Welcome
Hello
everyone and welcome to the August edition of “Keep Things
Flowing”, the monthly newsletter presented by Storm Water
Consulting.
This month
the latest instalment of the Queensland Urban Drainage Manual was
released. In this newsletter we bring you some of the important
updates from the new manual. For any follow up information about
these articles please respond to this email.
QUDM 2017
This month
the Institute of Public Works Engineering Australia released the
fourth edition of the Queensland Urban Drainage Manual (QUDM 2017).
The Queensland Urban Drainage Manual addresses technical and
regulatory requirements, provides details of appropriate design
methods and computational procedures and covers both hydrologic and
hydraulic procedures as well as environmental and legal elements.
So what are
the major changes to the 2017 version of QUDM? I’m glad you asked.
Some of the major changes to QUDM are presented below.
Background
to QUDM
A partner
document, “Background to QUDM”, has been created to assist with
explanations and reasoning behind the technical and regulatory
requirements made in QUDM. This document allowed QUDM to be
condensed and focus on requirements rather than provide reasoning
and justifications. At this time the “Background to QUDM” has not
been made available.
Lawful Point
of Discharge
The lawful
point of discharge for a site was previously based on a two rule
test:
1.
Stormwater
must be discharged to land owned by the local authority;
2.
Discharging
the stormwater must not create an adverse impact to neighbouring
properties.
The lawful
point of discharge test has been modified as follows:
A.
If
the proposed development does not alter the site’s stormwater
discharge characteristics in a manner that may substantially damage
a third party property, then no further steps are required to
obtain tenure for a lawful point of discharge (providing that the previous
circumstances were lawful).
If Item A
listed above is not met, then the standard two rule test will still
apply.
Initial
Basin Sizing
A simple
method for estimating the required volume of detention storage has
been provided in this edition of QUDM. The method involves
calculating the effective reduction in the site’s initial loss
capabilities. When a site becomes more impervious, less rainfall
can be absorbed by the ground, leading to increased runoff from the
site. QUDM recommends initial loss values representative of
different ground conditions. Whilst this method is useful for
planning a development, detailed hydrologic modelling is
recommended for the actual design of detention basins.
Wrap Up
We hope you
enjoyed this edition of Keep Things Flowing. Feedback on articles
presented is always welcomed and for further information on any of
the articles presented please don’t hesitate to contact our office.
As always,
Keep Things Flowing!
The Storm Team
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