From 22 through 25 July 2012, I had the pleasure of
attending a conference in Hamilton, New Zealand titled “Recent & Future
Innovations in Erosion & Environmental Control”. The conference was sponsored jointly by the
Australasia Chapter of the International Erosion Control Association (IECA) and
the New Zealand Institute of Highway Technology (NZIHT).
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Map shows locations of Auckland, Hamilton, and Christchurch |
Hamilton, a city of about 125,000 is located some 100km (60
miles) south of Auckland, New Zealand’s largest city. The local area is active geologically
although there have been no local volcanic eruptions in the past 5000
years. Hamilton is the administrative
center for the Waikato Region of the North Island. Hamilton is not a city to visit for exciting
night life (not my motivation for being there) or the spectacular scenery found
in many parts of New Zealand. However,
it’s a pleasant place and a convenient location for observing environmental
controls associated with construction of a new, badly needed, multi-lane
by-pass around the city.
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Riverside setting for the IECA Australasian conference in Hamilton, New Zealand
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This was the fourth joint conference of IECA and NZIHT. Maybe plenty of previous practice has taught
them how to do the job right. At any
rate, the conference was very ably organized by Jill Warner, a New Zealand
member of IECA, with help from Michael Francombe, the president of IECA
Australasia and Sandra Lanz, office manager for IECA’s new Region Two which
also includes chapters in Malaysia, India, and South Africa. It came off flawlessly and included
knowledgeable speakers, a very informative field trip, a nice venue, and lots
of great food! Also Jill made
arrangements with the local Maori (indigenous) gods for heavy rains during the
two days we were inside for the conference and a pleasant sunny winter day for
the field trip.
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The conference featured local and international exhibitors
showcasing their erosion and sediment control products |
On the first morning, we were welcomed to the conference by
a distinguished Maori gentleman in a business suit who spoke to us alternately
in English and Maori and acknowledged both the Creator and the Maori
ancestors. He also spoke of the history
of the area. We learned that Maori rights
in New Zealand had been guaranteed by an 1840 treaty with the British
settlers. However, the settlers
subsequently violated the treaty and illegally appropriated Maori lands. Recently, the Maori (who make up about 15% of
New Zealand’s population) have used the courts to regain some of their
traditional lands and win compensation for other lands which they lost.
Keynote Speaker – Day
1: Sustainable erosion control
President Michael Francombe, an Australian, introduced the
keynote speaker and couldn’t resist some light-hearted jabs at the New
Zealanders regarding the Aussie – Kiwi (New Zealander) rugby rivalry. The keynote speaker, John McCullah is an
erosion control and stormwater management consultant based in Redding, California
who specializes in training. John is
well known in the erosion control industry for his entertaining but very
educational series of “Dirt Time” training videos (www.watchyoudirt.com). Recently, he has worked with CALTRANS helping
them implement the U.S. Clean Water Act and stay out of trouble with California
regulators. John operates under a
philosophy of “dirt is good” as long as it’s properly managed.
John presented his “sustainability triangle” which
emphasizes the interrelationship between water, soil, and vegetation. In a sustainable system, of course, these
three elements are in balance. But, for
example, when you strip the soil of its natural vegetative cover, raindrop
impact erodes the soil as simply shown by the US Department of Agriculture’s
cartoon film, Junior Raindrop, which
dates way back to 1948 (John played it for us).
[I’m writing this as my Bali – Hong Kong flight passes over
the island of Borneo and crosses the equator.
It’s been a considerable visual diversion for nearly 2 hours. Now that we’re out over the South China Sea I
can continue.]
Here are
some good points about sustainable erosion control that I picked up from John’s
presentation:
- Mulching a
disturbed surface is the best type of erosion control
- Imprinting
is a better form of surface roughening than track walking with a dozer.
- Compost
blankets, berms, and socks are 97% effective in controlling erosion. They can hold 10 times their weight in water.
- Using dead
tree trunks is an effective and more aesthetic replacement for riprap.
- It’s
important to set the stage for natural succession by planting native grasses.
- Successful
use of native grasses increases infiltration minimizing impervious areas.
- Landform
grading (working along the contour) creates natural, curvilinear slopes.
Sustainable
erosion control meets stormwater quality standards and minimizes costs by:
- creating
long-term soil health
- providing
locally-appropriate healthy plant communities
- achieving
permanent soil stabilization.
John talked about and showed slides from the Lucas Creek
stream restoration project that he worked on in a northern suburb of
Auckland. In a later post, I’ll have
more to say about the project which I visited for a couple hours prior to
leaving New Zealand for Australia.
John mentioned a couple of useful references: Landforming
by Schor and Gray (Wiley, 2007) and the erosion control manuals found on the
CALTRANS website (www.dot.ca.gov). He can
be contacted at john@salicaec.com. My only complaint about his presentation was
that it contained so much useful information that my brain had a hard time
keeping up!
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“Dirt Man” John McCullah fires up conference participants |
Keynote Speaker – Day
2:
Rebuilding Christchurch after the big
quake
The keynote speaker for the second day of the conference was
Greg Slaughter with Christchurch Rebuild.
You may recall that the city of Christchurch (largest city on New
Zealand’s South Island) was devastated by a major earthquake in February
2011. Grey described the quake and the
damage it caused. He also gave us a
sobering but positive assessment of the progress to date in repairing some of
the damage.
The city is not located on a major fault, and the shallow
earthquake occurred on a previously unidentified, buried strike-slip fault. As a result of the earthquake, the city’s
location has moved slightly to the east with some areas moving up and others
down. The city is underlain by fine,
unconsolidated volcanic sediments which liquefy during shaking. The city’s building codes allowed for shaking
but not for liquefaction. The codes have
now been changed as a result.
The city’s natural drainage patterns changed as a result of
the earthquake. Sewer mains were
destroyed resulting in some 90,000 meters3/day of raw sewage initially
discharging to local streams. For a
couple months following the earthquake, total suspended solids and fecal
coliform levels went way up in these streams.
Fuel and chemical spills resulted in contaminated land issues which were
addressed by a site management plan. Parts
of the city were left with a high water table.
Dewatering efforts with well points using sand filters appeared to work
well at first but they were soon clogged by the fine volcanic sand. Fortunately, most of these environmental
impacts were only temporary.
The clean-up and reconstruction effort is costing some NZ$2
billion (US$2.5 billion), a hefty sum for a country of less than 5 million
people. It includes repair or
reconstruction of around 1000km (600 miles) of streets and highways and 100
bridges. The aim of Christchurch Rebuild
is to create a resilient infrastructure that the local people can feel
confident about.
Perhaps there was one positive effect of the quake and its
aftermath: It has brought the people of
Christchurch together and involved them in the clean-up and reconstruction effort.
It also provided an opportunity to
introduce sustainable design into new construction and adopt a policy of waste
minimization. The knowledge gained from
the quake and clean-up is being shared with Japan and California.
Other featured speakers
Amanda
Davis from URS spoke about a power cable trenching project in New Zealand
which had issues with dewatering, water crossings, and water pH issues. Staff environmental trainers faced some
communication challenges because a number of the workers were from the island
nation of Tonga in the South Pacific and English was their second language.
Fiona
Montfort from HEB Construction spoke about New Zealand’s 1999 erosion and
sediment control guidelines. She pointed
out that some required mitigation measures often cost significant dollars (yes,
they use New Zealand dollars not Pounds) for minimal environmental
benefits. She also emphasized the need
for early contractor involvement when planning environmental mitigation on
projects. Construction personal often understand
how to construct better environmental mitigation measures for a given situation
rather than going strictly by the book.
They can also help find cost-effective solutions as well as helping
price out costs for environmental measures.
Craig
Redmond with the New Zealand Transport Authority in Christchurch spoke
about the challenges in developing a national erosion and sediment control standard
as mandated by the Resource Management Act of 1991. He pointed out that a national standard needs
to allow for regional variations. He
pointed out that standards are often too rigid whereas guidelines encourage
innovation. Therefore, a combination of
general standards with more specific guidelines works well.
Graeme
Ridley (RDE Ltd.) spoke about the Long Bay Development Project. Some of the innovations they used were
baffles and reverse slopes within sedimentation ponds, double primary spillways,
fore bays with 15% of the pond volume, monitoring using automated samplers, and
silt fence as a last line of defense.
Michael
Francombe (Landloch) talked about his frustrations with contractors who
keep relying on the same methods after repeated failures. In particular, he chastised the mining
industry for its failure to learn from past mistakes. He also said there is generally a poor
knowledge among contractors regarding the science of revegetation. Michael noted some of the differences in the
quality of erosion control on construction projects among the various
Australian states. Whereas New South
Wales (Sydney is the state capital) has been a leader in erosion and sediment
controls since the 1980s, the state of Victoria (Melbourne is the state capital)
is “abysmal”.
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Michael Francombe provides an Australian perspective on erosion & sediment control innovation |
Jake
Crawford with HEB talked about wind erosion on “roading” projects (that’s “highway
construction” to you Yanks). Instead of
spraying exposed surfaces with water, longer-lasting alternatives are spraying
with soil stabilizing polymers which form a crust, magnesium chloride,
hydromulching in sandy areas, and use of agricultural bio-solids (which he
referred to colourfully as the “Power of Poo”).
Jake warned us to watch out for suppliers of these products who call for
higher application rates than are needed.
Robert
Coulson with Rural Supply Technologies Ltd. talked about stream erosion and
the “green fix” (i.e., bioengineering).
Stream rehabilitation which makes use of “living walls”, compost
blankets, created floodplains, and introduction of riffles with well-placed
aggregate is typically longer-lasting, cheaper, more aesthetic, and lower
impact than using traditional structures like gabions which often fail. Communities are also more likely to support
green fixes.
There were
about 15 other speakers including me. I
presented a report of my reconnaissance last July of erosion problems in a
mountain community in Ecuador.
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First slide of my presentation on Erosion in the Andes |
Kiwis say “seediment control”
Since the
conference featured both Australian and New Zealand speakers, I had fun trying to
pick out some subtle differences in their respective accents and word
pronunciations. Here are some
observations I made about Kiwi pronunciation or at least this is the way some
words sounded to my Yankee ears:
- Check dam sounds
like cheek dam.
- Trench
sounds like treench.
- Sediment
sounds like seediment.
- Hay bales sounds like high bales.
I’m not saying that Kiwi pronunciation is “incorrect”. Au contraire, I find it rather
delightful. And God knows, the Queen
must cringe when she hears us Yanks butcher Her English.
In my next post, I’ll include photos from the conference
field trip which gave us a chance to look at erosion and sediment controls on
the Hamilton by-pass construction project.