Sewer Flooding Assessments

Transcription

1 Sewer Flooding Assessments

2 Sewer Flooding Assessments Investigation Process (FMAP) Temporary Solutions Drainage Area Studies Capital Projects SUDS

3 Customer Contact and Response Investigation Process

4 Investigation Process Flood Management Action Plan (FMAP) Customer Contact Analyst Flooding Investigation Team (FIT) Sewer Squad Inspection FMAP Tracker On Site Investigation Operational Repair Incident management focused, reinstate service CCTV Investigation / Intervention ID Analyst Approval Intervention / Clean or Repair CCTV / DAS Flooding Register Temporary Solution Permanent Solution Intervention / Clean or Repair Site meetings Public meetings Council meetings Communication with Customer Root cause of incident / asset maintenance focused, property specific IFOC Confirm mechanism of incident IFOS / IFOC Temp / Perm Solutions Area and Reputation Focused

5 Knowledge Capture Data Capture Performance Monitoring Asset Records Promise Sewer Flooding Register circa 517 internally flooded Props Ellipse Business Processes to support data capture and recording Combined Sewer Overflow Register Drainage Area Studies Library circa 5000 overflows circa 235 reports / models GIS

6 Sewer Flooding Register Sewer Flooding Register 517 Internally Flooded Properties 1400 Externally Flooded Properties Newly reporter Register additions 72 properties per annum Criteria for Register entry - Internal flooding during a 1 in 10yr rainfall event Criteria for removal - No internal flooding during a 1 in 30yr design rainfall event

7 Working with our Customers Temporary Solutions

8 Appraising Solutions Customer Contact Investigation Temporary Solutions Design Modelling Permanent Solutions 341 Properties Protected By Temporary Solutions 02/ Removals 06/ Planned Removals

9 Hydraulic Flooding Assessment Drainage Area Studies

10 Drainage Area Studies Population Coverage 88% of domestic connected population 235 catchments covered 60 Data Requests Data 07/ No. Requests CATCHMENT MODEL MAINTENANCE FEBRUARY 2008 Copyright 2007 Scottish Water 0 MODEL STATUS COMPLETE (2007) (4) NO MAINTENANCE REQUIRED (6) WORK UNDERWAY (49) DESKTOP UPDATE FOLLOWED BY REASSESSMENT OF NEEDS (26) CSD - Flooding CSD - Rehab CSD - UID SR10 CSD - Unknown DIA External Liaisons Operational SEPA Liaisons PART VERIFICATION, FOLLOWED BY REASSESSMENT OF NEEDS (33) FULL VERIFICATION, FOLLOWED BY REASSESSMENT OF NEEDS (51) NEW BUILD (636)

11 Drainage Area Studies Standard SW specification Validated hydraulic model of the sewer network Identification / verification of hydraulic needs Identification of relationship with rivers and coastal waters (water quality and hydraulic interaction) Determination of asset condition Optioneer investment solutions Allow assessment of growth impact Allow assessment of flood prevention schemes impact Allow integration with storm water management modelling Optioneering and identification of strategic network needs

12 DAS Network Performance X-X Diagram

13 Capital Projects Permanent Solutions

14 Piped Watercourse B Overland Flow A Flooded Area C Overland Flow Overland Flow 2000 m3 FPV Flood Area Volume Flood Alleviation Scheme (22 Props Internally Affected) 700 m3 STV 1 in 30 yr upgrade

15 Understanding the Problem Partnership approach with local council authority Residents meetings to gather knowledge / history of flooding incidents Flooding map drawn up and flood volumes calculated Residents identify being flooded from the front and back of their properties, front from manholes surcharging sewer, back from rivers flowing down streets through back gardens and into houses (overland flow) Temporary solutions fitted to properties, periscope vents and flood guards DAS Model identifies the expected flood volume from sewer Hydraulic assessment of watercourse confirms capacity Solution, upsize sewer / divert overland flow to watercourse Optimized Investment Planning, ensured flooding solution delivered together

16 900 mm deep approx. Flooding Assessment (Integrated Modelling Results) Top Water Level Surface Flow Interceptor constructed (Local Authority) Sewer Upgraded SW) Nil (Modelled) WATERCOURSE OVERSPILL 1300 M 3 (Est.) URBAN OVERLAND FLOW 700 M 3 (Modelled) PUBLIC SEWERAGE SYSTEM WORST CASE FLOODING (SEVERE WEATHER EVENT) FLOOD COMPONENTS - ESTIMATE OF FLOOD VOLUMES

17 Problem Hydraulic Gradient Sewer Flooding - MHs DAS Model, Existing system long section 30 year design storm

18 Solution Sewer Storage Tank Sewer Surface Flow Interceptor High kerbs to divert flow Additional gullies 700 m3 DAS Model, Proposed system long section 30 Year Design Storm

19 Flooding Register Improvements No. of Props At Risk of Internal Flooding Today Q&SIII(a) Investment on Internal Flooding 06/07-4.1m for 37 props. 07/08-8.5m for 107 props 08/ m for 136 Props 09/10 circa 20m for 176 Props

20 Sustainable Urban Drainage Systems (SUDS) SUDS comprise one or more structures built to manage surface water run off. There are 4 general methods of control: filter strips and swales filter drains and permeable surfaces infiltration devices basins, ponds and wetlands

21 Typical SUDS Schemes Filter Drain Swale Basin in roundabout

22 Sharing Information

23 Information Available Flooding Register Combined Sewer Overflow Register Drainage Area Studies Reports Drainage Area Studies Models Current Investment Programmes where available

24 Benefits of Sharing Understanding catchment hydraulic interactions Integrated catchment modelling (sewers, overland flow, watercourses) Ensure that watercourse / coastal waters flood prevention schemes do not cause detriment to the sewer network eg the river stops flooding but the sewer now floods Ensure Water quality and habitat improvement Optimized Investment Planning

25 Managing Sharing Information changes daily and requires to be managed through a structured approach to ensure current data is used consistent reporting This will require Stakeholder communication plans Approval of responsible authorities

26 Questions