, 22 Jan 2010 21:58:04 +0000 hpigreen http://hpigreen.com/?p=758 ]]> There have been a few articles lately about the new Underwood Family Sonoran Landscape Laboratory which is a part of the School of Landscape Architecture at University of Arizona. Arizona is known for its arid climate, but this project uses an innovative take on irrigation to provide a lush landscape for this jewel of a space.

Photo Courtesy of Ten Eyck Landscape Architects Inc
Photo by: Bill Timmerman

In addition to creating a wetlands biome, complete with an 18,000 gallon pond, the project provides an 11,600 gallon cistern for water harvesting. The water harvesting is provided from four sources – and rainwater is not the largest source of water. Of the approximately 250,000 gallons of water harvested each year about 40% comes from condensate from the air conditioning units, 33% comes from rainwater runoff from the roof, 18% from well water blow off and 9% from greywater collection (from sinks and drinking fountains. This water harvesting accounts for 83% of the water required for the landscape on an annual basis.

Photo Courtesy of Ten Eyck Landscape Architects Inc
Photo by: Bill Timmerman

In addition to the water harvesting, the garden includes a significant green wall with planted vines adding to the shading from the hot desert sun on the southern façade of the building.

Next up, they are looking at creating a desert green roof which can be monitored for research data.

If this is available in a desert environment, think of the potentials for harvested water elsewhere.

University of Arizona News had an article about the facility that provides more information on the project. Check out their photo of the large water collection system in action. Ten Eyck Landscape Architects were the landscape architects for the project.

Photo Courtesy of Ten Eyck Landscape Architects Inc
Photo by: Bill Timmerman

Photo Courtesy of Ten Eyck Landscape Architects Inc
Photo by: Bill Timmerman

-Kim Hawkin

One of the Signs from Deaderick Street

Recently, the Forest Service has updated their Tree Carbon Calculator so that it works nationally instead of just for California. You can find the updated version in their Climate Change Resource Center. The calculator runs off an excel platform and allows you to input data for a single tree. Based on your region, tree species, distance for the building, and a number of other factors it will give a basic idea of how much annual energy, emissions and stored carbon you can expect. I used it to see the effects for a couple of trees I have outside my house. Even a small 6” tree has the potential to sequester over 65lbs of carbon dioxide from the atmosphere per year and that big 30” oak tree in my back yard, over 1000lbs per year, not to mention all the energy reductions too.

This is another useful tool to help prove the value trees. It is projected that over the next 50 years climate change will actually cause the southeast region to become warmer and drier, which would reduce the amount of forest growth. While the best option for managing this in the future is to keep forest as forest (per a publication from the US Forest Service titled ‘Forest and Carbon Storage‘), it can’t hurt by incorporating as much urban tree growth into new developments as possible, every little bit makes a difference.

-Sara Putney

When we plan and design for projects, within our trade, we try to use native species whenever possible. This is especially important when designing green infrastructure projects that tie so closely to our natural resources, in particular our waterways. Oftentimes people wonder why this is so important and how can it really affect them anyway? Whether it’s plant materials or animals, all invasive species are eventually extremely damaging to our native ecosystems. And also extremely costly; “The UN Convention on Biological Diversity says the spread of invasives costs 1.4 trillion dollars a year globally in damages and control measures. The U.S. alone loses 138 billion dollars a year in the fight.”

Image from ‘The Dirt’ website.

In ASLA’s blog ‘The Dirt’, a recent posts highlights the efforts for the State of Michigan to protect Lake Michigan and the entire Great Lakes Region from the Asian Carp. Like all invasive species these fish take over an ecosystem by consuming resources that would otherwise be used by the native species. Michigan is suing the State of Illinois in order that they shut down the waterways leading into Lake Michigan. According to the New York Times article Minnesota, Ohio, Wisconsin, and Indiana are all in support. This came to light due to recent evidence of the carp within 6 miles of Lake Michigan in the Chicago area waterway system that links the Mississippi River to the Great Lakes. And while the City of Chicago realizes that the carp overtaking Lake Michigan would be devastating they are wrestling with their own economic concerns over what closing the waterways would really mean. There is more detailed information in ‘The Dirt’ post and the New York Times Article.

Another item in the light recently is the efforts of the Chicago Botanic Garden and the Morton Arboretum to gather native seeds from around the Midwest. “Scientists from the botanic garden are sending teams out across the Midwest and West to the Rocky Mountains and Great Basin to collect seeds from different populations of 1,500 prairie species by 2010, and from 3,000 species by 2020. The goal is to preserve the species and, depending on changes in climate, perhaps even help species that generally grow near one another to migrate to a new range.” The idea is to catalogue, store and preserve native plants in the event that climate change or invasive species may require the migration of native plant materials to other areas. There is still much debate about the project and more detailed information can be found in the New York Times article.

These are just two examples in a long list of invasive species problems that continue to threaten the ecosystems of the US. Not only do invasives disrupt plants, animals and other natural resources, but as noted above they also can have huge negative economic impacts. This coming on the tails of National Invasive Species Awareness Week, (January 10-14th), to learn more visit the National Invasive Species Information Center’s website.

- Sara Putney

How much water can you harvest from fog? I hadn’t really thought about it until, I recently came across the work of FogQuest. FogQuest is a small Canadian all-volunteer organization founded in 2000 that constructs fog collection systems in areas where conventional sources such as wells, rivers and pipelines are not available.

While not as applicable in most of the United States as a primary source of water harvesting (where we use approximately 100gals of water per person per day), the technology is still fascinating and has been effective in developing countries. The system is comprised of a series of screens made of polyethylene or polypropylene erected on poles in areas that frequently experience fog events. According to FogQuest’s website, a 40m2 system can on average collect approximately 200L per day (53 gallons). Like rain harvesting, there are days where no water is harvested, but on some days the system has been reported to collect up to 1000L (264 gallons). FogQuest estimates that a 40m2 system cost between $1,000-$1,500. They have a number of videos on their site that describe the system in more detail (Link to Videos). Andrew R. Parker, a zoologist at the University of Oxford, and Chris R. Lawrence, an investigator at QinetiQ, have developed another fog collection technology based on the Namib Desert Beetle’s wings. They have been able to mimic the beetle’s process for collecting water. It is an interesting application of biomimicry. As the name suggest, the Namib Desert Beetle (see photo) lives in the Namib Desert where only a half-inch of rain falls annually. In response, the beetle has developed a unique survival mechanism. It is able to use its wings to collect water from fog that forms in the early morning and blows across the desert. The researchers discovered that this is accomplished through a series of small bumps on the surface of the beetle’s wings. When the beetle positions its body at 45 degrees the fog collects on its back and runs down the wings to its mouth. Here is a link to a website with more information about the process (link).

Namib Desert Beetle
Photo Credit: asknature.org

In places with high winds, it is thought that this new fog collecting material may be more efficient than the open polyethylene mesh used by FogQuest because the water cannot be blown through it. Other applications being considered for the material include using it to reclaim water vapor from cooling towers to developing tents that would capture fog for drinking water. This material has even been envisioned to reduce or eliminate fog that can disrupt transportation systems (i.e. airports, roads).