16-001014-02A (Ultimate SCMMP)

                                                                                                                              HumeGard® GPT
Design information                                           Sizing HumeGard® GPTs


To design a system suitable for your project it is           The large storage volumes of the HumeGard® GPT
necessary to review the configuration of the stormwater      enables more pollutants to be captured before
system, the location and purpose of other stormwater         maintenance is required, which greatly reduces its
management (WSUD) controls, the catchment area and           lifecycle costs. In accordance with accepted hydraulic
the hydrology.                                               principles the larger volumes in the HumeGard® GPT
                                                             results in lower velocities through the device, minimising
                                                             scour and re-suspension of sediment.
Configuration of the stormwater system
                                                             Humes Water Solutions has developed a design
The configuration of the stormwater system is important      request form (see page 30) for stormwater designers to
since the HumeGard® GPT operates with an “in-line”, 45°      complete and return to obtain a detailed design of the
or 90° alignment. Inlet pipe grades between 0.5% and         appropriate device.
5% are recommended for at least five pipe diameters
upstream of the HumeGard® GPT. The pipe grade and
flow velocity will determine whether a super-critical unit   MUSIC/pollutant export model inputs
is required.
                                                             Many local authorities utilise MUSIC or other pollutant
                                                             export models to assist in stormwater treatment train
Location in the stormwater system                            selection, and recommend generic inputs for GPTs.
                                                             Considering these against the independent research
Depending upon the site, the GPT can be oriented to          results, the following conservative removal efficiencies
have the treatment chamber on the left or right side of      (refer to Table 3 below) are recommended for the
the pipe to suit constraints. Humes Water Solutions can      HumeGard® GPT on an annual basis (i.e. no bypass).
work closely with stormwater designers to select the
appropriate location and orientation for their system.


                                                             Table 3 – MUSIC inputs for HumeGard® GPTs

Catchment area
                                                                Pollutant                      Removal efficiency
                                                                Gross pollutants                       90%
Research presented in Australian Runoff Quality                 (litter, vegetation)
(Engineers Australia 2006) concluded that roughly
                                                                TSS                                    41%
1 m3/hectare/year of gross pollutants and sediment
                                                                TP                                     34%
could be expected from a typical residential catchment.
Therefore, GPTs designed for an annual maintenance              TN                                     24%

interval should have a pollutant storage capacity roughly
equal to the number of hectares of catchment it treats
(e.g. 10 hectare catchment = 10 m3 pollutant storage).




                                                                                                          HumeGard® GPT   7