B07056.W-01A Complete - Stormwater [As Published] · 132007.2398

Total Nitrogen.                                                                             Suspended Solids
The paper “Evaluation of the Stormwater Management StormFilter system for the               The Enviropod 200 node has a transfer function developed from the “Wairau Road Trial”
Removal of total nitrogen: Kearny Mesa Maintenance Station case study” details the          paper. Figure 4 details the efficiency of a 100micron filter bag at different influent
performance of the StormFilter with a zeolite/perlite filter media mixture.                 EMC’s




                  Figure 3: Influent Total nitrogen vs. Effluent Total Nitrogen                               Figure 4: Upstream EMC vs. Event Contaminant Removal
         Source: Evaluation of the Stormwater Management StormFilter® system for the                                         Source: Wairau Road Trial
            Removal of total nitrogen: Kearny Mesa Maintenance Station case study
                                                                                            The efficiency of the 200 micron filter is approximate 10% less than the 100 micron filter
                                                                                            therefore the transform function has been reduced by 10%.
Gross Pollutants
It is assumed that the StormFilter will capture all particles over 5mm in size unless in    Also attached as supporting information, is the report “Auckland Cities Field and
bypass.                                                                                     Laboratory testing for Stormwater Catch Pit Filters”. This paper details a laboratory test
                                                                                            of an Enviropod 200 and shows there is approximate 10% reduction if a 400 micron
Enviropod Filter                                                                            screen is used. Figure 5 details the performance of the Enviropod with different particle
                                                                                            size distributions. The Enviropod 200 was tested up to 20 l/sec; a conservative value of
Sizing                                                                                      10 l/sec was therefore adopted as the treatable flow rate (see Enviropod Sizing).
There are two Enviropod nodes one for the GPT bag and one for the 200 micron filter.
For the 200micron Enviropod it is assumed that that the treatable flow rate (TF) of the
systems is 10 l/sec. For the GPT bag is assumed the TF is 50l/sec. When first installed
the systems have a much higher rate however the values are conservatively adopted as it
will eventually fill and clog.

Ingal’s research has shown that are approximately 4 Enviropods per hectare of residential
land use and approximately 5 for Commercial land use.