603 - 5885 1250 (4 lines) info@mes100.com
Select Page

# Comparison of OSD results between software calculation and excel spreadsheet using ‘Swinburne Method’

OSD Swinburne Method (MSMA 1)

1. Project file MiTS 2 here
2. Software Report here
4. Linear interpolator here

## Objective#

1. Comparison between software calculation and manual calculation. To ensure that the results are the same
2. Software extract the correct value from Design Chart/Table in MSMA 1

## Project Development details#

Area: 0.687 ha

100 m of overland flow

520 m flow in an open drain

Catchment area average slope 1%

MSMA 1st Edition

## OSD Sizing Procedure (MSMA 1 – Swinburne Method)#

### Select storage type to be used at the site#

• Below-ground storage
• Formula used to calculate PSD and SSR (referring to below-ground storage formula)

### Determine the area of the site that will be drained to the OSD storage system#

• Area: 0.687 ha
• 100 m of overland flow
• 520 m flow in an open drain
• Catchment area average slope 1%
• MSMA 1st Edition

### Determine the amount of impervious and pervious areas draining to the OSD storage system#

Pre-development

• Impervious = 0 ha
• Pervious = 0.687 ha

Post-development

• Impervious = 0.4809 ha
• Pervious   = 0.2061 ha

### Determine the time of concentration, tc and tcs#

Calculate the Pre-Development flows, Qp

Calculate the Post-Development flows, Qa

Determine the required PSD for the site

(Equation 19.1 with Equations 19.1c and 19.1d for below-ground storage)

Determine the required SSR for the site

(Equation 19.2 with Equations 19.2c and 19.2d for below-ground storage)

Determine storage Dimensions