Appendix 2 – Dunkeld Flood Study – Short List of Potential Options

Page 1

Appendix 2 – Dunkeld Flood Protection Study – Short List of Potential Options 
Option
1a
Option
1b
Option
2a
Option
2b
Option
3
Option
4a
Option
4b
Option
4c
Properties
protected in
1 in 100
year flood  
35 35 9 6 0 0 0 0
Standard of
Protection 1:100* 1:100** 1:200 +
CC 1:100 1:1000 1:100 1:100 1:200
Capital Cost £672k £628k £1,246k £839k £3,879k £1,831k £1,837k £1,966k
Benefit 
Cost Ratio
2.17 2.21 0.53 0.49 0.17 0 0 0.001
Assessment
*Option 1a provides an
additional degree of
flood protection (due to
higher culvert
headwalls) but does not
increase the number of
properties protected, as
flood mechanisms
change at higher return
periods.
**Option 1b provides a
degree of protection to
35 properties but flood
protection products are
required to be fitted to a
further three homes. 
Option 1b offers a
greater cost benefit,
with lower
environmental/social
impacts.
Option 2 meets the
study objectives by
providing flood
protection to all
properties at risk.
However significant
capital costs make
both options
unviable, and the size
of defences are
unlikely to be
environmentally or
socially acceptable.
Option 3 involves
returning
Burnmouth Road
to flood plain and
requires the
purchase (not
protection) of all
9 affected
properties, and
an additional 3
properties with
access from
Burnmouth Road.
The purchase
costs are
significant,
making this
option unviable.
It would also
have social
impacts.
Option 4a would involve a flood
wall only; 4b a combination of wall
and embankment; 4c a higher
wall/embankment. 
This option does not meet the study
objectives and has very limited
benefit in terms of reducing flood
risk to properties. This option was
initially considered to better
understand the interaction
between the Tay and the overland
flow discharging from the
Spoutwells and Sawmill Brae burns. 
The works would be intrusive and
require substantial construction and
land resources.