By Don Talend

A convention center is one of the most high-profile structures in an urban area. The sheer size of many draws more visitors than perhaps any other building in a given city, with the possible exception of museums and entertainment venues.

From an economic standpoint, they have become increasingly vital as many cities seek new sources of tax revenue. That’s why the stakes are very high when it comes to sustainable construction of a convention center. If the word gets out about a sustainability-enhancing process that does not deliver the intended results, for example, the community and venue can look bad and lose business.

Two sustainable convention center projects that utilize onsite water recycling, among other ‘green’ features, demonstrate how important it is to implement the most effective treatment technologies available to meet and even surpass such a high-profile project’s stated goals. Safeguarding and enriching the reputations of the construction team members—not to mention the building owners and local officials—depend on using the best available technology and know-how. So does advancing the practice of wastewater treatment and reuse.

A key element of LEED certification
A blackwater recycling system is a key sustainable feature of the Vancouver Convention Centre Expansion Project, which is being undertaken to address both a critical shortage of convention space in the city and serve as the international broadcast and media center during the 2010 Olympic and Paralympic Winter Games. In fact, the system is expected to earn four points under the United States Green Building Council’s Leadership in Energy and Environmental Design (LEED) rating system for new construction and major renovations.

This could be the difference between the new center achieving a LEED Gold rating versus a lesser LEED Silver rating. The LEED rating system involves a comprehensive process of auditing the material, design and construction processes used in building a facility, with the Gold rating a determined target.

The expansion project involves a completely new building that will be constructed adjacent to the existing Vancouver Convention and Exhibition Centre, which opened in 1987. That building was actually at capacity within 10 years and it was estimated that Vancouver lost about $100 million (USD) in revenue for 2003 because the city, despite its standing as one of the top convention destinations in North America, could not accommodate many leading trade shows that required more meeting space than the existing facility offers.

To address the situation, a Convention Centre Task Force, made up of members of the business community, was formed. The task force was charged with making a case to the Province of British Columbia for public financing of the expansion project. According to the approved expansion plan, convention floor space would be tripled with the addition of 1.1 million square feet.

The expansion is expected to generate an additional $107 million (USD) in convention business annually as the number of ‘delegate days’ is projected to increase from 150,000 to nearly 370,000 within the first five years of opening the new facility. Another positive economic impact for the city is the anticipated addition of 7,000 new jobs as a direct or indirect result of the expansion.

Due to these projected increases in revenue, plans were approved to finance the project, with the Province financing $623.1 million (CDN), Tourism Vancouver providing $90 million USD) and commercial revenues (define current venues) from the site itself accounting for $30 million (USD) of the project funding. The Vancouver Convention Centre Expansion Project Ltd., a company wholly owned by the Province, was formed to build the new facility, which was scheduled for completion in 2008.

The completed building is expected to be a model of both sustainable design and architecture. Part of the floor will consist of a marine deck sitting on more than 1,000 piles and protruding out onto Coal Harbor on the Vancouver waterfront.

Sustainability strategies
Two sustainability strategies used in construction of the new facility relate to water stewardship: blackwater recycling and a living roof. Water treatment and reuse were priorities from the start, according to the mechanical engineering consultant on the project. So was water conservation in general.

“We tested out things like dual-flush toilets and other types of lower water-consuming fixtures,” according to engineering principal Blair McCarry. “After testing them, the project oversight company said, ‘They’re OK, but we’d like to stick with the solid, low-flush, flush-valve kinds of fixtures that we have now because they work very well for us.’”

Another major decision had to be made regarding the blackwater recycling system that would be used. Systems were investigated that required sunlight for their processing and subsequent deployment on the roof.

One patented technology utilized mechanical, chemical and computer systems to mimic processes found in wetland environments. Similarly, another used a series of tanks equipped with the company’s own mini-ecosystems that purify the water.

But cost considerations prodded the engineering consultant to recommend a membrane-type filtration system. The recommendation of an internal membrane treatment system for the new building located in a seismic zone was more cost-conscious than utilizing seismically designed structures to support alternative systems on the rooftop.

Alternatives and options
“A number of alternatives and proposals on different technologies and different techniques were reviewed,” says McCarry. “Optional rooftop technologies that need access to sunlight to successfully employ their mechanisms would have been too cost-prohibitive.

”We would have spent too much money on structures to hold up that water. We eventually looked at building the system down in the base structure and sought a turnkey solution.”

Previous experience with the selected membrane filtration system gave the contractor an invaluable level of confidence for such a high-profile project. “The last thing you want is to have something fall flat on its face, particularly in a green building process,” says McCarry. “In addition to personal embarrassment, it would set back the overall movement somewhat significantly.

“There’s no room for taking a risk. A system needs to be designed with a high level of assurance that it can be commissioned, monitored and verified.”

“There are always challenges, issues and problems, but you want to start with a high probability of success and work from there rather than hope and trust,” McCarry continues.

“This is not experimentation. You want to be better than the regulation levels. If you’re at the regulation levels, you’ve already got a problem that needs fixing.

System operation
The system first separates large solids from the effluent in a primary-treatment compartment. Next, the effluent flows into a bioreactor (MBR) with ultrafiltration membranes that purify the wastewater with bacteria. The membranes are hollow, string-like fibers with billions of microscopic pores that trap material such as suspended solids, pathogens and some viruses.

Membrane modules are combined into cassettes, which can be added to expand system capacity along with wastewater volume. Separate chambers within the bioreactor grow different types of bacteria to purify the blackwater. An aerated, aerobic chamber incorporates oxygen and an anoxic chamber grows bacteria without an air addition.

A coagulant addition groups the materials and bacteria within the tanks break them down. The effluent is further treated by activated carbon, ultraviolet (UV) light and ozone to kill remaining pathogens and remove color and odor. The final UV and ozone treatments are critical in regard to how restroom visitors perceive water clarity.

During the winter, the treated water will be used primarily for toilet and urinal flushing. During the summer, more will be consumed by the other major water stewardship feature of the new building: the living roof.

Living roof
The living roof goes a step beyond green roofs constructed on buildings in many environmentally conscious areas. Besides utilizing plants to absorb stormwater runoff and mitigate the urban heat-island effect, it uses a holistic approach to achieving biodiversity via the active addition of elements such as insects and micro organisms.

A major factor in construction of the living roof is giving the new facility’s roof an attractive appearance from the surrounding tall buildings composing the Vancouver skyline, but it will also fit the overall water stewardship strategy of the expansion project. During the summer, some of the water treated in the blackwater recycling system will be pumped to the 290,000-square-foot living roof and used for irrigation.

The rooftop subsurface-drip-irrigation system will be activated in various zones by moisture meters, according to the evapotranspiration rate in each zone. Particularly during the winter there will be times when the water filtration system will produce a surplus and the new facility has received clearance to discharge treated effluent directly into Coal Harbor.

“We are using treated blackwater for flushing toilets and urinals throughout the year,” says McCarry. “The majority of treated blackwater is used for the roof during the summer, with the toilets and urinals receiving a higher share in the winter.

“The new facility will be thrust into the public eye early in its service life when it serves as the world media headquarters during the Winter Olympics. That’s another reason why recycled water purity cannot be left to chance.

“Of the facilities, this could be one of the better ones,” says McCarry. “This building will hold its head high in terms of its Olympic activities.”

Ultra-pure water addresses perceptions
Similar to the Vancouver convention center project, what turned out to be the world’s first-ever LEED-certified convention center, the $385 million (USD) 1.5 million-square-foot David L. Lawrence Convention Center in Pittsburgh, PA owes some of its LEED 2.0-2.1 Gold certification to the same type of membrane water filtration system. This building was arguably in the public eye to an even greater extent than is the Vancouver project.

An atmosphere of local environmental activism was pervasive when the center was in its planning stages, which had a lot to do with the fact that the Pittsburgh Sports & Exhibition Authority and the building team sought a LEED certification. Pittsburgh has a combined sewer overflow system constructed prior to the Clean Water Act that occasionally dispenses a mixture of stormwater and raw sewage directly into the city’s famous rivers following a major rain event.

“It was really a group called the Green Building Alliance that had a lot of influence in the overall design of the convention center from way back in the design competition,” says Dave Linamen, principal with the electrical/mechanical engineering firm on the project. “Emphasis was placed on sustainable design and the competition submission took that pretty far—we promised implementation of graywater recycling.”

LEED credits
As it turned out, funding for the center’s sustainability features from a major ‘green’ benefactor was largely contingent on water treatment and reuse in the facility. “The Green Building Alliance was able to influence the benefactor into giving a grant; the grant had to be paid back out of savings incurred from the sustainable and energy-efficiency strategies,” says Linamen.

“The foundation was so anxious to do this as a demonstration project that they insisted the graywater recycling system be implemented in order to get the grant. And the graywater recycling system made all the difference in the center’s awarding of LEED Gold certification.”

“That was what really tipped the scale,” says Linamen. “The project got five LEED points for saving a substantial amount of water, plus innovation credits, so it helped get a Gold rating.

“From the very beginning, the Green Building Alliance’s number-one goal was to get a Gold rating. At the end of the day, all of the possible points were needed, as the project just barely made it.”

Project operation
The Lawrence Center’s system works basically the same as the one to be installed in the Vancouver facility, except that it uses activated carbon for the final treatment process instead of ozone. “Being a public building, absolutely colorless and odorless water was needed,” says Linamen.

“Dyes can be put in the water to color correct it or make it more palatable for people. As a public facility, it was determined that this wasn’t going to be acceptable to people. The dyes, over time, stain some of the fixtures and colorless and odorless water options were selected.”

“During investigation and research of a number of system manufacturers, it was determined that a membrane was needed,” Linamen continues, “A biodigestion and membrane filtration system was desired with a final treatment process. Original specifications called for activated carbon filtration to ensure water quality as part of a multiple process.

”The multiple process system design produces ultrapure recycled water. From the ultrafiltration unit, it goes next to a UV system, where any residual is killed and then carbon filtration through a series of carbon drums.”

“The only thing that hasn’t been effectively treated at that point is viruses; bacteria are normally larger than a micron and they don’t make it through the submicron filter,” adds Linamen ”Once we got the system operating and got everything balanced as far as the biodigestion, it was a relatively foolproof system with quality effluent. You have to lubricate fans and pumps a little bit and check belts once in a while, but you only change the carbon drum once a month.”

“The carbon filtration system is a downstream process to take all of the color out,” according to Herschell Winfrey with an environmental engineering firm associated with the project. “The membranes take the impurities out, but it leaves a slight, what I’d call a ginger ale, color. That’s what the activated carbon is for.”

Future growth
As it turns out, the water treatment and recycling system is sized to accommodate higher utilization than the overall facility complex has seen since it first opened in September 2003. Several large hotels were to be built next to the new center, but they have not yet been constructed due to financing issues.

“It’s kind of a chicken-and-the-egg deal,” says Winfrey. “You should have more hotels built now that you have a good convention center, but the hotels don’t want to make the investment until they see that you haven’t lost conventions.”

The graywater recycling system was projected to reuse 50 percent of the center’s water and reduce potable water use by 75 percent. Linamen points out that the system can save even more potable water and eliminate the need for even more wastewater to enter the city’s combined sewer overflow system in the future.

“”The system is only saving about a million gallons annually compared with a total capability of saving 6.4 million gallons of potable water every year,” adds Linamen. “If they build hotels and gain national-level shows, the system has the potential to do that. It just has to be utilized; —they’ve got to get people into the convention center.”

A final water purity inspection process leaves nothing to chance. “For liability purposes, the operators continuously test the water for purity,” Linamen says. “They actually have a certified person come in and draw samples at regular intervals every week.

“They keep records of water purity quality to demonstrate to anybody who comes into the center that they’ve got quality water. No one is being put at risk. This is the best system for this application.

About the author
Don Talend of Write Results (www.write-results-p3.com) in West Dundee, IL is a publicity and communications project manager specializing in technology and innovation. He can be reached via phone at (847) 836-7010 or by e-mailing write-[email protected].

About the companies
Stantec Consulting was the mechanical engineering consultant on the Vancouver Convention and Exhibition Centre. Living Machine and the Solar Aquatics Systems were recommended for the graywater facility, as was the GE ZeeWeed internal membrane treatment system.

Burt Hill Kosar Rittelmann Associates in Butler, PA was the electrical/mechanical engineer on the David L. Lawrence Convention Center in Pittsburgh project. The Heinz Endowments foundation was a principal benefactor and the Land Development Division at Zenon Environmental Inc. the environmental engineer.

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