PROF. JOHN KLINGMAN | FALL 2017
TULANE UNIVERSITY, SCHOOL OF ARCHITECTURE
Infrastructure, Water and Architecture, New Orleans An Extension of the Greater New Orleans Urban Water Plan Congo Square and Louis Armstrong Place
Urban Design/ Water Issues In the early twentieth century an emphasis on urban infrastructure projects was a dominant force in the United States. New Orleans undertook centralized city water supply, sanitary sewer system and storm drainage along with electrical, gas, communications and transportation systems. A century later Hurricane Katrina severely damaged these systems, and their piecemeal repair has proceeded; but a new paradigm has not been established. Under the auspices first of the Dutch Dialogues engagement and later through the Greater New Orleans Urban Water Plan led by Waggonner and Ball Architects, it is possible to project necessary and important new ideas for water infrastructure in the twenty-first century. In the Vision Report and the Urban Design volumes of the Urban Water Plan (see www.livingwithwater.com), principles are established that can be extended and tested through design case studies. In relating these principles to the morphology of New Orleans, substantial modification of the existing stormwater drainage system is proposed. The current system can be overwhelmed by the increasingly extensive volume of runoff, and the sentiment among officials and the public is that major changes are necessary. Within the Greater New Orleans Water Plan and in the neighborhood scale study of Dutch Dialogues II, principles emerged that can now be extended and tested through design. The principles begin with finding places to store rainwater instead of forcing the water into a system that requires immediate pumping. Related to this is the need to reestablish a high level of groundwater to prevent subsidence, partially through a new network of “wet,” constantly flowing canals, as opposed to the “dry” drainage canals that now exist.
Hydrology Currently, New Orleans drainage canals act as water channels primarily during rainstorms. The Urban Water Plan proposal is to maintain them “wet” as water management entities and urban amenities at all times. The hydrostatic pressure from the Mississippi River allows for a spring of freshwater to be generated near the river. These springs can provide a source of available water that flows by gravity towards the lake. Water from the canal acts as a groundwater recharge source during dry weather. During rainy weather, it becomes a component of the water retention/storm drainage system. In months of low water, river water can be pumped into the canal as necessary. Thus, an ability to accommodate differing flows is an important characteristic of the canal design. The water network will be designed as a recreational amenity for walking, biking, running, etc. Planting will improve local microclimate. Streets will bridge the water network. At these locations a cascade, perhaps with a movable weir can be considered, or a siphon under the street is possible. In dry weather the system may carry moving water only a few inches deep. In rainy weather the storm water retention/discharge system will expand its capacity to hold as much rainwater as possible or as long as possible. Stormwater holding and storage areas include floodable green spaces, lagoons and holding ponds that will lessen flooding in periods of heavy rainfall. The initial flow of water is contaminated with urban detritus, so filtering and bioremediation strategies are necessary. New buildings in the neighborhood can hold rainwater for graywater, fire protection and irrigation use. This decentralized water system utilizing rainwater would be particularly useful during long dry periods or in emergencies when water pressure is low. In the areas of the city near the Mississippi River, all of the surface runoff flows away from the river because of the natural levee. Thus, in the area of Congo Square, surface water flows from the many impervious surfaces of the Vieux Carre and can be intercepted at the site. This would reduce flooding in the Treme neighborhood and beyond. Eventually, discharged water would connect to the Claiborne Avenue Canal and an expanded Lafitte Greenway Canal.