Blue Green UK
Promoting the use of Best Technical Knowledge to support Blue-Greening in our cities
SEE03: What are the costs and benefits associated with any adopted scheme?
Chris Binnie has scrutinised the costs and benefits declared for the Thames Tideway Tunnel [IND04]. Within this report a breakdown is given in areas such as health and ecology and it was shown that benefits can be closely related to the assumptions behind them with his calculations showing benefits far less than those previously quoted.
Additional studies are needed to understand current benefits for any scheme. For example, a recent "aspects of fish benefit" report [IND09] concludes, noting report should be read for full listing:
- The objective is to limit ecological damage by ensuring that fish species are sustainable.
- The two big fish kills in 2004 & 2011 were primarily due to Mogden STW overflows. The STW is now upgraded with spill frequency dropping from about 110 spills a year to about 20 spills a year, the limit proposed by the EC. Fish kills as a result of its overflows should not occur in future.
- Salmon are the most sensitive fish species but are no longer sustainable because of adverse temperature and marine conditions. It should be considered to replace them with a similar species or reconsider the dissolved oxygen table.
- Post the current works, fish in the Tideway would be sustainable and, subject
to the future conditions not worsening, no further works would be required to meet ecology sustainability.
Comments
A similar process needs to be adopted for BG solutions but, for appropriate comparisons to be made, all benefits need to be considered such as flexibility, immediacy and resilience together with all other by-products, such as better air quality, health, reduced pollution and employment opportunities - see "transforming our cities" bullet points on Home Page.