Flood Protection Scheme Feasibility Studies
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ITEM: 5 PAGE: 1 REPORT TO: ECONOMIC DEVELOPMENT AND INFRASTRUCTURE SERVICES COMMITTEE ON 20 OCTOBER 2015 SUBJECT: FLOOD PROTECTION SCHEME FEASIBILITY STUDIES BY: CORPORATE DIRECTOR (ECONOMIC DEVELOPMENT, PLANNING AND INFRASTRUCTURE) 1. REASON FOR REPORT 1.1 To ask the Committee to consider studies into potential flood protection schemes at Hopeman, Dallas, Portessie and Arradoul and agree a course of action, making recommendations to The Moray Council where there are budgetary implications. 1.2 To ask Committee to note the revised programme and a potential grant funding opportunity for Newmill Flood Protection Scheme Phase 2. 1.3 This report is submitted to Committee in terms of Section III (F) (21) of the Council's Scheme of Administration relating to the functions of the Council under the Flood Risk Management (Scotland) Act 2009. 2. RECOMMENDATION 2.1 It is recommended that Committee:- (i) recommend to The Moray Council that Flood Protection Schemes for Hopeman and Portessie are taken forward and the Capital Plan amended to include £830,000 for the Hopeman scheme and £3.65 million for the Portessie scheme; (ii) note that Dallas is considered to have flood protection to the normal 1 in 200 year design standard, and consider whether protection beyond that standard should be provided; (iii) agree that there is no practical or economic means of providing further flood protection to Arradoul by means of a Flood Protection Scheme and it therefore is not taken forward; and (iv) note the change to construction start date and opportunity of potential grant funding for Newmill Flood Protection Scheme Phase 2. ITEM: 5 PAGE: 2 3. BACKGROUND 3.1 On 10 February 2015 this Committee (Para 5 of the Minute refers) agreed: - (i) to note that actions to address flood risk in certain areas will be included in Flood Risk Management Strategies and Plans for 2016 – 2022; (ii) that four of the seven areas under consideration, namely Hopeman, Dallas, Portessie and Arradoul be taken forward to completion of a high level feasibility study in parallel. This study to be completed within six months, with the assistance of external consultants with associated cost implications; (iii) that the works required in regard to extending the flood wall upstream at Longmorn area be undertaken in house as outlined by the Consultancy Manager; (iv) to make recommendations to The Moray Council where there are budgetary implications of using external consultants, and (v) that the local ward members receive a map of the affected areas in relation to the Portessie area. 3.2 On 17 March 2015 Policy and Resources Committee agreed to allocate £150,000 from reserves to fund feasibility studies for four small flood protection schemes at Hopeman, Dallas, Portessie and Arradoul (paragraph 7 of the Minute refers). 3.3 Subsequently, the Council’s framework consultant, JBA Consulting, was appointed in March 2015 to undertake these studies. The findings from each study are discussed below and executive summaries are in the APPENDIX. Dallas 3.4 On 11 August 2014 a prolonged period of very intense rainfall was experienced across Moray. In the Dallas area 126mm of rain was recorded over a twelve hour period. This rainfall contributed to out of bank flow from the River Lossie, which caused 27 properties in Dallas to flood internally and a further twelve to flood externally, i.e., gardens. 3.5 JBA found that the flooding was representative of the predicted inundation that would occur during a 1 in 1,000 year flood event. Data from the upstream flow gauge at Torwinny suggests a 30 to 50 year flood event. Rain gauges near to Dallas recorded in excess of 1,000 years return period with a pulse of high intense rainfall to the north of Dallas between 5am and 6am. This may have concentrated extremely high river flows at Dallas. Modelling suggests other potential causes such as blockages are unlikely. As river flow is not gauged at Dallas there remain uncertainties but evidence indicates this was an extremely rare event. ITEM: 5 PAGE: 3 3.6 A number of options were appraised to protect the properties in the village and the road to Elgin but it is uneconomic to protect both Dallas and road to a 1 in 1,000 year standard. A lower cost option that would protect the properties in the village but not the road would involve constructing a set back embankment between the properties and the river. The estimated cost of this option would be £280,000, with a Benefit : Cost Ratio (BCR) of 1.82. 3.7 JBA found that properties at Dallas are currently protected to a 1 in 200 year standard. Normally the Council would not take action because 1 in 200 year is the normal design standard for flood schemes and is the standard of protection that would satisfy requirements for planning permission for building homes at this location. However given the aforementioned uncertainties, and that flooding actually occurred, the lower cost option highlighted in paragraph 3.6 above may be a consideration, bearing in mind that it is unusual to provide 1 in 1,000 year standard of protection other than to certain critical infrastructure. Hopeman 3.8 On 11 August and 9 October 2014 intense rainfall resulted in surface water runoff from the fields to the north of Hopeman flooding 22 properties internally and a further 11 externally. JBA found that during a 1 in 200 year flood event 62 properties would be inundated. 3.9 A number of options were appraised. The preferred option is a cut-off channel to the south of the village, which would convey flood flow to the burn that runs between the village and the golf course, discharging into the sea. The high level cost estimate is £830k with a BCR of 1.26 which is sensitive to any cost increase. There would remain residual flooding from rainfall on the urban landscape. Arradoul 3.10 Surface water flooding has been an issue at Arradoul for some time. A small scheme to address this flooding to the east of the village was completed in 2011. Properties in the west of the village remain at risk from surface water flowing from the fields to the north and from the A98. Information provided by local property owners indicates that four properties flood internally and a further seven flood externally. JBA found that a 1 in 200 year flood event would flood three properties internally and further twenty three may flood below floor level. 3.11 Because these properties sit in a hollow, intercepting flows makes little difference – rainfall directly over properties would cause flooding, which diminishes the BCR to less than 1. 3.12 The study considered property level protection (PLP) (e.g., door guards, airbrick covers, non-return valves, etc.). With no flood warning system, automatic PLP would be necessary at an estimated cost of £610,000 (all 26 properties) and a BCR of 1.62. The Council has not provided PLP to private properties previously and to do so may set a precedent for all of Moray. There are considerable unresolved issues relating to liability, operation and maintenance of PLP for private homes provided by Councils and this option is ITEM: 5 PAGE: 4 considered a high risk. Any scheme to assist owners of private property with PLP or install it as part of a scheme would require a study into the implications with a view to adopting a policy. The matter is currently the subject of a national discussion among local authorities and at this point in time it would be premature for this Council to progress a policy alone. Portessie 3.13 Properties along Great Eastern Road in Portessie have suffered flooding from wave action during recent storms. A door-to-door survey found that 19 properties have flooded internally during these storms. JBA found that during a 1 in 200 year coastal event 40 properties are at risk of flooding, increasing to 71 properties taking climate change into account. 3.14 A number of options were appraised including: replacing the existing set back wall with a higher and longer one; building a new wall to the rear of the revetment; increasing the width of the revetment; and, PLP. Only two options have a BCR of greater than 1; replacing the existing wall and PLP, the latter being unsuitable in a climate change scenario. The high level estimated cost of replacing the sea wall is £3.65 million with a BCR of 1.14. The BCR is sensitive to cost increases. 3.15 There would remain surface water flood risk which would be assessed as part of the Surface Water Management Plan for Buckie. 4. NEWMILL FLOOD PROTECTION SCHEME PHASE 2 4.1 Newmill Flood Protection Scheme Phase 2 was originally programmed to start construction in Autumn this year. In consultation with ward members, the Chair and Vice-Chair, this has been revised to May 2016 due to environmental constraints of fish migration and badger breeding. 4.2 As a consequence of the delay, SEPA has inserted this scheme into the Local Flood Risk Management Strategy for the North East (2015 – 2021). This means that the scheme now meets the eligibility criteria for 80% grant funding under new rules. The methodology for allocating grant funding across Scotland is not yet in place, so there are no guarantees. Equally, the amount of funding available is subject to the forthcoming spending review. 5. SUMMARY OF IMPLICATIONS (a) Moray 2023: A Plan for the Future/Service Plan (i) This is relevant to Section 4.2 of the Service Plan – “support sustainable economic development whilst safeguarding the natural and built environment”.