Reference Document MCU22-0102 Stormwater Management Plan

SQIDEP Evaluation                                                                                                        SPEL Basin, Sippy Downs


1.       INTRODUCTION ....................................................................................................................................... 4

     EVALUATORS INDEPENDENCE DECLARATIONS................................................................................................................ 4
     STATUTORY DECLARATION BY INDEPENDENT MONITORING SCIENTIST ............................................................................... 4
     BACKGROUND ........................................................................................................................................................ 4
     REVIEW DOCUMENTS............................................................................................................................................... 5
     SIPPY DOWNS SPEL BASIN ....................................................................................................................................... 5
     PERFORMANCE CLAIM.............................................................................................................................................. 8
     SITE BACKGROUND AND ASSUMPTIONS ....................................................................................................................... 8

2.       SQIDEP COMPLIANCE ............................................................................................................................ 11

     COMPARISON OF INFLOW CONCENTRATIONS .............................................................................................................. 20
     DISSOLVED INORGANIC NITROGEN............................................................................................................................ 21
     POLLUTANT REMOVAL AND STATISTICAL ANALYSIS ........................................................................................................ 21
     REPORTED CONCENTRATIONS ANALYSIS .................................................................................................................... 21
     RAINFALL REVIEW ................................................................................................................................................. 25
     CHERRY PICKING OF STORM EVENTS ......................................................................................................................... 27

3.       EVALUATION OF ENDURING PERFORMANCE ......................................................................................... 29

4.       DISCUSSION ........................................................................................................................................... 30

5.       CONCLUSIONS ....................................................................................................................................... 33

6.       REFERENCES .......................................................................................................................................... 34

7.       APPENDIX A – TYPICAL CONCENTRATIONS ............................................................................................ 35

8.       APPENDIX B – STATISTICAL CHECK ......................................................................................................... 37

     APPENDIX C – RAINFALL AT PALMWOOD ACROSS TESTING PERIOD .................................................................................. 42


FIGURE 1 SPEL BASIN DIAGRAM AND CATCHMENT TEST LOCATION (DRAPPER, 2019) ......................................... 6
FIGURE 2 SQIDEP PATHWAYS ................................................................................................................................. 7
FIGURE 3 STREETVIEW OF MONITORING STATION (GOOGLE STREETVIEW , IMAGE CAPTURED JUNE 2017) ..... 10
FIGURE 4 RADAR RAINFALL CHECKS ..................................................................................................................... 26
FIGURE 5 REPORTED RAINFALL AND MONITORING RECORDS. ............................................................................ 27
FIGURE 6 FINAL AGREED POLLUTANT REDUCTION PERFORMANCE .................................................................... 31


TABLE 1: TYPICAL POLLUTANT CONCENTRATIONS FOR ROAD CATCHMENTS ..................................................... 20
TABLE 2 COMPARISON OF CONCENTRATIONS AND ANTECEDENT CONDITIONS ................................................. 22




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