Making space for water
Urban flood risk and integrated drainage
Camborne, Pool & Redruth (Kerrier District Council with CRP Regeneration)
Pilot Summary
This report has been prepared to present the findings of the CPR Integrated Urban Drainage (IUD) Pilot Study. It should be read in conjunction with the CPR Surface Water Management Plan (SWMP), which is the main deliverable from the study and which is supplied as a separate volume to the report.
The SWMP has been developed by a steering group led by CPR Regeneration (URC) and including representatives from the Environment Agency, Kerrier District Council, South West Water, Cornwall County Council, Red River Working Party and South West Regional Development Agency. Entec UK were the consultants to CPR and carried out much of the technical work and preparation of the reports. Camborne-Pool-Redruth (CPR) is a former mining area in south Cornwall currently seeking to develop through a substantial regeneration programme.
It has a number of drainage problems primarily relating to lack of capacity within the existing combined foul and surface water sewerage system and resulting in poor water quality in receiving watercourses and on nearby coastal beaches due to excessive CSO spills. The area is underlain by deep mines which contribute poor water quality base flow to the watercourses.
This report describes the approaches and methods used in developing a SWMP for the CPR area. These have included the formulation of general drainage principles for the area, review of available data and models and the development of a strategic approach to modelling based on eight sub-catchments established during the study. The main objectives are to draw water away from the existing sewerage system by the establishment of above-ground drainage systems incorporating overland routes and storage areas allied with green corridors and other amenity features. A second aim has been to avoid infiltration to the mines beneath which would exacerbate water quality problems downstream and inhibit possible future return to tin mining.
The strengths and weaknesses of the modelling approach are outlined together with the limitations of the data and due to time and cost constraints. Guidance is given for more detailed studies appropriate to the scale of the study envisaged.
The report also sets out the main benefits of the SWMP approach which include the facilitation of forward planning of new development and the provision of greater clarity on the drainage requirements for potential developers. A key benefit is the removal of surface water from the existing combined sewers thereby releasing capacity for future foul flow from development and resulting in improved water quality in the rivers and on the coastal beaches. A further benefit is that redevelopment of urban areas (and their drainage system) provides an opportunity to mitigate the impacts of climate change with respect to flood risk. If left alone the urban area would be at increased risk of flooding under climate change.
Potential barriers to implementation are discussed including planning and the timing of ongoing development. Key to the success of the SWMP will be the long-term adoption of the SWMP as a planning support document and its ongoing maintenance as a 'live' document. It is proposed that some form of Drainage Trust is set up to operate and maintain the strategic drainage infrastructure. The form that this trust will take is the subject of further investigation. It is hoped that this pioneer study can be applied to other urban areas and provide a template for further IUD studies of this nature.
Outputs
- Final Report
- Appendix
- Surface Water Management Plan
- Surface Water Management Plan Appendix A
- Surface Water Management Plan Appendix B
- Surface Water Management Plan Appendix C
- Surface Water Management Plan Appendix D-F
Page last modified: 25 June 2008
Page published: 5 March 2007