2160 IWMP Report_Jan2022

                                                                                  Callaghan & Toth

5         WATER CYCLE MANAGEMENT PLAN
This development has been designed to ‘Complying Solutions’ for Water Cycle Management.

To this end, 100% of the existing roof area and the increase in roof area for the new Kauri
building, being a total of 4,118m2 on the site will be connected to three rainwater tanks. The
tanks will have a capacity of 72,000 litres (three x 24,000 litre tanks) which is just below the
complying solutions requirement.

The rainwater tanks will supply water to cold water washing machine supply, toilet flushing and
hose cocks adjacent the building for hand watering of landscaping.
       For landscaping the Water by Design Guidelines specify
       Annual Irrigation Rate = 1,030m2 x 75% x 0.548m = 546 kl/yr
   Daily irrigation rate = 1467 L / day

The tanks sizing can be checked in accordance with the Queensland Development Code MP4.3
per compliance with storage for toilet flushing and Water by Design Music Guidelines Version 1
December 2010 for storage for irrigation of landscaping to Commercial sites.

Complying Solution 1:

Queensland Development Code MP4.3 per compliance with storage for toilet flushing
1500L/pedestal (toilet) @ 45 toilets = 67,500L

10 Day Demand Check

Landscape Area = (1,030m2x0.53m) ÷ 364 x 10 days demand = 15,000L for irrigation.

Total Storage for 10 day Supply = 67,500 + 15,000 = 83,500L

The proposed rainwater tank capacity is 72,000L which is short of the 10 day demand detailed
above. It is considered that this capacity will ensure stormwater quality targets are achieved,
and that reuse demand can be topped up by reticulated water supply for the site when tanks
shortfall.

6         FLOODING ASSESMENT REPORT
6.1       Existing Conditions

This site is subject to ponding of floodwaters from the adjacent channels and the Q100 year ARI
flood levels. The habitable floor areas of the new buildings and new carpark are above the
Q100 year ARI flood levels.

6.2       Proposed Drainage System

The carpark surface level is proposed to be drained to an underground drainage system
capable of taking a Q2 flow. The overflow will discharge to the existing car park and existing
vegetated Bio-Swale.

The habitable minimum floor level for the new Kauri building is to be set at RL107.20 at the
ground level and the upper level is at RL110.62.


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2160, Kabara Upgrade, Cooroy             IWMP.doc                               January 2022