Tree on St. Charles Street in New Orleans, LA

Top 10 Takeaways: Water Environment Federation Technical Exhibition and Conference

Last month we shared a “Top 10 Takeaways” blog post about the International Society of Arboriculture conference. Today we’re sharing the Top 10s – well, actually, Top 6 – of the WEFTEC conference, held in New Orleans, LA from September 27th to October 1st. As before, this list is compiled by L. Peter MacDonagh, FASLA, and is a totally subjective assessment of the key things to know about based for the design, planning, and arboricultural communities. We hope these lists will entertain, and also be helpful for people who weren’t able to attend or want a reminder of the key conclusions.  -LM

The 2014 WEFTEC (Water Environment Federation Technical Exhibition and Conference) conference was held, once again, in the wettest and most flood vulnerable large city in North America – New Orleans. It’s not without irony that past hubristic water management has us discussing the future of water in the convention center of a city that is largely below sea level. Although the convention center sits 8′ above sea level and escaped major hurricane damage, almost 10 years after Hurricane Katrina the greater city of New Orleans seems hardly recovered.

Outside the doors of this convention center, the Mississippi River rolls by the last large city before it arrives at the Gulf of Mexico. I live on the other end of the river, in the ‘Mississippi River Headwaters State’ – Minnesota. Seeing the river in NOLA, over a mile wide, is humbling. River water passes this convention center at a rate of several hundred thousand cubic feet of water per second. Here the “Big Muddy” is loaded with the rich soils, heavy metals, petro-carbons and toxins (145 million metric tons per year) running off 40 percent of the continental United States’ landmass.

6) Stormwater treatment isn’t either/or

WEFTEC is, and always has been, a brawny, muscular conference of gigantic water treatment machines exhibited in a convention hall that runs thousands of feet in length. There is something awesome and reassuring in walking through a hall filled with huge water treatment machines that are the size of houses. However, it is also humbling to realize that all of these machines together would not make a dent in improving the water quality of the “Father of Waters” outside the doors.

It will take both green and gray infrastructure to achieve water quality success – not either/or. We won’t be able to accomplish this water quality task without these machines (gray infrastructure), but for us to achieve a swimmable and fishable Mississippi, without going broke as a country, we will need to get serious about green infrastructure. Pollutant-eating soil and plant roots that provide the footing for this process are modest in size, but effective at the work, and orders of magnitude less expensive than machines. We need to capture the power of roots and soil more aggressively.

5) A Growing Focus on Rain

was and have been impressed by the ascension of stormwater into the WEFTEC pantheon. For the past three years there has been a growing stormwater presence on the exhibit floor of WEFTEC and in the halls of the technical sessions. Within the WEFTEC organization a small cadre of stormwater advocates led by Seth Brown have heroically elevated the status of stormwater within WEF. Surprising as it now seems, five years ago I found only one booth on stormwater treatment at the world’s largest water quality conference. Now there are dozens of booths, a stormwater pavilion, 145 sessions, and 31 workshops. Well done to Seth and his team.

4) TMDL Diets are Not a Fad

TMDLs (or the cumbersome sounding Total Maximum Daily Load), from the United States Environmental Protection Agency, are essentially a pollution diet for receiving waters to meet a water quality designation. In other words: how much pollution can a river, lake, or ocean take from its watershed before it is a hazard for people swimming or fishing in its waters. There are lots of different offending pollutants (dirt, nitrogen, phosphorus, heavy metals, infectious diseases) and a single water body can have TMDL impairments for multiple types of pollution.

One of the most significant TMDLs in the country is the Chesapeake Bay, affecting multiple large cities and several states. TMDL’s are a performance-based guideline for the watershed that is generating this pollution. Most of the pollutants that cause TMDLs are non-point run-off from towns, cities and farms. The EPA allows the local government bodies to figure out the how, what and where of limiting the offending pollutants within the watershed boundaries of that lake or river that’s causing the TMDL impairments.

Currently less than 20 percent of our streams, rivers, lakes, and oceans have been sampled to get a TMDL designation. The EPA requests that the water bodies that are in the worst condition go to the top of the list for impairment testing, planning, and then fixing. Randy Neprash has been representing the League of Minnesota Cities in negotiating the terms of TMDLs with the Minnesota Pollution Control Agency (EPA’s regulatory enforcer in Minnesota). The word negotiation is absolutely accurate in describing this laborious process of all being in this together. When it comes to TMDLs statewide, Minnesota is a leader, thanks to Randy. Eventually, every major polluted receiving water body in the United States will have its own TMDL pollution diet.

3) What’s Keeping Me Up at Night?

Probably the biggest thing of all the keeps me awake at night is compaction of soils, particularly compaction of soils where vegetation is expected to grow. When it comes to soil in the ultra urban environment, the needs of vegetation (light compaction) and the needs of supporting structures (heavy compaction) are fundamentally opposed. Sidewalks and streets need to support heavy weights and take an incredible amount of wear, while all plant and tree roots need to breath air.

Like many complicated problems the answer is simple, it’s the execution that’s hard. But to have any chance of water sustainability for our future cities the challenge is that we must have both high and low compaction side-by-side. Just as no road paving engineer would accept, or even be asked to accept, compaction rates of less than 95 percent where a street is being built, so it also must be that no arborist or landscape architect can accept compaction rates of more than 88 percent where vegetation is expected to grow and infiltration is expected to occur.

2) There’s No Such Thing as Magic Media

Following my presentation on the newest research around using trees and soils to treat stormwater, a number of audience questions were in the vein of the search for a silver bullet, a solution for infiltration and vegetation growth in cities that does NOT involve real soil. I’ve been asked this question many, many times before. Why can’t tree roots and plant roots grow in muddy rock or dirty sand? Isn’t there some way that it can happen? Please give us some hope that we don’t have to rely on fussy soils. Please give us a way to compact with abandon and without negative effects to tree roots.

I so want to answer “yes.” But in most of North America, with our Type II storms (high-intensity, short duration, infrequent), there is no possible way that muddy rock or dirty sand is a sustainable solution for growing plants, especially trees. I’m sorry, but we must accept our storm patterns as they are, not as we would want them to be.

And a drum roll for # 1…

1) The Saddest Trees That Ever Were

The most impactful thing for me at 2014 WEFTEC was just outside the conference hall doors on Riverfront Avenue. Spaced about 30′ to 40′ apart are Red, Live and Willow Oaks, each one surrounded by a 4′ by 4′ cast iron tree grate. Based on the extremely poor health of these trees, it’s a pretty safe bet that the amount of actual soil the trees are growing in is less than 100 cubic feet. Along the mile or so of Riverfront Avenue I walked back and forth to my hotel, there was not a single large, healthy tree on either side. Many of these trees predate Hurricane Katrina, which did not flood this area.

What do I consider a large healthy tree?

1) Enough dark green leaves that I can’t see straight through the canopy;

2) Full rounded canopy without holes or chunks missing;

3) Leaves to the very end of the smallest twigs;

4) Branches elongating at least a foot per year;

5) Trunks increasing in diameter at least 1″ (2.5 cm) per year;

6) A clearly visible trunk flare, unrestricted by grates, curbs, wires, cables or sidewalks;

7) A sound single stem and no co-dominant branches.

Here’s my question: How can a city whose main source of revenues are from out of town conventioneers put up with this lousy of a front door at their convention center and gateway to the Mississippi? Why as a convention attendee do I have to walk on blazing hot sidewalks without any shade from trees, even in October?

New Orleans receives over 60 inches of rain per year, 20″+ more than Seattle and 10″+ more than Atlanta, which has 40 percent tree canopy. New Orleans is the wettest large city in North America and sits on rich, silty delta soils. It never freezes or goes more than a couple of days between rains. In such conditions it’s almost harder to not grow trees than it is to grow them. How is it that these are some of the worst street trees I’ve ever laid eyes on?

P.S.: The New Orleans Convention Center has hired the landscape architecture firm of Spackman, Mossop and Michaels. The project’s main goals are to grow very large groves of trees (300) to scale down the Convention Center and manage the 1.5”/24 hour storm. Thank the tree gods! I look forward to visiting in a few decades and seeing something very different.

Peter MacDonagh, FASLA is the Director of Science + Design at The Kestrel Design Group.

Daniel X. O’NeilCC BY 2.0

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