O2 stormwater Report Rev Oct 2015

 3.            Land Use and Nutrient Loads

3.1.         Historical Land Use
The site was previously approved and used as a turf farm for approximately 30 years where, due to the
activities large quantities of fertilizers and pesticides were employed. Calculations using data provided to
O2 Environment + Engineering by the client show Total Nitrogen and Phosphorus applied at the site (in the
form of fertilizer and pesticide) to be:

         Total Nitrogen - 9.95 tonnes per year, and
         Total Phosphorus - 3.34 tonnes per year

Further details in relation to the assumptions made and calculations undertaken to determine the nutrient
loads are contained in Appendix B.

3.2.         Proposed Land Use
The proposed development seeks a Development Permit for a Material Change of Use for a Cultivation
Type 2 Intensive for crops within a 140 x 144 m greenhouse on the site. The greenhouse will be used to
grow tomatoes hydroponically. The current arrangement contains rows of tomato plants in “growbags”, as
shown in Figure 3. Watering of the plants is undertaken using a drip irrigation system as shown in Figure 4.
Irrigation is typically undertaken at a rate of approximately 4L/m² per day.

Each row of growbags and plants are located in lined trenches, with an ag. pipe collection system below the
growbags to collect any excess water. The ag. pipe conveys excess runoff to a 300mm diameter pipe which
conveys runoff out of the greenhouse to a sump, before returning it to the mixing tank for re-use in the
irrigation system. Therefore, the irrigation system is a closed loop system, with any water not utilised by
the plants being recycled. Therefore, there is no chance that unused effluent associated with the
greenhouse irrigation system can either leach down to groundwater then migrate to the adjoining creek
system.




Figure 3 – Hydroponic Tomato Setup                                 Figure 4 – Drip Irrigation System

Based on the information provided by the operators of the greenhouse, current fertilizer and pesticide use
of the tomato farm are substantially less than the turf farm, being approximately:

         Total Nitrogen - 3.84 tonnes per year, and
         Total Phosphorus – 0.52 tonnes per year.

Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive                               Page 3

D’VINERIPE
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