OPW 15-0099 RFI Response combined scan

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

PO Box 10349 Adelaide Street
Brisbane QLD 4000

T (07) 3895 3444

ABN 38 169 428 506

Project:

Sediment Basin Sizing

Palm Lakes Resort, Cooroy

C=

calibre

CONSULTING

 

Designed: |AY

 

 

Date: 28.07.15

 

 

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*Riyx, s-aay)"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 | Frys, saay)
Basin "any Cv Total Area (Ha)
1 43.10 0.63 2.34
Table 2: Sediment Basin Volumes
Sediment
Sediment Settling Storage | Total Volume
Basin | Volume (m*)| Volume (m’)
(m’)
1 635 318 953

 

 

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 Spliiiway Design

 

 

 

 

 

 

 

 

 

 

Sediment 7 Time of Coeftieint of
Basin | Design ARI Q(m*/s) | concentration eer Runoff
Spillway (years) (min) omy (impervious)
1 20 1.14 10.00 190 0.92
Weir Length: 8.5m
Depth of water over welr: 0.199 m
Freeboard over water level to Crest: 0.30 m