OPW 15-0099 RFI Response combined scan

Calibre Consulting (Qid) Pty Ltd
Ground Floor, 545 Queen Street
Brisbane QLD 4000

C#

 

 

 

 

 

PO Box 10349 Adelaide Street a
Brisbane QLD 4000 Calibre
T (07) 3895 3444 CONSULTING
ABN 38 109 428 506
Project: Palm Lakes Resort, Cooroy Designed: [AY
Date: 28.07.15
Sediment Basin Sizing

The sediment basin volume has been obtained by calculating the ‘settling volume’ and ‘sediment
storage volume’. In accordance with the IECA Guidelines (2008), the settling volume has been
calculated using the following formulas.

Basin Type: D
The settling volume (m*) = Vs = 10*Riya, sday)"Cv"A
Where: R= Y%, 5-day rainfall depth (mm) (Table B5 of Guidelines)
Cv= Volumetric run-off co-efficient (Table B7 of Guidelines)
A= Catchment area draining to basin (Ha)
NB (The volumetric run-off coefficient has been determined based on a Group D Clay soil type as a worst case scenario)
The sediment storage volume for Type D basins are calculated using Table B8 of the Guidelines

The storage volume (m°) = 50% of the settling volume

 

 

 

 

 

Table 1: Sediment basin catchment details
Sediment | Risse | cy — | Total Area (Ha)
Basin (mm)
3 43.10 0.63 2.51
Table 2: Sediment Basin Volumes
Sediment
Sediment Settling Storage | Total Volume
Basin | Volume (m*)| Volume (m’)
(m*)
3 682 341 1022

 

 

 

 

 

 

The emergency spillway has been designed to cater for a design storm ARI based on table B12 of
the Guidelines. The spillway length and depth has been designed based on the formula Q=
1.5LH‘1.5 where;

Table 3: Sediment Basin Emergency Spltiway Design

 

 

 

 

 

 

 

 

 

 

Sediment Time of Coeftieint of
Basin | Design ARI ., (m’/s) | concentration ey Runoff
Splilway | 2S) (min) (mm/hr) | ampervious
3 20 1.22 10.00 190 0.92

Weir Length: 9m
Depth of water over weir: 0.201 m
Freeboard over water level to Crest: 0.30 m