Sustainable storm water management schemes must be integrated design solutions involving a set of measures suited to specific local conditions. Such an integrated storm water system has not only to consider and manage storm water in present climate conditions, but also all potential future climate change scenarios (e.g. more intense rain events, less rain, rising temperatures etc.). Comprehensive long-term planning for storm water is crucial and should involve integrated designs utilizing various innovative technical solutions, including BGI.
There are three basic recommended stages to be taken when managing storm water in urbanized areas:
- The first step is based on the idea of keeping storm water where it falls and retaining it locally.
- If the amount of water is too great for local retention, then in the second step it is necessary to store storm water in extra storage capacity – either naturally or artificially created.
- Excess storm water that cannot be retained or stored must be, in a third step, slowly drained through available or created waterways.
It is important to consider the design, construction and maintenance costs of BGI. Experience from many European countries suggests that maintenance costs and responsibility for maintenance of Sustainable Drainage System (SuDS) is usually more challenging than the cost of implementing SuDS in new developments. Responsibility for maintenance of SuDS needs to be clearly defined in legislation. However, financial costs of implementation can still present obstacles, particularly when robust legislation requiring SuDS is not in place. Various tools exist for comparing costs, potential benefits and cost savings over the lifetime of projects.
SuDS are sometimes incorrectly viewed as being more expensive than conventional storm water management. This misconception comes from too narrow a focus on investment costs for projects in city centres. On the contrary, they are usually more cost effective than conventional methods, and they also bring additional multiple benefits.