Sink holes, cracks, lateral
spread, elevation changes and liquefaction
Posted in Personal Finance
July 23, 2012 - 09:35am, Janine Starks
By Janine Starks*
When it comes to land
claims one large group of homeowners have the most
unanswered questions and the most uncertainty; those sitting
on liquefied land.
Not enough time has
been spent asking EQC and insurers detailed questions about
liquefaction. So a few weeks back, I dived into the mucky
stuff and tried to clarify a host of questions readers have
As is often the case,
the deeper you dig, the more you realise you’ve disappeared
down a hole. So with sink holes, cracks, lateral spread,
elevation changes and liquefaction in mind, here are the
issues we discussed:
What is land damage?
Gosh that sounds like an odd question. Don’t most of us
think that liquefaction has altered the pre-quake condition
of land, therefore it’s damaged?
But we need to take a
step back. Our definition of damage might not be the same as
Their view is that land
damage “means a not inconsequential change in the land,
caused by natural disaster, which affects its utility”.
The important word here
Can you still use it?
In short, if you can still use it (i.e. there is foundation
solution which supports a rebuild), then it’s not damaged.
Surely if you have 10 or 20
metres of liquefied soil beneath your lawn and house, before
a solid layer is reached, you have damaged land? No,
Concentrate hard on this next
sentence. “Liquefaction is a process not an outcome”. As EQC
explain “Land will only liquefy and eject sand and silt
above the surface, during an earthquake. Once the earthquake
has finished, the land resolidifies”. While EQC won’t go so
far as claiming that your land is back in its exact
pre-quake condition, the fact that the silt goes solid means
it is now viewed as useable and undamaged.
EQC see no need to
remediate the soils below ground level.
They tell me the vast
majority of people will only get the surface damage fixed -
that is, sink holes and cracks filled in, silt removed and
ponding fixed. This has been well covered in the media as
the ‘rake and roll’ technique.
There will be very few
people whose land is uneconomic to repair and who will
receive the maximum payout under the law (that is, generally
a cash payment to the value of the smallest allowable
section size in the local area – of which there are 19
different sizes in various areas).
Will EQC fix liquefied
land to make it less susceptible to new doses of
liquefaction? In short, no.
The solution is
restricted to ‘rake and roll’. If land is no more
susceptible to liquefaction than it was prior to the
earthquakes, they will not ‘better’ it by building it up or
strengthening it. Even land that has had repeated doses of
mud and silt will not be strengthened.
It seems if your land
is ‘more susceptible’ to liquefaction you may have a case
for strengthening. This one ties EQC up in knots. How do you
prove pre versus post quake susceptibility? Being a fan of
simple answers, I quote the obvious example of streets where
heavy trucks now cause liquefaction to rise forth.
Pre-quake, a truck
could drive on these streets with no side effects. It seems
clear that plenty of people could prove they are now more
susceptible. EQC explained that a geotechnical engineer will
decide on this and their work is being reviewed by experts
at Universities such as Canterbury and Berkeley in the US.
While that’s admirable, I hope the professors take the
‘truck-test’ into account. Unless ‘susceptibility’ is tested
legally, EQC probably don’t have much to worry about.
Cantabrians are proving to be rather limp-wristed in their
willingness to litigate or form action groups, so I doubt
this one will get tested.
Will EQC fix a change in elevation if land has sunk? Again
If the ability of the
landowner to use the land has not changed, the solution will
be restricted to fixing any observable surface damage.
If an elevation change
has occurred in the Flood Management Areas (FMA) like
Redcliffs, Southshore, Sumner and river suburbs, EQC have
obligations. Check on the councils website to see if you are
in the FMA as rebuilds are likely to prove a challenge.
Rumour has it the council will widen the net and capture
more homes in the FMA due to land sinking in the quakes.
‘existing rights’ for earthquake rebuilds and can skirt
around the need for resource consent.
But building consents
may catch you, as the floor level must counter a 1 in 50
year flood (your old house may be beneath this).
The new rules mean you
have to counter a larger 1 in 200 year flood. Land that has
sunk in the earthquakes will need to be raised by EQC or an
alternative solution negotiated between EQC and insurers.
Sounds messy doesn’t it. Even messier when you consider the
volume of homes in these areas.
Will land damage be
categorised using a new scale? EQC were unable to offer any
comment on this. Reliable sources tell me it will be.
The new categories are
likely to be labeled Category 1 through to 9 with 1 being
the least damage and 9 requiring more difficult solutions.
You can find early evidence of this in the original Tonkin &
Taylor reports but the categories were in reverse. The rumor
mill says insurers are very wary of carrying out rebuilds in
the 8 and 9 categories and these may in some way be linked
to the Flood Management Areas around the rivers and coast
where land has sunk. Insurers and EQC will need to negotiate
higher floor levels versus the practicality of building land
Are insurers beginning
rebuilds on liquefied land?
Some insurers have
started planning rebuilds in Green-blue areas (TC3) on the
basis they have been in the 1-7 categories, with no
elevation change and are not in the Flood Management Areas.
We can only guess that these categories will become more
evident as land assessments are revealed to homeowners by
EQC. For now they are silent on the matter. The new
categories can’t come soon enough. There has been too much
confusion over TC2 and TC3 land. These labels only reflect
how susceptible land is and what foundation solution is
required. They don’t tell us the real level of physical
When will land
assessments be completed for those who have suffered
liquefaction? They are complete. All the work is done and
has been for some time.
EQC have completed over
56,000 land inspections in the hardest hit flat-land areas.
Inspectors have gone door to door – if you didn’t see one,
you will have been at work (or you owned a big dog that
scared them off). While there are engineers currently
carrying out drilling all over the Eastern suburbs, this
data is not required for land assessments – it’s solely to
determine foundation solutions.
EQC are sitting on all
the data they need. They’ve done aerial flyovers and have
previously completed 2000 drillings to give the elevation
changes. Combine that with the visual house-to-house visits
and it’s all done. The missing link is they haven’t yet
designed a model that determines how remediation and
compensation will work. This will be available at roughly
the same time as the completion of the drilling for
foundation solutions, so the two elements will roughly run
What are insurers doing
regarding carrying out their own GeoTech reports?
Insurers have been very
slow to move in TC3 areas. On one hand it’s because of the
continued seismic activity making the risks too high. On the
other hand they could get off their chuffs, send in their
own GeoTechs and start the planning phase. I’ve asked
insurers what is causing the stalling and they tell me it
has nothing to do with a lack of resources. At the drop of a
hat they can get as many GeoTech rigs and people as they
need. Instead, they prefer to wait for EQC to release their
area wide land assessments in the hardest hit suburbs.
On digging a little
deeper there seem to be a couple of reasons. First, on some
sites where shallow foundations and light-weight cladding
can be used, they believe there will be no requirement to
individually drill those sections. On other sites where
heavy brick veneer is being rebuilt, or deep pile
foundations are needed, they will need individual GeoTech
If insurers wait for
EQC to release their results, they can concentrate on
drilling only those sections that require it. Second, they
are very concerned about category 8 and 9 land damage and
want to work closely with EQC on this. Just to be clear,
this is the insurers point of view – whether it’s
contractually acceptable to delay is another matter.