Aug 012013
 

A rendering of a proposed floodplain park around the Monticello Canal in Hollygrove, similar to those proposed for other canals around the city in a new water-management strategy for New Orleans.

Rainfall should be diverted out of Uptown via the Mississippi River instead of carrying it all the way to Lake Pontchartrain, and major drainage ditches like the Monticello Canal should be expanded into interior floodplains and water-storage features, according to two recommendations that illustrate how New Orleans should be better managing its water instead of just pumping it away.

The Water Management Strategy presented by architect David Waggonner to a standing-room only crowd Thursday evening at Xavier University is a regional plan for making more efficient use of rainfall, slowing it down and storing it in natural canals to reduce the sinking of the land that contributes to flooding. The recommendations in the Uptown area are only a small part of the plan, but they illustrate some of its key elements and some of its challenges.

“We’re proposing this is a new era for water management,” Waggonner said. “It’s not just about flood protection any more. It’s really about quality and sustainability.”

The ridge and the floodplains
One major change envisioned by the plan is to respect the natural ridge through the center of the city as a drainage barrier. Instead of pumping all the water from the neighborhoods along the Mississippi River across the entire city to the lake, the new plan would use the existing canals to bring Uptown-area rainwater to a new pumping station on the Mississippi River, near the current Sewerage and Water Board facility. (Similarly, downtown rainwater between the ridge and the river would be pumped into the Industrial Canal.)

The change would have two major structural effects, Waggonner said. Currently, junctures in the drainage system can get backed up in major rainfall events, causing flooding backwards along the overloaded system, but “disconnecting” the Uptown water from the lakeside drainage system would prevent that buildup from happening. Secondly, it would separate the city into discrete “water units” that would minimize damage if heavy flooding occurred.

A second major change would be to create major natural floodplains along the current canals — the Monticello Canal would be a major example, but it would be applied to canals around the city. The canals are now intended to funnel water out of the city as quickly as possible along a narrow chute. Instead, Waggonner proposed a dramatic widening of the spare around the canals, creating parks and greenspace that could flood naturally during heavy rainfall.

The new spillways would be wide enough to preserve drainage capability but also take direct aim at reducing subsidence, the sinking of the soil that breaks the streets and will cost New Orleans $20 billion in increased flood exposure in the coming decades, Waggonner said. Subsidence is caused by dry soil that compacts easily, so the large new swaths of green space would provide more opportunity for rainwater to soak in and fight that process naturally (similar to rain gardens, on an individual level). Further, if the canals were used for storing water, instead of remaining empty, that would allow the water table under the soil to rise, further combating subsidence.

Between rains, these spillways would serve as parks that will increase New Orleanians’ quality of life with 18 miles of new waterfront inside the city, Waggoner said. Whereas the canal areas are currently hidden in the “back of town” areas like Hollygrove, the spillway parks would instead become assets. And creating open canals is much less expensive than expanding underground drainage.

Changing the old ways
Many of the questions surrounding Waggonner’s presentation concerned the political will to bring his $5.2 billion vision to reality, perhaps most succinctly put by City Councilwoman Susan Guidry, who noted the preponderance of recommendations around her district, which runs from Uptown to Lakeview and includes Hollygrove.

Guidry said major projects are already happening at many of the key points in the Waggonner plan — the Lafitte Greenway, remediation of the Monticello Canal flooding, and the SELA drainage-canal installations along South Claiborne, Jefferson and Napoleon avenues. But the Lafitte Greenway is under criticism for insufficient attention to water management, and she’s seen no indications of Waggonner’s ideas for how the neutral grounds will be built after the SELA projects, she said — with so much work already ongoing, is anyone buying into this strategy?

“Everything seems to have already been planned, and it’s been planned in the traditional way,” Guidry said. “When are we going to put the brakes on?”

Marcia St. Martin of the Sewerage & Water Board responded that her agency was fully on board with Waggonner’s ideas. When the neutral grounds are rebuilt above the SELA canals, for example, she has received a commitment from the U.S. Army Corps of Engineers to include some water-management features (an idea City Councilwoman LaToya Cantrell has also recently proposed). It won’t be a “Ph.D.”-level change like Waggonner proposes, St. Martin said, but more at the “kindergarten” level, a “baby step” in the right direction.

The presence of other city leaders voicing support for the ideas — Deputy Mayor Cedric Grant and GNO Inc. President Michael Hecht both participated in the presentation — suggests that the proposed water-management strategy is on its way to becoming part of the city’s long-term planning. Architect Ray Manning, a new member of the Sewerage & Water Board who participated in Waggonner’s research trips to the Netherlands, said that a whole host of changes are coming to the agency’s leadership, and that he expects ideas like Waggonner’s to find a strong foothold in the immediate future.

“I think we are poised, with the completion of this work, to be able to embark on a new way of looking at these issues,” Manning says. “It is the only reason I’m on this board — to do it in a different way.”

The full plan will be made public Sept. 6 at the livingwithwater.com website. To read more details of Waggonner’s presentation, see below for our live coverage of Thursday’s meeting.

  15 Responses to “Major changes to Uptown drainage systems represent citywide water-management proposal”

  1. It’s unfortunate that Deputy Mayor Grant had to leave due to some sort of emergency. I would have like to have talked with him about the reinvest initiative he has been discussing with the CPC. Commissioner Chair Kelly Brown shared copies of information about the reinvest initiative with members of the public at the last CPC ops meeting. http://www.reinvestinitiative.org/about-reinvest/. Michael Hecht indicated that he is also looking at such a plan for New Orleans. I’m liking it so far.

  2. After Katrina, how can their be a “lack of political will” to carry forth Waggonner’s proposals.

    Sewerage & Water Board: “It won’t be a “Ph.D.”-level change like Waggonner proposes, St. Martin said, but more at the “kindergarten” level, a “baby step” in the right direction.”

    A “BABY STEP”!

    This is surreal…..

  3. What the hell?!?

    Guidry is asking Waggonner when “someone” is gong to put the brakes on all the haphazard shortsighted “development” that’s being done daily but only exacerbates the problem!

    That’s pretty ironic since I’ve been trying to get Guidry and her staff to pay attention to these very issues for years now and the only thing she’s ever told me is “I don’t know,” “I don’t understand,” “I am confused,” “there are problems with the sidewalks?” “that’s not my department,” “that’s not my job,” oh and the most recent “are you going to actually have something constructive to say?”

    Guidry and all of Landrieu’s out-of-town hirees running public works are right at the centre of why nothing is getting done and why people like David Waggonner can get more people to listed to what he has to say about New Orleans’ water problems in Washington than he can here in actual New Orleans!

    There are dozens upon dozens of simple, easy, cheap things that can be done to help rectify the problems with flooding and subsidence in this city in addition to the needed larger scope of David’s plans. They’re things that should have been done already, and they’re things that I have personally been doing with volunteers here in town. These very things that we have asked the city to work with us on, asked public works to support, asked Susan Guidry, nay, begged Susan Guidry to give us any support, things we’ve plead with Mayor Landrieu over, written about to Senator Landrieu countless times, and even been told our chances of support were next to nothing from the Mayor’s ‘office of neighbourhood engagement’. The fact is, we’ve gotten ZERO support, ZERO acknowledgement…NOTHING!

    What were these expensive terrible ideas that no one will even talk to us about?

    –Rebuilding Brick Sidewalks

    (they’re a water-permeable surface that absorbs rainfall rather than forcing it to the lake — when maintained, they actually stay dry during a storm!)

    –Restoring the Gravity Drainage System

    (breaking up and digging out the 1-2.5 feet of oyster shells, gravel, tar, dirt, and asphalt that currently covers the gravity drainage ditches; they’re actually completely functional but are covered as today’s “parking areas”. All it would take is a backhoe to clear them and yes, you’d still be able to park there — where we’ve cleared them, flooding has gone away entirely)

    –Dig out the catchment basins

    (that 9 inches or so of metal grate you see is only the top 1/3 of the catchment basins. They go another 18 inches or so down to create a huge high-volume opening (the bottom being level with the actual bottom of the drainage ditch if it were cleaned out); If they were just dug out, the volume of water able to be carried away would be increased 4-5 times what it currently is).

    There are plenty more things that should be done that require money, but are still cheaper in the long run than the mess they keep doing such as installing permeable brick sidewalks and streets rather than the impermeable concrete and asphalt the city seems so intent on blanketing the entire metro area with (and which because it can’t move with the soils the way brick can, only lasts a few years here and is prone to catastrophic cracking). But all that can easily be done after you do the simple stuff like pulling weeds, digging out your drains, and keeping your city clean.

    Check out the project page for our sidewalk restoration project:

    http://Facebook.com/Back2Brick

    Maybe Guidry will respond on here to explain why she’s surprised by Waggonner’s presentation yet has yet to find interest in this work in the 6 months that her constituents have taken their own time, their own labour, their own money, and their own tools from the back yard to return 10 blocks of previously impassible sidewalks to public use (and to allow them to drain water for the first time in 35 years).

    Blaming politics for the problem is one thing, being the politics and the problem and then pretending it’s someone else is another thing altogether.

    Shame on Guidry!

    • The Back 2 Brick method sounds like a good idea and worth taking a longer look at when talking about sidewalks in New Orleans, especially around Oak trees and subsidence. Appears to be financially better in the long run.

  4. “I’m all in”- please keep us posted on if and how we can push this forward.
    Best from Freret,
    Andy Brott

  5. INCREASE FLOODPLAIN CAPACITY
    “Instead, Waggonner proposed a dramatic widening of the spare around the canals, creating parks and greenspace that could flood naturally during heavy rainfall.?

    DECREASE FLOODPLAIN CAPACITY
    “Further, if the canals were used for storing water, instead of remaining empty, that would allow the water table under the soil to rise, further combating subsidence.”

    So, let’s see, widen the canal green space, but fill the canal with water all the time thus the water table will be higher all the time?

    Sounds like this plan just gets rid of the basic canal water capacity and shifts it to just outside the canal boundaries just to combat subsidence. Yet unfortunately, in attempting to combat subsidence, it appears to REDUCE the water holding capacity of the entire area by RAISING the water table.

    What’s the point of having things like water permeable concrete/asphalt for parking lots if the ground underneath is already saturated with water via having the “canal used for storing water 24/7/365”?

    This plan in order to reduce subsidence “appears” to lessen the capacity to handle “flash floods” from heavy thunderstorms as the water table is now HIGHER?

    • Remember, the drainage canals are traditionally “drawn down” prior to an anticipated rain event. They don’t remain full all the time. Rest of the time, yes, water storage capacity.

      • “drawn down” prior to an anticipated rain event???

        So does this uptown new live with the water plan take into account INACCURATE weather forecasts?

        You did know that It only takes ONE TIME for flooding (as well as damages) to occur from a severe thunderstorm as the ground would be SATURATED, or partially saturated.

        And how long would it take to drain the canals and likewise LOWER the ENTIRE WATER TABLE of city BEFORE any anticipated water event? A heavy thunderstorm can easily cause flooding problems.

        Draining and allowing to fill up canals based upon weather forecasts would seem to be not much different that what’s going on now, don’t you think?

        Who is to say that it will rain this much at this time at this location?

        And throw in a measure of safety and the canals might be empty a lot of the time as it is now.

        Additionally, the ground would most likely REMAIN SQUISHY and WET for a lot longer with a higher water table. It might introduce more MOSQUITOES and hence diseases with the water table being so high. Grass fields and parks might remain wet or flooded longer with a higher water table, thus postponing grass field games, like football, baseball, softball, soccer and so on.

      • Long term, a higher water table would also cause the ROOTS of Oak trees to not grow downward, and deep enough, as the roots can easily absorb water up high, hence, no need to grow downward in search of water with a high water table. This could WEAKEN the wind strength of Oak trees.

        Furthermore, Oak trees as well as other trees on water saturated ground are more susceptible to wind gusts. This could cause significantly more uprooted trees, Oak and others.

        Plus, insects like roaches might be more noticeable, annoying and perhaps a bigger problem with a higher water table.

        • I think this study may help out address some of your concerns …

          http://web.mst.edu/~rogersda/levees/Geology%20New%20Orleans-Chapter%203.pdf

          The short version = the water table in New Orleans is catastrophically low, as a result of over pumping. The types of soil in our city require water to be healthy, and they have none. Which is why they are oxidising, evaporating, and subsequently leading to subsidence. Currently New Orleans is falling 4 feet per century, as our soil decays from the lack of water.

          Also … don’t think of the water table as being the first 6 feet from the top down.

          Hope that helps.
          Cheers.

    • This is fun the think about …

      Let’s say you have a …

      1 gallon bucket (empty)
      +
      5 gallon bucket (1/2 full)

      If you where to fill the buckets with garden hose, which puts out 1 gpm … which bucket would fill first?

      That’s the theory behind the green space. If I’m correct in assuming more volume allows for more capacity before a flood event (regardless of whether or not there is water in the canal at the time of the rain event).

  6. I’d like to see someone ask the Mosquito Control experts as to what the affect would be when we have more natural water basins holding water year round.

  7. Personally … I’m really excited about this whole project.

    I’d love to see the whole region with more “Bayou St. John”s and LESS flood walls.

    Imagine it. How cool would it be to take a small boat from uptown to the lake … or downtown for that matter.

    I wonder how the property value around Bayou St. John is effected by being soooooo close to water??? Hmmm.

  8. We already know about subsidence in the LONG TERM. Trying to address the very long term subsidence with a unreliable and perhaps dangerous solution by raising the water table could end up flooding NOLA with only a heavy thunderstorm.

    • I don’t find anything unreliable or dangerous about Bayou St. John … Oddly enough, it’s also one of the few areas of the city that isn’t sinking as fast as the rest.

      It’s an opinion, but I have to say … I kind of like the idea of living with/around/next to water.

      The whole notion of Flood Walls and Drainage Canals seems a bit silly, understanding other communities have handled their water “issues” by turning them into “assets”.

      Our current way of doing things, isn’t the most correct simply because we’re already doing it. More importantly, I believe our understanding of engineering has progressed since the 1940s and we’d be doing ourselves a disservice by ignoring the science and technology in front of us.

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