GI In Seattle: The Importance of Pilot Project Success For All Green Infrastructure

4 01 2012

Image
Ballard Roadside Rain Gardens, Credit: Seattle Public Utilities

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


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NYC’s Green Infrastructure Plan

18 11 2010

Last week, the Economist in an articled titled “Trees grow in Brooklyn” reported on U.S. cities implementing green infrastructure strategies to address the pollution of their waterways from storm water runoff. The article focused primarily on New York City and Philadelphia.

According to the article nearly 27 billion gallons of untreated water overflows into the New York harbor each year. NYC’s recently released green infrastructure plan seeks to address run-off from 10% of the impervious surfaces in the City with green infrastructure storm water strategies that range from rain barrels to pervious pavements to green roofs.

The plan estimates that on average the cost per gallon of Combined Sewer Overflow (CSO) avoided ranges between $1 to $2 per gallon. In addition, the City calculates that over a twenty-year period, it will receive between $139 million and $418 million in additional triple-bottom line benefits (i.e. energy savings, increase in property values, health) from the green infrastructure.

While NYC’s strategy is also employing grey infrastructure, they see the combination of the two costing less than a grey only approach. The cost of the green-grey strategy is approximately $5.3 billion of which $2.4 billion makes up the cost of the green infrastructure. This is $1.5 billion less than the grey only solution.

Chris Strickland, a deputy commissioner with the New York’s Department of Environmental Protection sums it up in the article saying that this (green infrastructure plan) is a way of achieving more than one thing with tax dollars.

Link to NYC Green Infrastructure Plan

-Brian Phelps


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Metro Green Infrastructure Master Plan Now On-line

1 09 2010

Metropolitan Nashville-Davidson County’s Green Infrastructure Master Plan is now available on Metro Water Services’ website. The plan was prepared by amec, Hawkins Partners, Urban Blueprint, and the Low Impact Development Center. The plan includes the following:

  • Green Infrastructure Practice – Overview of Green Infrastructure and descriptions of various practices.
  • Technical Analysis of Green Infrastructure – Analysis of the CSS area with respect to green roofs, three kinds of infiltration practices, tree planting, and rainfall harvesting (cisterns and rain barrels) and its potential impacts on the CSS.
  • Green Infrastructure Projects – Brief overview of the preliminary design concepts for six projects.
  • Green Infrastructure Incentives and Financing – Summary of various potentially applicable incentive practices that have been applied in other cities to encourage the use of Green Infrastructure.

Click here to download the entire plan in PDF format


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Categories : Bioretention, Green roof, Green Street, Hawkins Partners, Pervious Pavement, Plans and studies, Sustainable Site Strategies, Water Harvesting

Density as a Best Management Practice (BMP)

4 06 2010

High Point Neighborhood mentioned in Ped Shed Post
photo credit: sitephocus.com

The Ped Shed, a blog focused on walkable urban design and sustainable placemaking by Laurence “L.J.” Aurbach, recently had a post about density as a best management practice (BMP). The post provides a good outline of the evolution of the stormwater regulatory environment. The main point of the post is that well intentioned stormwater regulations make it difficult to build dense walkable environments that ultimately exacerbate stormwater management issues.

The author states:

“But the universal and inflexible application of BMPs and LID can have significantly negative consequences on the quality of urban places and the health of watersheds. LID purports to encourage smart growth and urban redevelopment, but as a rule this support is nominal, little more than lip service. In general practice, LID puts urban density at a competitive disadvantage.”

He cites three studies, two by the EPA (Protecting Water Resources with Higher-Density Development, Using Smart Growth Techniques as Stormwater Best Management Practices) and one by Jacob and Lopez (Is Denser Greener? An evaluation of higher density development as an urban stormwater quality best management practice.) All of them provide compelling data as to the benefits of density with regard to stormwater run-off and pollutant loads, and are well worth reading.

I agree with him that when developing an urban vs suburban site, more expensive stormwater BMPs are typically utilized (i.e. underground detention, green roofs) to meet stormwater regulations.

However, site area, property costs, and market dynamics are a large factor in determining appropriate BMPs and cost effective solutions. If you can build significantly more square footage due to a better market environment and/or need to maximize your investment in land cost (which often reflects the market potential and property entitlements) then the cost of best management practices that maximize these potentials can be offset.

The examples of offsite mitigation are very intriguing. I wholeheartly agree that opportunities for this on properties in close proximity to the development is an effective way to mitigate stormwater impacts while spreading (and hopefuly lowering) the cost across multiple properties. In regard to infill developement, this can be very difficult in practices but not impossible. Public space can be designed to accommodate the needs of neighboring properties. Using green roofs, pervious pavements, and other BMPs on surrounding properties can greatly reduce the volume of runoff being diverted to these offsite areas and therefore their size  can be diminished to a point that can be integrated better into urban environments.

-Brian Phelps


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BLUE is the New Green

16 04 2010

I think I may have heard the term “blue roof” before last Saturday, but I must not have paid attention.  I was fascinated as I read New York City’s NYC Stormwater Sustainability Report 2008. It included a full description of a blue roof as an LID measure.   I checked out  few other leads to find this LID technique also being explored in Washington state and a recent article in EDC Magazine discussing it as well.

Bottom line:  a blue roof detains water on the roof of a structure in order to reduce the stormwater impacts.  The detention is done through a  flow restriction device around the roof drain which slowly releases the water or, in the Washington modeling, all of the rainwater on the rooftop is collected and stored.  The roof-harvested water can used to fill a water cistern for irrigation, a site infiltration system like a bioswale or rain garden or discharged slowly to the storm system.

The blue roof is best suited to a large flat roof in more urban areas with limited availability of ground level detention.  There are also designs which provide wide “gutters” near the perimeter of the roof to concentrate the water roof load where it can be supported structurally.  If the primary goal is stormwater reduction, then a blue roof can achieve that goal at considerably less cost than a vegetated green roof.  The estimates I found ranged from $1/s.f. to $4/s.f. for a blue roof while estimates for an extensive green roof might be $18-25/s.f.   Blue roofs also don’t have the same maintenance costs of green roof either – they basically require the same maintenance as a conventional roof..

Of course, the blue roof doesn’t provide the multi-benefit that green roofs do (such as energy use reduction, habitat, aesthetic, life cycle roof cost), but 2008 modeling conducted by Douglas Beyerlein, PE, Clear Creek Solutions in Mill Creek Washington does show the blue roof slightly outperforming the green roof for stormwater reduction.

-Kim Hawkins


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Olympic Sized Green Roof

17 02 2010

Courtesy Vancouver Convention Centre website

The winter Olympics just kicked off with the opening ceremonies from BC Place Stadium in Vancouver. But serving as the International Broadcasting hub for the games is the Vancouver Convention Centre — the world’s first LEED Canada Platinum rated convention building. The 1.2 million SF center boasts a 6-acre green roof, which also now makes it the largest green roof in North America.

The roof is planted with over 400,000 native plants and collects rainwater for irrigation which contributes to the buildings stormwater credits as well. Other interesting sustainable features include marine and shoreline habitat restoration. Fish habitat was actually built into the buildings foundations. The building also uses seawater for heating and cooling and incorporates on-site water treatment.

The following video “Vancouver’s 6 Acre Living Green Roof”, posted on You Tube gives a great sense of the scale and context of the green roof. The landscape architect who worked on the project, Bruce Hemstock, discusses the plants used, soil media and the idea behind habitat linking into urban centers that is beginning to be made possible with the inclusion of more green roof in our cities. Interestingly enough he says one of the biggest challenges of the project was initially convincing people that it was the right thing to do.


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Interview with Portland BES Part 3 of 3

8 02 2010

Mt. Tabor Middle School Rain Garden
Source: City of Portland, Environmental Services ©2009

The following is the third and final part of an email interview I recently conducted with Emily Hauth, project manager with Portland Bureau of Environmental Services (BES)’s Sustainable Stormwater Management Division. Their agency has been a leader in sustainable stormwater implmentation over the last twenty years.

Green Infrastructure Digest (GrID): When it comes to new construction or public projects, it is much easier to require and/or encourage the use of green infrastructure best management practices. Existing development has proven to be much harder, what strategies has the City used to encourage existing developments to retrofit their properties to include green infrastructure and reduce/cleanse stormwater runoff?

Ms. Emily Hauth:

  • Downspout Disconnection Program (1995- present) – Disconnecting downspouts from the sewer system allows roof water to drain to lawns and gardens. Downspouts on many homes are connected directly to the combined sewer system and disconnecting them keeps clean stormwater runoff out of the combined sewer system, which reduces CSO volume. Over 56,000 downspouts have been disconnected since the program began 15 years ago
  • Community Watershed Stewardship Program (1995-present) – provides grants of up to $10,000 to schools, churches, businesses and other community organizations for projects that connect people with watersheds and protect and enhance watershed health.
  • Willamette Stormwater Control Program (2001-2003) – The city offered financial grants and technical support for several projects to retrofit existing commercial properties served by the combined sewer. This was to research the feasibility, cost and performance of commercial sustainable stormwater approaches. The city distributed about $350,000 to 11 projects.
  • Innovative Wet Weather Program (2002-) – promotes stormwater management projects that contribute to healthy Portland watersheds. Between 2002 and 2005, the U.S. Environmental Protection Agency (EPA) granted the city $2.6 million to fund over 25 innovative public and private projects throughout the city that demonstrate sustainable, low-impact stormwater management solutions.
  • Clean River Rewards (2006-present) – a stormwater utility discount program for private property owners who manage stormwater on their property. They can receive a discount of up to 100% of their on-site stormwater management charge.
  • Grey to Green Program (2008-) – The city offers incentives of up to $5 per square foot to add new ecoroofs. The city also offers treebates to encourage people to plant eligible yard trees. The treebate is a credit on the recipient’s sewer bill of up to $40 per tree ($50 for native species).
  • Private Property Retrofit Program (2009-) – The Tabor to the River Program offers design assistance and construction dollars for on-site stormwater management on targeted private properties. The program is available only in areas where stormwater retrofits will allow the city to avoid more costly sewer replacement projects. The city will install rain gardens, stormwater planters, swales or ecoroofs on sites that meet program criteria at no cost to the property owner. Property owners who want to install a facility themselves could qualify to receive financial incentives and technical assistance.
  • WorkingGreenPortland.com (2009-) – includes information on private property stormwater management technique, calculators to determine impacts for individual properties, and links to stormwater retrofit professionals and other resources.
  • Ecoroof Floor Area Ratio Bonus – Development proposals in the central city that include a green roof, can receive bonus floor area.
  • Education and Outreach – Numerous efforts to engage communities and increase public understanding and acceptance are critical to the success of all city programs.
  • Technical Assistance – the city offers technical assistance to professionals and property owners for implementation of sustainable stormwater management approaches.

12th Avenue Green Street
Source: City of Portland, Environmental Services ©2009

GrID: What do you see as the future of green infrastructure?

Ms. Hauth: I would say future green infrastructure in our urban environment will include:

  • Green connectors – streets that connect parks and open space, schools, and commercial areas to neighborhoods; encourage walking and biking by providing enhanced and safer pedestrian and/or bicycle routes; and provide environmental benefits.
  • Green refuges within our urban environment – reclaiming unused spaces or derelict sites within our cities for stormwater management and passive recreation.
  • Ecodistricts – integrated neighborhoods that capture, manage, and reuse a majority of energy, water, and waste on site; offer a range of transportation options; provide a rich diversity of habitat and open space; and enhance community engagement and well-being.
  • Volunteer Green Street Maintenance Program – engaging community members to help in the care and maintenance of green streets.
  • Possible onsite stormwater management discount to property owners for adjacent public green streets.
  • Cost benefit analysis of the ecosystem services provided by green infrastructure in meeting the triple bottom line.

For more information visit our wesbite

If you missed the first parts of the interview, you can find them here.

Part 1

Part 2

-Brian Phelps


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Interview with Portland BES Part 1 of 3

3 02 2010

Portland Building (Location of Portland BES Offices)
Source: City of Portland, Environmental Services ©2009

The following is the first part of an email interview I recently conducted with Emily Hauth, project manager with Portland Bureau of Environmental Services (BES)’s Sustainable Stormwater Management Division. Their agency has been a leader in sustainable stormwater implmentation over the last twenty years.

Green Infrastructure Digest (GrID): The City of Portland has been and continues to be a leader in implementing green infrastructure facilities. Please tell our readers a little bit about the work the Bureau of Environmental Services (BES) is doing in regard to increasing the use of green infrastructure. What new innovations should we expect to see out of BES in the coming years?

Ms. Emily Hauth: Our sustainable stormwater management solutions have evolved from a single purpose regulatory driven approach to one that achieves multiple objectives. We are designing our urban landscapes and street systems with an eye toward community enhancement, cooling of the air and water, increased wildlife habitat and greenspace, safe bike and pedestrian linkages, greenway connections to services and amenities, and of course capturing and treating stormwater at the source on the surface. In this way we are achieving watershed health goals and meeting regulatory compliance while informing a new approach to urban development.

We are incorporating green infrastructure approaches into our policy development and planning processes. We have a number of policy initiatives that recognize green infrastructure solutions as a smart way to plan for watershed health and the city’s future and direct city bureaus and agencies to cooperatively plan and implement green infrastructure elements as part of all work programs. Our bureau works collaboratively with other City bureaus and agencies such as our Bureau Of Transportation and the Portland Development Commission on projects that promote environmental concepts while addressing auto, pedestrian, and bicycle safety. We are also fully integrating our watershed health and stormwater/sanitary collection goals into our Systems planning process. Portland’s Grey to Green initiative, established in 2007, sets a 5-year goal to increase green infrastructure elements throughout Portland including 900 Green Streets, 43 acres of Ecoroofs, and over 50,000 new trees.

In one particular area of the city where pipes are failing or undersized, we are incorporating green street facilities into the solutions plan. This area is referred to as Tabor to the River. In this area alone, we will be constructing 500 green streets. We’re also working closely with targeted private property owners to help them manage stormwater on their sites and play a role in the solution. All future work to address similar issues will follow this model of combining grey and green infrastructure solutions.

We don’t feel we have all the answers so we continue to ask ourselves, is it working? We continue to monitor our facilities, modify designs, research components such as plants and soils, to refine our knowledge base and maximize facility function and performance. We’re always looking for efficiencies in design and construction so we’re evaluating use of modular or prefabricated components for sustainable stormwater solutions. Other innovations we’re exploring include using a curbless green street design, new design options that manage both public and private runoff, and green walls that manage stormwater. We’re also developing a volunteer green street maintenance program that engages the community while helping the city meet its maintenance needs.

Planter at Mississippi Commons
Source: City of Portland, Environmental Services ©2009

Part 2-On Friday

-Brian Phelps


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Trees Please

11 12 2009

Street Trees at Hill Center Green Hills

This year many cities in the Southeast have already exceeded their average rainfall by over 20%. As a result, we’ve heard many stories about flooding and 500 year flood events in the Atlanta area and elsewhere. I wondered about the ability of tree planting to affect stormwater. I have seen various reports referring to the benefits of trees based on their ability to reduce stormwater through evaporation of rainwater which lands on its leaves and branches back into the atmosphere, and through the infiltration of rainwater into the ground reducing the total amount of runoff and also affecting the peak flows by making slight reductions to the volume of stormwater runoff.

Over the past few decades, American Forests has developed an analysis that they refer to as an Urban Ecosystem Analysis (UEA) in over 40 metro areas in the U.S. These reports quantify a number of benefits provided by trees especially relating to stormwater benefits , air pollution reduction and carbon sequestration. The assessment is based on specific GIS modeling of tree canopy for regional and site specific areas within each municipality it studies. The GIS studies also show that impervious surfaces have increased by 20% over the past 2 decades in urban areas. American Forests has developed tree canopy goals for various areas in the United States, with the following recommended generally for cities east of the Mississippi.

AMERICAN FORESTS’ General Tree Canopy Goals
40% tree canopy overall
50% tree canopy in suburban residential
25% tree canopy in urban residential
15% tree canopy in central business districts

I noted that several southeastern cities had had an Urban Ecosystem Analysis including nearby Chattanooga and Knoxville. I also found some data for Charlotte/Mecklenburg County. One of the critical items that the UEA measures is loss of tree canopy. Some of the losses noted are staggering.

Between 1984 and 2001, Mecklenburg County (Charlotte, NC) lost over 22% of its tree cover and 22% of its open space. Over that same time period, the county’s impervious surfaces increased by 127%. By comparison between 1974 to 1996 Chattanooga and its nearby neighbor, Atlanta, both lost 17% of its regional tree cover.

Even with the dramatic percentage of loss noted in Mecklenburg Co, the 2002 UEA still noted that Charlotte, whose city limits are within Mecklenburg County, still exceeds the Tree Canopy Goals mentioned above at 49% Tree Canopy. The city’s tree canopy is valued of $398 million dollars based on a total stormwater retention capacity of Charlotte’s existing urban forest of more than 199 million cubic feet. This translates into a value of approximately $398 million dollars (based on construction costs estimated at $2 per cubic foot to build equivalent retention facilities). Chattanooga comparatively achieved a Tree Canopy Goal of 22.5%.

In a ten year period from 1989 to 1999, Knox County (Knoxville, TN) lost a less dramatic 2.2% of its regional tree cover. Knoxville’s tree canopy measured at 40% of the total land area just met the 40% American Forest Tree Canopy Goal. This was assessed by the UEA to have a value equal to $280 million dollars.. This value is based on a total stormwater retention capacity and related construction costs to build equivalent retention facilities noted in the above Charlotte example. UEA also quantified that the tree cover in Knoxville sequesters more than 2.3 million pounds of pollutants from the air, with a value of more than $5.9 million.

As we consider the goal of increasing our Tree Canopy cover and, especially, the American Forests recommendation of 15% Tree Canopy cover for central business districts, consider that the Knoxville UEA study and The Green Build-out Model: Quantifying the Stormwater Benefits of Trees and Green Roofs in Washington, D.C . completed in 2007, noted a difference in a tree’s stormwater benefit based on whether it was over a pervious or impervious surface. The D.C. report modeled that trees over impervious areas, such as a sidewalk or parking lot, provided a stormwater benefit that was over 5 times that of a tree over a pervious surface such as grass or planting beds. The Knoxville report further noted that it requires ten or more newly planted trees to equal a single large mature tree’s ecological value.

-Kim Hawkins


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Making Green Infrastructure Common Place

6 11 2009

Philly_Green_City1

Getting more for less is an approach almost everyone can appreciate. Why wouldn’t you want to get the most out of your investments? Appropriately applying green infrastructure in ways that effectively addresses critical stormwater issues while creating a more beautiful and economically vibrant community is common sense. Unfortunately, it isn’t common place. As the use of the available sustainable site tools and technologies continues to grow, it may not be long before green infrastructure is the conventional approach to stormwater management.

With the Release of their “Green Cities Clean Waters Plan”, Philadelphia joins a handful of cities across the Country that have committed to green infrastructure and seek to institutionalizing it throughout the city. Philadelphia’s plan published last September sets forth a bold plan to invest $1.6 billion. Of this total 62% ($1 billion) of it will allocated directly to green stormwater infrastructure. Another 18% ($290M) will directed to stream corridor restoration and preservation and 20%($320M) will address wet weather treatment plant upgrades.

Over the next few weeks we will take a closer look at Philadelphia’s plan. At over 3,000 pages, there is a lot of information to sift through. In addition, we will also look at Pennsylvania Environmental Council released a report titled “Implementing Green Infrastructure: Developing a Winning Strategy to Fund Philadelphia’s Ambitious Plan” that looks at the economic benefits of the plan and how other cities across the country are funding their stormwater initiatives. Together they are an impressive step forward for the City of Philadelphia and the Nation.

-Brian Phelps


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