Rainwater Harvesting Commercial

26 02 2010

I know this video has been out a while (since 2007). I recently ran across it again on Youtube and thought it would be worth sharing. The video is a 90-second public service commercial that promotes urban rainwater harvesting in India. It was created for/or by  The Centre for Science and Environment (CSE), a public interest research and advocacy organisation based in New Delhi. It is a simple but powerful message. Enjoy.

-Brian Phelps





Water and the Southeast False Creek Olympic Village

22 02 2010

Cover of Water + Building Landscape (Chapter 6)
from The Challenge Series Website

Staying with the Olympic theme from last week’s post on the Vancouver Convention Centre, the Southeast False Creek Olympic Village is another spectacular example of sustainable building in Vancouver. The Olympic Village will house the athletes throughout the games. Afterward, it will become the home of over 16,000 residents. The following is a link to the diversity of uses that will be or are already included in the development.

A website called “The Challenge Series” has been set up to help educate the public about the Olympic Village’s sustainable features. A well-designed booklet describing the sustainable features of the development is available on the site in pdf format. One that particularly caught my attention was the Water + Building Landscape section (See Cover Above). It explains many sustainable water strategies employed throughout. Some highlights include:

  • The design team recognized the size was not large enough to handle all of the stormwater in the constructed wetland incorporated into Hinge Park. As a result, the team prioritized the water into a two-tier system. The first tier was considered the “cleaner” water that came from the rooftops and podium sections of the building. This water was directed to the cisterns in the basements of each building. The water was then used to flush toilets, supply water features, or irrigate the landscape. Additional water overflowed the cisterns and entered the South False Creek. The second tier included “dirtier” water. This water came from the roadways and other areas. The water from these areas was directed into the constructed wetland or underground gravel/sand infiltration cells.
  • The development reduced potable water use by 40 percent.
  • The site plan incorporates a number of water features that utilize the water collected on the site. The circulation through the water features provides a means of making what would otherwise be invisible visible, while at the same time improving the quality of the water.
  • 287,000 s.f. of green roof covers the development. The roofs include both extensive and intensive green roofs. This was in part because the City of Vancouver mandated that 50% of the roofs be green roofs.
  • The City also mandated the inclusion of urban agriculture at a rate of 24sf for 30% of the units whose balconies were less than 100sf.

The development has received LEED-ND Platinum certification. I look forward to seeing it one day when I return to Vancouver. There have been a number of articles on the development, but I highly recommend reading the information found on The Challenge Series website.

-Brian Phelps





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.





Interview with Dr. Allen P. Davis, P.E. Part 2 of 2

15 02 2010

Bioretention at Mercury View Lofts Parking. Nashville, TN
Source: Hawkins Partners, Inc. ©2010

The following is the second part of my email interview with Dr. Allen P. Davis, P.E. the Director of the Maryland Water Resource Research Center at the University of Maryland. Dr. Davis is a leading researcher on bioretention and has published numerous studies quantifying the benefits of its use in urbanized watersheds and low impact development (LID) concepts. In 1993, he received the National Science Foundation Young Investigator Award.

Green Infrastructure Digest: One of the many benefits of bioretention is that it addresses quality of the run-off. How effective are bioretention areas at removing common pollutants (i.e. suspended solids, metals, pathogens, thermal heat gain) and to what extent?

Dr. Allen P. Davis: Bioretention, as with most stormwater practices, addresses water quality through both volume management and pollutant treatment. So first, it is important to reduce runoff volume, which will have an overall beneficial impact on all respective pollutant loads. On the treatment side, we have significant data showing excellent removal of suspended solids and metals. Solids are effectively filtered by the bioretention media. Metals are captured with solids, as some are particulate bound. Also, bioretention media has a significant capacity for metals adsorption. Hydrocarbons are adsorbed and we have data indicating that they are readily biodegraded. Research by us and others have shown some removal of pathogens, although pathogen concentrations in runoff vary by many orders of magnitude throughout the year, making quantification difficult. Dr. Bill Hunt at North Carolina State has shown some thermal mitigation through bioretention media.

As mentioned above, removal of nitrogen and phosphorus is found, but this is highly variable from site to site and is media dependent. Very low concentrations of phosphorus are targeted for water quality protection. The performance of bioretention for phosphorus will depend on the source and characteristics of the soil used for the bioretention media. Some soils will have relatively high native concentrations of phosphorus. These media will perform poorly and may even export the excess nutrient.

Bioretention is probably least effective for nitrate and chloride, both anions. Some nitrate may be taken up by a thick stand of vegetation. In snowy areas, chlorides, as deicing agents, may be applied to roadways and parking lots at very high levels. Chlorides are minimally held by bioretention media and will pass through, though not immediately, to surface and ground waters.

GrID: When designing bioretention facilities, what factors have the most impact on their success (i.e. soils, soil depths, slope, plant material, infiltration rates)? Why?

Dr. Davis: First, the answer to this question depends on how you define success. We are trying to come up with a good set of performance metrics to define success. Is it to replicate the hydrology, water quality, and habitat of a pre-existing forested area? If so, the bar is set very (unrealistically?) high. I don’t think we’ll be able to completely replicate the forested watershed. Hydrologically, we can attempt to manage volumes and flow rates, and couple these with groundwater and baseflow recharge. We can exploit various physical, chemical, and biological processes for water quality improvement.

That said, what we are finding is that design and site factors have different impacts on different performance metrics. For volume and flow management, bigger is better (deeper media, greater surface area), and greater infiltrating surrounding soils will always help. Capture of metals, suspended solids, and some toxic organics varies little with design parameters. They are readily filtered and adsorbed on the surface of the media. Nutrients have very complex fate pathways. We haven’t gotten a full handle on these pollutants and it appears that most of your listed design and site parameters will affect their removal.

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

Dr. Davis: We’re still working against a lot of inertia. As we continue to install, understand, and learn, green infrastructure will become more prevalent. We continue to need more demonstrations, more performance data. Each implementation will make the next one easier. Regulations and codes need to be updated to allow the inclusion of novel technologies, where we have the science to back it up. As alluded to above, we must understand the fundamentals of how these various green technologies perform. They are not “black boxes” that we can stick a performance number on. Each is a complex combination of an engineered and natural system. We will continue to take advantage of their capabilities, but also look for design and operational modifications to improve performances. We should be able to tailor specific designs and design characteristics to the specific needs of a watershed.

Part 1

-Brian Phelps





Interview with Dr. Allen P. Davis, P.E. Part 1 of 2

12 02 2010

Bioretention Diagram
Source: Hawkins Partners, Inc. ©2010

The following is an email interview with Dr. Allen P. Davis, P.E. the Director of the Maryland Water Resource Research Center at the University of Maryland. Dr. Davis is a leading researcher on bioretention and has published numerous studies quantifying the benefits of its use in urbanized watersheds and low impact development (LID) concepts. In 1993, he received the National Science Foundation Young Investigator Award.

Green Infrastructure Digest (GrID): Over the last 20 years, you and your department have been instrumental in building the current body of knowledge regarding the design and effectiveness of bioretention systems to address stormwater run-off in urban areas. In regard to your current stormwater research, what issues are you and your department studying? Beyond your current projects, what are the issues that you think need to be studied in the coming years?

Dr. Allen P. Davis: While we find bioretention to be effective in the management of urban runoff, we still have many unanswered questions and opportunities for improvement. First, we need to be able to quantify performance results. Bioretention systems are all not the same, we should not expect each of them to perform identically, and our (and others) research show that they don’t. Bioretention performance will depend upon the characteristics of the contributing watershed and surrounding soils/hydrogeology, surface area, media depth, placement of underdrains, media characteristics, flow patterns, vegetation, and other factors. As we better understand the fundamentals of bioretention, we can better predict the effects of these parameters, leading to better designs and more effective watershed management.

Additionally, we are interested in improving the performance of bioretention in removing nitrogen and phosphorus compounds. These nutrients are the pollutants of primary concern for many water bodies, certainly for us in the Chesapeake Bay watershed. Bioretention performance for these nutrients is marginal and modifications to standard designs are being investigated to improve N and P removal.

The list for research topics is very long: what are the fates of captured pollutants? what is the role of biological processes (hydrocarbon degradation, plant uptake, nitrification/denitrification)? what are the best vegetation and vegetation management practices?

GriD: Over the past few years, green stormwater infrastructure has increasingly been employed within various Cities’ stormwater overflow control plans. As you know, bioretention is one of the dominant tools within the green infrastructure toolbox. Are bioretention facilities an effective tool for reducing stormwater run-off particularly in CSO events within our urbanized areas? If so, what impact has your research or others been able to demonstrate? If not, why?

Dr. Davis: Bioretention clearly can play a role in stormwater volume reduction. The larger the bioretention facility, the greater the reduction. CSOs present a greater challenge than suburban bioretention because of the lack of available land in cities. Some creative thinking can help to improve infiltration and storage in highly urbanized areas, but this is a major challenge. Some cities are looking to expand green space, even through opening up vacant lots for stormwater management. This can be helpful, but must be done on a large scale to show meaningful results.

Part 2-Monday

-Brian Phelps





Pervious Concrete and Solar Reflectance

10 02 2010

Pervious Concrete A=20% Fly Ash Mix B=50% Slag Mix
Center of the photo is the stalite base of the concrete

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





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