RFI - Attachment B - Stormwater management Report · MCU20/0026

       50mg/L of total suspended solids (TSS) as a maximum concentration;

       Turbidity (NTU) value less than 10% above background;

       pH value must be in a range 6.5-8.5 except where, and to the extent that, the natural receiving
        waters lie outside this range.

Defects in erosion and sediment control devices, such as sediment fences, are to be inspected and
documented. Upon Inspection, the contractor is to determine whether the device should be replaced or
repaired. Documentation is to include how the damage was caused and what measures can be
implemented to reduce the possibility of repeat occurrences. Any damage to either permanent or
temporary water quality control structures or devices is to be immediately rectified at the contractor’s
expense.

The effectiveness of the erosion and sediment control devices can be monitored by visual audits. All
ESC measures are to be inspected:
       at least daily (when work is occurring on site) or weekly (when work is not occurring on site);

       within 24 hours of expected rain; and

       within 18 hours of a rainfall event (i.e. an event of sufficient intensity and duration to mobilise
        sediment on site).

Drainage paths are to be inspected to ensure the sediment fences are not being bypassed as a result
of soil erosion.

Sediment laden runoff shall be prevented from entering neighbouring properties. This shall be achieved
by landscaping disturbed areas immediately and prior to a rainfall event.
4.2.3 M aint en an ce and M onit o ri ng R equ ir em ent s

Periodic maintenance and monitoring of stormwater devices proposed in this report is crucial to ensure
effective operation and design life.

Inspect field inlet grates, pits and underground pipes for blockage or damage at least 6 monthly or after
significant rainfall event. The filter baskets shall be inspected and maintained preferably by the
manufacturer to avoid damage to units and to ensure adequate cleaning and record keeping. For the
first 12 months routine inspections of filter baskets shall be carried out monthly with routine clean out
at alternate months. Results of the initial 12 months maintenance program shall be used to determine
future maintenance intervals. Refer manufactures maintenance and monitoring methodology for
specific details. Maintenance of ESC measures must occur in accordance with Table 10.

Table 8 - ESC maintenance requirements.

               ESC Measure                      Maintenance Trigger              Timeframe for Completion
                                                                                     of Maintenance

 Sediment basins                         When settled sediment exceeds          Within 7 days of the
                                         the volume of the sediment             inspection.
                                         storage zone

 Other ESC measures                      The capacity of ESC measures           By the end of the day.
                                         falls below 75%.

Sediment accumulation on ESC devices is to be removed and disposed of to the satisfaction of NSC.




11 June 2020                           Stormwater Management Report                                      11
S20-023                              40 Park Crescent, Sunrise Beach