CDR/2011/034 1. Purpose of the Re

Report to the:- Wards All Cabinet – July 2011 Planning Committee – 21 June Hull City Council Aqua Greens Progress Report Report Number: CDR/2011/034 Report of the City Planning Manager on behalf of the Corporate Director for Regeneration 1. Purpose of the Report and Summary 1.1 The purpose of this report is to brief members on the Aqua Greens project progress. The project has reached the end of the feasibility stage and a review of the document prepared by the Councils Flood Risk Planning Manager is presented below, it can be used alone or as a guide when viewing the document. Future funding options have been explored and recommended next steps are given in the options section. 1.2 The council developed a Surface Water Management Plan which was completed in December 2009, the plan recommended surface water storage options as Aqua Greens – dual purpose flood storage and amenity green spaces – at Orchard Park and Derringham. The council retained Halcrow Group Limited to deliver the feasibility study for these two locations. Funding is via DEFRA surface water management grant and Yorkshire Flood Defence Committee Local Levy. 1.3 The study has investigated the options to develop a business case to fund technically, environmentally and financially beneficial schemes at both sites through hydraulic modelling, survey and investigations. 1.4 Aqua Greens have been shown as feasible at both sites with flood storage options at Springhead Park Golf Course in Derringham and diversions of Creyke and Wanlass Beck north of Cottingham and an Aqua Green storage site protecting Orchard Park. Both schemes present wider benefits to Willerby and Cottingham respectively. 1.5 Additional schemes are being promoted by East Riding of Yorkshire Council, these schemes look to address the origins of flood flows nearer their source to the west of the city. Funding organisations recognise that there are benefits to the city in these additional schemes and have recommended that they receive joint bids for funding where ERYC and HCC schemes are hydraulically dependant upon each other. 1.6 All appraisal information is being shared and joint funding bids are currently being prepared for DEFRA grant in aid and European Regional Development Fund financial support, these would be match funders delivering 100% of scheme costs. This will give the maximum benefits to all residents and businesses across the whole catchment and will show close partnership working between two Lead Local Flood Authorities. 2 Recommendations It is recommended that the Committee: 2.1 Agree to the findings of the Aqua Greens Feasibility document and to agree to the progression of the Aqua Greens options in combination with ERYC schemes – a combined Willerby and Derringham scheme and a combined Cottingham and Orchard Park scheme through partnership working and joint funding submissions. This is a none key decision. 3. Introduction 3.1 The Hull City Council Surface Water Management Plan (SWMP) identified high risk surface water flooding locations across the city, it recommended development of Aqua Greens, dual purpose surface water flood storage and green space amenity sites, at Derringham and Orchard Park. Halcrow Group Limited were retained to deliver a feasibility study to develop the business case for these options. Funding has been obtained from DEFRA surface water management and Yorkshire Flood Defence Committee Local Levy grants. 3.2 Flood modelling and mapping has been undertaken at both locations to develop the findings of the SWMP, survey and site investigations have been undertaken and discussions have been held with all partners to further understand the issues during flood conditions. 3.3 Preferred options have been developed at both sites which reduce the risk of flooding in the Derringham and Orchard Park areas of the city and provide wider benefits across the administrative border to Willerby and Cottingham respectively. Both solutions are cost beneficial and would allow further funding discussions to be progressed with partners. 3.4 Funding bids have been made to DEFRA Grant in Aid (GiA, via the Environment Agency) and European Regional Development Funding (ERDF). Recommendations have been made that works progressing further to the west of the city by ERYC should be considered with Aqua Greens schemes and joint funding bids would be most likely to receive future funding allocations. This is currently being considered by both authorities. 4. Aqua Greens Feasibility Report Derringham 4.1 A technical note appended to this paper as Appendix 1 details the approaches taken within this commission, further information on the options considered is given within this note. The full report will be made available to members if required. 4.2 Halcrow Group Limited developed their work on the SWMP through detailed hydraulic modelling of the watercourses and surface water flow routes affecting Derringham and Orchard Park. An assessment of the major sources of flood risk for both sites was made and options were developed to reduce the impacts of future flooding. 4.3 Flood flow routes into the Derringham area were confirmed to be from the higher rural areas to the west, flows pass through Willerby and surrounding urban areas and eventually pond in the lower lying land around Derringham. Flows pass along Willerby Road, Wolfreton Lane and ultimately spread through surrounding streets. 4.4 Options considered looked at attenuating flows at Derringham – an aqua green at Springhead Park Golf Course, attenuating flows north of Derringham (Willerby Carrs) and diverting flows from the north of Derringham. The major flows into the area were found to be from the west and north west and although attenuation or diversion of flows from the Willerby Carrs area would have some benefit this would be minimal in comparison, all flows held or diverted in this area would also ultimately pass into the Setting Dyke system which would put further pressure on the sewerage infrastructure as the Setting Dyke flows directly into the main trunk sewer. 4.5 The proposed option is to store surface water flood flows in a terraced set of lagoons on Springhead Park Golf Course, flows would be diverted in a new dyke constructed from Well Lane at Willerby Carr Lane Primary school. Flood flows would be carried in a new dyke system to the north- west corner of the golf course to utilise the terraced storage system. 4.6 The costs of the scheme would be £2.56M providing benefits of £3.31M for Derringham and Willerby through the reduction of flood damages – a 60% optimism bias is included in the costs according to HM Treasury guidelines, all relevant HM Treasury approaches have been used throughout. The scheme has a benefit cost ratio of 1.3. Orchard Park 4.7 The hydraulic modelling confirmed that flood flows into Orchard Park were derived from the large rural areas to the north and west draining through Wanlass and Creyke Becks to the north of Cottingham, when flows overtop the left banks of these watercourses surface water flows into the Orchard Park area. Further flood flows are derived from the west of Cottingham, ERYC are currently developing a scheme to attenuate flows from the Raywell Valley. This scheme has received planning permissions and construction is due to start, the flood storage and resultant reduction of flood levels in Orchard Park due to this work have been factored into the base case scenarios for the Orchard Park Aqua Green feasibility works. 4.8 The project team considered options, 20 options were identified, and these are discussed further in the technical note, Appendix 1. Options included the Raywell Valley Scheme and an increased version of this but this still left flood flows from the north and west of Cottingham as an issue. Attenuation further north and west around Skidby provides benefits but this is too far up the catchment to have significant effect, a diversion to the Humber would be too costly. Property level protection was considered and a range of diversion and attenuation of Creyke and Wanlass Beck options were investigated. 4.9 The preferred option is the diversion of Creyke and Wanlass Beck into the Beverley and Barmston Drain via Counter Dyke, attenuation is required to ensure flood flows do not present an increased flood risk to the drain during storm conditions. Storage would be provided around the edge of the Orchard Park estate as an Aqua Green site, this could be a linear site along the length of Counter Dyke or a separate storage area, amenity values would be considered for both options. The resultant stored flood flows would be slowly released into Beverley and Barmston Drain when levels in the drain recede. 4.10 The costs of the scheme would be £2.92M providing benefits of £22.92M for Orchard Park and Cottingham through the reduction of flood damages – a 60% optimism bias is included in the costs according to HM Treasury guidelines, all relevant HM Treasury approaches have been used throughout. The scheme has a benefit cost ratio of 7.6. 4.11 Both proposed options have significant implications for land purchase or acquisition (although the majority of land lies in Local Authority ownership), cross boundary working, land management and options working alongside existing land usages – i.e. the operations of the golf course. These issues are raised and discussed to some extent in the feasibility study but considerable work will be required to ensure that all partners understand the issues and risks and these are managed as the projects move forward. Future Funding Options 4.12 HCC have made funding bids to DEFRA Grant in Aid (GiA, via the Environment Agency) and European Regional Development Funding (ERDF) via the Adaptation to Climate Change operational programme to take the Aqua Green options through their detailed design and construction phases.

Load more