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Membrane filtration systems play a major role in environmental certification and public relations at convention centers in Vancouver and Pittsburgh.
By Don Talend
Few structures in an urban area are as high profile as a convention center. To businesspeople that come from every corner of the nation—and in some cases, the globe—these facilities must represent their cities. Unlike many commercial office buildings, large portions of convention centers are public spaces that much of the local population will enter at some point. 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 ill-conceived design, a sustainability-enhancing process that does not deliver the intended results, or cost overruns, a large number of individuals can look bad.
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Photo: by VCCEP |
The Vancouver Convention Center Expansion Project is on track for a Leadership in Energy and Environmental Design Gold
rating, largely due to a blackwater recycling system that will use a membrane ultrafiltration system. |
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 even city officials—depend on using the best available technology and know-how. So does advancing the practice of wastewater treatment and reuse.
A Rating Difference-Maker
A blackwater recycling system is a key sustainable feature of the Vancouver Convention Centre Expansion Project, which is being undertaken to both address 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—which could be the difference between the new center achieving a LEED Gold rating versus a LEED Silver rating.
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. The existing building was actually at capacity within 10 years and it was estimated that Vancouver lost about $100 million in revenue in 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 for 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 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 of British Columbia financing $623.1 million Canadian, Tourism Vancouver providing $90 million, and commercial revenues from the site itself accounting for $30 million of the project funding. The Vancouver Convention Centre Expansion Project Ltd., a company wholly owned by the Province of British Columbia, was formed to build the new facility, which is scheduled for completion in 2008. The completed building is expected to be a model of both sustainable design and architecture, as 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.
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, says Blair McCarry, principal with Stantec Consulting, 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 and the [project oversight company], after testing them, 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. Stantec investigated systems that required sunlight for their processing and thus deployment on the roof, such as the Living Machine and the Solar Aquatics System. The Living Machine uses patented technology that utilizes mechanical, chemical, and computer systems to mimic processes found in wetland environments. Similarly, the Solar Aquatics System uses a series of tanks equipped with their own mini-ecosystems that purify the water. But, says McCarry, cost considerations prodded Stantec to recommend a membrane-type filtration system.
McCarry attributes the recommendation of the GE ZeeWeed internal membrane treatment system to the fact that the new building is located in a seismic zone and building seismically designed structures to support the alternative systems on the rooftop would have been cost-prohibitive. “We did look at lots of alternatives and got proposals on different technologies and different techniques,” he says. “Some wanted to go up on the roof and they all wanted to have access to sunlight because of their mechanisms, and we [would have] wound up spending too much money on structures to hold up that water. We ended up looking at building it down in the base structure and we wanted a package, a turnkey solution.”
Just as importantly, McCarry adds, he had previous experience with the membrane filtration system; that experience gave Stantec an invaluable level of confidence for such a high-profile project.
“We’re doing a lot with green building and the last thing you want is to have something fall flat on its face,” he says. “Outside of personal embarrassment, it would set back the overall movement somewhat significantly. I’m very conscious of that and we want to protect ourselves, our clients, and the public from any potential danger. There’s no room for taking a risk on this stuff; I mean, you’ve got to sleep at night. This has got to be as solid as you can make it. You want to come in with a system that can get commissioned and monitored and verified with a really high level of assurance that things are going to work out well.
“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 got a problem—you’d better be already fixing it.”
The system first separates large solids from the effluent in a primary-treatment compartment. Next, the effluent flows into a bioreactor, where ultrafiltration membranes 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 to be filtered out, and these materials are trapped on the membranes, where bacteria trapped within the membranes break them down. Finally, the effluent is further treated by charcoal, ultraviolet (UV) light, and ozone to kill any 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 in the restrooms. During the summer, more will be consumed by the other major water stewardship feature of the new building: the living roof.
The living roof goes a step beyond green roofs constructed on buildings in many environmentally conscious areas in that, 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 microorganisms. 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 roof and used to irrigate the living roof. McCarry points out that 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, he says, there will be times when the water filtration system will produce a surplus, and the new facility has received clearance to discharge the treated effluent directly into Coal Harbor.
“We are using the treated blackwater for flushing the toilets and urinals throughout the year,” says McCarry. “The bias in water consumption goes to the living roof in the drier summer, and in the other seasons, it shifts over to flushing toilets.”
The new facility will be thrust into the public eye early on in its service life when it serves as the world media headquarters during the Winter Olympics, McCarry notes. That’s another reason why the recycled water purity cannot be left to chance. “Of the facilities, this could be one of the better ones,” he says. “This building will hold its head high in terms of its Olympic activities.”
Leaving Nothing to Chance
Similarly to the Vancouver convention center project, what turned out to be the world’s first-ever LEED-certified convention center, the $385 million, 1.5 million-square-foot David L. Lawrence Convention Center in Pittsburgh 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 the Vancouver project is.
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Photo: by VCCEP |
| Recycled water will be used in the restrooms throughout the year, as well as to
irrigate a living roof on the facility during the dry summer months. |
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Dave Linamen, principal with Butler, PA–based Burt Hill Kosar Rittelmann Associates, the electrical/mechanical engineer on the project, recalls that 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 thePittsburgh Sports & Exhibition Authority and the building team sought a LEED certification. Like many of the nation’s northern industrial cities, 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 Linamen. “They had put emphasis on sustainable design, and I think our team was selected because we promised to give them that. In our submission into the competition, we took that pretty far—we promised them that we would implement graywater recycling.”
As it turned out, Linamen says, funding for the center’s sustainability features from major “green” benefactor The Heinz Endowments was largely contingent on water treatment and reuse in the facility. “The Green Building Alliance was able to influence the Heinz foundation into giving a grant; the grant had to be paid back out of savings incurred from the sustainable and energy-efficiency strategies,” he says. “The Heinz foundation was so anxious to do this as a demonstration project that they insisted that the graywater recycling system be implemented in order to get the grant.” Linamen adds that the graywater recycling system made all the difference in the center’s awarding of LEED Gold certification. “That was what really tipped the scale,” he says. “I think we got five LEED points for saving a substantial amount of water; plus we got innovation credits, so it helped us to 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, we needed all of those points—we just barely made it.”
The Lawrence Center’s system works basically the same as the one to be installed in the Vancouver facility, except that it uses charcoal for the final treatment process instead of ozone. “Being a public building, we felt that we needed absolutely colorless and odorless water,” says Linamen. “You can put dyes and things in the water to help if it’s off color to help correct that or make it more palatable for people, but I was afraid that, being a public facility, that wasn’t going to be acceptable to people. The dyes, over time, stain some of the fixtures. We made a decision, based on our judgment, that we needed completely colorless and odorless water.
“As we looked around and talked to a number of system manufacturers when we did our own research and went to facilities that had working systems and talked to people who occupied the facilities, we came to the conclusion that we needed a membrane,” Linamen continues, “a biodigestion and membrane filtration system and then some kind of final treatment; our original specification was charcoal. We felt that that was the requirement to get the kind of water quality that we needed. We talked to some people; some could get good-quality water with a little bit of dye, which may have been acceptable for 95% or 97% of the people who use the facility, but every little thing that happens over there gets so much attention. We figured that if anyone started questioning the quality of the water, it could be very damaging, so we just made the decision that it had to be colorless and odorless and to have confidence that it was OK to use the fixtures.”
Linamen explains how the multiple processes in the system produce ultra-pure recycled water. “The submicron filtration—I think it’s three-tenths of a micron—from there it goes to the UV, and if there’s any residual at all, the UV will kill that, and finally to the carbon filtration, which is a series of carbon drums. The only thing at that point that it hasn’t been treated for is viruses; bacteria are normally larger than a micron—they’re normally 5 to 6 microns, so they don’t make it through a submicron filter. We could have found a less-expensive system, but just the quality of the effluent and everything about it—once we got the system operating and got everything balanced as far as the biodigestion—it’s a relatively foolproof system. You have to go through it and lubricate fans and pumps a little bit and check belts once in a while, but you change the carbon drum once a month.”
“That’s an add-on, a downstream process to take all of the color out,” Herschell Winfrey, general manager of the Land Development Division at Zenon Environmental Inc. says of the carbon filtration system. “The membranes take the impurities out, but it leaves a slight, what I’d call ginger ale color. That’s what the charcoal is for.”
As it turns out, the water treatment and recycling system is sized to accommodate higher utilization than the facility has seen since it first opened in September 2003. Several large hotels were to be built next to the new center in addition to a Westin Hotel that is connected to it by a skywalk, but they have not yet been constructed due to financing issues. “It’s kind of a chicken-and-the-egg deal there,” 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, I guess.”
While the graywater recycling system was projected to reuse 50% of the center’s water and reduce potable water use by 75%, 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. “I don’t think we’re saving as much water as we thought; we’re probably 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. “It has the potential, if they build the hotels and get the national-level shows, to do that. It’s just got to get the utilization—they’ve got to get the people into the convention center.”
A final water purity inspection process leaves nothing to chance. “For liability purposes, they continuously test the water,” Linamen says. “They actually have a certified person come in and draw samples at regular intervals every week, and then they keep records of water quality just to demonstrate to anybody who comes into the center that they’ve got the quality water; we’re not putting anybody at risk.”
Linamen’s planning has not put the reputations of Pittsburgh or his firm at much risk, either. “I’m still convinced that this is the best system for this application,” he says. “I think for a public building and demonstration project, this was the best system.”
Don Talend of Write Results, West Dundee, IL, is a communications and publicity consultant with more than 15 years of experience in print media.
OW - September/October 2007 |
