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Holding the Line on Waterworld in Southeast Louisiana An Integrated Water Management Strategy by Colleen Morgan
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orward-thinking designers across the city working on an Integrated Water Management Strategy are now moving into the project’s second phase. They are meeting with community leaders to solicit public input about how to make the urban landscape more resilient. The study, funded by Greater New Orleans, Inc. and led by Waggoner and Ball Architects, is to investigate the study area’s drainage system and develop innovative solutions for managing excess water during heavy rainstorms. Since 80 percent of the city is below sea level, the stormwater system pumps water out to Lake Pontchartrain through a complicated system of pipes and canals. During serious rains, which occur regularly in this region, the system can be overwhelmed by the large amounts of water that need to be pumped, leading to street flooding and related problems. The first phase of the 18-month study was to collect data about the drainage systems of the East Bank of Jefferson and Orleans and all of St. Bernard Parish. This phase, which began in September 2011, focused on developing an inventory of the existing infrastructure, understanding how water flows, and identifying the most substantial problems within the system, according to Aron Chang of Waggonner and Ball. One of the biggest problems, and of most concern to residents, Chang said, is flooding. The current system has a finite capacity – it can only pump stormwater at a certain rate, and if it rains harder and faster New Orleans
than that rate, then there will be localized flooding. In addition to pumping capacity, there are old drainage pipes that are too small, the water funnels into the low-lying areas, or catch basins are poorly maintained, all problems that exacerbate the flooding, Chang explained. The other, related situation is subsidence: pumping out the stormwater causes the ground to sink further, which requires greater pumping capacity. “For example, Jefferson Parish’s Department of Drainage has had to install small pumps along certain canals to bring water from adjoining neighborhoods into the pile-supported canals, which can be higher than the surrounding areas,” Chang said. “The cycles of drawing down water in canals in advance of storms only worsens the problem as that also draws the water table in adjoining areas down and accelerates subsidence.” Many neighborhoods in the study area are between five and 10 feet below sea level and every time rainwater is pumped out the soils oxidize, which causes them to sink. “Originally this place was filled with swamps and bayous and to live here we had to draw down the water level,” Chang said. Because the study area is on a river delta, the ground also naturally subsides under its own weight, and there are geologic faults that make it worse in some places. A pre-Katrina study showed that New Orleans East and Kenner subside at a rate of one inch per year. “Gentilly, Lakeview and Kenner are 5-8 feet below sea level after 40-50 years
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City Park oaks & open water with diagram of underground storm drainage network of development,” Chang said. That equates to about 1.7 inches per year, or 8.5 inches every five years. The operators of the drainage systems for Jefferson, Orleans, and St. Bernard have been successful in draining the water from the landscape as quickly as possible, fulfilling their mandate to decrease flood insurance claims, Chang said. However, as the agency drains the study area better, the faster the ground sinks – and harder it is to pump. In addition, subsidence negatively impacts infrastructure, including pipes, streets and building foundations. “In some cases, fixing one problem exacerbates another,” Chang said. This study is designed to look at the big picture for future planning: “Our job is to think holistically, about flooding and subsidence. … The operators are just trying to keep up – they don’t have the resources and time to step back and look at all the pieces and across parish lines.” Designers from the Netherlands are key
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August 2012
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Network of pipes, canals and massive pump stations to move stormwater to Lake Pontchartrain and Central Wetlands Unit. members of the team because of the abundant experience the Dutch have had in managing water. In Amsterdam, which is also built in a delta and is below sea level, there are water monitoring wells all over the city, and the water can be set at the same level. “They know where their water is,” Chang said. He also noted that The Netherlands is ahead of New Orleans in its water management system and that the mistakes that the Dutch have made and the successes that the Dutch have had will be lessons for the U.S. The next phase of the study is for formal outreach, even though the firm’s partners have been giving talks on the subject of “Living with Water” since they engaged with the Dutch just after Katrina. The lead team started meeting with community leaders in July to begin to build awareness, educate, and create advocates for the project. The team is particularly interested in gleaning information about residents’ interest and feelings about the role of water in their lives, and the potential for incorporating more New Orleans
The Westersingel in Rotterdam open water into the urban landscape. “Even though people say they fear open water and mosquitoes, our favorite public spaces are built around water,” Chang said, citing Audubon Park and Bayou St. John as examples. “Water is a part of the city’s history, but we’ve been so successful at removing the water that it is hidden,” he said. “There are people who come here and not ever see any water, or they have to climb over a wall to see it.” Surface water features and landscaping that absorbs water are much less expensive than installing larger pipes, Chang noted.
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These strategies and others like them help “drag out” the time that the pumps have to drain water out of the study area. Once initial input has been gathered from community leaders, the design teams will incorporate those comments into prototypical solutions at different scales, from system wide to neighborhood scale to individual properties. Solutions will be tested in areas where they have the potential to have the highest impact on safety and quality of life. With feedback from the stakeholders in those neighborhoods in small design workshops, the final report will catalog various locations where the proposed solutions can be further tested and replicated. “Where can we do this [or that project] in New Orleans, physically and culturally,” Chang said. “There is a lot of innate fear and discomfort with water – there are safety issues – and water infrastructure can mirror class distinctions. These are the issues we want to talk to community leaders about.” Presentations are scheduled for December or January, with the purpose of explaining the project and potential solutions to the general public, with the support of community leaders that the Water Management Strategy team is reaching out to now. This approach for incorporating community members in the design not only informs it, so that potential concerns are addressed early in the design, it involves community members in the process so they become advocates for the plan, and gives it a much better chance at achieving funding down the road. Photos and diagram courtesy of Waggoner & Ball. Aron Chang may be reached at aron@wbarchitects.com Colleen Morgan is a free-lance writer and environmental editor for Natural Awakenings. She may be reached at colleen.nolahealthyliving@yahoo.com.
natural awakenings
August 2012