A96 Dualling Programme Strategic Environmental Assessment Tier 2 Environmental Report An agency of Buidheann le Appendix F - A96 Dualling Strategic Flood Risk Assessment (SFRA) (shortlisted Improvement Strategy Options May 2015 An agency of Buidheann le A96 Dualling Programme Inverness to Aberdeen Strategic Flood Risk Assessment (SFRA) Main Report Transport Scotland March 2015 A96 Dualling Programme Strategic Flood Risk Assessment (SFRA) Report Document history A96 Dualling Programme Inverness to Aberdeen Strategic Flood Risk Assessment (SFRA) Report Transport Scotland This document has been issued and amended as follows: Version Date Description Created Verified Approved by by by 1.0 Dec 2014 Draft for internal comment CS / SP HC/ GG 1.1 Jan 2015 Revised following internal review – for SP HC JF client issue 1.2 Feb 2015 Revised following client feedback – for GG JF JF SEPA issue 1.3 Mar 2015 Finalised following SEPA feedback SP/ GG JF JF A96 Dualling Programme Strategic Flood Risk Assessment (SFRA) Report A96 Dualling Programme Strategic Flood Risk Assessment (SFRA) Report Contents Executive Summary i Introduction 1 1.1 Background to Project 1 1.2 Outline Approach 1 1.3 SFRA Scoping Outcome 2 Design Manual and Policy Context 3 2.1 Design Manual for Roads and Bridges (DMRB) 3 2.2 National Policy 4 2.3 Regional Plans 7 2.4 Guidance 8 SFRA Baseline Information 9 3.1 Study Area 9 3.2 Hydrological Catchments 10 3.3 Tidal Limits 11 3.4 Geology 12 3.5 Settlements 15 3.6 Agricultural land 16 Existing Flood Risk 17 4.1 Identification of Flood Risk 17 4.2 SEPA Flood Maps 18 4.3 Flood History 19 4.4 River (Fluvial) Flooding 20 4.5 Coastal Flooding 23 4.6 Surface Water (Pluvial) Flooding 24 4.7 Groundwater Flooding 25 4.8 Sewer Flooding 25 4.9 Flooding from Failure of Infrastructure 26 4.10 Potentially Vulnerable Areas 26 SFRA of A96 Improvement Strategy Options 28 5.1 Introduction 28 5.2 Typical Nature of Dualling Works 29 5.3 SFRA Constraints Assessment Approach 30 5.4 ‘Schematic’ Presentation of SFRA Constraints Assessments 31 5.5 Assessment of Constraints (A96 Dualling as the receptor) 32 5.6 Assessment of Constraints (A96 Dualling as a source of change) 41 5.7 Temporary Works 50 5.8 March 2015 Addendum – SEPA Feedback 50 Discussion on SFRA Findings 51 6.1 Summary of Constraints Assessment 51 6.2 Next Steps – Strategic Environmental Assessment (SEA) 55 6.3 Next Steps – Overview on DMRB Levels of Assessment 55 6.4 SFRA Design Recommendations 57 6.5 March 2015 Addendum – SEPA Feedback 58 List of Appendices 59 A96 Dualling Programme Strategic Flood Risk Assessment (SFRA) Report Tables Table 2—1 [sic] Scottish Planning Policy flood risk framework (2014) .................................................................. 5 Table 3—1 A96 SEA/ PES study area sections ................................................................................................... 10 Table 3—2 Catchment descriptors of key hydrological catchment ...................................................................... 11 Table 3—3 Settlements within the A96 study area .............................................................................................. 15 Table 4—1 SEPA flood maps information ............................................................................................................ 18 Table 4—2 Existing watercourse crossings on the A96 ....................................................................................... 21 Table 4—3 Flood prevention schemes within the A96 study area ....................................................................... 22 Table 4—4 Summary of potentially vulnerable areas along the A96 route ......................................................... 27 Table 5—1 Typical A96 Dualling works and potential effect on flood risk ........................................................... 29 Table 5—2 ‘Schematic’ presentation of A96 Dualling SFRA of improvement strategy options assessment ...... 31 Table 5—3 Fluvial floodplain as a constraint to A96 Dualling .............................................................................. 33 Table 5—4 Small watercourses as a constraint to A96 Dualling ......................................................................... 34 Table 5—5 Coastal floodplain as a constraint to A96 Dualling ............................................................................ 35 Table 5—6 Surface water flooding as a constraint to A96 Dualling ..................................................................... 36 Table 5—7 Groundwater flooding as a constraint to A96 Dualling ...................................................................... 37 Table 5—8 Water crossings as a constraint to A96 Dualling ............................................................................... 40 Table 5—9 [sic] Estimating the importance of water environment attributes (flood risk) .................................... 42 Table 5—10 Properties within functional floodplains (within 15km wide study area) ............................................ 42 Table 5—11 Properties within functional floodplains (within improvement strategy option extents) ..................... 43 Table 5—12 Properties as a constraint to A96 Dualling ........................................................................................ 45 Table 5—13 Scheduled monuments located within functional floodplain .............................................................. 46 Table 5—14 Scheduled Monuments (in the floodplain) as a constraint to A96 Dualling....................................... 47 Table 5—15 Flood alleviation schemes as a constraint to A96 Dualling ............................................................... 48 Table 5—16 Arable agricultural land (changing flood risk) as a constraint to A96 Dualling .................................. 49 Table 6—1 Summary of constraints assessment – potential flooding sources ................................................... 52 Table 6—2 Summary of constraints assessment – potential flooding receptors ................................................. 53 A96 Dualling Programme Strategic Flood Risk Assessment (SFRA) Report Figures Figure 3—1 A96 SFRA study area and sections. ................................................................................................. 9 Figure 3—2 Key hydrological catchments .......................................................................................................... 10 Figure 3—3 SEPA tidal flood extents ................................................................................................................. 11 Figure 3—4 Solid geology within the A96 study area ......................................................................................... 12 Figure 3—5 Superficial geology within the A96 study area ................................................................................ 13 Figure 3—6 Aquifer classification within the A96 study area ............................................................................. 14 Figure 3—7 Properties within the A96 study area and surround ....................................................................... 15 Figure 3—8 Land capability for agriculture classification within the A96 study area and surroundings ............ 16 Figure 4—1 [sic] Components of definition of ‘flood risk’ Source: SEPA strategic flood risk assessment technical guidance, 2012 ................................................................................................................ 17 Figure 4—2 Flood history .................................................................................................................................... 19 Figure 4—3 Fluvial floodplain within the A96 dualling study area ...................................................................... 20 Figure 4—4 Locations of flood prevention schemes within A96 study area ...................................................... 23 Figure 4—5 Coastal floodplain within A96 study area ........................................................................................ 23 Figure 4—6 Surface water flood extent within A96 study area .......................................................................... 24 Figure 4—7 SEPA groundwater flood map showing areas where groundwater could contribute to flooding ... 25 Figure 5—1 A96 Dualling Improvement Strategy Options ................................................................................. 28 Figure 5—2 Colour key for A96 Dualling SFRA assessment of likely levels of flood risk constraint ................. 31 Figure 5—3 A96 Dualling improvement strategy options on fluvial floodplain constraints ................................ 32 Figure 5—4 A96 Dualling improvement strategy options on fluvial floodplain constraints ................................ 35 Figure 5—5 A96 Dualling improvement strategy options on surface water flood risk constraints ..................... 36 Figure 5—6 A96 Dualling improvement strategy options on groundwater flood risk constraints ...................... 37 Figure 5—7 A96 Dualling improvement strategy options on water crossing constraints ................................... 39 Figure 5—8 A96 Dualling improvement strategy options on settlements and properties constraints ............... 41 Figure 5—9 A96 Dualling improvement strategy options on: properties within fluvial flood map zones (upper figure), and coastal flood map zones (lower figure) ..................... 44 Figure 5—10 A96 Dualling improvement strategy