Invasive Species in the News

15 01 2010

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





Sustainability Resource Guides from ASLA

14 12 2009

The website for ASLA (American Society of Landscape Architects) has a fairly new section devoted to resources for sustainable design and planning. If you haven’t wandered across it already you should take a minute to see what it has to offer. It is aimed at national and local policymakers, government agencies, design professionals, planners and students. Resources include hundreds of project case studies, research papers, organizations and other government resources on sustainable design.

The following description of the five resource categories is taken from an announcement by ASLA, they include:

  • Green Infrastructure (www.asla.org/greeninfrastructure) covers park systems, wildlife habitat and corridors, urban forestry and green roofs.
  • Sustainable Transportation (www.asla.org/sustainabletransport) covers sustainable transportation planning, siting sustainable transportation infrastructure, designing safe and visually appealing transportation infrastructure, green streets and reducing the urban heat island effect.
  • Sustainable Urban Development (www.asla.org/sustainableurban) covers fighting sprawl, sustainable zoning, reusing brownfields, investing in downtowns, open spaces and sustainable urban design.
  • Livable Communities (www.asla.org/livable) covers sustainable land use, place making, green schools, sustainable housing, sustainable employment growth and health, safety and security.
  • Combating Climate Change with Landscape Architecture (www.asla.org/climatechange) covers site planning, open spaces, plant selection, stormwater management and other areas.

While the site is a little hard to navigate, (if you like what you see, I suggest you bookmark the above links to be able to find them again) this is a good resource that pulls a lot of varied information together into one area. It has potential to be not only helpful for designers, planners and people who speak the sustainability language, but also to be useful to vastly wider audience. I understand they are also always looking for new projects, research, case studies, etc. to highlight, if you want to contribute you can contact ASLA @ info@alsa.org

-Sara Putney





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





EPA Releases Technical Guidance for Implementing EISA Section 438

9 12 2009

Just in case you missed it last week among all of the other pressing news stories, the EPA released a report outlining technical guidelines for implementing the stormwater runoff requirements for federal projects under Section 438 of the Energy and Independence and Security Act (EISA). In effort to afford designers maximum flexibility, the guidance provided is performance-based. The Section 438 of the EISA established the following requirements:

“Storm water runoff requirements for federal development projects. The sponsor of any development or redevelopment project involving a Federal facility with a footprint that exceeds 5,000 square feet shall use site planning, design, construction, and maintenance strategies for the property to maintain or restore, to the maximum extent technically feasible, the predevelopment hydrology of the property with regard to the temperature, rate, volume, and duration of flow.”

On October 5th, the White House issued a Presidential Executive Order addressing this requirement. The Executive Order titled “Federal Leadership in Environmental, Energy, and Economic Performance.” It required the EPA in coordination with other agencies to develop guidelines for implementing Section 438 of the EISA within 60 days. The current publication meets these guidelines.

The guidelines establish two options for meeting Section 438. The first option is to retain 100% of a rainfall event on site that is less than or equal to a 95th percentile. A 95th percentile rainfall event is an event with a volume over a 24-hr period that is equal to or less than the volume of 95% of all rain events for a period of record (i.e. 20 to 30 years). The table from the report provided below shows the size of the 95th percentile events for various cities across the Country. The events range between 0.7 to 1.8 inches of rainfall. These events commonly known as a “first flush” event were identified because they often contain the highest level of pollutants. Option 2 allows designers to conduct their own hydrological analysis and determine the site specific pre-development hydrological conditions. This options states that “temperature of runoff should not exceed the pre-development rates and the predevelopment hydrology should be replicated.”

For both of these options, the guidelines encourage the use of green infrastructure stategies. The guidelines recognize that “runoff event frequency, volume and rate can be diminished or eliminated through the use of green infrastructure (GI)/Low Impact Design (LID) designs and practices, which infiltrate, evapotranspire and capture and use stormwater”. The guidelines provide a number of studies that illustrate how green infrastructure can meet the established criteria. It is exciting to see the continued momentum green infrastructure is experiencing. If your considering working on federal projects, you will need to take a serious look at green infrastructure as an integral part of your site strategy.





Kansas City Stormwater Overflow Control Plan

4 12 2009

Source: Kansas City, Missouri Overflow Control Plan Overview Document

This year Kansas City embarked on a massive $2.3 billion stormwater overflow control plan to address sewer overflows throughout the city. Its inclusion of a major $28 million green infrastructure pilot project has gained a lot of attention. The project has been recognized as the largest green infrastructure project in the United States. The Marlborough Neighborhood Pilot Project, as it is called, is located in the Middle Blue River Basin, one of the four major watersheds addressed by the plan. The entire pilot project encompasses nearly 100 acres of primarily residential neighborhoods. This program is anticipated to be expanded over a larger 744 acre area that will eventually include over 25 acres of mixed green infrastructure strategies (i.e. rain gardens, bioswales, permeable pavement, and green roofs) that have the capacity to sequester 3.5 million gallons of water. The green infrastructure strategies employed are designed to replace two underground tanks of similar capacity. In total the pilot project and its expansion are budgeted to cost $68 million.

Video of compiled images from Mark O’Hara’s Greenbuild Presentation about the Kansas City Plan. The video shows various Green Infrastructure Strategies recommended in the plan. Video compiled by Hawkins Partners Images provided by BNIM (Click here to see it if  video is not present)

In addition to the Marlborough Neighborhood Pilot Project, the plan also recommends the enhancement of the area’s highly acclaimed 10,000 Rain Garden Program. Over the past two years, the initiative is reported to have installed several hundred rain gardens, bioswales, and rain barrels. The purpose of the expansion it to develop an incentive program to accelerate the program’s progress and complement the public investments being made.

Wet retention basin projects have been identified as an appropriate strategy for treating stormwater downstream from six separated sewer system (SSS). The plan acknowledges that green infrastructure is beneficial and should be included where it is practical. The plan states:

“Every decision should be viewed as an opportunity to incorporate a green-solutions approach. The City has adopted an “every drop counts” philosophy, meaning it is important to reduce stormwater entering the system wherever practicable. This will be accomplished through changing the way the community develops and redevelops its sewer and stormwater infrastructure, educating citizens regarding steps they can take to reduce the amount of stormwater entering the sewer system, enabling citizens to take those steps, incorporating green infrastructure in the design of public infrastructure, and making targeted public investments in green infrastructure projects early in the Plan implementation.”

Areas identified that should be considered for green infrastructure projects include those meeting the following criteria:

  • Areas for which no or minimal conventional structural controls are proposed.
  • Areas in which widespread implementation of green solutions by the community at large offer the greatest opportunities for reducing the size and cost of conventional structural controls included in the Plan.
  • Areas for which it would be particularly desirable to further reduce the projected overflow
    activation frequency following completion of recommended controls.
  • Areas in which sewer separation is proposed but where no Water Services Department (WSD) investment in treating the separate stormwater runoff has been included in the Plan.
  • The plan’s ambitious Marlborough Neighborhood Pilot Project is very encouraging, particularly as a stand alone project. It is very significant and the City should be commended for their efforts. However based on the $2.3 billion budget established by the plan, it is evident that green infrastructure will play a supporting role. The plan was developed during the recent significant shift in the way we address stormwater management across the country over the last few years. It is not surprise to see this. What is encouraging is the magnitude of the pilot project and the extensive monitoring that will be conducted.

    The monitoring component will provide valuable data for the City and others across the country. In addition to understanding green infrastructure’s effectiveness to control Combined Sewer Overflows (CSOs) and improving water quality, monitoring it will provide insight into conflicts with local codes and ordinance, social-economic benefits, construction techniques, associated cost, and maintenance practices.

    The plan stresses that it is an evolutionary document, referring to it as an “adaptive management” approach. The approach involves evaluation of the strategy throughout the life of the project based on their experiences and data gathered through the monitoring efforts. While green infrastructure may not be the predominant tool of choice at this point, the longer-term nature of the plan provides the opportunity to adjust its course as confidence increases in green infrastructure. The City’s plan can become more green overtime as it builds upon its successes.

    Fairly or unfairly, like many pilot projects much rests on the success of the Marlborough Neighborhood Pilot Project. Many, both locally and nationally will be watching it with great interest. Failure of such a high profile project could significantly set back the growth of green infrastructure as the stormwater management tool of choice. Therefore, it is critical it is done to the highest standards possible. The project will serve as an example for those involved in stormwater planning and design to have full confidence and understanding of the complexities of utilizing natural systems. Natural processes are complex making them more difficult to quantify. A paper prepared in 2007 by the Center for Neighborhood Technology titled “Managing Urban Stormwater with Green Infrastructure: Case Studies of Five U.S. Local Governments”, identified the lack of performance data as a barrier to green infrastructure implementation. The more research we do and data we collect the better off we will all be.

    I anticipate this will be a successful demonstration of green infrastructure. It is exciting to see another city embrace green infrastructure on such a large scale. We will all eagerly await the results and follow its realization. Construction is expected to start soon.

    -Brian Phelps





    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