A number of years ago, the then Ewan Associates Ltd (now part of Mouchel) were commissioned to carry out a flood study in Stranraer initially focussing on the Black Stank in Stranraer where it passes the Blackparks Industrial Estate through to the A75.

This work culminated in the July 2009 version of the Stranraer Flood Study Options Report which deals with flooding issues and options for alleviation from all three watercourses – the Sheuchan Burn, the Town Burn and the Black Stank.

•  Stranraer Flood Study Options Report [11Mb]
•  Appendix A - Stranraer Catchment Boundaries [1Mb]
•  Appendix B - Historic Mapping / Drainage Paths of Stranraer [1Mb]
•  Appendix C - West Freugh Hourly Rainfall Totals [9kb]
• Appendix D - Benefit / Cost Analysis -The information contained in these appendices forms the basis of the economic appraisals carried out for the various Work Items. These sheets only contain the key Present Value (PV) (cost and benefit) workings. Various supplementary calculations have been undertaken outside these working spreadsheets to derive the figures contained in the report. Supplementary calculations have included such things as capping, residual damages, updates to the Retail Price Index, optimism bias adjustments and variations to the baseline (do nothing) scenario. The final Work Item B/C ratios are those contained in the report. Further information please contact the Flood Risk Management Team.

Damage Calculations - 13 Flood Damages Files

Stranraer Flood Damages - Work Item 1 (total culvert collapse) [55kb]	Stranraer Flood Damages - Work Item 2 (0% blockage) [53kb]
Stranraer Flood Damages - Work Item 2 (50% blockage) [211kb]	Stranraer Flood Damages - Work Item 3 (50% blockage) [38kb]
Stranraer Flood Damages - Work Item 3 (50% blockage) [38kb]	Stranraer Flood Damages - Work item 4 (50% blockage) [41kb]
Stranraer Flood Damages - Work Item 4 (80% blockage) [36kb]	Stranraer Flood Damages - Work Item 5 (both pipes collapsing) [17kb]
Stranraer Flood Damages - Work Item 5 (single pipe collapsing) [15kb]	Stranraer Flood Damages - Work Item 5 (single pipe collapsing) [15kb]
Stranraer Flood Damages - Work item 6 (culvert opened) [60kb]	Stranraer Flood Damages - Work Item 6 (existing culvert) [48kb]
Stranraer Flood Damages - Work Item 7 [38kb]	Stranraer Flood Damages - Work Item 8 [45kb]

FLAIR Data

 FLAIR 2003 Non Residential Flood Damage Data [13kb]
 FLAIR 2003 Residential Flood Damage Data [16kb]

Benefit Cost Summary Sheets

BC Summary Sheet - Work Item 1 [13kb]	BC Summary Sheet - Work Item 2 (0% blockage baseline) [13kb]
BC Summary Sheet - Work Item 2 (50% blockage baseline) [13kb]	BC Summary Sheet - Work Item 3 (50% blockage baseline) [13kb]
BC Summary Sheet - Work Item 4 (50% blockage baseline) [13kb]	BC Summary Sheet - Work Item 4 (80% blockage baseline) [13kb]
BC Summary Sheet - Work Item 5 [13kb]	BC Summary Sheet - Work Item 6 (culvert opened baseline) [13kb]
BC Summary Sheet - Work Item 6 (existing culvert baseline) [13kb]	BC Summary Sheet - Work Item 7 [13kb]
BC Summary Sheet - Work Item 8 [13kb]

On the basis that the findings of the July 2009 version was being used to determine flood protection options, the decision was taken in Spring of 2011 to finalise the report and publish on this website. The report comes with the following caveat:

This report represents work done over a number of years and as such, reflects the approach and methods of the time. The report has evolved through various iterations of assessment. The main purpose of this report has been to support the development of a number of options for alleviating capacity and flooding issues around Stranraer. It should be noted that some elements of the report are not up to date in terms of the latest appraisal guidance or standards. It has been considered (upon agreement with Dumfries and Galloway Council) that a full and comprehensive update (considering the associated time and cost) is not required as this would not likely affect the overall conclusions or the nature of the various 'Work Items' developed to alleviate current flood risk issues.

In acknowledging the fact that the report was fully completed in 2009, as advised above, there are out-of-date elements and while not considered to affect the necessity or design of flood protection works for completeness these are summarised as follows:

• Hydrological analyses could be updated (modelling approach and new software is also available).
• Climate Change – UKCIP09 is the latest document so would supersede any reference to UKCIP02 or UKCIP98
• Scottish Planning Policy (SPP) replaces the referenced Scottish Planning Policy 7 – Planning and Flooding (SPP7)
• Cost Benefit Analysis:
  • Retail Price Index (RPI) and base year taken as April 2008
  • FCDPAG now superseded by FCERM-AG. There are updates to Multicoloured handbook and depth/damage data also.
• The works have been modelled based on a 1:200 year (0.5% Annual Exceedence Probability (AEP)) event. Current SEPA guidance would recommend an uplift of 20% as an allowance for Climate Change. However, the design of the scheme to protect from a 1:100 (1% AEP) event plus 20% climate change is a recognised standard and is essentially the same as 1:200 year event.
• If modelling work was being completed now, SEPA would be more prescriptive on certain technical information to be included including detailed model boundary sensitivity analyses (e.g. friction, flows and upstream / downstream model boundaries).

Notwithstanding the above, if, in future, in promoting elements of works using the Flood Risk Management (Scotland) Act 2009, clearly the Council will take advice from stakeholders (specifically SEPA) if further information or updating of previously undertaken works is required.

Any questions on the report, should, in the first instance be addressed to the Council's Flood Risk Management Team.

The work carried out by Mouchel has allowed the Council to identify works that will reduce the flood risk from all three watercourses. Construction work at certain locations within Stranraer has been on-going since early 2010, and details of the various Work Items and their progress are available online.