Attachment C - Stormwater report

Pollutant                                                                                    Pollutant Load

Total Phosphorus (kg/yr)                                                                        11,600

Total Nitrogen (kg/yr)                                                                          60,500

Gross Pollutants (kg/yr)                                                                        491,000
These results show the average annual flow rate and pollutant loads generated by the (approximately)
3600 ha catchment based on the QLUMP mapping and assumptions described in previous sections of the
report. As detailed in Section 3.2, the tomato farm utilises approximately 3,840 kg/yr of TN and 512 kg/yr of
TP. This represents only 6.3% and 4.4% of the total TN and TP loads respectively. It is important to note that
these values for the tomato farm represent the total nutrient load for the hydroponic operation in a year.
The actual load in the irrigation system at any one time is far less than this and these calculations do not
take into consideration the uptake of nutrients by the plants. Furthermore, as previously discussed, the
operators can flush the system and remove the irrigation water from the greenhouse in the event of a
major storm event. Therefore, the likelihood of any of this water entering the adjacent waterway is
extremely low.

4.4.         Site Specific MUSIC Model
4.4.1.       Model Objectives
The objective of the MUSIC model is to accurately represent the site and facilitate stormwater quality
management. Stormwater quality management aims to protect the quality of receiving waters by limiting
the quantity of stormwater pollutants discharged to the receiving environment as a result of urban
development.

4.4.2.       Pollutant Export Parameters
The pollutant export parameters have been adopted from Table 3.8 of the MUSIC Modelling Guidelines
Version 1.0, as summarised in Table 7.
Table 7 - Pollutant export parameters for Roof source nodes (extracted from Table 3.8, Water by Design, 2010).

                                                                10                         10                         10
             Flow Type         Pollutant Source         TSS log values              TP log values             TN log values

                                                        Mean           St. dev.     Mean        St. dev.      Mean         St. dev.

               Baseflow        Roof                        N/A             N/A       N/A           N/A         N/A           N/A

               Stormflow       Roof                        1.30            0.39      -0.89         0.31        0.26          0.23



The following water quality objectives have been adopted from the Queensland State Planning Policy’s
Water Quality Code.
Table 8 - Water Quality Objectives.


                         Minimum reductions in Mean Annual Loads from unmitigated catchment

   Total Suspended Solids                Total Phosphorus                   Total Nitrogen                 Gross Pollutants


Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive                                                     Page 16

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