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 38 109 428 506

Project:

Sediment Basin Sizing

Paim 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*Royx, 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 | Ryys,saay) cv Total (Ha)
Basin (mm)
4 43.10 0.63 3.22
Table 2: Sediment Basin Volumes
Sediment
Sediment Settling Storage | Total Volume
Basin | Volume (m*)/ Volume (m’)
(m*)
4 874 437 1311

 

 

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 Spiliway Design

 

 

 

 

 

 

 

 

 

 

Sediment Time of Coeffielnt of
Basin | Design ARI Q(m*vs) | concentration viene Runoff
| spiliway | 8rs) (min) (mm/ht) | impervious)
4 20 1.56 10.00 190 0.92
Welr Length: 12m

Depth of water over welr: 0.196 m
Freeboard over waiter level to Crest: 0.30 m