RFI - Attachment F - Engineering Report

Evaluation of Gully Pit Inlet Litter Control Systems– Brisbane City Council and Gold Coast City Council

                3.3 Tray Basket


                The tray basket insert (Appendix A) was tested for capture and hydraulic
                performance under similar conditions.


                Test results and observations:


                Litter capture performance.
                On-grade
                •    40% of the litter added to the approach flow (25L/sec) was retained
                     in the basket for all on-grade longitudinal slopes.
                •    Once the basket became blocked nearly all (90%) of pollution added
                     thereafter bypassed the basket.
                •    At the steeper (12%) grade the basket was more effective in capturing
                     the litter.
                •    As the approach flow increased, the litter capture performance of the
                     basket was marginally better at the 12% grade than for 1% and 4%.
                     However, when subjected to an approach flow of 330L/sec, only 2%
                     of the pollution was retained in the basket for all grades.


                Sag
                •    The pit was bisected for the sag test to simulate flow from opposing
                     directions (see Figure 5). The basket retained 80% of the litter with
                     the approach flow set at 50L/sec. However it did not retain any of the
                     larger plastic litter.




                Urban Water Resources Centre              12             University of South Australia