John Here –

Hello Friends or as they say in Kiwi-land ” G’day Mate “

The IECA / NZIHT conference in Auckland was well attended, about half Aussies, half Kiwis, one Californian (Callie) and one South African – by my math it was 102% attendance! But then I’m a geologist/erosion control specialist!

There was lots of interest in all things erosion and I learned a lot from presentations. The New Zealand Institute of Highway Technology was co-sponsor, their mission is education so this conference was a perfect match for these two groups.

For instance, there is a lot of erosion control and restoration work in the Auckland area, “good on you mates!” Also, the Highway Agencies are using and implementing many state-of-the-art BMPs. Silt fence for instance. Never saw one shoddy silt fence installation and the filter fabric was strong, made of good quality geotextiles. The Wall Mart-type, pre-attached stakes would never pass muster here. Auckland Regional Council (ARC) has some really comprehensive BMP Manuals. TP-90 has BMPs for temporary construction site management and TP-10 has permanent Stormwater BMPs.

Lot of emphasis on what they call alliances, which is parallel to what we are attempting in CA – especially in the area of “watershed restoration”. We try to build Cooperative Resource Management plans and Technical Working Groups. Nothing worse than having a really great restoration project get funded (grants are so competitive!), permitted, etc. and then have an agency delay or make costly changes because they were “not in the loop”. Oops, I’ll stop my too personal commentary. Back to NZ.

Auckland is really comprised of several local city councils, each one regulates development over its area but then the developments are also regulated by the ARC and council representing the indigenous peoples.

For a conference field trip we got to visit a big Highway “Deviation” project (we’d call it a bypass me thinks). This project was a huge example of an alliance, most of the work being a design-build with much oversite by ARC, Northshore Regional Council, and the indigenous group. As you will see from the photos, it is now rainy season and almost all bare soil has been surface stabilized with straw mulch – good on ya! They also rely heavily on sediment basins. The “TP-90 Basins” are designed with a 3:1 L:W ratio, have a chamber called forebay, level spreader, main pond area and a decant. The decants you’ll notice are somewhat similar to the Faircloth Skimmer outlet devises. I can’t understand why we in the west keep designing ponds with slotted risers – don’t get me started!.

Check out the Photos:

Straw mulching bare areas during winter

they got the Cilverts in before winter, good “Phasing and Scheduling”. Note the proper silt fence!!Michael Francombe, President of Australasia IECA. Michael is a most experienced erosion professional and very knowledgeable leader. Conference is in Noosa, Queensland, Australia next year.this ponds “fore bay” is full. No floc used on this sediment trapThis is a typical ARC TP-90 Sed Pond with flocculant shed (meters floc into the inflow based on rainfall) up by group, level spreader forming fore bay, the black pipe is leave catcher, and then Triple-level decant. It is possible that this pond will be converted into a permanent stormwater basin at end of construction.floc shed, really an ingenious idea for metering the flocculant. The floc is poly-aluminiun chloride (PAC). I don’t know how it compares to PAM. I do know that aquatic organisms and the substrate habitat is a ket driver for regulating construction site runoff.

Cheers Mates!  More to come, stay tuned!


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