Attachment C - Stormwater Mangement Plan

6.0    PROPOSED INCREASE IN IMPERVIOUS AREA DUE TO DEVELOPMENT:
       1. Total site area of Lot 2 = 15,997m2

       2. Proposed increase in impervious area
           Car Park A.                                =       110.4m2
           Car Park B.                                =       87.4m2
           Car Park C.                                =       87.4m2
           Caretakers Residence                       =       194m2
           Caretakers Shed = 12 x 10                  =       120m2
           Recreation Shelter = 12 x 12               =       144m2
           18 x Glamping Tents = 18 x 12.5 x 4.8      =       1080m2
           Total Proposed Impervious Area (m2) =              1,823.2m2
           Total Proposed Impervious Area (%) =               1823.2/15997 = 11.4%

7.0    WATER HARVESTING TO PROVIDE POTABLE SUPPLY:
This proposed development in Cooroibah is located just 12.5km North East from the
township of Cooroy. Cooroy enjoys an annual rainfall of 1.5m per year (Source Noosa
Shire Council Water Department June 2007).
For each pair of Glamping Tents, all rainwater from each tent roof will be harvested
and directed into the adjacent 23kL rainwater tank. During the year that 1.5m rainfall
will translate into 2 x 12.5 x 4.8 x 1.5 = 180m3 = 180kL ------------------------------(1)
This equates to 180/23 = 7.8 tank fills of water each year.
From Unity water consumption figures, the average daily consumption for the
Sunshine Coast is 150L/person/day.
Using conservative occupancy estimates we get the water demand created for each
pair of Glamping Tents (1 x 23kL tank)
       Week Ends 90% Occupancy = 0.9 x 52 x 2 x 2 = 187.2 guest days/tent
       School Holidays (mid week) 90% Occupancy = 0.9 x 10 x 5 x 2 = 90.0 guest days/tent
       Bal of mid week @ 40% Occupancy = 0.4 x 42 x 5 x 2 = 168.0 guest days/tent

Total Guest Occupancy Day per Tent = 351.6 so 2 tents = 445.2 x 2 = 890.4 guest days/tank (pair of
tents)
So estimated water consumption becomes 890.4 x 150L/person/day = 133,560L = 133kL ---------(2)

When the annual water consumption of 133kL is subtracted from the harvest of 180kL
this only leaves an excess of 47kL and the overflow Vegetated Infiltration & Level
Spreader Swale has a capacity in excess of 22kL, meaning a small volume will top
and become overland flows.


 Revision: B – 2nd August 2021
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