Appendix 3 - Stormwater quality management plan

Operational Management and Maintenance Manual for Stormwater Quality Improvement Devices                                                                       CC-3668



                                            Table 4.1 – Inspection and Maintenance Plan for Bioretention Systems
                                                                                                                   Maintenance         Preventative / Corrective
     Aspect             Performance Indicator           Inspection Frequency          Inspection Activities
                                                                                                                    Frequency           Maintenance Activities
 Vegetation
 Plant height         Average      plant     height                                 Assess plant height       to                     Increase frequency of watering
                      >500mm.                                                       ensure an average         of                     and application of fertiliser. If
                                                                                    >500mm.                                          necessary, re-establish with
                                                                                                                                     species that are growing well in
                                                                                                                                     other parts of the bioretention
                                                                                                                                     system.
                                                       2 monthly during wet
 Plant density        Minimum 95% vegetation                                        Assess plant densities to                        Plant additional vegetation to
                                                       season / 4 monthly
                      cover     (minimal bare                                       ensure a minimum of 95%                          increase the density. Increase
                                                       during dry season
                      patches).                                                     vegetation cover.                                the frequency of watering and
                                                                                                                                     application of fertiliser.
 Pests          and   Plants healthy and free from                                  Assess plants for disease,     As inspection     Prune, treat or replace as
 diseases             pests and diseases.                                           pest infection, stunted        results dictate   necessary to remove dead or
                                                                                    growth    or    senescent                        diseased vegetation material
                                                                                    plants.                                          and to stimulate new growth.
 Weeds                No declared weeds (or            2 monthly during wet         Identify the occurrence                          Implement the most appropriate
                      declared     weeds are           season / 4 monthly           and coverage of any weed                         control method (e.g. physical
                      controlled).                     during dry season.           species.                                         removal, containment, biological
                      Maximum 10% cover of             Inspection frequency                                                          control, herbicide application,
                      weeds.                           may need to be                                                                etc) for the weed species
                                                       increased whilst                                                              identified. Inspection frequency
                                                       implementing weed                                                             may need to be increased during
                                                       control measures.                                                             active control of weeds.
 Inlet
 Erosion              Inlet is structurally sound                                   Identify any scouring of                         Repair damage to the inlet
                      and there is no evidence of                                   the inlet from storm                             resulting from scour and if
                      erosion or subsidence /          Immediately following        flows.                                           necessary        install    scour
                      settlement.                      first 3 storm events after                                                    protection or energy dissipation.
 Damaged       or     No damage that poses a risk      construction complete.       Check the inlet structure      As inspection     Repair and/or replace damaged
 removed              to public safety or structural   Then 2 monthly during        for any damage or loss of      results dictate   or lost infrastructure.
 structures           integrity.                       wet season / 4 monthly       infrastructure.
 Sediment, litter     No blockage.                     during dry season            Identify any blockage.                           Remove sediment, litter or
 or debris                                                                                                                           debris to remove blockage or
                                                                                                                                     potential blockage.



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