Christchurch Infrastructure Recovery
The 2011 earthquake activity in Christchurch cause widespread liquefaction
and seismic settlement resulting in considerable damage to the wastewater
network. One of the greatest resulting concerns was loss of reticulation grade
in the wastewater network (which in turn affects capacity of the pipe). In order
to answer the question of how much loss of grade can be accepted before renewal
of a gravity pipe is necessary; Christchurch City Council (CCC) implemented a
policy which compared the post-earthquake grades of the network with the
pre-earthquake grades and the pre-Infrastructure Design Standard grades.
Following the implementation of the CCC policy, it then became apparent that the
team needed to find a way of comparing the original grades of the network
“pre-earthquake” to the surveyed inverts and grade “post-earthquake”. Other
designers had done this comparison by using Excel spreadsheets, but they wanted
a visual means of representing the data which could easily be reviewed and form
part of the concept design report for a particular project area.
They decided to use 12d Model to build two wastewater networks for a particular
project area - one to represent the pre-earthquake network and the other the
post-earthquake network. The post wastewater network was built using manhole lid
and invert data provided by the survey team.
This model was then copied and
pre earthquake data taken from the Council GIS maps were inputted to form the
pre model. Using 12d Model’s exporting/importing functionality, pre-earthquake
grades and inverts were copied from the pre model and included as separate
attributes to the post model. Following this, pre and post long sections were
plotted using a 12d plot file.
The result was a quick and visual means to assess the loss of grade and
settlement within the wastewater network and assist in the design of the network
Download this Case Study as a PDF