RFI - Attachment F - Engineering Report

assess the effectiveness of these systems. He found that 38 to 58% of the TN were
NH3/NH4 and NOx, which is very similar to Contech (2012) study in USA where 44%
of TN were in the category of NH3/NH4 and NOx.

The Contech (2012) did not include a PSD breakdown of the suspended solid load
and only refers to the < 2000 μm fraction and the < 500 μm fraction. Pace and Test
America referred to the texture of the suspended solids sampled as loamy sand.
However, additional sieve analyses of the sediment, captured within the system,
undertaken by GeoTesting Express on 5 September 2014, determined that in excess
of 80% of the sediment was < 75 μm in diameter. This is consistent to the
suspended solid loads used in Australian design (≤ 125 μm) (Brodie & Rosewell,
2008, Hunter, 2008).


5. Conclusion
Based on this literature review, the following conclusions can be made:

    The sampling and monitoring protocol of the Mitchell Community College
     carpark undertaken by the Contech Engineered Solutions are largely consistent
     with the Australian and New Zealand Guidelines, NQWMS (2000). Hence, the
     test results from Mitchell Community College carpark are deemed to be
     reliable.

    The concentrations of pollutants in the influent of the Mitchell Community
     College carpark testing are found to be much smaller than Australian observed
     data reported in the literature. Hence, the efficiency ratio for StormFilter®
     system could be higher for typical Australian conditions.

    StormFilter uses activated alumina as filter media, which has a very high
     surface-area-to-weight ratio due to the many tunnel-like pores within it, and
     hence it is ideal to remove significant proportion of pollutants from urban runoff.

    StormFilter system is used with a storage tank, which allows releasing of
     appropriate volume of runoff to the StormFilter, and hence its performance is
     unlikely to be affected by rainfall intensity at the site of interest.

    Significant reductions for solid and nutrient pollutants were observed in the
     Mitchell Community College carpark testing between influent and effluent
     sampling locations using the Efficiency Ratio (ER) calculation (TSS 90.4%, TP
     86.1%, and TN 55.9%). This compares very well for typical Australian design
     criteria of removing minimum 85% of the Suspended Solids, 65% of the Total
     Phosphorus and 45% of the Total Nitrogen average annual loads. Hence,
     StormFilter is likely to achieve pollution removal targets from urban runoff
     required by local councils in Australia.




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