Sewer Collector Mains Design
Project Summary
Sewer Collector sub-main design and drafting.
The Challenge
The 2012 earthquakes in Canterbury highlighted the high cost of repairing deep
property connections. The Christchurch City design standards were updated as a
result of this disaster, to allow for construction of collector sewer sub-mains
for property connections. When these collector pipes are located within the same
trench directly above the main pipe, difficulties arise in DNE and PPF options
within 12d Model. It is possible using existing DNE tools to design the sub-main
and main DNE networks separately and plot individual XS for each pipe. However,
this causes issues with the construction when contractors want to see all the
information about that trench on one section. City design officers checking
these plans want to see pipes and their grades, inverts types, etc. on one plan
for ease of checking. It is also the requirement by the local city council and
their Design Standards.
Therefore, it was necessary for the team to create an innovative way around this
challenge. There are two parts to this:
Design – creation
of 3D strings with pipe diameter, type and properties
Drafting LS plots and combine Sewer main and sub-main pipes and information.
The client had an added difficulty with designing a
process that can be quickly and easily implemented with large number of users
working on earthquake recovery works.
The Solution
The team created a 12d Model macro that allows users to add a secondary pipe to
a DNE network pipe, draws a superstring for visualisation and drafting purposes,
and stores design information as attributes on the DNE drainage string. Within
the PPF editor, they used these attributes to label information about the
sub-main, showing them in the same boxes as the main pipe.
Design
settings were available for users to automatically calculate inverts for the
sub-main, either by clearance to main pipe or depth from ground TIN.
The Result
The team’s Clip-On sub-main macro and PPF files achieved all the requirements by
the client and consenting authority. Their innovative use of 12d Model gave them
the results they needed for this important project.
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